hf messaging system with automatic link...

HF MESSAGING SYSTEM WITH AUTOMATIC LINK ESTABLISHMENT

(ALE) CAPABILITY

NURULFADZILAH BT HASAN

A thesis submitted in fulfilment of the

requirements for the award of the degree of

Master of Engineering (Electrical)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

JANUARY 2006

iii

Dedicated to my beloved husband and parents

Thank you for the inspirations

iv

ACKNOWLEDGEMENT

First and foremost the greatest praise to Allah for the blessings, guidance and

for the gift of courage for me to accomplish this research.

Highest gratitude and appreciation goes to my supervisor, Assoc. Prof. Dr.

Ahmad Zuri Sha’ameri, Thank you for the invaluable guidance, support, knowledge

and advices given to me throughout this study. I would also like to thank En. Wan

Roz for the priceless help and information he gave to make me better understand this

research.

To En. Jeffri Ismail, DSP lab technician, I would like to thank him for his

technical assistance throughout my study. Also, special thanks to Rahim, Sazali and

Fong Fong for helping me complete the field-testing for this research. To my friends

who are always there for me, thank you so much.

Finally, I would like to express endless appreciation to my family for their

love, patience and prayers.

v

ABSTRACT

HF radio spectrum, ranging from 3 to 30 MHz can be utilized for voice and

data communication. One of the benefit of using HF for communicating is that HF

system is low-cost, requires minimum equipments and easy to set up. But due to the

unpredictability and propagation problems such as multipath fading, interference and

attenuation, communication using HF becomes very challenging. Besides, the

availability of the channels varies depending on the time of day, seasons and the

condition of the ionosphere. The purpose of this research is to design a HF

messaging system equipped with Automatic Link Establishment (ALE) capability.

ALE is an adaptive radio technology for automatically establishing communications

over HF single sideband (SSB) links using the best frequency possible. The objective

of the research is to design a messaging system that permits reliable data

transmission over the HF radio with minimum cost and equipments. This research

also looked at the feasibility of implementing ALE as software, designed using

Visual C++ programming language. Equipments used in this research are

commercial HF radio and modem, which are both controlled by the software. Field

testing is conducted between UTM Skudai and several places in Malaysia to verify

the performance of the system. From the results, it is proven that by applying

adaptive radio technology, propagation problems can be overcome and reliability of

data transmission can be improved. Moreover, amateur radio users can use the

system, as it requires minimum equipment.

vi

ABSTRAK

Spektrum radio berfrekuensi tinggi atau HF iaitu dari 3 hingga 30 MHz boleh

digunakan untuk komunikasi suara dan juga data. Salah satu kebaikan menggunakan

HF ialah ia memerlukan kos yang rendah, memerlukan peralatan yang minimum dan

mudah untuk dibangunkan. Tetapi disebabkan keadaan HF yang sukar dijangka dan

masalah perambatan seperti multipath fading, gangguan dan pelemahan isyarat

menjadikan komunikasi menggunakan HF mencabar. Selain itu, kebolehan sesuatu

frekuensi bergantung kepada faktor masa, musim dan keadaan lapisan ionosfera.

Tujuan kajian ini adalah untuk membina sebuah sistem pesanan HF yang dilengkapi

dengan kebolehan capaian pautan secara automatik (ALE). ALE merupakan

teknologi radio ubah suai yang digunakan untuk menghasilkan jaringan komunikasi

dalam jalur tunggal (SSB) HF menggunakan frekuensi yang terbaik. Objektif kajian

ini adalah untuk menghasilkan sistem pesanan HF yang membolehkan penghantaran

data melalui HF dilakukan dengan baik menggunakan kos serta peralatan yang

minimum. Kajian ini juga bertujuan mengkaji kesesuaian menghasilkan ALE dalam

bentuk perisian, yang dibangunkan menggunakan bahasa pengaturcaraan Visual

C++. Peralatan yang digunakan dalam kajian ini adalah radio HF dan modem HF

komersil yang mana keduanya akan dikawal oleh perisian yang dinyatakan tadi.

