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NTIA REPORT 89-241

METEOR BURST SYSTEMCOMMUNICATIONS

COMPATIBILITY

David CohenWilliam GrantFrancis Steeie

U.S. DEPARTMENT OF COMMERCERobert A. Mosbacher, SecretaryAlfred C. Sikes, Assistant Secretaryfor Communications and Information

MARCH 1989

SkyTel:

See other SkyTel MBC doumentson the Scribd MBC Collection forbackground of MBC. Thisdocument is presented here topoint out the following: See:

- p. 20: A past plan of theFederal Emerg ency ManagementAgency to use MBC for a

nationwide "Meteor BurstWarning/ CommunicationsSubsystem."

- p. 20: MBC for remote pipelinemonitoring.

- p. 21: MBC for back- up tosatellite communications, andregular telephone and mi crowavesystems.

- p. 23 : MBC backpack terminals,and MBC for t wo- way commswith trucks.


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ABSTRACT

The t e c h n i c a l and o p e r a t i n g c h a r a c t e r i s t i c s o f m e te or b u r s t s ystem s o fimpo r tance f o r spec t rum management ap p l i a t i ons a r e i d e n t i f i e d . A t e c h n i c a la ss es sm ent i s i n c l u d e d w h ic h i d e n t i f i e s t h e mo st a p p r o p r i a t e f r e q u e nc ys ub ba nd s w i t h i n t h e VHF s p e c t ru m t o s u p p o r t me te o r b u r s t s ys te ms. Thee l e c t r o m a g n e t i c c o m p a t i b i l i t y o f m e t e or b u r s t sy st em s w i t h o t h e r eq ui pm e nt s i nt h e VHF s p e c t ru m i s d e t e r m i n e d u s i n g c o m p u t e r i ze d a n a l y s i s m e th od s f o r b o t hio no sp he r i c and g roundwave p rop ag a t ion modes. It i s shown t h a t m e te o r b u r s te q ui pm e nt s c an c au se and a r e s u s c e p t i b l e t o g ro un dw av e i n t e r f e r e n c e f ro m o t h e rVHF equ i pmen ts . The r e p o r t in c l ud es ta b1 e s of g e o g ra p h i c a l d i s t a n c es e p a ra t i o n s b e tw e en me te or b u r s t a nd o th e r VHF e q u ip me nts w h i c h s a t i s f yi n t e r f e re n c e th r e s h o l d c r i t e r i a.

KEY WORDS

C o m p a t i b i l i t yI n t e r f e r e n c eM e t e o r B u r s t

Spectrum Management

iii


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TABLE OF CONTENTS

Subsection PageSECTION 1

INTRODUCTION

BACKGROUND ................................................................ 1OBJECTIVES ................................................................ 2APPROACH .................................................................. 2

SECTION 2CONCLUSIONS AND RECOMMENDATIONS

..............................................................ONCLUSIONS. 4.............................................................REQUENCY USE 4COMPATIBLE OPERATIONS ..................................................... 5OTHER ..................................................................... 6............................................................ECOMMENDATIONS 7

SECTION 3TECHNICAL CHARACTERIS TICS OF METEOR BURST SYST EMS

3.1 INTRODUCTION ......................................................... 8..........................2 METEOR TRAIL ELECTROMAGNETIC CHARACTERISTICS 83.3 METEOR BURST SYSTEM PROTOCOLS ........................................ 11

SECTION 4FREQUENCY BANDS AND EMISSION CHARACTERISTI CS

FOR METEOR BURST COMMUNICATION S YSTEMS

........................................................1 FREQUENCY BANDS 14.....................................................2 SPECTRUM STANDARDS 17


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Subsection

TABLE OF CONTENTS(continued)

PageSECTION 5

METEOR BURST AND OTHER VHF SYSTEMS

INTRODUCTION......................................................... 19METEOR BURST TELEMETRY SYSTEMS ....................................... 19METEOR BURST EMERGENCY COMMUNICATIONS................................ 20METEOR BURST COMMUNICATION SYSTEMS ................................... 21..........................................................HF SYSTEMS 23SYSTEM CHARACTERISTICS............................................... 26TELEVISION RECEIVER INTERMEDIATE FREQUENCIES ( IF) .................... 27

SECTION 6IONOSPHERIC COMPATIBILITY

INTRODUCTION......................................................... 28METEOR IONIZATION.................................................... 28SPORADIC E REFLECTIONS ............................................... 29.........................................EGULAR F REGION REFLECTIONS 31..............................UMMARY OF VHF IONOSPHERIC INTERFERENCE 31AIRPLANE REFLECTIONS................................................. 32

SECTION 7GROUNDWAVE COMPATIBILITY

....................................NTERFERENCE PATHS AND CONDITIONS 33...............................AND MOBILE COMMUNICATION SERVICE AREA 36................................................NTERFERENCE CRITERIA 37...........ETEOR BUR ST SYSTEM COMPATIBILITY WITH LAND MOBILE SYSTEMS 38...............................ORDLESS TELEPHONES AND CHILD MONITORS 50...........................ETEOR BUR ST TO METEOR BURST COMPATIBILITY 64


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TABLE OF CONTENTS(continued)

S u b s e c t i o n Page

SECTION 8APPLICABLE RULES AND REGULATIONS

8.1 ALLOCATIONS .......................................................... 698 - 7 TECHNICAL STANDARDS.................................................. 7 18.3 CHANNELING PLAN ...................................................... 7 18.4 DEFIN ITION OF METEOR BURST SYSTEMS................................... 72

.......................5 ADJACENT CHANNEL EMISSIONS (UNWANTED EMISSIONS) 72....................................6 BILATERAL INTERNATIONAL AGREEMENTS 72APPENDICES

APPENDIX A: INTERNATIONAL AND NATIONAL RADIO FREQUENCY APPLICATION............ABLE INCLUDING FOOTNOTES FOR THE 30-100 MHz BAND 74............................PPENDIX B: FOOTNOTES FOR THE 30-100 MHz BAND 8 1APPENDIX C: NATIONAL REGULATIONS CONCERNING TECHNICAL PARAMETERSAND OPERATIONS............................................... 8 4.............................PPENDIX D: DESCRIPTION OF THE PRODSIR MODEL 9 3................................PPENDIX E: GROUND WAVE PROPAGATION MODEL 96

REFERENCES .REFERENCES................................................................ 102

L I S T OF ILLUSTRATIONS

1 Meteor Burs t Sys tem Geomet ry . F i g u r e 1 shows ray pa th s t o..................t h e r i o n o sp h e r i c r e f l e c t o r s a t VHF f r e q u e n c i e s 1 0.................Frequency Dependent Terms i n t h e rang e 40-50 MHz 15


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TABLE OF CONTENTS( c o n t i nued)LIST OF ILLUSTRATIONS( c o n t i nu ed )

F i gu r e Page3 R e ce iv e d po we r v s. d i s t a n c e s e p a r a t i o n b etw ee n t r a n s m i t t e rand r e c e i v e r . 10,000 w a t t t r a n s m i t t e r GT = Go = 10 dB i ,i onosphe r e f o = 13 MHz.......... ................................... 304 Groundwave i n t e r f e r en ce pa t hs bet ween m e t eo r bu r s t and o t he requ ip ments i n t h e 30 -5 0 MHz band.................................. 335 E l ec t ro mag net i c Env i ronment wh ich i c l udes bo t h a l nd mobi 1e

and met eor b u r s t system. When D = Ds i n t e r f e r e n c e p r o t e c t i o ni s p ro vi de d.. . .................................................... 386 M e t eo r Bu r s t t o Land M ob i l e Base S t a t i o n . M a i n l obe M e teo rBurst............................................................. 40

7 M e t eo r Bu r s t t o Land M ob i l e Base S t a t i on . S i de l ob e M e t eo rBurst............................................................. 42

8 I n t e r f e r e n c e fr o m Me teo r B u rs t t o Base Receiver................... 43D i s ta n c e M e te o r B u r s t t o Base S t a t i o n . I n t e r f e r e n c e t oMobil Recei v e r (Mai nbeam) ........................................ 46D i s t a n c e M et eo r B u r s t t o Base S t a t i o n . I n t e r f e r e n c e t o.......................................o b i l e R e c e i v er ( O f f - A x i s ) . 47.................and M o b i l e Base S t a t i o n t o M e te o r B u r s t R e c e i v e r 49D i s t a n c e Base S t a t i o n t o M e t eo r B u r s t R e c e i v e r.( I n t e r f e r e n c e Mobi 1e T r a n s m i t t e r t o M e te or B u r s tR e c e i v e r ) . ........................................................ 5 1...........................0 mkW C or dl e ss Tele pho ne, G+ = -10 dB i 55

.......miss ion Spec t ra , C a r r i e r and S ide Frequenc ies , 50 kHz Span 57Em issi on Spe ctra , C a r r i e r and Sid e Fre que ncie s, 10 kHz Span....... 58Emiss ion Spect ra, C a r r i e r and Side Frequ encies , 50 kHz Span..... .. 59Cordless Phone Channels........................................... 6 1I n t e r f e r e n c e t o a C o r d l e s s T e le p ho n e f ro m a M e te o rB u r s t Transmitter................................................. 62

v i i i


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F i gu r e

TABLE OF CONTENTS(continued)LIST OF ILLUSTRATIONS(continued )

Page19 Received Power f ro m Meteor B ur s t Tr an sm i t t er , Mainbeamt o Mainbeam, Me te or B u r s t t o M et eo r Burst......................... 652 0 R e ce iv e d P o w e r f r o m M e t e o r B u r s t T r a n s m i t t e r , Mainbeamt o S i de1 obe, M e t eo r Bu r s t t o M e te o r B u r s t. . . 6621 Recei ved Power f r om M e teo r Bu r s t T r an sm i t t e r , S i de l obe t oS id e lo be , Mete or B u r s t t o M et eo r Burst............................ 6722 I TU I n t e r n a t i o na l Rad io F requency U ti i a t i on d i v i d e d i n t oThree Geographic Regions .......................................... 7023 XMTR Unwanted E m is s io n Standards.................................. 73

LIST OF TABLESTABLE

METEOR BURST SYSTEM PROTOCOLS..................................... 13ADJACENT CHANNEL SPECTRUM......................................... 18METEOR BURST SYSTEM CHARACTERISTICS............................... 22EQUIPMENTS.. ...................................................... 34METEOR BURST SYSTEM............................................... 35LAND MOBILE SYSTEM (30-50 MHz). . . ,. . 35DISTANCE SEPARATION (D METEOR TO BASE) TO PROVIDEINTERFERENCE PROTECT IOB 'TO MOBILE SYSTEMS.. . 44DISTANCE SEPARATION ( D METEOR TO BASE) TO PROVIDEINTERFERENCE PROTECTION TO METEOR BURST RECEIVERS ...... .... ... 52CORDLESS TELEPHONE TECHNICAL PARAMETERS........................... 53COCHANNEL SEPARATION DISTANCES (METEOR BURST TO METEOR BURST) ..... 68


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SECTION 1INTRODUCTION

BACKGROUND

The Na t io na l Tel ecommuni c a t i ns and In fo rm at io n Admi n i s t a t i o n (NTIA) , h eE x e c u t i v e B ra n ch ag en cy p r i n c i p a l 1 r e s p o ns i b l e f o r t h e d ev elo pm en t o f b o t h

. d o m e st ic a nd i n t e r n a t i o n a l t e le c o mm u n ic a ti on s p o l c y , i s a1 so r e s p o n s i b l e f o rmanaging t h e Federa l Government I s use o f t h e r a d io f requen cy spec t rum. NTIAe s t a b l s h e s p o l c i e s c o n c e r n i n g s p e c tr u m a s si gn m en t , a1 l o c a t i o n and use, andp r o v i d e s t h e v a r i o u s f e d e r a l d e p ar tm e n ts a nd a g e n ci e s w i t h g u id a n ce t o e n s u ret h a t t h e i r c on du ct o f t e le co mm un ic at io ns a c t i v i t i e s i s c o n s is t e n t w i t h t he s epo l i c i es . 1 I n suppo r t o f t hese r equ i r em en t s , NTIA has com p l e ted a number o fspec t rum reso urce assessments (SRAs). The ob je c t i v es o f t hes e assessments a ret o e v a l u a t e s pe ct ru m u se, i d e n t i f y e x i s t i n g o r p o t e n t i a1 compat i b i 1i yp ro b le m s, p r o v i d e re co mm e nd at io ns t o p ro m o te e f f i c i e n t u s e o f t h e r a d i of req uen cy spect rum, and imp rove spec t rum management proce dures. T h isassessment documents th e e l ec t ro mag net i c compat i b i 1 t y o f m e teo r bu r s t syst em si n t h e VHF spect rum.

