1. TD-1235 Loop Group Multiplexer
CECOM LAR Tropo Operation Course
TD-1235 Loop Group Multiplexer
CECOM LAR Course
CONUS Branch
FT McPherson, GA
This is the 1st Level of multiplexer in the TRC-170.
TD-1235 LGM

2. CECOM LAR Tropo Operation Course
Purpose
Multiplexes 7, 8, 15 or 16 Channels at a channel rate of 16 or 32 KB/s into one Group
Recap slide
Explain how multiplexers work.
TD-1235 LGM

3. CECOM LAR Tropo Operation Course
Specifications
Dimensions 17.25” X 8.5” X 12” deep
Weight 35.2 LB
Input Power 115 V AC  10%, 47.5 to 440 Hz
Recap slide
Point out power requirements
TD-1235 LGM

4. CECOM LAR Tropo Operation Course
Output Data Rate
16 KB/s Channels Rate
7 Channels 128 KB/s
8 Channels 144 KB/s
15 Channels 256 KB/s
16 Channels 288 KB/s
32 KB/s Channels Rate
7 Channels 256 KB/s
8 Channels 288 KB/s
15 Channels 512 KB/s
16 Channels 576 KB/s
Recap Slide
TD-1235 LGM

5. CECOM LAR Tropo Operation Course
Block Diagram
Recap Slide
TD-1235 LGM

6. CECOM LAR Tropo Operation Course
CCA Locations
A) AC INPUT-A1-Provides rectified ac, sums system faults, drives indicator lamps, and initiates nuclear shutdown.
B) MULTI VDC-A2-Provides +/- 5 and +/- 10 VDC
C) 52 VDC-A3-Provides +52 VDC for loop modem CCAs
D) BITE 2-A4-Detects and indicates faults.
E) TMG GEN-A5-Provides timing signals necessary for framing, synchronization and multiplexing/demultiplexing.
F) LP MDM-A6 to A13- Provides modulation and demodulation of the digital channels. Provides power for DNVT AND DSVT.
G) AAU A6 to A13- Provides duplex processing with 2 independent analog channels. Simultaneously converts digital baseband NRZ data to analog voice. Converts analog voice to digital baseband.
H) MUX DEMUX-A14- Multiplexes/demultiplexes channels and subchannels into/out of a group data stream.
I) GP FRG-A15- Controls framing routine
J) INTFC-A16- Provides group interface of data and timing signals.
TD-1235 LGM

7. CECOM LAR Tropo Operation Course
Lamps and Switches
A) ALARM TEST-Push-button Energizes the BITE circuits in a test mode to light up all fault lamps on the LGM, and fault LEDs on logic CCAs.
B) ALARM- LOSS OF INPUT- Lamp Lights if the LGM loses an external input. The appropriate CCA fault lamp also lights
C) ALARM-PWR SPLY-Lamp Lights if one or more power supply output voltages are out of tolerance.
D) ALARM-SUMMARY-Lamp Lights if any fault is detected by the LGM
E) LABEL-Label Identifies internal controls and indicators.
F) POWER-ON/OFF-Toggle switch Switches 115 VAC to power supply ON or OFF.
G) POWER Lamp- Lights when power to power supply circuits is on.
H) MAIN POWER BREAKER Circuit Breaker-Trips when an overload exists in the LGM. Can be reset by throwing the circuit breaker to the on position.
TD-1235 LGM

8. CECOM LAR Tropo Operation Course
Switches (Contd)
K. Selects 16 or 32 kbs data rate
Provides power to external phones when set to ON. Note that lower switch is for ODD channels and upper switch is for EVEN channels
When AAU card is in these slots, switch is set down for test or loopback to user. Should be Up for Normal operation.
If TGM is used, set to Loop. If standalone LGM, set to STA.
TD-1235 LGM

9. CECOM LAR Tropo Operation Course
Fault Indicators
A) FAULT Red LED- Lights if fault is detected on AC input CCA.
B) FAULT Red LED- Lights if fault is detected on multi VDC CCA.
C) FAULT Red LED- Lights if fault is detected on 52 VDC CCA.
D) FAULT Red LED- Lights if timing generator CCA malfunction or lacks proper input.
E) FAULT Red LED- Lights if Loop modem CCA malfunction or lacks proper input.
F) FAULT Red LED- Lights if analog applique CCA malfunction or lacks proper input.
G) FAULT Red LED- Lights if mux/demux CCA malfunction or lacks proper input.
H) FAULT Red LED- Lights if group framing CCA malfunction or lacks proper input.
I) FAULT Red LED- Lights if interface CCA malfunction or lacks proper input.
J) OOF Red LED- Lights if receive group frame sync is lost.
TD-1235 LGM

10. CECOM LAR Tropo Operation Course
AAU Card Settings
P) CHANNEL TRANSMIT GAIN
4 POLE SLIDE ACTUATOR DIP SWITCH SPST Selects required channel INPUT gain
Q) CHANNEL RECEIVE GAIN
4 POLE SLIDE ACTUATOR DIP SWITCH SPST Selects required channel OUTPUT gain
TD-1235 LGM

11. Group Rate Switch Settings
CECOM LAR Tropo Operation Course
Group Rate Switch Settings
Rate Switch KB/s Channels
Recap Slide
TD-1235 LGM

12. CECOM LAR Tropo Operation Course
Summary
1st Level Multiplexer
7-16 Channels at 16 or 32 KB/s
Analog or Digital Channels
Output Data Rates of 128 to 576 KB/s
Recap slide
TD-1235 LGM