Kajian lapangan diadakan antara UTM Skudai dan beberapa tempat di Malaysia

untuk menguji prestasi sistem tersebut. Keputusan yang diperolehi dapat

membuktikan bahawa dengan menggunakan teknologi radio mudah ubah suai,

masalah perambatan dapat diatasi dan kebolehpercayaan penghantaran data

ditingkatkan. Malah, sistem tersebut dapat digunakan oleh pengguna radio amatur

kerana ia memerlukan peralatan yang minimum.

vii

TABLE OF CONTENT

CHAPTER TITLE PAGE

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xiii

LIST OF SYMBOLS xvii

LIST OF ABBREVIATIONS xviii

LIST OF APPENDICES xx

1 INTRODUCTION

1.1 Background

1.2 Objective

1.3 Problem Statements

1.4 Scope of Study

1.5 Research methodology

1.6 Thesis Outline

1

2

3

4

4

5

2 LITERATURE REVIEW

2.1 Introduction

2.2 The Ionosphere

2.2.1 Variations of the Ionosphere

2.3 HF Radio Propagation

2.3.1 Multipath Effects on HF Propagation

7

8

10

12

14

viii

2.4 Automatic and Adaptive HF Communication System

2.5 Recent Developments in HF ALE Messaging

2.6 Summary

16

17

19

3 FREQUENCY PREDICTION FOR HF

COMMUNICATION

3.1 Introduction

3.2 Types of Frequency Prediction

3.3 Ionospheric Measurement

3.3.1 Ionograms

3.3.2 MUF and LUF Calculations

3.4 Important Factors in Frequency Prediction

3.4.1 Ionospheric Models

3.4.2 Geometry of The Circuit

3.4.3 Ionospheric Index

3.4.4 Other Parameters

3.5 Advanced Stand-Alone Prediction System (ASAPS)

3.5.1 ASAPS GRAFEX Frequency Prediction

3.5.2 ASAPS Field Strength Prediction

3.5.3 Frequency Prediction for UTM Skudai-Kota

Bahru Circuit

3.5.4 Frequency Prediction for UTM Skudai-

Chemor Circuit

3.6 Summary

20

21

21

22

23

24

24

25

25

26

27

27

30

30

34

37

4 AUTOMATIC LINK ESTABLISHMENT (ALE)

4.1 Introduction

4.2 ALE Protocols and Operational Rules

4.2.1 ALE Signal Structure

4.2.1.1 Word Structure

39

40

42

43

ix

4.2.1.2 Coding

4.2.1.3 Frame Structure

4.2.2 Calling Protocol

4.2.3 Scanning

4.2.4 Sounding

4.2.5 Link Quality Analysis (LQA)

4.2.6 Automatic Channel Selection

4.2.7 Oderwire Messages

4.3 Summary

45

46

47

50

51

52

53

54

55

5 SYSTEM DESIGN and IMPLEMENTATION

5.1 Introduction

5.2 Equipments Setup

5.2.1 HF Transceiver

5.2.2 HF Modem

5.2.3 Dipole Antenna

5.3 System Design

5.3.1 PACTOR Data Format

5.3.2 ALE protocols

5.3.2.1 Frame Structure

5.3.2.2 Linking to another station

5.3.2.3 Sounding and Link Quality Analysis

(LQA)