R e c en t ly , t h e r e h as been i nc r ea s e d i n t e r e s t i n u t i l i z i n g m ete or b u r s ts ys te ms f o r 1ong range VHF beyond the 1i e-of - s i gh t (BLOS) communicat ions andt e l e m e t r y . The lo w e r io n o sp h e re i s d a i l y bombarded w o r ld w i d e b y b i l l i o n s o fsm a l l m e t eo r s wh ich , as t he y bu r n up i n t h e uppe r a tm osphe re , c r e a t e sh o r t -l i v e d i o n i z e d t r a i l s . These t r a i l s a r e a b l e t o p ro v i de a BLOS i on o s ph e r i cp r op aga t i on pa t h bet ween g round -based t r an sm i t t e r s and r ece i ve r s . A meteort r a i l i s a v a i l a b l e t o p r o v i d e a t r a n s m i s s i o n c ha nn el b etw ee n t wo BLOS l o c a t i o n sonce every 4 t o 2 0 s ec on ds . The 1 f e t i m e o f t h e ch a nn e l i s s h o r t ( 1 12 s ec on dd u r a t i o n ) a l l o w i n g o n l y e nough t i m e fo r a " b u r s t " o f i n f o r m a t i o n t o bet r a n s m i t t e d b e f o r e t h e m ete or t r a i l d ec ay s.

'NTIA, Manua l o f Regu l a t i o n s and Procedures fo r Fede ra l Radi o FrequencyManagement, U.S. Department of Commerce, N at io na l Tel ecommuni c a t o n s andI n f o r m a t i o n A d m i n i s t r a t i o n , W as hi ng to n, DC, r ev i sed Sep t em ber 1988.


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The ex i s t en ce o f m e teo r r e f l e c t i o n s a t VHF f r eque nc i e s has been known f o rsev e r a l decades and t h e r e has been seve r a l pas t expe r i m en t a l p rog ram s t oe x p l o r e t h e u s e f u l n e s s o f m e te o r r e f l e c t i o n s f o r c o mm u ni ca ti on p u rp o se s . Therenewed i t e r e s t i n m e te o r b u r s t c o m m un ic a ti on s s te ms f r o m t h e r e c e n ta v a i l a b i l i t y o f s o l i d s t a t e memory d ev i c es w h ic h ha s made i t p o s s ib l e t o s t o r ei n f o rm a t i o n and t r a n s m i t t h i s i n f o r m a t i o n i n a p a c k et iz e d d i g i t a l b i t s t re am"b u r s t " when a m e t eo r t r a i l channel opens.

M e te o r b u r s t s y ste ms o p e r a t e i n t h e l o w e r VHF b an d i n t h e f r eq u e n c y r an g e30-100 MHz. The g r e a t e s t u s e o f m e te o r b u r s t s ys te ms i s e xp ec te d t o be i n t h e30-50 MHz f r equency r ange . Th i s spec tr um i s a l l o ca t e d p r edom i nan t l y t o t h ef i x e d and mob i 1e se rv i ces. Bo th co nv en t i ona l and spread spec t rum systems a rei n t h e band u t i l i z i n g b o th a n a l o g a n d d i g i t a l m o d u l a t i o n s .

OBJECTIVES

The o b j e c t i v e o f t h i s s t u dy was t o r e sp o nd t o a re q u e s t o f t he Spec t r umPlan n ing Subcommi ttee (SPS) o f t h e IRAC t o assess th e imp act t h a t expanded useo f t he m e t eo r bu r s t com m uni cat ion syst em s w i l l have on t h e gove rnm en t VHFs p e ct ru m a nd i d e n t i f y a pp ro ac he s t o w ar d s e f f e c t i v e s p e c tr u m management o f t h i stechno 1 ogy .APPROACH

1. The t e c h n i c a l and o p e r a t i o n a l c h a r a c t e r i s t i c s f o r p r e s e n t and e x pe c te df u t u r e m e t eo r b u r s t com m un ica ti ons syst ems ' we re de f i ned . Cur ren t usage andr e gu l a t o r y i s su es we re docum en ted bo t h i n t h e gove rnm en t and com m erc ia lcommon c a r r i e r sec t o r s .

2. The t e c h n i c a l and o p e r a t i o n a l c h a r a c t e r i s t i c s o f c o n v e n ti o n al VHFgovernment comm unicat ion equipme nts were de f ine d, and an assessment wasmade o f t h e av a i l a b l e gove rnment VHF spec t rum t o s uppo r t m e t eo r bu r s tapp l i a t i ons.


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3. Meteor Trail Channel Compatibility - An analysis was made of possiblein te r f e rence f rom s igna l s ref1 ected from ionized meteor t r a i l s .

4. Groundwave Compatibility - Although meteor burst probe transmitters providecommuni c a t i on by in t e r m i t te n t meteor ref 1ec t i ons , the meteor burs tequipment also continuously propagates groundwave signals. An analysis wasmade of the in ter fer en ce poten t ia l of the meteor burst groundwave signal t ocochannel and adjac ent channel re ce iv er s in th e geographical a rea of themeteor bu r s t t r an sm i t t e r . A1 so , the pos s ib le in te r f e re nce e f f e c t s ofr e f lec t ion f rom h i g h f ly in g a i rc r a f t was examined.

5. Ionospher ic Compat ib i l i ty - The "footprint" and received signal from ameteor r e f l ec t io n a re qu i te smal l. Thus, the re i s b u t a small chance ofincompat ib le ope rat i on from th e meteor sc at te r i ng i t s e l f . However, duri n gce r ta in so la r cond i t ions , e .g ., Sporad ic E, blanketing Sporadic E , F 2r e f l e c t i o n VHF s ig na ls in tended fo r meteor bu rs t will also be ref le cte dfrom th e background ionosphere . During th e s e c o n d i t io n s , the receiveds igna l s t r eng ths may be s ign i f i c an t ly l a rge r and pe r s i s t e n t r e l a t iv e to the112-second du ratio n meteor bur st retu rns . The int erf ere nc e ef fe ct s ofthese modes were assessed.

6. Shar ing cr i ter ia were developed t o help ensure at VHF f r equenc iescomp atible opera tion between meteor bur st systems, a s well as ot he rradiocommunication equipments.


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SECTION 2CONCLUSIONS AND RECOMMENDATIONS

CONCLUSIONS

The c on c l u s io n s o f t h i s s t u d y a r e gro up ed i n t o t h r e e a re a s: f re q u e nc yuse , c om pa t i b l e ope r a t i o ns , and o t h e r s .

FREQUENCY USE

1. Meteor bu rs t systems o per a te i n t h e f requency range 30-100 MHz. It i sg e n e r a l l y a ck no wl ed ge d t h a t t h e o p tim um ba nd f o r n o rm a l o p e r a t i o n o f m e te o rb u r s t s ys te m s i s 4 0-5 0 MHz. T h i s o p t i m a l i t y ste ms fr o m t h e i o n o s p h e r i cr e f 1e c t i o n p r o p e r t - ies o f me t eo rs .

2. The U.S. Government 'a l l o c a te d subbands i n t h e band 40-50 MHz ar e 40-42 MHz,46.6-47 MHz and 49.6-50 MHz. The adva ntage s o f o p e ra t i n g me teo r b u r s tsystems i n t h e l ow er subband 40-42 MHz, ra th e r t h an th e upper bands 46 /49MHz, a r e a somewhat l a r g e r me t eo r s c a t t e r s i g na l r e t u r n and g r e a t e r channelt h r o ugh pu t ( s ee Sec t i on 4. 1).

3. Nonli ensed consumer d ev i ces , such as cord1 ess te le pho ne s , o p e r a t e( u n p r o t e c t e d a nd o n a n o n i n t e r f e r e n c e b a s i s ) a1 ong w i t h government sys temsi n t h e uppe r s ubbands 46 and 49 MHz. F o r t y pe r c en t o f t he bandw i d t h i nt h e s e bands, ( s ee F i g u r e 17 ), i s a v a i l a b l e f o r u se b y t h e s e u n l i c e n s e dd e v i c e s . Met eo r bu r s t s y s t ems ope r a t i ng c oc hanne l may r e c e i ve i n t e r f e r e n c ewhen l o c a t e d as f a r as 10 km away from th ese d ev i c es ( see F i g ur e 13) .

4. When th e re i s au ro ra l abs orp t i on , meteor b u rs t systems may advantageous lymake us e o f t h e up pe r subband s 46.6-47 MHz and 49.6-50 MHz. Mo re ov er ,d u r i n g s e v e r e i o n o s p h e r i c d i s t u r b a n c e s and a cc om pa ny in g i n c r e a s e dio no sp he r i c ab so rp t i on , me teor b u rs t sys tems ope ra te above 50 MHz. Theon l y gove rnmen t a l l o c a t e d band i n t h e f r equenc y r ange 50-100 MHz wh i c h


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p e r m i t s t r a n s m i t t e r power g r e a t e r t h a n 1 w a tt i s 74.8-75.2 MHz. Th i s bandi s a l l o c a t e d t o t h e A e ro n a ut ic a l R a d io n a vi ga t io n S e r v i c e and i s n o ta p p r o pr i a t e f o r m et eo r b u r s t o p e r a ti o n s . However, government op e ra t i nsmay employ f r eq ue nc ie s i n nongovernment a l l o c a te d bands between 25-2400 MHzf o r t a c t i c a l and t r a i n i n g p urp os es i n ac co rd an ce w i t h t h e NTIA Manual .^(See APPEND IX Cd

Al thoug h t h e op timum band f o r meteor bu rs t systems i s 40-50 MHz, th e bands36-37 MHz and 38.25-39 MHz mi gh t al s o be co ns id er ed f o r government me teo rb u r s t s ys te m u se. B ased o n e l e c t r o m a g n e t i c c o m p a t i b i l i t y c o n s i d e r a t i o n s ,u se o f t h e s e b ands i s a c o n s i d e r a t i o n o n l y when t h e m ete or b u r s t s i g n a lr e t u r n s f r o m o t h e r i o n o s p h e ri c modes i s n o t l i k e l y t o c au se i n t e r f e r e n c eand groundwave c ornpat i b i 1i y i s a1 so a s su re d .

COMPATIBLE OPERATIONS

The i o n o s p h e r i c s i g n a l r e t u r n s f r o m m ete or b u r s t s t a t i o n s h av e a s m al lp r o b a b i l y o f c aus i n g an i n t e r f e r en c e ou tage. When i t e r f e r e n c e d o e soc c u r , most l i k e l y du r i n g a s uns po t maximum, r e a l t i me equi pmen tad j us t men t s s uc h as power, f r equenc y o r an tenna c hanges a r e r e qu i r e d t oel i m i n a t e t h e i n t e r fe r e n c e .

