Comtech EF Data SNM-1001 - Manual (Page 51)

Maintenance SNM-1001 Network Control Modem
5–6 Rev. 1
5.1.3 Test Points
The modem does not have accessible test points. When troubleshooting is required at
board level, the cover must be removed.
The following is a list of test points located on the PCB, and a description of the signals
that should be present under normal operation.
5.1.3.1 Modulator Test Points
TP 1 DATA CLOCK TTL level clock that is locked to the incoming data to the interface
card.
TP 2 SYMBOL CLOCK TTL level clock that is locked to the incoming clock to the interface
card. This clock is running at the symbol frequency and not at the
data rate. The frequency is equal to:
•
BPSK = 2 x Bit Clock
•
QPSK1/2 = Bit Clock
•
QPSK3/4 = 2/3 Bit Clock
•
QPSK7/8 = 4/7 Bit Clock
TP 3 Q MIXER Analog output of the Q channel baseband reconstruction filter and
the input to the RF modulator.
TP 4 Q DIGITAL FILTER Analog output from the Digital filter.
TP 5 I DIGITAL FILTER Analog output from the Digital filter.
TP 6 I MIXER Analog output of the I channel baseband reconstruction filter and the
input to the RF modulator.