5.3.2.4 Scanning

5.3.2.5 ALE Database

5.3.2.6 Comparison With Standard ALE

Systems

5.3.3 Graphical User Interface (GUI)

5.4 Summary

56

56

57

58

61

67

69

70

70

72

73

75

76

78

79

80

83

6 FIELD TESTING RESULT

6.1 Introduction

6.2 Equipments setup

6.3 Selection of Field-test Sites

85

86

87

x

6.3.1 Kota Bahru

6.3.2 Chemor

6.4 Channels Selection

6.5 Field-testing Timeslots

6.6 Results and Discussions

6.6.1 Skudai-Kota Bahru Reults

6.6.1.1 Sounding Results During Timeslot 1

6.6.1.2 Sounding Result During Timeslot 2

6.6.1.3 Sounding Result During Timeslot 3

6.6.1.4 Comparisons Between Skudai-Kota

Bahru Results and ASAPS Prediction

Results

6.6.2 Skudai-Chemor Result

6.6.2.1 Skudai-Chemor Sounding Results

During Timeslot 1

6.6.2.2 Skudai-Chemor Sounding Results

during Timeslot 2

6.6.2.3 Comparisons Between Skudai-Kota

Bahru Results and ASAPS Prediction

Results

6.7 Summary

88

90

91

92

93

96

97

103

109

116

118

118

125

131

133

7 Conclusions and Recommendations

7.1 Conclusions

7.2 Recommendations for Future Works

135

136

REFERENCES 138

APPENDICES 143

xi

LIST OF TABLES

TABLE

NO.

TITLE PAGE

3.1 Station specification for Skudai-Kota Bahru circuit 31

3.2 Station specification for Skudai-Chemor frequency

prediction

34

4.1 ALE Operational Rules (listed in order of decreasing

precedence)