7. M e t eo r b u r s t m a s t e r s t a t i o n s may be b o t h a s o u r c e (p r o b e s i g n a l s ) a n dr e c e pt o r t o VHF g roundwav e i n t e r f e r e nc e . The s e pa r a t i on d i s t a nc e s be tweene q ui pm e nt s f o r c o m p a t i b l e c oc h an n el s h a r i n g ( j o i n t s im u l a n e ou s o p e r a t i o n )w i t h l an d mob i l e ope r a t i on s a r e i n t h e range 90-320 km. When t h ee qu ip me nt s a r e o n a d j a c e n t c h a nn e ls t h e s e p a r a t i o n d i s t a n c e s a r e i n t h erange 7-60 km. TABLES 7 and 8 o f t h i s r e p o r t i n c l u d e n um er ic al v a lu e s f o rt h e s e s e p a ra t io n d is t an c e s f o r a v a r i e t y o f i n t e r f e r e n c e s i t u a t i o n s .

bid., Sect ion 7.15.3.


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M et eo r b u r s t r em ote s t a t i o n s a r e s u s c e p t i b l e t o g rou nd wa ve i n t e r f e r e n c ef rom o th er VHF equ ipments . The se pa ra t i o n d i s tan ce s fo r cochannel use a re90-250 km and f o r adja ce nt cha nnel use 10-38 km. See TABLE 8 o f th e re p o r tf o r t h e r e q u i r e d s e p a r a t i o n d i s t a n c e s f o r s i mu l ta n e ou s o p e r a t i o n . Thes i g n a l s t r a n s m i t t e d f ro m re mo te me te or b u r s t s t a t i o n s a r e i n t e r m i t t e n t andu n l i k e l y t o a f f e c t t h e i n t e l l i g i b i l i t y o f o t h e r VHF systems. Thus, t h ey a r en o t ju d g ed t o b e an i n t e r f e r e n c e p ro b le m .

A d a p t i v e d a t a r a t e me t eo r b u r s t s ys te ms , when t h e y e x t e n d t h e i r b a n d w id t hsi n t o a d j a c e n t c h a n n el s, a r e m ore 1i e l y t o e n co u nt er i n t e r f e r e n c e . T h i sw i l l be p a r t i c u l a r l y t r u e i f t h e adap t ed bandw id t h ex pands i n t o anu n l i ensed d ev ic e (e.g., cor d1ess phone) channel .The v i d e o I F f re q u e n c y i n U.S. t e l e v i s i o n r e c e i v e r s i s a t 45.75 MHz w i t h abandw i d t h o f 6 MHz (43.75-48.75 MHz) and t h e au dio I F i s a t 41.25 w i t h a200 kHz ba n d w id t h. I n t e r f e r e n c e f r o m m e te o r b u r s t s ys te m s t o t e le v i s i onhas no t been r epo r t e d bu t i s of c onc e r n ( s ee Sec t i on 5.7). It i s a1 sono t e d t h a t t h e A l l o c a t i o n Tab l e ( s ee APPENDIX A) does no t p r o t e c t TVf re qu en c ie s f o r government bands i n 40-50 MHz.

The 20 kHz ch an ne l i ng p la n f o r t h e 30-50 MHz band (NTIA Man ua lY3 seeAppendix C ) i s a good g u id e f o r m ete or b u r s t p r o be s i g n a l s t o f o l l o w a ndh e l p s a s s ur e e l e c t r o m a g n e t i c c o mp a ti b i1 t y w i t h o t h e r s ys te ms u s i n g t h e VHFs pe c tr um . The i n t e r m i t t e n t m e te o r b u r s t s i g n a l s w h ic h h av e a d a p t i v eb a n dw i dt h s g r e a t e r t h a n 20 kHz a r e a n a p p r o p r i a t e e x c e p t i o n t o t h ec h a n n e l i n g p l a n ( s e e S e c t i o n 7 . 1 ) .

OTHER

12. A t t h e p r e s e n to p e r a t i o n a l m e t e o r

^bid. , Se ct io n 4.3.6.

t im e , w i t h i n t h e U n i t e d S t at es , t h e r e a r e s e ve r a lbu r s t s ys tems and a number of ex pe r i m en t a l and t r a i n i n g


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systems. The ap p li ca ti on s, usage, and techno1 ogy fo r meteor bur st systemsa re undergoing con ti nual change and improvement.

13. The SNOwpack TELemetry (SNOTEL) meteor b u r s t syste m i s an example of anef fe ct iv e and e f f ic ie n t use of the spectrum. Dai ly , data t ransfer f rom 550remote terminals to a mas ter s ta t ion i s accomplished by time share d use ofa s ingle f requency. Meteor burs t sys tems are a lso being ef fect ively usedin A1 ask a f o r communication purposes.

14. There is expected t o be much gr ea te r use of meteor bur st systems o ut si deth e United St a te s, Meteor bu rst systems can be used advantageo usly a tgeographical lo ca tio ns where th e i nf ra s tr uc tu re of t e l ecommunicati onequipments is not fully developed.

RECOMMENDATIONS

The following are recommendatNTIA management wi 11 eval ua te th e s e

ions based on the findings of t hrecommendations to determine if t

i s r e p o r t ,hey ' can or

sho uld be impl emented from a pol ic y , r egu la to ry , or proc edu ral vi ewpoi n t . Anya c t io n t o impl ement th e se recommendati ons wi 11 be v i a separate correspondencemodifying established rules, regulations and procedures. The recommendationsare as fo l lows .

The Spectrum Planning Subcommittee (SPS) and the Frequency AssignmentSubcommi t t e e (FAS) should u t i l iz e the conc lusion s and r e s u lt s of t h i sstudy when ass ess ing spectrum management s it u a ti o n s involv ing meteorburs t sys tems ,The SPS should co nti nu e to m onitor meteor b ur st system usage andtechnology.NTIA should use t h i s study in th e plannin g of frequency bands t h a tsupport meteor burst communication systems.


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SECTION 3TECHNICAL CHARACTERISTICS OF METEOR BURST SYSTEMS

3.1 INTRODUCTION

T h i s s e c t i o n d e s c r i b e s t h e o p e r a t i o n o f a m e te o r b u r s t s ys te m. Th oset e c h n i c a l c h a r a c t e r i s t i c s w h i ch may a f f e c t t h e e l e c t r o m a g n e t ic c o mp ati b i1i yand sp ec t rum management of meteor b u rs t sys tems a re d i scussed and ' ex p l a i ned.These i nc l u de power, f requenc y, em i s s i on s pec tr um, and p r o t oc o l s o f ope r a t i on .

3.2 METEOR TRAIL ELECTROMAGNETIC CHARACTERISTICS

E v e ry day , b i l l i o n s o f m e te o rs e n t e r t h e E a r t h ' s u p p e r a tm os ph er e ( a ro u n d100 km) and bu rn up. The bu rn in g up o f each meteor p roduces an i o n i z e dt r a i l . Rad i o waves w i t h f r equenc i es i n t h e l ower VHF s pec t rum ( 30 -100 MHz) canbe r e f l e c t e d f ro m t h e s e m ete or t r a i l s a s a beyond t h e l i n e - o f - s i g h t (BLOS)p r op aga t i on mode f o r d i s t anc es up t o 2000 km. To p r ov i de a c ommun i c a t i onchanne l be tw een tw o s t a t i o n s , t h e m ete or t r a i l m ust be s p a t i a l l y l o c a t e d i n t h ecommon vo lume o f t h e an tenna pa t t e r n s o f t wo s t a t i o ns . The ant ennas us ed w i t hmeteor bu rs t sys tems us u a l l y have ha l f -powe r beamwidths o f about 30 degrees .

A m e te o r b u r s t c om m un ic atio n l i n k f u n c t i o n s i n t h e f o l l o w i n g manner. Ap ro be s i g n a l i s s e n t r e p e a t e d l y i n t o t h e u p p er atm os ph ere f r o m a m a s te rs t a t i o n . A re mo te s t a t i o n w a i t s and l i s t e n s f o r t h e p ro b e t o b e r e f le c t e d b y am e te o r t r a i l . When t h e r em ote s t a t i o n r e c e i v e s t h e p ro b e s i g n a l i t sends amessage back t o th e mas ter t h a t a communicat i on channe l i s open. The mas te racknowledges t h e remote and t h e "handshake" i s comple te . The mas ter and remotecommence c o m m un i ca t io n i n h a l f o r f u l l d u p l e x mode a nd c o n t i n u e t o o p e r a t eu n t i 1 t h e m ete or t r a i 1 decays and t h e channe l c lo se s (ap pro x im ate l y 112-secondd u r a t i o n ) . The m a s te r t h e n r e t u r n s t o t r a n s m i t t i n g t h e pr o be s i g n a l , b e g i n n i n gthe process anew.


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The magnitude of the signal received from an underdense meteor t r a i lref lec tion , see Sugar 1 96 4, ~ s

P G G 2~ $ 1 = ' S (C ) exp [ - T ( c ) ~ I e x p ( - ~ t )f 3

wherep@) = received powerp~ = transmitter powerGT, Go = antenna gainf = frequencyS ( C) T( S) = geometric and physical dependent factor s

to - " and U ( 6 ) = geometric and physical dependent factors.- 7-The time dependence e - l o in Equation (1) accounts for the observed fact thatth e shape of the meteor return i s a decaying exponential in time. The Equation(1) shows that the factors which determine the signal return for a meteor burstsystem are PT , G T , Go, f , and geometric and physical dependent factors,Operationally, some representative values for the parameters in Equation 1 arePT = 300 watts, GT = GR = 10 dBi and f in the range 40-50 MHz. Thecommuni cati on performance depends no t only on P o ( t ) , b u t i s a1 so dependent u p o nthe required ( E b / N o ) for the particular digital modulation utilized and N o thenoise level in the vic ini ty of the receiver. Examples of the modulations usedare PSK and FSK b o t h coherent and incoherent. -

Examples of peak returns from underdense meteor scatter, shown in Weitzenand ~ a l s t o n , ~ary from -112 dBm t o -95 dBm. A typical return from an

^sugar, G.R. Radio Propagation by Ref 1ecti on from Meteor Trai 1s, Proceedi ngsIRE, Vol. 52, pp . 116-136, 1964.^ ~ e i t z e n , J . A. and W e T . Ralston, Meteor Scatter: An overview, IEEETransactions on Antennas and Propagation, December 1988.


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individual underdense meteor for th is study will be assumed t o have a return o f-110 dBm. Typical noise powers for a 16 kH z occupied bandwidth in the40-50 MHz frequency range are: man-made suburban (-106 dBm), and galacticnoise (-120 dBm). Since the man-made noise and the typical meteor burst signalare comparable i n magnitude, whenever possible, meteor burst receivers areplaced a t low noise sites.

The times between available meteor channel openings are random anddistributed exponentially with time as a Poisson process. The coherencebandwidth of the meteor sca tt er i s qu it e large, up t o 1 MHz. Some meteor burstsystems take advantage of t his la rge coherence bandwidth and during a burstexpand thei r transmit and receive bandwidth t o optimi ze the throughput possi bl eduring the burst. A diagram of a meteor burst system is shown in Figure 1.The diagram shows the ray paths t o the meteor t r a i l along with ray paths t oother ionospheric re flec tors which may be prevalent a t VHF frequencies. The .maximum range for a meteor burst path i s 2000 kilometers. This maximum distanceis fixed by the ray path geometry over a curved earth to a meteor trail a t a nal ti tu de of 100 km . Meteors can be categorized as either underdense (electrondensities < l o el ectrons/meter) or overdense (electron densi ties > 1014electrons/meter) . The underdense meteors are more common and provide themajority of the communication channel s.

