The document describes the Gesmod management and control system for a transmitter. Gesmod provides centralized supervision and control, interfaces between system components, and implements encoding algorithms. It contains several electronic boards including an SBC computer board, digital I/O boards, an MMI interface, and boards for safety devices, measurements, blocking functions, and encoding. Gesmod processes inputs, generates control signals, and monitors the transmitter system.

1. Ge s mo d
[Management and Control system]

2. Gesmod functions
 Provides the centralized supervision and control function for the
entire transmitter.
 Provides interface to I/O between the MMI, computer and the
transmitter.
 Provided with DSP tools for processing the encoding algorithm for
generating fourth command to CSM and phase controlled PAs.
 Provided with supervision circuit to maintain the transmitter in proper
working condition
 Provided with instrumentation circuits to acquire critical analog feeds
of the transmitter
 The control function is implemented through a 16 bit micro processor
based DAQ unit consisting of industry standard Gespac bus, SBC
and data I/O cards.

3. Gesmod electronics
 Single board computer board, type SBC 330 for control function
 Three numbers of 16 digital input, 16 digital output boards, type MPL 4253-1 and one
number of 32 bit digital input board, type MPL 4255 for digital I/O
 Man machine interface unit [MMI] for local operation
 Ethernet (LAN) board for remote operation
 Fast blocking board for processing operational commands, interlocking, alarms, blocking
the transmitter etc
 Fast VSWR board to monitor the load and for generating emergency blocking command,
if required
 Encoder board for processing the modulation algorithm
 Safety device/measurement board for processing the analog metering feeds
 Internal bus board GESBUS G96 for interconnecting and data exchange for above boards.
 Two numbers of Pilot boards and selection board for generating carrier frequency
 LED bargraph Indication for transmitter I/O signals to ease fault tracing and debugging
 Motherboard for providing external signal connections and interconnection for all the above
boards

4. Block schematic of Gesmod

5. LED Bargraph DS-1 to DS4
details
There are 120 such LED indication on the transmitter

6. Transmitter interface

7. SBC330 card
 Based on Motorola 16 bit MC68330 micro processor
 Two sockets for 16-bit EPROM: 1 or 4 Mbits versions.
 Standard 256 Kbytes of SRAM memory included.
 Two 32-pin DIL sockets for additional memory devices:
SRAM, PEROM or EPROM devices accepted.
 Battery back up for SRAM.
 Real-time clock and calendar DP8570A with battery.
 Three general-purpose timers, plus bus time-out logic,
software watchdog, periodic interrupt timer etc.

8. Digital Input/Output boards, MPL 4253 [1/2]
 16 industrial optically inputs
 16 industrial outputs
 Sink or source input selectable
 Input voltage range from 12V to 24V
 Input current 14mA at 24V, Output current up to 100mA per
channel
 1500VDC opto-coupler isolation voltage
 Full G-64/96 bus interface
 Compact 3U height Euro card design (100*160mm)
 Single power supply +5V/ typical

9. Digital Input/Output boards, MPL 4253 [2/2]

10. Man-machine interface
 Alpha numeric, dot matrix, touch screen LCD display for Control,
supervision and status display
 Control and monitoring through remote computer using Ethernet
interface
 Emergency shut down control button

11. Safety device and measurement board [1/4]
 Signal conditioning circuits
 Parameter extraction circuits
 Data converter devices
 Analog comparators for threshold setting of important feeds
This board contains following electronic hardware circuits for
measuring, extracting and computing the various important
analog feeds of the transmitter.

12. Safety device and measurement board [2/4]
Analog feeds acquired

13. Safety device and measurement board [3/4]

14. Safety device and measurement board [4/4]
Analog set detector

15. Fast VSWR board
 Board receives forward and reflected RF signal directly
from the directional coupler mounted at the output.
 Provided with the ultra fast analog comparator which
compares the set VSWR to the actual VSWR to
generate a direct hardware command to the control
system to block the transmitter, in case, of abnormal
load conditions.

16. Fast blocking board
 This board centralizes, processes and controls all the
alarms and fault signals of the transmitter.
 All the type-I faults and some of the type-2 fault related to
external elements of the transmitter is supplied to this
card for processing.
 This board also processes user initiated intentional
blockages, emergency shutdown commands, set up
command from SBC 330 card, status signals like switch
position, switching signals from sensors from MPL 4253
and MPL 4255 card, analog status signals from safety
device and measurement board.
 On appearance of a fault or on command, the board
generates a command to the encoder which in turn blocks
the RF excitation and switching command to PAs thus
shutting down the transmitter followed by flashing of
appropriate indications on the MMI.
Functions [1/2]

17. Fast blocking board
 In the event to type-1 fault, which is categorised as a
temporary fault, the transmitter is returned to service after
500 mSec or a 3 second interruptions depending on the
number of transmitter faults.
 For each operation of type-1 fault, an integrator counter is
incremented by one unit. When the counter reaches a value
greater than or equal to 4, an integrator fault is generated
and transmitter is forced to stop by the board.
 These signals are processed and necessary command,
fault/alarm signals are generated by this board for display on
the MMI and also for controlling the transmitter through
Encoder card.
 All the specific Boolean function/expression required for the
control/logic function of the transmitter is implemented by
the card using six numbers of CMOS flash erasable
Programmable Array Logic (PAL) devices type P22V10.
 PAL is loosely defined as a device with configurable logic
realized through flip-flops linked together with programmable
Functions [2/2]