41

4.2 ALE word type and its functions 43

5.1 Preambles and their functions 71

5.2 Example results of LQA 77

5.3 Tables in ALE database. 79

5.4 Comparisons of ALE 80

5.5 Functions available on the system’s GUI 82

6.1 List of channels used in field-testing 92

6.2 Timeslots allocation 93

6.3 LQA Score categories 95

6.4 Skudai-Kota Bahru Result Analysis for Sounding made

by Skudai during timeslot 1

99


by Kota Bahru during timeslot 1

102

6.6 Summary of LQA results for Skudai-Kota Bahru Circuit

during timeslot 1

103



105

xii



108

6.9 Summary of LQA Result for Skudai-Kota Bahru Result

during Timeslot 2

109



111



114

6.12 Summary of LQA Result for Skudai-Kota Bahru Circuit

during Timeslot 3

115

6.13 Result analysis for Sounding made by Skudai during

timeslot 1

120

6.14 Result analysis for Sounding made by Chemor during

timeslot 1

123

6.15 Summary of LQA Results for Skudai-Chemor Circuit

during Timeslot 1

125

6.16 Result analysis for Sounding Made by Skudai during

Timeslot 2

127

6.17 Result analysis for Sounding made by Chemor during

timeslot 2

129

6.18 Summary of LQA results for Skudai-Chemor Circuit

during Timeslot 2

131

xiii

LIST OF FIGURES

FIGURES NO. TITLE PAGE

2.1 The ionosphere layers 9

2.2 HF propagations 13

2.3 Multipath in HF propagation 15

3.1 Vertically indices ionosonde 22

3.2 Upper and lower frequency range for HF sky wave

communication

28

3.3 GRAFEX frequency prediction table for Skudai-Kota

Bahru circuit

31

3.4 Field Strength Table for Skudai-Kota Bahru circuit 34

3.5 GRAFEX frequency prediction table for Skudai-

Chemor circuit

35

3.6 Field Strength Table for Skudai-Chemor Circuit 37

4.1 ALE state diagram 42

4.2 The general structure of an ALE word 43

4.3 ALE word coding and interleaving process 45

4.4 Frame Structure 46

4.5 Basic call structure 48

4.6 Multiple channel call protocol 49

4.7 Structure of a sound 52

5.1 Kenwood TS570D HF transceiver 57

5.2 Connection between transceiver to computer using

RS-232C cable

58

5.3 Kantronics KAM ’98 modem 59

5.4 Wiring to connect the modem and transceiver 60

xiv

5.5 Connection between HF modem and transceiver 60

5.6 System setup 61

5.7 Dipole antenna 62

5.8 Dipole Antenna Vertical Plane Radiation Pattern 63

5.9 Dipole antenna horizontal Plane Radiation Pattern 64

5.10 Yagi antenna horizontal radiation pattern 65

5.11 Contruction of dipole antenna 66

5.12 Dipole antenna at DSP Lab, UTM 68

5.13 System flowchart 66

5.14 Basic structure of ALE 70

5.15 General structure of an ALE frame 71

5.16 Flowchart for link establishment 72

5.17 Call, response and acknowledgment frames 73

5.18 Sounding frame 75

5.19 Sounding process 73

5.20 User interface for the system 79

6.1 Equipments setup for field-testing 86

6.2 Location of field testing sites with estimated antenna

radiation pattern

87

6.3 Equipments setup at Kota Bahru station 89

6.4 Antenna setup at Kota Bahru 89

6.5 Equipments setup in Chemor 90

6.6 Antenna setup at Chemor 91

6.7 LQA result for sounding by Skudai station during

timeslot 1

98

6.8 Channels Ranking for Sounding by Skudai During

timeslot 1

98

6.9 LQA result for sounding made by Kota Bahru during

timeslot 1

101

6.10 Channels ranking for sounding by Kota Bahru during

timeslot 1

101

6.11 LQA result for sounding made by Skudai station

during timeslot 2

104

xv

6.12 Channels Ranking for Sounding by Skudai during

Timeslot 2

105


timeslot 2

107


timeslot 2

107

6.15 LQA result for sounding made by Skudai station

during timeslot 3

110

6.16 Channels ranking for sounding by Skudai during

timeslot 3

111


timeslot 3

113


timeslot 3

113

6.19 Comparisons between highest-ranked channels and

OWF values for Skudai-Kota Bahru circuit: sounding

by Skudai

116


OWF values for Skudai-Kota Bahru circuit: sounding

by Kota Bahru

117

6.21 LQA result of sounding by Skudai during timeslot 1 119

6.22 Channel ranking for sounding by Skudai during

timeslot 1

120

6.23 LQA result of sounding by Chemor during Timeslot 1 122

6.24 Channel ranking for sounding by Chemor during

timeslot 1

123

6.25 LQA result of sounding by Skudai during timeslot 2 126

6.26 Channel ranking for sounding by Skudai during

timeslot 2

126

6.27 LQA result of sounding by Chemor during timeslot 2 128

6.28 Channel ranking for sounding by Chemor during

timeslot 2

129

xvi


OWF for Skudai-Chemor Circuit: sounding by

Skudai

132


OWF for Skudai-Chemor circuit: sounding by

Chemor

132

xvii

LIST OF SYMBOLS

Iφ - Angle of incidence

cf - Critical frequency

k - Correction factor

Nf - Plasma frequency

h - Height

mh - Height of a layer’s peak

R - Levels of solar activity

Ap - Geomagnetic effects

Kp - Geomagnetic effects

TCC - Calling cycle

TSC - Scanning call cycle

TLC - Leading call section

Ts - Total scan period

Td - Dwell time

Trw - Redundant word time

Ts - Total scan period

Twr - Wait-for-response time

L - Length of the antenna

F - Desired dipole antenna frequency