Figure 1. Meteor Burst System Geometry.meteor scatters along w i t h rayref1 ectors at VHF frequencies.Figure 1 shows ray paths to thepaths t o other ionospheric


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3.3 METEOR BURST SYSTEM PROTOCOLS

T he re a r e a t p r e s e n t t h r e e b a s i c e qu ip me nt c o n f i g u r a t i o n s f o r m et eo rb u rs t systems . These ar e one- to -one communica t ion , ne twork ing , andb r o a d ca s t . F o r b o t h o n e- to -o n e a nd n e t w o r k i n g t h e m a s t e r s t a t i o n t r a n s m i t sr e p e a t e d l y a p r o b e s i g n a l o f f re q u en c y fi. The rem ote s t a t i o n l i s t e n s f o r t h emaster and when i t d e t e c t s a s i g n a l i n t e n d e d f o r i t, s ends back a s i gn a l ( a tf r equenc y fi o r a d i f f e r e n t f re qu en cy f 2 ) t o t h e m a st er s t a t i o n . The m a st erd e t e c t s t h e s i g n a l a nd r e t u r n s an a ck no wle dg me nt t o t h e re mo te . T h i scomple tes t h e handshake and communica ti ons can proceed. I n th e "b road cas t "mode. t h e mas ter sends a message rep ea ted ly w i t ho ut acknowledgment f r om th er em o te s. The message i s r e p e at e d a s u f f i c i e n t number o f t i m e s t o , h o p e f u l l y ,a s s u r e r e c e p t i o n .

It i s a p pa re nt t h a t f o r a l l eq uipm en t c o n f ig u r a t i o n s t h e d u t y c y c l e( on -t im e ) f o r t h e m as te r s t a t i o n i s q u i t e h i g h and t h e d ut y c y c l e f o r t h er emo t es i s s ma l l ( one - to - one and ne t w o r k i n g ) o r z e r o ( b r oa dc as t modes),

The above d e s c r i b e s t h e g e n er a l o p e r a t i n g p r i n c i p l e f o r a m et eo r b u r s tsystem. Based upon th e se gener-a1 p r in c i p l es , a1 o ng w i t h c e r t a i n v a r i a t i o n s i no p e r a ti o n , a t l e a s t f i v e d i f f e r e n t o p e r a t i n g p r o t o c o l s have been c o n si de r ed t oe f f e c t i v e l y u t i l i z e m ete or b u r s t c h an n el s f o r c om m un ic at io n. TABLE 1 l i s t st he s e p r o t o c o l s and t h e i r c h a r a c t e r i s t i c s . P r ot o co l ( 1 ) i s used f o r d a t aa c q u i s i t i o n s s uc h as d e t e r m i n i n g snow d e p t h a t a r em o te s i t e . M e t eo r b u r s ts ys te ms o p e r a t i n g w i t h t h i s p r o t o c o l a f t e r t h e ha nd sha ke ha s t a k e n p l a c eo p e r a t e on a h a l f - d u p l e x b a s i s . P r o t o c o l ( 2 ) i s a c o mm u ni ca ti on s y st e mpr o t o co l . Once th e handshake has tak en p lace , communica ti on on twof r e q u e n c i e s t a k e s p l a c e i n a f u l l d u p l e x m anner. The c o mm u ni ca ti on c o n s i s t so f i n d i v i d u a l p a c k et s o f a d i g i t a l m essage w hi ch m ig h t be v oi ce . A v a r i a t i o no n p r o t o c o l ( 2 ) i s t h a t fo un d i n p r o t o co l ( 3 ) . I n t h i s p ro t oc o l , b e fo r e t h eh and sh ake t a k e s p l a c e , b o t h t h e m a s te r and r e mo te a r e c o n t i n u a l l y t r a n s m i t t i n gp r o b e s i g n a l s . The ad v an ta g e o f s uc h a s y s te m i s t h a t d a t a t r a n s m i s s i o n ca ns t a r t q u i c k e r and t h e ch an ne l i s u se d m ore e f f e c t i v e l y . However, t h i sr e q u i r e s t h e re mo te t o b e on c o n t i n u a l l y . It i s o u r u nd e rs ta n di ng t h a t t h i s


27/122

p r o t o c o l i s n o t b e i n g us ed i n t h e U n i t e d S ta t e s b u t may be u n de r c o n s i d e r a t i o nf o r u se e ls e wh e re i s t h e w o rl d . T h i s p r o t o c o l s h a l l n o t be c o n si d er e d f u r t h e rhere.

P r o t o c o l (4 ) i s a p p l i c a b l e t o a d a p t i v e d a t a r a t e systems. I n an a da p t iv ed a t a r a t e s ys te m, d u r i n g t h e h an ds ha ke and a f te r w a r d s , a q u a n t i t a t i v e m ea su rei s made o f t h e m a gn itu de o f t h e s i g n a l f r o m t h e m ete or t r a i l . Based upon th i sm eas ure, t h e d a t a r a t e ( K b l s ) a nd t h e t r a n s m i t t e r a nd r e c e i v e r b a n dw i dt h a r ea l t e r e d t o s en d t h e optim um d a t a r a t e t h e m e te o r t r a i l c an s u p po r t. The u seo f a d a p t i v e d a t a r a t e s a nd a c o r re s p o n d i n g l y l a r g e r b a nd w id th h as t h ep o t e n t i a l t o im pr ov e t h e t h r o u g h p u t f o r a me te or b u r s t s ys te m b y a f a c t o r o f10 (see Reference 5 on page 9 ) . Bo t h adap t i v e and non - adap t iv e s y s temo p e r a t i o n s a r e i d e n t i c a l p r i o r t o a h an ds ha ke . Once t h i s ha nd sh ak e h as t a k e np la c e , t h e p r o t o c o l ( 4 ) i n c l u d e d t h e a b i l i t y t o a da pt t h e s yste m pa ra me te rssuch as bandwid th and da ta ra tes .

P r o t o c o l ( 5 ) i s a b r o a d c as t m e t eo r b u r s t mode. The p r o t o c o l ( 1 ) t o ( 4 )a r e o ne -to -o ne . I n p r o t o c o l (5), t h e m as te r s t a t i o n r e pe a te d ly t r a n s m i ts i t smessage, on a s in g le f requ ency f1 t o N re mo te s ho p in g t h a t o v e r a s u f f i c i e n tt i m e p e r i od , a m et eo r b u r s t ch an ne l w i l l open t o a l l N o f t h e r emo tes . Ther emot es a r e i n a r e c e i v e mode on l y .


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TABLE 1METEOR BURST SYSTEM PROTOCOLS

1Pr o t oco l Pu r pose1. D ata A c q u i s i t i o nHal f -Dupl exf 1 9 f 2I f1 - f 2 \; MHz

' 2. Communicat ionF u l l 0 up l exf 1 9 f 2If, - f,l - 1 MHz

3. Communi c a t i o nF u l l D upl e xf l s f 2I f l - f21 1 1 MHz

4. Communicat ionF u l l D u pl exAdapti eData Rate

5. Br oadcas t

Before HandshakeMaster onRemote o f f

Master onRemote o f f

Master onRemote on

I n 20 kHz channelMaster onRemote o f fBeyond 20 kHzchanne lM a st er o f fRemote o f f


A f te r HandshakeM a st er on b u t a l t e r n a t i n gRemote on but a 1 e r n a t i n g

Master onRemote on

Master onRemote on

I n 20 kHz channe lMaster onRemote onBeyond 20 kHzchanne lMaster onRemote on



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SECTION 4FREQUENCY BANDS AND EMISSION CHARACTERISTICS

FOR METEOR BUR ST COMMUNICATION SYST EMS

4.1 FREQUENCY BANDS

The gene r a l bounds on t h e f r equency o f op e r a t i o n f o r m e t eo r - bu r s t syst em sf a l l i n t h e ra n g e 3 0-1 00 MHz. The c o m p le t e i n t e r n a t i o n a l and n a t i o n a lf r e q ue n c y a l l o c a t i o n s f o r t h i s f re q u e nc y r an ge a r e i n c l u d e d i n APPENDIX A o ft h i s r e p o r t . A d d i t i o n a l r u l e s and r e g u l a t i o n s f r o m t h e NTIA Manual r e l a t i n gt o f r equency use f o r sys tem s i n t h i s r ange a r e f ound i n APPENDICES B and C.U nd er n or ma l i o n o s p h e r i c c o n d i t i o n s (ic l u d i n g a u r o r a l a b s o r p t i o n ) , t h eoptimum f req uen cy band fo r meteo r b u r s t systems i s 40-50 MHz. The opt imumf reque ncy range (40-50 MHz) i s t hu s a 10 MHz f req uen cy segment. W i t h in t h i sop timu m band, t h e U.S. Governm ent subband s a r e 40.0-42.0 MHz, 46.6-47 MHz, and49.6-50 MHz.

The pe ak s i g n a l p ow er r e t u r n fr o m a m e te o r t r a i l v a r i e s as f "3 and t he'a ve ra ge t i m e d u r a t i o n o f a me te or r e f l e c t i o n v a r i e s as f - ^ . Combin ing theset wo f a c t o r s t o g e t h e r and i n c l u d i n g t h e f a c t t h a t g a l a c t i c n o i s e ( wh ic hd e te r m in e s t h e r e q u i r e d t h re s h 0 1d s i g n a l ) v a r i e s a s f '**^, t h e i n f o r m a t i o nd u t y c y c l e ( I p ) f o r a m e te o r b u r s t s y s te m ha s a fr e q u e n c y d ep en de nce o f

where Ir i n f o r m a t i o n d u t y c y c l e (CCIR R e p o r t 25 1-4 )= p r o p o r t i o n o f t i m e a g i v e n s i g n a l / n o i s e r a t i o i s exceeded.

F i g u r e 2 p l o t s t o g e t h e r e ac h of t h e s e f re q u e nc y d ep en de nt te r m s o v e r t h eoptimum f requen cy range 40-50 MHz. Each o f t h e te rms i n F i g ur e 2 has beenn o rm a l i z ed t o a v a l u e o f 1 a t f= 40 Megaher t z so t h a t a compar ison can be madeamong t h e v a r i a b i l i t y o f t h e t e rm s i n t h e r an g e 40-50 MHz. It can be seen


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1OO

-95

.90

.85

-80

.75

-7 0Average Burst Length.65 f2

.601-- 5 5 , 2 .7 Throughput Informat io nduty cycle)

.50 ' 140 42 44 4 6 48 7 eak Power ReturnFREQUENCY (MHz)

F i g u r e 2 . Frequency Dependent Terms i n t h e r an g e 4 0-50 MHz.


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t h a t t h e I n f o r m a t i o n D u t y C y c l e , In, h ich i s d i r e c t l y r e l a t e d t o t het h r o u g h p u t o f t h e m e te o r ch a nn e l i s a b o u t t wo t i m e s l a r g e r a t 40 MHz t h a n t h et h r o ugh pu t a t 50 MHz. The peak s i g na l power l e v e l i s a l s o abou t t wo t i m e sl a r g e r a t 40 MHz t h a n a t 5 0 MHz. S i m i l a r l y , t h e a v e ra g e t i m e d u r a t i o n o f a

1m ete or s i g n a l i s a b ou t ly t ime s l a r g e r a t 40 MHz than a t 50 MHz. Thus, underr e g u l a r i o n o s p h e r i c c o n d i t i o n s a nd c o n s i d e r i n g t h o s e p a r am e te rs o f m et eo rb u r s t syst em s wh i ch a r e f r equency dependen t, i t can be conc luded t h a t i t i sadvantageous t o ope ra te i n t h e l ow er ranges o f t h e 40-50 MHz band.

