AMT-70/AMT-73/AMT-75 Installation and Operation
This example will change the 5 Mbps data rate to 2.048 Mbps, the FEC to eTPC (Turbo) with a 8/9
code rate. The Tx and Rx frequencies also change from 1 GHz to 950 MHz.
4.1.2 Placing Modem Online
Before placing a modem online, it is important to turn off the transmit carrier and perhaps the DC
voltages and 10 MHz Reference to the BUC and LNB. These are found in menus TX – SGN OFF,
FUNC – CONTROL – BUC - REF OFF, FUNC – CONTROL – LNB –LNBPWR OFF, and FUNC –
CONTROL – LNB - LNBREF OFF.
The following example programs the modem to 8PSK, ¾ Rate TPC, the data rate to 256 kbps, and the
Tx and Rx L band frequencies set as indicated. The demodulator utilizes the FFT mode for acquisition.
Figure 10: Modem Commands Quick Start Guide
PARAMETER CURRENT
VALUE
DESIRED
VALUE
PARAMETER CURRENT
VALUE
DESIRED
VALUE
TX Main Menu RX Main Menu
MOD QPSK 8PSK DEMOD QPSK 8PSK
UNITS BPS BPS UNITS BPS BPS
CARR FRQ 1000000000Hz 1234567000Hz CARR FRQ 1000000000Hz 1234590000Hz
DATA 005000000BPS 256000BPS DATA 005000000BPS 256000BPS
CODE INTELSAT TPC4K CODE INTELSAT TPC4K
RATE 1/2 3/4 RATE 1/2 3/4
RSRATE OFF OFF DESCRAM ON ON
SGN ON OFF RSRATE OFF OFF
DIFF ON ON LNBTO OFF OFF or ON
INPUT INTERNAL_PRBS EXTERNAL LNBVP OFF OFF or ON
OUTPUT LBAND LBAND LNBPWR OFF OFF
TX 2_23 Any REF EXT INT or EXT
SPTRM INV NORMAL Either ALPHA 0.35 0.35
ALPHA 0.35 0.35 DIFF ON ON
SCRAM ON ON SSIZE 50000 Auto, FFT mode
INTL DEPTH4 Either SWEEP 250000 Auto, FFT mode
REF OFF Either SPTRM INV AUTO AUTO
INTERFACE Menu CARD
INPUT INPUT1 INPUT1 or 2
MODE rs530 Any, except
disable
RAW DATA
INTERLEAVER DEPTH4 Either
59
NOTE:
When completed with the bench testing, remember that the Modulator is in the BER test mode. To
return the Modulator to an operational status (passing external data), go to TX (MAIN MENU), hit
ENT, arrow down to INPUT, hit ENT, arrow to EXTERNAL or required ASI mode, and hit ENT
again. Follow this with TX RECONFIGURE and hit ENT twice.
NOTE:
The BUC and LNB Power and Reference are not currently available for the AMT-73L modem. The
AMT-73L also has only one Rx input.
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General