xviii

LIST OF ABBREVIATIONS

AFSK - Audio FSK

ALE - Automatic Link Establishment

ALF - Absorption limiting Frequency

AMD - Automatic Message Display

AMTOR - AMateur Teleprinting Over Radio

ASAPS - Advanced Stand-Alone Prediction System

ASCII - American Standard Code for Information Interchange

BER - Bit-Error Rate

BUF - Best Usable Frequency

CDMA - Code Division Multiple Access

CME’s - Coronal Mass Ejection

CRC - Cyclic Redundancy Check

CS - Control Signals

CSMA - Carrier Sense Multiple Access

CW - Morse Code

DBM - Data Block Mode

DCE - DataCircuit-terminating Equipment

DTE - Data Terminal Equipment

DTM - Data Text Message

EIRP - Effective Isotropic Radiated Power

EMUF - E-layer Maximum Usable Frequency

EPR - Estimated Power Required

EUV - Extreme Ultraviolet

FEC - Forward Error Correction

xix

FSK - Frequency Shift Keying

GTOR - Golay Teleprinting Over Radio

HF - High Frequency

ISI - Inter Symbol Interference

LAN - Local Area Network

LQA - Link Quality Analysis

LSB - Least Significant Bit

LSB - Lower Side Band

LUF - Lowest Usable Frequency

MCMC - Malaysian Communications and Multimedia

Commission

MSB - Most Significant Bits

MUF - Maximum Usable Frequency

OWF - Optimum working Frequency

PACTOR - Packet Teleprinting Over Radio

RTCE - Real-Time Channel-Evaluation

RTTY - Radio Teletypewriter

SINAD - Signal–plus-noise-plus-distortion to noise-plus-

distortion ratio

SMARTNET - Skywave Management for Automatic Robust

Transmission Network

SNR - Signal-to-Noise Ratio

SSB - Single Sideband

TDMA - Time Division Multiple Access

TNC - Digital Terminal Node Controller

UD MUF - Upper Deciles Maximum Usable Frequency

UT - Universal Time

xx

LIST OF APPENDICES

APPENDIX TITLE PAGE

A ASAPS Prediction Results

143

B Kenwood TS570D Transceiver Specifications

148

C Kantronics Kam ’98 Modem Specifications

150

D Experimental License For HF

153

E LQA Results For Skudai-Kota Bahru Field-Testing

156

F LQA Results For Skudai-Chemor Field-Testing

161

CHAPTER I

INTRODUCTION

1.1 Background

For decades, HF radio frequencies spectrum from 3 to 30 MHz has been used

as a medium for long distance communication. This is possible because these bands

of frequencies are reflected back to earth by free electrons in the ionosphere layer.

By using the proper frequency and set of equipments, a person can communicate

with another person as far away as on the other end of the earth via the HF layer.

Moreover, transmissions of digital data such as text, fax and images is also possible

by using HF modem, which converts digital data into analog form when transmitting,

and converts analog data to digital form when receiving.

Compared to satellite communication, the cost to set up and maintain a HF

communication system is much lower [Abdullah et. all, 2003]. Also, unlike the high

payment needed to use satellite communication services, the usage of HF does not

require payment to any service provider. HF communication however, suffers from

several propagation problems and effects from the variation of the ionosphere layer.

But today, with new technologies and many researches done, HF radio’s usage has

been expanded and propagation problems can be overcome. Adaptive and automatic

2

radio technology for example, permits modern radio systems to adjust automatically

to changing propagation condition [Hess, 2000].

The purpose of this research is to design a HF messaging system that has

automatic link establishment (ALE) capability. The messaging system allows digital

data to be exchanged via HF medium. ALE is an adaptive radio technology, which

make HF radio communication more reliable and less prone to propagation problems

by automatically selecting the best channel to use at any given time and place.

1.2 Objective

The objective of this research is to allow effective and reliable data

transmission over HF radio with ALE capability. The system is to be built with

minimum cost and equipments so that it can be made available to amateur radio

operator, telemetry and shipping. The main features of this research are as follows:

i) Design a HF messaging system

ii) Improve the reliability of data transmission of the messaging system

by including ALE capability to the messaging system.

iii) ALE is implemented as software.

iv) Commercial modems and radios are used as the building block of

the system.

v) Field testing is conducted to verify the system.

3

1.3 Problem Statement

Unlike telephone line and fiber optic, the HF environment is not noiseless as

interference does exist; transmitted signal is distorted and with high noise levels

[Goodman, 1992]. The effects of multipath fading and interference are significant in

HF communication. Moreover, its propagation environment is also constantly

changing due to the seasonal and diurnal variations in the ionosphere. Propagation

conditions vary by location, frequency, season, time of day, and can be affected by

unexpected ionospheric disturbance.