As d i s c u s s e d e a r l i e r , t h e r e a r e c a se s when n o n r e g u l a r an d d i s t u r b e di o n o s p h e r i c c o n d i t i o n s d i c t a t e t h e u se o f h i g h e r f r e q ue n c ie s . One example i st h e o cc u rr en c e o f a u r o r a l s c a t t e r i n h i g h l a t i t u d e o p e ra t io n s (e.g.,~lska) .^ When oc c a s io n a l a u r o r a l s c a t t e r i s p re s e n t , t h e r e i s c o n s i d e r a b l ef a d i n g and m u l t i p a t h . T he se a u r o r a l e f f e c t s ca n u s u a l l y be o ve rco me b yo p e r a t i n g a t h i g h e r f r e q u e n c i e s .

The t ra n s m is s i on e q ua t i on s f o r t h e m ete or b u r s t p ro ce ss i t s e l f y i e l d at h r o u g h p u t - -2.7 2s i g n a l r e t u r n - f 3 n d a v e r a g e b u r s t l e n g t h - f - .T h i s w o u l d s u g ge s t, f o r a n u n d i s t u r b e d io n o s p h e re , t h e u se o f as l o w afre qu en cy as p os si b le , i .e., belo w 40 MHz. However, when f re qu en cie s below 40MHz are used ot h e r i on os ph er ic modes such as Sp orad ic E, i o n s c a t t e r , a n d Fr e g i on r e f l e c t i o n become m ore l i k e l y . These modes have a much g r ea t e rp o s s i b i l i t y o f occur re nce as f requen cy decreases be low 40 MHz. When the semodes a r e p r e v a l e n t , t h e i r s i g n a l s t r e n g t h s w i l l t e n d t o e xc ee d o r m ask t h em e t eo r s i g na l r e t u r n . These modes, a l t ho ugh a bonus , a r e ch a r a c t e r i ze d bym u l t i p a t h e f f e c t s w h ic h a r e o f t e n t im e s l e s s t h a n ad va nta geo us f o r r e l i a b l ecom m uni cat ions . Neve r t he l ess , t h e op e r a t i on o f m e teo r bu r s t syst em s a tf re qu en c ie s be low 40 MHz sho u ld be cons id ered . F rom an i n te r f e re n c ep e r s p e c t i v e , t h e b e s t t i m e s a r e th o s e when o t h e r i o n o s p h e r i c p r o p a g a t i o n modesa re l e s s l i k e l y t o occu r .

' ~ e i t z e n , J.A., M.J. Sona and R.A. S co f i d i o, "C ha r ac t e r i z i n g t h e Mu1t i a t h andDopp l e r Sp reads o f t h e H i gh - La t i t u de M e t eo r Bu r s t Comm uni ca ti on Channel ,"IEEE Tr an sa ct io n s on Commu nication, Vol . COM-35, No. 10, Oct ob er 1987.


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The COMET s y st em o p e r a t e d s u c c e s s f u l l y i n t h e e a r l y 6 0 ' s u s i n gf requenc ies be tween 35-40 M H Z * ~ The government bands i n th e ra nge 35-40 MHzar e t h e f i x e d and mo bi le bands 36-37 MHz and 38e25-39 MHz. Al th oug h th eopti mum band f o r m e t eo r b u r s t i s g en e r a l l y ag r eed t o be 40 -50 MHz, t hes e bandsbe tween 35-40 MHz shou l d be cons i de r ed f o r me t eo r bu r s t use, p a r t i c u l a r l y i ft h e r e i s f re q u e n c y c o n g e s t i o n and g ro un dw av e i n t e r f e r e n c e i n t h e 4 0 -5 0 MHzf r equency r eg i on .

The op e r a t i o n o f a m e teo r bu r s t sys tem a t f r equ enc i es above 50 MHzr e s u l t s i n l e s s t hr o ug h p ut and l o n g e r w a i t t i m e s f o r t ra n s m i ss i o n of amessage. U nd er m o st i o n o s p h e r i c c o n d i t i o n s , t h e d e l e t e r i o u s e f f e c t on m e t eo rb u r s t sy ste ms o f D r e g io n a b s o r p t io n i s u nd er 1 dB and no t even i nc l u de d i nd e t e r m i n i n g s y st em p a ra m e te r s f o r a m e t eo r b u r s t sy ste m. D u r i n g t h e t i m e s o fa s e v e r el y d i s t u r b e d i o no s ph e re s i g n i f i c a n t D r e g i o n a b s o r p t i o n p r e v a i l s . Thea b s o r p t i o n h a s a f'^ f r equen cy dependence wh i ch means t h a t t h e use o f h i gh e rVHF f r e q u e n c i e s w i l l h a ve l e s s l o s s d ue t o a b s o r p t i o n . Thus d u r i n g as e v e r e l y d i s t u r b e d (man-made o r n a t u r a l ) i onosphe re , m e t eo r bu r s t sys tem sw i l l o per a te above 50 MHz. I n t h e f requency range 50-100, MHz, t h e o n l y .g ov ern me nt b a nd p e r m i t t e d w i t h t r a n s m i t t e r p ow ers g r e a t e r t h a n 1 w a t t i s74.8-75.2 MHz. T h is band i s a1 1o c a te d t o t h e A e r o n a u t i c a l R ad i o n a v i g a t i nS e r v i c e an d i s n o t a p p r o p r i a t e f o r m e te o r b u r s t s y s te m u se . How ever,government op era t i on s may employ f re qu en c ie s i n non-government a1l ca ted bandsb etw ee n 2 5-2 40 0 MHz f o r t a c t i c a l a nd t r a i n i n g pu rp o se s i n a cc o rd a nc e w i t h t h eNTIA Manual (se e Ref. I ) , S e c ti o n s 7.15.3-7 (s ee APPENDIX C).

4.2 SPECTRUM STANDARDS

D i g i t a l m o d u l a t i o n s a r e u se d f o r m e t eo r b u r s t s ys te ms . The n e c e ss a ryb a n d wi d th s f o r t h e s e m o d u l a t i o n s a r e f ou nd i n A pp en dix J o f t h e N TIA M a n u a l*Fo r a g i ven c l a ss of em i ss i on ( m o d u la t io n t y p e ) t h e n e c e ss a ry b a n d wi d th i s t h ew i d t h o f t h e f re qu en cy band w hic h i s j u s t s u f f i c i e n t t o e ns ur e t h e

7 ~ a r t h o l o m e , P i e r r e J. a n d I r m f r i e d M. Vogt, "Comet - A New Meteor BurstSys tem I n co r p o r a t i n g ARQ and D i v e r s i t y Recep t i on ," EEE Tra ns . on Comm., Vo l aCOM-16 No. 2, pp. 268-278, A p r i l 1968.


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t r an s m i s si o n of i n f o r m a t io n a t t h e r a t e ( b i s / se c o nd f o r d i g i t a l m o d u la t io n )and w i t h t h e qua1 i t y r e q u i re d .

Ano t he r m easu re o f bandw i d th i s t h e occup i ed bandw i dt h . The occup i edb a n d w i d th f o r te l e c o m m u n i c a t i o n e qu ip me nt i s t h e w i d t h o f a f r e q ue n c y b an ds uc h t h a t , b e lo w t h e l o w e r a nd abo ve t h e u p p e r f r e qu e n c y l i m i t s , t h e meanp ow ers e m i t t e d a r e e ac h e qu al t o a s p e c i f i e d p e r c en t ag e B /2 o f t h e t o t a l m eanpower o f a g i ven em i ss i on . U n l e s s o t h e r w i s e s p e c i f i e d b y t h e C C I R , t h e v a l u eo f B/2 s h o ul d b e t a k e n as 0.5%. I n p r a c t i c e , a l l r e a so n a bl e e f f o r t s h a l l b ea f f o r d e d t o m a i n t a i n t h e o c c u p ie d b a n dw i dt h as c l o s e t o t h e n e c e ss a ryb a n d w i d th as p r a c t i c a l . M e t eo r b u r s t s y ste m d e s i g n e r s h a ve i n q u i r e d w ha ts p ec tr um p r o p e r t i e s o f m e te o r b u r s t s i g n a l s a r e o f i m p or ta n c e f o re l e c t o m a g ne t i c c o mp a ti b i 1i y. Each p r ob e s i g n a l f o r a m e te o r b u r s t s t a t i ons h o u l d f o l l o w t h e NTIA c h a n n e l i n g p l a n f o r a s si gn m en ts i n t h e 3 0-5 0 MHz ba nd(NTIA Manual (see Ref. 1) S ec t i o n 4.3.6, APPENDIX (C) of t h i s r e p o r t ) . Probes i g n a l s c a n f i t i n t o one channel of t h e 30-50 MHz channel p la n. Each channelhas a f r equen cy w i d t h o f 20 kHz. The p r obe s i gn a l spec tr um , ou t s i d e t h echanne l bandwid th , shou ld obey th e co n s t r a in t s shown i n TABLE 2.

TABLE 2ADJACENT CHANNEL SPECTRUM

Id. A t t e n u a t i n5 kHz < fd < 10 kHz 83 l o g ( f d l 5 ) dB10 kHz < f d < 250% BW 29 l o g ( f d 2 / l l ) o r 50 dB,w hic he ve r i s l e s s

f d > 250% BW Land, Fix ed , Mobi 1e50 + 10 l o g ( u n mo d ul at ed c a r r i e r p o w er ) dBP o r t a b l e 4 3 + 1 0 l o g ( un mo du la te d c a r r i e rpower) dB

where fd = d e v i a t i o n f r o m c a r r i e r f r e q u e n c y .

These c o n s t r a i n t s a r e d e si g ne d t o 1 m i t a d j a c e n t c h an ne l i n t e r f e r e n c efrom a nd t o m o b i l e sys te ms. A ls o , l a n d ( f i x e d and m o b i l e ) r e c e i v e r s i n t h e30-50 MHz f requen cy re g i on have f o r ad j ac en t channe l s e l e c t i v i t y a s ta nd ard i nt h e NTIA Manual o f 80 dB.


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SECTION 5METEOR BURST AND OTHER VHF SYSTEMS

5.1 INTRODUCTION

The u s e o f m ete or b u r s t s yste ms a r e e i t h e r f o r t e l e m e t r y o r f o rcom m uni cat ions . M e t eo r bu r s t t e l e m e t r y sys tem s a r e used t o t r a ns m i t f r om ar em o te s t a t i o n b ac k t o a m a s te r s t a t i o n e n v i r o n m e nt a l a nd o t h e r d a t a m ea su re da t t h e r em ot e s t a t i o n . Com mun ica ti on m e t eo r bu r s t sys tem s p r o v i d e a l ow da t ar a t e BLOS l i n k b etw ee n t h e m a s t e r and re m ot e s t a t i o n s . I n t h e U n i t e d S t a t e s ,th e ma jor us ers o f t he VHF spec t rum i n the f req uency range 30-100 MHz are l a n dm o b i l e , b r o a d c a s t i n g and a e r o n a u t i c a l r a d i o n a v i g a t i o n . A l s o u s i n g t h e VHFs p e c t r u m a r e u n l i ensed l w power communicat ion de vic es such as co rd1 esst e le p h o n e s w h i c h o p e r a te i n a cc o rd a nc e w i t h P a r t 15 o f t h e FCC Ru les andRegu l a ti ns .5.2 METEOR BURST TELEMETRY SYSTEMS

Pro bab ly th e l a r g e s t meteor b u rs t sys tem i s t h e SNOWPACK Te lem et ry System(SNOTEL) o p e r a t e d b y t h e S o i l C o n s e r v a t i o n S e r v i c e o f t h e U n i t e d S t a t e sDepartment o f Ag r i cu l t u r e . Th i s system, begun i n 1977, measures andt r a n s m i t s , on a d a i l y ba s i s , snowpack and p r e c i p i t a t i o n d a t a fr o m l o c a t i o n st h r o u g h o u t t h e West. A bo ut 550 s t a t i o n s a r e i n o p e r a t i o n w i t h t h e re mo tes i t e s powered b y s o l a r p a ne ls . M a s te r s t a t i o n s a r e i n B o is e , Idaho and Ogden,U tah. The SNOTEL syst em i s an exam pl e o f an - e f f e c t i v e and e f f i c i e n t use o ft h e VHF s p e c tr u m s i n c e o n l y a s i n g l e f r e q u e n c y i s u se d t o c om mu nic ate w i t h a l l550 r em o t e s t a t i ons ,

A n ot he r s ys te m us ed t o g a t h e r t e l e m e t r y d a t a i s t h e A l a sk a Me te o r B u r s tCommunication System (AMBCS). Th i s sys tem i s used by f i v e gover nm en t ag enc i est o g a t h e r d a t a : N a t i o n a l W e ath er S e r v i c e ( re m o t e w e a th e r d a t a ) , Bureau o fLand Management ( s ur ve y i ng camps). So i 1 Cons erva t i on Se rv i ce (wat er re sou rcesd a t a ) , U.S. Geo l og i ca l Su rvey ( s t r eam and wa t e r gaug i ng) , and t h e Co rps o fE n g i n ee r s ( ac cu mu l a t e e n v ir o n m e n ta l d a t a ) . The m a s t e r s t a t i o n i s i n


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Ancho rage , A l aska . The t r a n s m i t t e r and r e ce i v e r f r eq uen c i es a r e sepa r a t edabout 1 MHz t o p e r m i t f u l l d u p le x o p e r a t i o n .