18. Encoder board

19. Encoder board [2/7]
 Converts the the analogue modulating signal to a digital
word using Σ-∆ analog to digital converter
 Generates 4th
state command for the CSM PA module
 Generates 4th
state command for the phase control of the
dedicated modules
 Implements rotation of the modules to ensure thermal
distribution among the PA modules
 Blocks the 4th
state command to all the PAs in case of fault
situation
Functions of Encoder board [2/2]

20. Encoder board [1/7]
Number of PA modules to be switched is function of:
 Instantaneous amplitude of the modulating audio signal.
 Audio attenuation level set by the user.
 Modulation type i.e. AM-DSB/DCC chosen by the user.
 Number of healthy module in the transmitter
 Power level set by the user or determined by the transmitter control in
case of faulty condition.
Functions of Encoder board [1/2]

21. Encoder board [3/7]
• Adopts patented MPM-P3 technique for modulation
[Multi parameter modulator with pulse precision phase]
Algorithm [1/4]

22. Encoder board [4/7]
• The time interval between the two successive computations is close of 0.5 µs
and number of dedicated modules to be activated can range from 1 to 7.
• The instantaneous amplitude of the modulated RF signal is obtained by vector
summing of the output of the CSM and dedicated modules in real-time.
• The envelope is processed for obtaining the information on audio attenuation
setting made by the user and instantaneous amplitude of the modulating signal
i.e. audio.
• Above information along with type of modulation process selected by the user
i.e. AM-DSB or DCC and the RF power level shall determine the number of
CSM PA modules to be switched ON or OFF at a particular instance.
• The number of dedicated modules to be activated at a particular instance is
computed from the number of CSM modules activated at time ‘t’ [N(t)] in
relation to the value to be reached at time t+1 [N(t+1)]. This information is
obtained by delaying the processing by 1 cycle and saving the information.
Algorithm [2/4]

23. Encoder board [5/7]
• If N(t) > N(t+1) then, negative slope process is selected or
if N(t) < N(t+1) then, positive slope process is selected. Using this
information, the number of dedicated modules to be switched will be
decided.
• The N(t) - N(t+1) shall decide the rotation processing strategy for the
main module.
• The module pairs to be activated are distributed in an equal number (to
within one) on the 4 amplifier assemblies of a block.
• To maintain RF current balance in both the RF lines, rotation is affected in
unison in Bank A- B and Bank C- D.
• Rotation is effected in first-in-last-out basis
• Encoder sends out status and the number of the module to be switched
ON or OFF in binary encoded format to the daughter board of the remote
distribution circuits through optically isolated electronics (DH1 to DH28).
Algorithm [3/4]

24. Encoder board [6/7]
• Remote distribution board decodes this information and controls the
change of state of the modules.
• Information on the valid (healthy) module pairs is obtained from the
control system through the remote distribution circuits via optically
isolated signal path. GESMOD polls each PA module to obtain this
information.
• Data from DSP is interfaced to the transmitter through 1K x 8
Dual-Port Static RAM CY7C131 (MN49 to MN52) / 16-bit edge-
triggered D-type registers 74FCT16374 (MN81 and MN82) / Opto
coupler HCPC 7101 (DH1 to DH 28) and switching transistors
MPQ2222 (Q4A to Q9D) to G64/96 bus of GESMOD (A4 to A29).
 All above computation, processing and implementation is
carried out in real time using industrial grade DSP
processors.
Algorithm [4/4]

25. Encoder board [7/7]
M o d u l a t io n S t r a t e g y F u n c t io n a l A r c h it e c t u r e
N ( t ) - N ( t + 1 )
M e m o r y
D e l a y
R o t a t i o n
C l o c k
P r o c e s s i n g
S t r a t e g y
5
R o t a t i o n C l o c k
E n v e l o p e
P r o c e s s i n g
B a n k A B
R o t a t i o n p r o c e s s i n g
+ C o m p u t a t i o n N ( t ) - N ( t + 1 )
B a n k C D
R o t a t i o n p r o c e s s i n g
+ C o m p u t a t i o n N ( t ) - N ( t + 1 )
B a n k
A B C D
R e p a r t i t i o n
R F
P r o c e s s i n g
R F
S l o p e
P r o c e s s i n g
N ( t + n )
N ( t )
S t a n d a r d M o d u le s
M ( 1 - 1 2 4 )
E n v e lo p e
R A M D P A
R A M D P B
R A M D P C
R A M D P D
F r o m c o n t r o l S y s t e m
( G e s m o d )
R e a l t i m e t a b l e o f
O p e r a t i o n R F M o d u l e s
2 x 3 1
2 x 3 1
2 x 3 1
2 x 3 1
D e d ic a t e d m o d u le s m ( 1 - 7 )
C l o c k M
C l o c k M
S +
S -
M U X
m
D i s t r i b u t o r
p o s i t i o n S l o p e
p r o c e s s i n g a n d
p h a s e d e l a y
o p t i m i s e r
7
S lo p e S ig n C o n t r o l
N e g a t i v e S l o p e
p r o c e s s i n g a n d
p h a s e d e l a y
o p t i m i s e r
3
21
4
7
3
6
6
6
1 1
1 08
9
9
6