The main challenge in HF communication is to choose the most suitable

frequency to be used for communication. Conventionally, radio operators must

always listen to HF channels, to find available channel for communication. However,

in order to do this, the operators must be highly trained in operating a HF radio,

besides knowledgeable in HF radio propagation and channel predictions. Another

way is by using propagation prediction programs that predict the best channel based

on empirical data. Unfortunately, this is not the best way to determine the best

channel for communication. The frequency prediction method does not give real time

channel evaluation because all the data are obtained from calculation and forecasting.

Sometimes, the data acquired are not accurate. This is due to unpredictable

propagation factors such as sporadic E-layer propagations, interference from other

users on an otherwise usable channel [Johnson et al, 1997]. To solve this problem,

ALE is used. ALE performs real time channel evaluation, and helps select the most

suitable frequency to be used at different time of day.

Even though ALE can help improve the reliability of HF communication,

available ALE systems today are in a form of optional equipment for HF system. The

equipment is usually known as ALE controller and has its own modem for ALE

purposes. Thus users who want to experience the benefits of using ALE, has to buy

the expensive equipments and end up having two different modems, each for ALE

and data transmission.

4

1.4 Scope of Study

Existing systems such as ALE controllers developed by Rockwell-Collins

Company [Rockwell-Collins, 2004] and Rhode-Schwarz Company [Rohde-Schwarz, 2004],

implement ALE as additional equipment, which controls an HF radio. However in

this research, ALE is implemented as software and part of a messaging system. Thus

in the system developed in this research, no additional equipment is needed for ALE.

The scope of this research are as follows:

i) This research does not involve building a HF radio and HF modem.

Existing radio and modem is used.

ii) The equipment compatible with the system are limited to

KENWOOD TS-570D HF Transceiver and Kantronics Kam 98 HF

modem. This is because other equipments require different

controlling methods and may not be suitable for the system

designed in this research.

iii) Unlike existing systems, this system will use the same modem for

both data transmission and ALE purposes.

1.5 Research Methodology

The following steps are taken to achieve the research objective:

i) To understand the basic concept and problems, literature and

technology review on HF communication was done. Review on ALE

technology and available HF messaging systems is also required for

comparison and reference.

5

ii) Attend DSP and digital communication courses to enhance basic

knowledge on the area of the research.

iii) The system design begun with building a messaging system using

Visual C++. This system connects two computers via HF radio as a

medium. The program is capable to control basic functions of both

transceiver and modem such as transmitting data and scanning

through channels (for transceiver).

iv) The next step is to design the ALE system, first for single channel

followed by multiple channels. Next sounding processes, together

with link quality analysis (LQA) are included to the system.

v) Before testing the system, frequency prediction was done. The

purpose of this is to choose the suitable channel to use for field-

testing. Advanced Stand-Alone Prediction System (ASAPS) is the

frequency prediction software chosen used for this purpose.

vi) The final step was field-testing that which was conducted at several

sites in Malaysia.

1.6 Thesis Outline

This report is divided into seven chapters. Chapter 1 is the introduction;

which includes objective, scope of study, and problem statement. Next, in chapter 2,

the literature review on HF radio, including its propagation characteristic and

problems. Other than that, recent developments in adaptive HF radio communication

systems are also presented. Then chapter 3 describes on frequency management and

prediction, an important tool in HF communication. Next, explanation on ALE is

presented in chapter 4. In this chapter, the concept and theory of ALE is described

6

including the frame structures and protocols used. Following after that is Chapter 5,

which concentrate in explaining system design and implementation. This chapter

explains in detail how the system is built, including equipments used, system

requirements and ALE protocols. Then the result of the system’s field-testing is

presented in chapter 6. Here, the LQA results are presented using graphs and then

discussions are done based on the results. Finally the last chapter, which is chapter 7,

is for conclusion and recommendations.