A n o t h e r p o s s i b l e f u t u r e u se of t h e m e te o r b u r s t s ys te m may be t o m o n i t o rp i p e l n e s . T hes e e n v i r on m en ta l d a t a g a t h e r i n g m e te o r b u r s t o p e r a t i o n s u s u a l l yope r a t e w i t h 300-500 wa t t m as t e r s t a t i o ns and 300 wa t t s r em o te . They ope r a t ei n t he l ow e r p a r t o f t h e 40 MHz band w i t h 20 kHz bandw i d t h channe l s .

5.3 METEOR BURST EMERGENCY COMMUNICATIONS

The Fe de ra l Emergency Management Agency (FEMA) has dev elo ped t h e co nce ptf o r a Me te or B u r s t Wa rnin g/C om mu nic atio ns Sub syste m (MBWCS). The FEMA MBWCSc o n ce p t, w h ic h i s c o mp le me nt ar y t o t h e l a n d 1i e o r i e n t e d N a t i o n a l W a r n i n gSys tem (NAWAS), i s t o i n c l u de 10 r eg i on a l m e t eo r bu r s t (MB) m as t e r s t a t i o nt e r m i na l s (MST) , MB t r a ns ce i v e r s a t t he Emergency Ope r a t i ons Cen t e r s (EOC) o ft h e 48 c o n t i g u o u s s t a t e s , and MB w a r n i n g r e c e i v e r s a t 5000 d e s i g n a t e d w a r n i n gp o i n t s ( i n c l u d i n g 2 60 0 c u r r e n t NAWAS w a r n i n g p o i n t s ) t h r o u g h o u t t h e N a t io n .Coded n a t i o n a l w a r n in g me ss ag es, i n j e c t e d b y HF r a d i o o r l a n d l i n e f r o m t h eNa t io na l Warning Ce nter (NWC) o r A1 t e r n a t e NWC, w i l l be acknowl edged,a u t o m a t i c a l l y c o n v e r t e d t o s h o r t p r e f o r m a t t e d messages, and b r o a d c a s t t oad ja ce nt ma ste r s ta t i o n s , S ta te EOCs, and wa rni ng re ce iv er s. The MBWCS a ls ow i 11 p r ov i de two-way po i n t - t o - po i n t com m uni cat ions between a d j ac en t m as t e rs t a t i o n s , a nd m a s t e r s t a t i o n s a n d S t a t e EOCs w i t h i n d e s i g n a t e d a r e as . Thes y st em i s n o n a d a p t iv e .

The e qu ip me nt c h a r a c t e r i s t i c s f o r t h e s y st em a re :

Transmitters: M a s t e r S t a t i o n s - 10State EOCs - 4 8 ( T r a n s c e i v e r s )Power - 1 kWM odul a t i on - B i - phase s h i f t keyed (BPSK)Warning-Omni - Communicat ions ( P t - P t )

Receivers: A t Ma s te r S t a t i o n s s i t e s - 2-4 (approx. 24 t o t a l )State EOCs - 4 8 ( T r a n s c e i v e r s )A t W a r n i n g P o i n t s - 5000


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Messages : Data Rate - 4000 bpsFormat - A S C I I c od ed t e l e t y p e ( P t - P t ) B i n a r y ( W a rn in g)

Frequency: 40-50 MHz (Th ree f r eq ue nc ies f o r th e sys tem; each MST w i l lt r an s m i t on one and re ce iv e on two f reque nc i es . Each EOC w i 11u s e on e t r a n s m i t a n d o ne re c e i v e f r e q u e nc y .

5.4 METEOR BURST COMMUNICATION SYSTEMS

M e t eo r b u r s t c o m m u ni c at i on s ys te ms o p e r a t e b y t r a n s m i t t i n g p a c k e t s o fd i g i t i z e d i n f o r m a t i o n d u r i n g t h e c ha n ne l op en in gs . The a dv an ta ge o f m et eo rb u r s t i s t h a t i t c an p r o v i d e r e l i a b l e co mm u ni ca ti on s f o r l o w - r a t e d a t a ands l o w t e l e t y p e s t o a n d f r o m r em o te s i t e s w he re o t h e r modes o f c o m m u n ic a ti o n( s a t e 1 i t e , m ic ro wa ve , a nd t e l e p h o n e ) a r e u n a v a i l a b l e o r may b e l o s t i n ane me rg en cy . P re v io u s l y , HF ha s b e e n u s e d i n t h e s e c i c u ms ta n c es , b u t HFf r e q u e n c i e s m us t b e ' c ha ng ed r e g u l a r l y a nd a t t i m e s HF s i g n a l s c an b eu n a v a i l a b l e f o r l o n g p er i o d s o f t i m e due t o t h e v a ri an c es o f t h e i o n o sp h e r icp r o p e r t i e s . M ete or b u r s t systems, a l th o u gh i n t e r m i t t e n t , u t i l i z e a r e l i a b l es ta t i o n a ry c o mmu n ic a t i o n c h a n n e l .

M e t e o r b u r s t s y s te m u s e r s c h oo se t r a n s m i t t e r p ow er a nt en n a s i z e , r e c e i v e rth re sh0 1 d, f requency , and da t a r a t e depend i ng upon t h e commun ica t ionre q u i r e me n t . F o r ex amp le , l o w e r d a ta r a t e s a r e u s e d when t h e mes sa ge w a i t i n gt i m e i s m ore i m p o r ta n t t h an t h e amount o f d at a t o b e t r a n s m i t t e d i n a g i v e namoun t o f t ime .

M e te or b u r s t s ys te ms h av e f ou nd a p l a c e i n A la sk a t o p r o v i d e a t h i n r o u t elow da ta r a t e commun ica t ion sys tem f o r p r i v a t e use rs . The company, A lascom,p ro v id e s l o n g d i s t a n c e c o mmu n ic a ti o n l i n k s a c ro s s A las k a. The companyo p e ra te s a me te o r b u r s t c o mmu n ic a t io n s y s te m a s a s a te 1 i t e b ac k-up . The FCC(1988) p r o v i s io n on t h e use a r e t h e a l low ed f req uen c ies 42.4, 44.10, 44.2, and45.9 MHz. The b a se s t a t i o n p ow er i s l i m i t e d t o 2000 w a t t s f o r b as e s t a t i o n sa nd 500 w a t t s f o r re m ot e s t a t i o n s . C oc ha nn el b a se s t a t i o n s o f d i f f e r e n tl i c e n s e e s a r e t o b e l o c a t e d 1 50 m i l e s a p a rt . ( A w a iv e r o f t h e d i s t a n c es e p a r a t i o n r e qu ir em e nt s i s p o s s i b l e i f a c o o p e r a t i v e s h a r i n g a rra n ge me n t ca n


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be reached. ) The emi ss io n i s t o a1 ow f o r PSK o r FSK ke y in g and th e maximuma u t h o r i ze d b a n d wi dt h i s 20 kHz.

M e te o r b u r s t r e s ea r ch i s p r o ce e d i ng to w a rd s i m p r o v in g t h e u n d e r s t a n d i n go f t h e p r o p a g a t i o n m ec ha ni sm a n d i p r o v i n g t h e t e c h n o 1ogy and tec hn i ques ( seeR e fe re n ce 5) . T h er e i s c u r r e n t l y c o n s i d e r a b l e t e s t i n g o f me te or b u r s t s ys te mst o d e t e r m i n e t h e b ou nd s on t h e c o m mu n ic a ti o n c a p a b i l i t i e s (e.g., t h r o u g h p u t ,w a i t t i m e ) o f m e t e o r - b u r s t s ys te ms . Some of t h e t e s t i n g e x p e r i m e n t s h a v e b e e nc a r r i e d o u t a t h i g h l a t i t u d e s s i n c e m ete or b u r s t t ec h no lo g y has b o t ha p p l i c a t i o n s and a dv an ta ge s a t h i g h l a t i t u d e s . A n ot he r s u b j e c t o f i n t e r e s t i st h e a p p l i c a t i o n o f m e te o r b u r s t s c a t t e r f o r s h o r t ra ng e RLOS co mm un ic at io nd i s t a n c e s l e s s t h a n 4 00 km.^

M e t e o r b u r s t c o m mu n ic a ti o n s ys te m s i n 1 9 87 h a ve a dv an ce d t o i n c l u d e t h ec o m m u n ic a t io n c a p a b i l i t i e s s hown i n TABLE 3.

TABLE 3METEOR BURST SYSTEM CHARACTERISTICS(SOURCE: See R e fe re n ce 9 )

A d a p t i v e D a t a R a t e sF o r w a r d E r r o r C o r r e c t i o nN e t w o r k i n g8000 Charac te r Message Leng thsAverage Throug hpu t : 300 Words Per M i nu teMessage W ait Time: 1.5 M in ut es

The m e te o r b u r s t t e c h n o l o g y i s c o n t i n u a l l y i m p r o v i n g an d much ha sh ap pe ne d d u r i n g t h e p a s t f i v e y e a rs . It i s t h e r e f o r e d i f f i c u l t t o e x t r a p o l a t e

Qe i t z en , J.A., Commun icat ing V i a Mete or B u rs t a t Sh or t Ranges, IEEET ra n sa ct io n s on Com munica t ions, Vo l. COM-35, No. 11, November 1987.~ o r ~ a n ,.J., "Meteor B u rs t Communicat ions : An Update," S ig n a l , pp. 55-61,March 1988.


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into the future the expected numbers and uses for meteor burst systems in theUnited St ates. One area in which progress has been made is in the si ze andcomplexity of the meteor burst equipments Backpack terminals with easy set u pare now feas ibl e. Another appl icat ion i s t o provide two-way communicationwith trucks (see Mickelson, 1989). lo he FCC has authorized such a system t obe operated on motor car r ier se rv ice frequencies. The number of mobile un it si s expected t o be in th e tens of thousands,

5.5 VHF SYSTEMS

The U.S. VHF spectrum from 30-110 MHz i s divided into 26 bands. Thesebands general ly a1 ternate between excl usi ve government and excl usi ve non-government bands as seen in APPENDIX A c There are only two bands that areshared between government and nongovernment from 30 t o 50 MHz, and these ar eshared radio astronomy al locat ions. From 50-110 MHz, there are four sharedbands, which are all in the 73-75.4 MHz spectrum region. These shared bandsbetween government and nongovernment include radio astronomy from 73-74.6 MHz,fixed and mobile between 74.6 and 74.8 MHz and 75.2 to 75.4 MHz, andaeronautical radionavigation from 74.8 t o 75.2 MHz

In the 30 to 40 MHz band, the greatest use by government i s for landmobile systems. The st at ion cl as s ML (a land mobile station) has the greatestnumber of assignments. In the 40 t o 50 MHz band, the greatest number ofassignments for a given stat ion cla ss i s t o ML. The meteor burstcommuni cati on system, which is comprised of the Department of Agricul ture sSNOTEL network, makeup the major assignments for the second most used stationclass in t h i s band--FXH. The FXH designator "is a fixed st at ion used for theautomatic transmission of either hydrological or meteorological data, or both.Most uses in this band are for land mobile systems, although aeronauticalmobile and maritime mobile are also in use.

