Evolution of High power AM transmitter technology

and

Comparison of type S7HP and TMW2100 transmitters

AM-DSB modulation in communication

AM is the least efficient mode of communication

Hence, the process of generation of high power AM-DSB signals needs to be highly efficient

Evolution of AM Transmitter technology

Class-C PA and Class-B modulator using triodes Class-D PA and Class-B modulator using tetrodes PSM modulator using GTOs replaces Class-B

modulator Dynamic carrier control for electrical energy saving MOSFET as high speed switching element and DSP

to implement the switching algorithm

Connection topology of RF modules in series

DSPem

Ec

Connection topology of RF modules in parallel

Connection topology of RF modules in series || parallel

Comparison of the topology

SERIAL PARALLEL MIXED

O P ER A T IO N

M O D UL E V O L T A G E AD D E DSA M E C UR R E NT

M O D UL E C UR R ENT AD D E DSA M E V O L T A G E

M O D UL E V O L T A G E ANDC UR R ENT

AD D E D A ND C O M B INE D

S T A B IL IT Y W IT H O NE O RM O R E M O D UL E O UT O F

O R D E R

ST A B L EP O W ER D E C R E A S ES

UNS T AB L EPO W E R R E M A INS C O NS T ANT

S T A B L E UND E R C O ND IT IO NSM A L L UNBA L A NC E D V O L T A G E

D IF F E R ENC E

D IS A B L E D M O D UL EM O D UL E F AUL T A L L O W ED

S HO R T -C IR C UITT HE NO R M A L T R A NS IST O R

F A IL UR E M O D E

O PE N C IR C UITNE E D A D D IT IO NA L

PR O T E C T IO N

S HO R T C IR C UIT L IM IT E DNUM B E R O F F A UL T Y M O D UL E

L IM IT E D

L IM IT A T IO N HIG H V O L T A G E L INE L E NG T HL O AD V A R IA T IO N

HIG H C UR R E NTL O W IM P E D A NC E

INC R EA S E D L O S S E S

VO L T A G E A NDC UR R E NT C O M B INED

T HO M C AS T S O L UT IO N1 2 0 T O 1 6 0 M O D UL E S

IN S ER IAL1 5 0 kW

NIL2 L INE S O F 1 2 8 M O D UL E S IN

SE R IA L4 0 0 kW

P HA S E VA R IA T IO N AL L O W E D F O R BID D EN AL L O W E D

Comparison of S7HP and TMW 2100

Similarities in S7HP and TMW 2100 The electronic designs are very much similar Solid state modules are used in RF power building Uses MOSFETs as high speed Switching devices in a

H-bridge configuration for developing the final RF power Uses DSP processors for implementing the algorithms for

module switching, thermal balancing, rotation etc No hot plugging of PA modules Uses phase modulation to get fine envelope Control through MMI, remote terminal etc Boards are not inter-changeable Built in DCC DRM ready

Differences in S7HP and TMW 2100

PA connection topology Series – parallel Series

Cooling Water and air Air

Phase control 7 Dedicated PAs All PAs

Signal distribution

Through distribution

board one each for 16 modules

Through distribution

board one for block of each 5

modules

Differences in S7HP and TMW 2100

Power output of each module 2.34 kW 1.25 kW

Number of PAs 255 80

PA Module monitoring Through fuse status

Through fuse status and

differential phase of I/P and O/P

signals

Power build up239 CSM

controlled PAAll 80 are CSM cum

phase controlled

5 kW Power pack of TMW2100

Schematic of PA used in TMW 2100

Timing diagram of the control signals fc+ and fc- in PA module of TMW 2100

Schematic of PA used in S7HP