137

ii) Other ALE features such as orderwire message capability and multi stations

application can also be added to the system.

iii) To upgrade the efficiency of this system, the predicted results from

propagation prediction programs such as ASAPS should be uploaded

automatically by the system. The system can also be made able to select

which frequencies to be used automatically based on the results from

propagation prediction software. Frequency selection should be based on

predicted OWF, MUF, ALF and also the SNR of the possibly usable

frequencies.

iv) The field-testing sites selected in this research are both located in peninsular

Malaysia. For future work, the field-testing sites can be expanded to location

outside peninsular Malaysia. Other than that, field-testing can also be done

between land and sea (on ship).

v) Finally, this system can also be upgraded to make it available to use with

other type of HF radio and modem.

138

REFFERENCES

Cook, S.C. (1997), HF Communications In the Information Age, IEEE Conference

on HF Radio Systems and Techniques, July 7 –9. Nottingham UK: IEEE, 1-5.

Abdullah, M.A., Husni, E.M., S. Hassan, S.I. (2003), Investigation of a Rural

telecommunication System using VSAT Technology in Malaysia. 9th Asia

Pacific Conference on Communications, 2003(APCC), Septrmber 21-24,

Penang,Malaysia: IEEE, 990-993.

National Telecommunications and Information Administration (NTIA) (1998). High

Frequency Radio Automatic Link Establishment (ALE) Application Handbook.

Washington D.C, U.S.A: NTIA.

U.S. National Communications System Office of Technology & Standards (NCS)

(1993). Federal Standard 1045A:Telecommunications: HF Radio Automatic

Link Establishment. Washington D.C., FED-STD 1045A.

U.S. National Communications System Office Of Technology & Standards (NCS)

(1996). Federal Standard 1037C Telecommunications: Glossary of

Telecommunication Term. Washington D.C., FED-STD 1037C.

U.S Department of Defense (1999). Interoperability and Performance Standards For

Medium And High Frequency Radio System. Washington D.C., MIL-STD-188-

141B.

Harris Corporation (1996). Radio Communications in the Digital Age Volume I: HF

Technology. U.S.A: Harris Corporation.

139

McNamara, L.F. (1991). Ionosphere: Communications, Surveillence, and Direction

Finding. Malabar, Florida: Krieger Publishing Company.

Goodman, J.M (1992), HF Communications Science and Technology. New York:

Van Nostrand Reinhold.

Goodman J.M, Reilly M.H. (1998), “Shortwave Propagation Prediction

Methodologies”, IEEE Transactions on Broadcasting. IEEE, Vol. 34, No. 2.

Johnson, E.E., Desourdis Jr., R. I., Earle, G.D., Cook, S.C., and Ostergaard, J.C.

(1997). Advanced High-Frequency Radio Communications. Norwood, M.A.:

Artech House.

Johnson, E.E. (1998), Third-Generation Technologies for HF Radio Networking.

1998 IEEE Military Communications Conference (MILCOM '98). October 18 –

21. Boston, MA: IEEE, 386-390 vol.2.

Johnson, E.E. (2000), Analysis of Third-Generation Technologies for HF Radio

Networking. 2000 IEEE Military Communications Conference (MILCOM

2000). October 20-25. Los Angeles, CA: IEEE, 1139-1143 vol.2.

Johnson, E.E. (2001). E-Mail Standards for HF Radio: Technical Report. New

Mexico: New Mexico State University.

Lay, R (1996), Error correction in high frequency automatic link establishment

radios with and without link protection, Military Communications

Conference1996 (MILCOM '96). October 21-24. McLean, VA: IEEE, 696 -

699 vol.3.

Beamish B. (1991). Automatic Link Establishment (ALE) – The Automation of HF

Radio. Engineering Application Note AP-8. Harris Corporation.

Redding, C., Weddle, D. (1994 ). Adaptive HF radio test results using real-time

channel evaluation systems. Military Communications Conference, 1994.

140

(MILCOM '94). 1994, 2-5 November Fort Monmouth, NJ: IEEE, 890 - 894

vol.3.

