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CDM-625 Advanced Satellite Modem
Front Panel Operation
5.2.2 SELECT: Test Menus
TEST:
CnC-APC-Monitor
Use the
◄ ►
arrow keys to select Mode, BERT, CnC-APC-Monitor, or Uncorrected-BER, and
then press ENTER.
SELECT: TEST Mode
5.2.2.1
(NORM,Tx-CW,Tx-1/0,IF↓,RF↓,DIG↓,I/O↓)
Select Normal Operation or a Test Mode from the parameters shown in the parentheses. Use
the
arrow keys, and then press ENTER, to select one of the following modes:
▲▼
Selection
NORM
Tx-CW
Tx-Alt-1/0
(Tx-1/0)
IF-LOOP (IF↓)
RF-LOOP (RF↓)
Dig-Loop
(DIG↓)
I/O-Loop (IF↓)
Mode
BERT
Modem Test Mode = Normal
Function
(Normal) This c lears any t est modes or l oopbacks, and pl aces t he uni t bac k i nto an
operational state.
(Transmit C W) Use t his test m ode to f orce t he m odulator t o t ransmit a pur e c arrier
(unmodulated).
(Transmit an al ternating 1, 0,1,0 p attern) Use t his test mode t o c heck t he carrier
suppression of the Modulator This mode forces the modulator to transmit a carrier modulated
with an al ternating 1,0,1,0 pat tern, at the currently selected symbol rate; t his causes two
discrete s pectral l ines t o appe ar, s paced at ± half t he s ymbol r ate, about t he c arrier
frequency.
(IF Loopback) Use this test mode to invoke an i nternal IF loop. This is a par ticularly useful
feature, as it permits you to perform a quick diagnostic test without having to disturb external
cabling. Furthermore, all of the receive configuration parameters are temporarily changed to
match t hose of t he t ransmit s ide. All pr evious values ar e restored onc e Normal is agai n
selected.
(RF Loopback) Use this test mode to perform a satellite loopback. It is almost identical to the
IF loop mode, except that all receive configuration parameters (except Rx Spectrum Invert)
are temporarily changed to match those of the transmit side; however, no internal connection
is made. All previous values are restored once Normal is again selected.
(Digital Loopback) Use this test mode to invoke a di gital loopback, which loops data at the
output of the Reed-Solomon encoder on t he transmit side and back into the Reed-Solomon
decoder on t he receive side. This tests the entire interface, transmit baseband circuits, FEC
encoder, FEC decoder, and buffer.
(Inward/Outward Loopback) Use this test mode to invoke two distinct loopbacks. The first is
the i nward l oop, w hich t akes dat a bei ng r eceived f rom t he s atellite di rection and pas ses i t
directly to the modulator. Simultaneously, the outward loop is invoked, whereby data being
fed to the transmit data interface is routed directly back out of the receive data interface.
Uncorrected-BER
5–67
Revision 13
MN-CDM625
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