^~ i cke l on, K . D . Tracking 64,000 vehicles with meteor s cat ter radio, Mobi 1eRadio Techno1 ogy, pp 24-38, January 1989.


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I n t h e b an d fr o m 50 t o 100 MHz, t h e m a j o r us e i s b y t h e p r i v a t e s e c t o r .w i t h ama teu r, TV b r oad c as t i ng, and FM r a d i o b r oa dc a s t i ng be i n g ma j o r s pec t ruma l l o c a t i o n s . The m a j o r g ov ernm en t r e qu ir e m en t i n t h i s band i s f o rae r on au t i c a l r ad i ona v i ga t i o n i n t h e s ub-band 74.8-75.2 MHz ( 78 pe r c en t o fa s si gn m en ts ) t o t h e RLA s t a t i o n c l a s s , w h ic h i s f o r a e r o n a u t i c a l m a r ke r beacons t a t i o n s . V a ri o us t y p e s o f m o b i l e s t a t i o n s make up t h e g r e a t e s t p o r t i o n o ft he r ema i n i ng as s i gnmen t s .

Nongove rnment a l l o c a t i on s f rom 30 t o 40 MHz a r e ma i n l y t o l an d mo b i l e( s i x subbands ) and one subband t o ex c l us i v e r a d io as t ronomy and one secondarya l l o c a t i o n a l s o t o r a d i o as tro no my s ha re d w i t h l a n d m o b i le p ri ma ry . T he re i sa w id e v a r i e t y o f c o mm u ni ca ti on s e r v i c e s i n t h e s e b an ds . T h er e a r e f o u rs e r v i c e t y p e s u n de r t h e l a n d m o b i l e a l l o c a t i o n t h a t a ss ig nm e nt s a r e made t o i nt h e 30 t o 40 MHz band. These a r e i n d u s t r i a l , l a n d t r a n s p o r t a t i o n , p u b l i cs a f e t y , and d o m e st ic p u b l i c .

As s i gnments unde r i d u s t r i a1 i c l ude bus i nes s es s uc h as c o ns t r u c t i o ncompanies, p l umbi ng compani es, we1 1 d r i 11i g compani es, p e t r o l eum and gasp i p e 1i e c ompan ies, c ompanies i n v o l v ed i n f o r e s t p r oduc t s , and a l mos t any

b u s i n e ss t h a t ha s a r a d i o d i s p a t c h e d v e h i c l e . T he re a r e a f ew a s si gn m e nt s i nt h e 30- 40 MHz band t o l a nd t r a n s p o r t a t i o n s e r v i c es . Howeve r, as s ignment s t o1and t r a n s p o r t a t i o n i n c l u d e bus l i n e s , r a p i d t r a n s i t s ystems, m e tr o a r eat r a n s i t a u t h o r i t i e s , t r u c k i n g com panies, and a i r t r a n s i t com panies.A ss ig nm en ts t o d o m e s t ic p u b l c s e r v i c e s i n c lude r a d i o pag i ng s ys tems , r a d i ot e l epho ne sy st ems, and t e l ephone ans wer i ng s e r v i c es . Ass i gnments unde r p u b l is a f e t y i n c l u d e p o l i c e and hi gh w ay p a t r o l , e me rg en cy v e h i c l e s s uc h asambul ances and paramedi c t eams, c i t y and r u r a l f i e d e p ar tm e n ts , h i ghwaymai n t enanc e v eh i c l es, s t a t e pa r k s and r e c r e a t i o n a r eas , and 1o c a l governmentv e h i c l es . The re a r e Fede r a l Gove rnment ass i gnmen ts i n some o f t he s e p u b l i cs a f e t y s ub ba nd s, p a r t ic u l a r l y t h o s e d e pa rt m en ts and a g e n ci e s w i t h 1awe n fo r ce m e n t r e s p o n s i b i 1i i e s s o t h e y c an c om mu nic ate w i t h l o c a l and s t a t e 1awen f o r c emen t pe r s onne l and o f f i c es .

The 40 t o 5 0 MHz ba nd f o r n on go ve rn me nt a l l o c a t i o n s i s t o l a n d m o b i l e i ntwo subbands f ro m 42 t o 46 MHz and fr om 47 t o 49.6 MHz. The ass ignments a r e t ot h e same f o u r a c t i v i t i e s u n d e r l a n d m o b i l e as g i v e n a bo ve f o r t h e 30 t o 4 0 MHzband. T he re a r e as sig nm en ts i n t h i s b and t o t h e l a n d t r a n s p o r t a t i o n s e r v i c e s


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and t o p ow er c om pa nie s u n d er t h e i n d u s t r i a l a l l o c a t i o n . T he re a r e a l s oa s si gn m en ts t o t h e e x p e r i m e n t a l s t a t i o n c l a s s e s s uc h as e x p e r i m e n t a ldeve lopmen t, expe r i m en t a l r esea r ch , and expe r i m en t a l con t r a c t s t h a t a r e usedm ai n l y f o r new sys tem development. The 40 t o 50 MHz band i s used ex te ns i v e l yby the pub1i s a f e t y s e r v i c e s i c l u d i n g 1o c a l p o l c e de p a rt m en t s, h i ghwayp a t r o l , f i r e s t a t i o n v e h i c l e s , a mb ula nc es , a nd h ig h wa y m a in te n an c e v e h i c l e s .

T he re i s an a1 l o c a t i o n t o i n d u s t r i a1, s c i e n t i f i c and m e di ca l ( IS M)equipment i n th e subband 40.66-40.70 MHz. I n d u s t r i a1 h e a t i n g equipment em i tsr a d i a t i o n i n t h e band 40,66-40.70 MHz. M e t eo r bu r s t r ec e i v e r s op e r a t i n g i ni n d u s t r i a l a re a s may be i n c l o s e p r o x i m i t y t o t h e se i n d u s t r i a l d e vi ce s.

A l s o a l l o c a t e d i n p o r t i o n s o f t h e b an d 4 0-5 0 MHz a r e l o w power u n l i c e n s e dcommunica ti on dev i ce s . These i n c l ude cord1ess te lephones and ch i 1d m o n i t o r s .Co r d l ess t e l ephon e use i s i n c r ea s i ng d r am a t i ca l l y . Fo r examp le , 3 ,343 ,511c o r d l e s s t e l e p h o n e s w er e i m p o r t e d i n 1985; i n 1 9 86 t h e number i n c r e a s e d t o5,377,999; and i n 1987 t h e t o t a l number im po r te d was 8,666,473.l l

The 5 0 t o 1 00 MHz b an d i s d i v i d e d i n t o t e n s ub ba nd s; s i x a r e t o e x c l u s i v enongovernment use and fo u r a re sha red w i t h government. From 50 t o 73 MHz i se x c l u s i v e l y n on -g ov ern m en t w i t h a ma te ur a1 o c a t i ons f r om 50 t o 54 MHz,t e l e v i s i o n b r o a d c a s t i n g f r o m 54 t o 7 2 MHz, and f i x e d an d m o b i l e f ro m 72 t o 73MHz.

The spect rum f ro m 73 t o 75.4 MHz i s share d eq u a l l y between government andnon -gover nm ent . From 73 t o 74.6 MHz, t h e a l l o c a t i o n i s t o r a d i o as tr onom y .F ro m 74.6 t o 74.8, t h e a l l o c a t i o n i s t o f i x e d and m o b i l e c o eq u al p r i m a r y . Thesu bb an d f r o m 74.8 t o 75.2 MHz i s a l l o c a t e d t o a e r o n a u t i c a l r a d i o n a v i g a t i o n ,a nd t h e s ub ban d f r o m 75.2 t o 75.4 MHz i s a l l o c a t e d t o f i x e d an d m o b i l e a g a i ncoequa l p r i m a r y .

The spec t r um f r om 75.6 t o 108 MHz i s a l l oc a t ed t o non- gover nm ente x c l u s i v e s e r v i c e s . From 75.4 t o 76 MHz, t h e a l l o c a t i o n i s t o n on -g ov ern m en tf i x e d and m o b i le c oe qu al p r im a ry ; 76 t o 8 8 MHz i s a l l o c a t e d t o t e l e v i s i o nb r o a d c a s t i n g ; and 8 8 t o 1 08 MHz i s a l l o c a t e d t o FM r a d i o b r o a d c a s t i n g .

l l~ureau o f t h e Census, p r i v a t e comp un ica t i on, 1988.

25


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Nongovernment uses are v a r i e d and i c l ude pub l i s a f e t y , i d u s t r i 1 , andex pe r im en ta l f r om 50 t o 57 MHz w i t h many TV assign men ts a t 57 MHz. Between 57an d 63 MHz, t h e r e a r e a b o u t t h e same d i s t r i b u t i o n o f a s s ig n m en ts a s i n t h e 50t o 57 MHz subband w i t h many TV as sig nm en ts a t 63 MHz. From 63 t o 69 MHz, t h ea s si gn m en ts a r e m a i n l y t o i n d u s t r i a1 b u s i n e ss w i t h some e x p e r i m e n t a ldeve lopme nt assig nm ent s. Th ere a re many TV ass ignm en ts a t 69 MHz. From 69.1t o 74.6 MHz, t h e r e a r e many as s ig n m en ts t o t h e i n d u s t r i a l m a n u f a c t u r i n g .T he re a r e a l s o many a ss ig nm e nts t o p u b l i c s a f e t y s e r v i c e s i n c l u d i n g p o l i c e ,h i g h w a y p a t r o l , f i e f i g h t i n g v e h i c l e s , and o t h e r em erge nc y v e h i c l e s . A t 75MHz, th e re a re many ass ignments t o th e AR s t a t i o n d e s i g n at o r w hi ch i s a s s ig n edf o r a e r o n a u t i c a l r a d i o n a v i g a t i o n . From 75.1 t o 78.5, t h e a s si gn m en ts a r e t oi n d u s t r i a l , p ub l i c s a f e t y , d o me s ti c p u bl c , 1and t r a n s p o r t a t i o n , a nde x p e r i m e n t a l . A t 79 MHz t h e r e a re a number of TV ass ign me nts , and fr o m 79.1t o 84.5, t h e a ss ig nm en ts a r e m a i n l y t o i n d u s t r i a l s e r v i c e s . From 8 5 t o 88MHz, th e ass ignments a re t o TV s ta t i on s , and f rom 88 t o 108 MHz, th ea ss ig nm en ts a r e t o t h e B r o a d c a s ti n g s e r v i c e f o r FM r a d i o s t a t i o n s .

Frequ enc ies i n t h e band 40 .66-40.70 MHz may be au th or i z ed t o governmenta nd no ng ov ern me nt s t a t i o n s on a se c on d ar y b a s i s f o r t h e t r a c k i n g o f , a ndt e l e m e t e ri n g o f s c i e n t i f i c d a t a f r o m o ce an b u oy s and w i l d 1 f e (U.S. F o o t n o t e2 10 ). The o p e ra t' i on i n t h i s b and i s s u b j e c t t o t h e t e c h n i c a l s t an d a rd ss p e c i f i e d i n (a ) S ec t i o n 8.2.42 o f t h e NTIA Manua l ( see APPENDIX C f o r t h et e x t ) o r S e c t i o n 5.108 o f t h e F CC's R u le s .

