Demodulator; Figure 6-8. Demodulator Test Points - Comtech EF Data SDM-650B Installation And Operation Manual

SDM-650B Satellite Modem

6.1.3.2 Demodulator

Refer to Figure 6-8.
TP10
TP23
TPG1
TP1
TP2
TP3
TP4
TP5
TP6
TP7
TP8
Rev. 6
VCXO Control Voltage.
Approximately 0 to +2.5V sweep range.
Discriminator Voltage.
Nominally +2.5V with 6 dB noise at 128 kbit/s.
Ground.
Q EYE Pattern.
Level is 1 Vp-p at the center of the eye crossing. The DC offset is about +2.4V.
Q THRS — Q channel threshold voltage, +2.9 VDC.
I THRS — I channel threshold voltage, +2.9 VDC.
I EYE Pattern.
Level is 1 Vp-p at the center of the eye crossing. The DC offset is about +2.4V.
Q CLK THRS +.
Q channel + clock threshold, +2 to +3 VDC.
Q CLK THRS -.
Q channel - clock threshold, +2 to +3 VDC.
I CLK THRS -.
I channel + clock threshold, +2 to +3 VDC.
I CLK THRS +.
I channel — clock threshold. +2 to +3 VDC.

Figure 6-8. Demodulator Test Points

Maintenance
6–9