Street, M.D., Darnell, M. (1996). Results of New Automatic Link Establishment and

Maintenance Techniques for HF Rradio Systems. Proceedings of Military

Communications Conference 1994 (MILCOM 1996). 2-5 November. Fort

Monmouth, NJ: IEEE, 1067-1071.

Willink, T.J.; Davies, N.C.; Clarke, J.; Jorgenson, M.B. (1996), Validation of HF

channel simulators, IEE Colloquium on Frequency Selection and Management

Techniques for HF Communications. 7-8 February 1996. London, UK: IEEE,

13/1 -13/6

Riley, T.J. (1997) A comparison of HF radio digital protocols., HF Radio Systems

and Techniques, Seventh International Conference on. 7-10 July 1997,

Nottingham: IEEE, 206 – 210.

Soyer, L. (2001) HF Messenger: European Trials and R&D Efforts, IEEE Military

Communications Conference 2001. (MILCOM 2001). 28-31 October. Mclean,

VA: IEEE, 491- 500 vol.1

Renfree, P. ( 2001), The US Navy returns to HF with STANAG 5066 as the path.

Military Communications Conference, 2001 (MILCOM 2001). 28-31 October,

Mclean, VA: IEEE, 471-476 vol.1

Blair, W., Au, T.A., Taylor, R. (2000), Improving the performance of a high

frequency radio message network. Proceedings of Military Communications

Conference 2000 (Milcom 2000). 22-25 October, Los Angeles: IEEE, 48-53.

Hess, A.M., ( 2000), Advanced Use of LQA data in improving the quality and the

speed of ALE link establishment while reducing sounding requirements in HF

141

networks, Eighth International Conference on HF Radio Systems and

Techniques, 10-13 July. Guildford, UK: IEEE, 91-94.

Kenwood Corp., HF Transceiver TS-570D Instruction Manual.

Kantronics Co. (1998), Kantronics KAM ’98 Multi-Mode HF/VHF Digital Controller

User’s Guide. U.S.A: Kantronics Co.

Australian Space Weather Agency (2003). ASAPS 5 User Guide

Rohde-Schwarz (2005). ALE - Automatic Link Establishment. In: Application Note.

©2005 ROHDE&SCHWARZ. All rights reserved. http://www.rohde-

schwarz.com.

Australian Space Weather Agency (2005). Introduction to HF Radio Propagation. In

IPS Radio and Space Services. http://www.ips.gov.au

Rockwell Collins (2004), Automatic link Establishment: Product Catalog.

http://www.rockwellcollins.com/

Cruiseemail (2004), CruiseEmail User manual. http://www.cruiseemail.com/

Army Knowledge Online (2003). Multi-Service Tactics, Techniques, and Procedures

for The High Frequency-Automatic Link Establishment (HF-ALE) Radios. In:

Army Knowledge Online. U.S Air, Land and Sea Application Center.

www.us.army.mil

Sailmail (2005), Sailmail : Email Services for Yachts via Marine HF SSB Radio. In:

http://www.sailmail.com/

Wan Roz Wan Hussain (2004), Meeting with UTM on HF Communication, RF

Communications (M) Sdn Bhd, Kuala Lumpur, 19 June 2004.

142

ARRL (2001). The Arrl Handbook for Radio Amateurs 2002. 79th edition. USA: The

American Radio Relay league, Inc.

U.S. Department of Commerce (2005). U.S. Department of Commerce NTIA/ITS

Institute for Telecommunication Sciences High Frequency Propagation Models in

http://elbert.its.bldrdoc.gov/hf.html

Rockwell-Collins (2005). PropMan-2000-Propagation Resource Manager product

catalog In: http://www.rockwellcollins.com/ecat/gs/PropMan-2000.html © Rockwell

Collins, Inc. All rights reserved.

Carr J. J (2001), Practical Antenna Handbook Fourth Edition. Hightstown, N.J:

McGraw-Hill.

hf messaging system with automatic link...

Documents