The f r eq ue nc ie s 36.25 and 41.71 MHz may be a u th o r i z e d t o government andnongovernm ent s t a t i o n s i n t h e P e t ro le u m R ad io S e r vi c e f o r o i l s p i l lc o n t a in m e n t and c l e a n u p o p e r a t i o n s . The u se of t h e s e fr e q u e n c ie s i s l i m i t e d t ot h e i n l a n d a nd c o a s t a l w at erw a y r e g i o n s . (See APPENDIX C f o r t h e te x t . )

5.6 SYSTEM CHARACTERISTICS

M a j o r s y st em s i n t h e 30 t o 1 00 MHz b an d a r e m a i n l y l a n d m o b i l e a nd o t h e rf i x e d and m ob i 1e t yp es f o r bo th government and nongovernment. Concern ing VHFt e c h n i c a l p a ra m et er s, r e c e i v e r s e n s i t i v i t i e s a r e a ro un d 0.5 vV/m f o r m os t1a nd m o b i l e s ys te ms . Pow ers r an g e f r o m t e n t h s o f a w a t t f o r c e r t a i n r em o tec o n t r o l and r e m ot e s e n s i n g sy ste m s t o 1 00 W f o r l a n d m o b i l e sy ste ms ( a f ew


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h i g h e r ) w i t h m e te o r b u r s t s ys te ms r u n n i n g u p t o 10,000 W e There a re a fews p e c ia l i z e d r a d a r s y s te ms u s ed b y NOAA f o r r e s e a rc h i n w in d s tu d ie s a nda u ro ra l s c a t t e r t h a t r a ng e i n po we r f r o m 10 t o 40 kW. NASA h as a s y ste m t h a tope ra tes a round 50 MHz t h a t can t r an sm i t 400 kW and sup por t s i t s deep spacep ro b es . The NSF h as a 2 00 kW t r a n s m i t t e r a t A re c ib o , P u e r to R i c o , u s e d t os u p p o r t r e s e a rc h e x p e r ime n ts .

5.7 TELEVISION RECEIVER INTERMEDIATE FREQUENCIES ( IF)

The v i d e o I F i n U.S. t e l e v i s i o n s i s a t 45.75 MHz w i t h a b a n d w id th oMHz (43.75-48.75 MHz) and t h e aud io I F i s a t 41.25 MHz w i t h a 200 KHzbandw id th .

The FCC i n i t s R e p o r t and O rd e r 83 -3 48 a u th o r i z i n g me te o r b u r s to p e ra t i on s i n A la sk a n o t ed t h a t t h e m ete or b u r s t t r a n s m i t t e r f r e qu e n c ie s t h e yw ere p r o po s in g t o a u t h o r i z e f e l l w i t h i n t h e passband o f t e l e v i s i o n I Ff r e q u e n c i e s . l2 c c o r d i n g l y , t h e y d e c i d e d t o i s s u e m e te o r b u r s t g r a n t s o n ad e v e lo p me n tal g ra n t b a s i s . The FCC s t a t e d i n t h e R e p o r t and O rd e r t h a t " w h i l ei t i s . t r u e t h a t no r e p o r t e d i n t e r f e r e n c e c o m p l a i n ts h ave been r e c e i v e dre ga rd in g Governmen t o r expe r im en ta l nongovernmen t ope ra t io ns i n A1 aska , ou re x pe r ie n ce w i t h t h i s b and i n d i c a t e s t h a t i t i s p o s s i b l e t o have i n t e r f e r e n c et o t e l e v i s i o n r e c e i v e r s as was d ev el op ed i n FCC d oc ke t 8 0 - 1 8 9 ~ ' ' ~ ~

I n te r f e r e n ce t o t e l e v i s i o n i s o f c oncern , b u t i t i s a l s o no te d t h a t t h eA l o c a t i o n Tab le (APPENDIX A) does no t p r o t e c t TV re ce iv e r I F f r e q u e n c i es .

^FCC, Re po rt and Ord er 83-348 Amendment of P a rt s 2, 22, and 90 o f t h e FCC~ u l e s a n d R e g u l a t io n s t o P r o v id e f o r t h e Use of M et eo r B u r s tCommuni ca t i o n s . J u l v 22. 1983.^FCC Docke t 80-189 Au tho r iz ed t h e Use o f Ce r t a i n 40-50 MHz F requen c ies f o rOne-way S ig n a l i n g (Me te o r B u rs t ) , u l y 28, 1981.


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SECTION 6IONOSPHERIC COMPATIBILITY

6.1 INTRODUCTION

T h is s e c t i o n i s t h e c om pa ti b i 1i y assessm en t f o r i nosphe r i c propagatedmodes.

C C I R R ep or t 259-6 i d e n t i f i e s t h o s e io n o s p h e r i c r e f 1 e c t e d s i g n a l s w h ic hmay l ea d t o i n t e r f e r e nc e a t f requenc i es be tween 30 and 300 M H ~ . ~ ~he most

Ip r e v a l e n t of t h es e i n t e r f e r e n c e s i g n a l s a r e r e f l e c t i o n s o r s c a t t e r fr om : (1)m e t e o r i o n i z a t i o n , ( 2 ) Spor ad i c E r e f l e c t i o n and s c a t t e r , and ( 3 ) r e g u l a rF - l aye r s . Because t h e maximum p r op aga t i on range o f t hese t ypes o f i ono sph e r i cs i g n a l s c a n e x te n d t o r an ge s o f 500-4000 km, t h e r e i s t h e p o t e n t i a l f o ri n t e r f e r e n c e o v e r l a r g e g e o g r a p h i c a l a re a s. The m os t 1i e l y o c c ur re n c es o fe ach o f t h e s e i n t e r f e r e n c e s o u rc e s i s t i m e (e.g., d i u r n a l , s e a so n a l, andy e a r l y ) dependent and a1 so s pa t i 1 y dependen t ( i e., 1ow-1 a t i u d e , t empera te ,e q u a t o r i a l ) . The a c t u a l t i m e s o f oc c u rr e nc e s o f e ac h o f t h e s e i n t e r f e r e n c es i g n a l s can o n l y be p r e d i c te d s t a t i s t i c a l l y . Each o f t h es e d i f f e r e n t t yp e s o fi o n o s p h e r i c ' p ro p a ga t ed i n t e r f e r e n c e s i g n a l s w i 11 b e c o n s i d e r e d s e p a r a t e l y .

6.2 METEOR IONIZATION

E x p e r i m e n t a l l y , i t has b een f o un d t h a t t y p i c a l r e c e i v e d s i g n a l s f r o mm et eo r t r a i l s r e f l e c t i o n h av e s i g n a l m ag ni t ud es o f - 110 dBm w i t h r e t u r n ssepa r a t ed on an ave r age o f 4 t o 20 seconds. The ave r age du r a t i o n o f a s i g na li s .58 seconds.15 Du r i n g t h e t i m e s o f m e teo r showers , t h e ave r age t i m eb etw een m et eo r r e f l e c t i o n i s l e s s .

^CCIR Report 259-6, VHF Pr opaga t i on by Regu l a r Laye rs , Spo r ad i c E o r o t h e rAnomalous Ioni z a t i on, Doc. X V I P Iena r y , 1986a) .1 5 0 e t t i n q , J .D., An An a l y s i s o f M e t eo r B u r s t Com m un icat i ons f o r M i l t a r y


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Based u po n t h e a bo ve s i g n a l c h a r a c t e r i s t i c s , i t i s a p pa re nt t h a t ani n t e r f e r i n g s i g n a l fro m a m et eo r t r a i l i s s h o r t l i v e d and m ig h t ca us e a t m os ta s h o r t i n t e r r u p t i o n t o a w anted s i g n a l . M i l l e r and L i c k l i d e r have d et er mi ne dt h e i m pa c t o f s h o r t i n t e r r u p t i o n on p e rc e n t w ord a r t i c u l a t i o n in de x.1 6 Thei mp a ct d epends upon tw o p a r am e te rs ; t h e n o i s e t i m e f r a c t i o n w h ic h i s t h e d u t yf a c t o r o f t h e n o i s e and t h e number o f i n t e r r u p t i o n s p e r second. The t y p i c a lm e te or b u r s t s i g n a l d e s c r i b e d above h as a n o i s e t i m e f a c t o r = ( .58/4) = 1a nd t h e n umber o f i n t e r r u p t i o n s / s e c o n d = ( 1 / 4 ) = .25. The p er ce nt worda r t i c u l a t i o n i n d e x f o r t h i s i n t e r f e r e n c e w ou ld be ab ou t .95 w hi ch i s more t h a na c c e p t ab l e f o r m o st, i f n o t a1 1, commu nicat ion purposes. Moreover , t h et y p i c a l s i g n a l r e t u r n o f - 110 dBm i s a r e l a t i v e l y weak s i g n a l on a p a r w i t hg a l a c t i c n o i s e l e v e l s and i s u n l i k e l y t o c aus e i n t e r f e r e n c e t o o t h e r VHFsy ste ms su ch as l a n d m o bi le . The p o s s i b i l i t y o f i n t e r f e r e n c e i s f u r t h e rr ed u ce d s i n c e ea ch m et e or a c t s as a d i r e c t i o n a l a n te n na a nd f o c us e s t h e e n e r g yi t r a d i a t e s t o t h e g ro un d i n a sm al l " f o o t p r i n t " w i t h d im en sio ns o f5 x 40 km. It i s c on clu de d t h a t m e te or s c a t t e r s i g n a l s a r e n o t a 1 k e l ys o ur ce o f i n t e r f e r e n c e t o o t h e r u s e rs o f t h e VHF s p ec tru m.

ti SPORADIC E REFLECTIONS '

The p o t e n t i a l f o r me te or b u r s t s t a t i o n s i g n a l s w h ic h a r e r e f l e c t e d f romSpor ad i c E i o n i z a t i o n t o c au se i n t e r f e r e n c e c an b e a ss es se d by us e o f t h e C C I Rrecommended Sporadic E f i e l d s t r e n g t h c a l c u l a t i o n method.^ T h is c a l c u l a t i o nm e thod was used t o comput e expec t ed s i gn a l r e t u r n s f r om Spo r ad i c E i o n i z a t i o nf o r t h e e q ui pm e nt p a r a m e te r s: P-r = 10 kw, GT = GR = 10 d B i . F i g u r e 3 p l o t st h e c a l c u l a t e d e x p e c te d r e c e i ved po we r as a f u n c t i on o f t r a n s m i t t e r f r eq u e n c ya n d s e p a r a t i o n d i s t a n c e b etw een t h e t r a n s m i t t e r and r e c e i v e r. The c r i t i c a lf r e qu e n c y o f S p o r a d ic E was 1 3 MHz f o r t h e c a l c u l a t i o n s . F i g u r e 3 shows t h a tt h e s i g n a l p ow ers f r o m S p o r a d ic E r e t u r n s a r e o f t h e same o r d e r o f m a g ni tu d e( i e., - 110 dBm) as m e t eo r t r a i l r e t u r n s .

f i l l e r and J . C. L i c k l i d e r , I n t e l l i g i b i l i t y o f I n t e r r u p t e d Speech, J ou rn alAc ou st ic a l S o ci et y o f Amer ica, Vol . 22, No. 2, March 1950.~ C I R Recommendat ion 534-2 , Methods f o r C a lc u la t i n g Sporad i c -E F i e l dSt rength , Doc . X V I P l ena r y , 1986b.


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us ntia-meteor burst comm for nationwide fema emergency system, truck fleets, etc. 1989

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