Transmit (tx) assembly
COM1002 BPSK/QPSK/OQPSK Digital Modulator
  --> COM2001 Digital-to-Analog Converter
    -->  COM4003 1500 - 1740 MHz Modulator

Attenuator

Receive (rx) assembly
COM3003 1500 - 1740 MHz Receiver
  --> COM1001 BPSK/QPSK Demodulator




Objective: test an L-band BPSK modulator/demodulator using NOAA LRIT configuration 
over a noiseless channel (back to back). 
A stable 10 MHz external frequency reference is used to minimize frequency errors
between transmitter and receiver.

Configuration: 
center frequency 1.691 GHz
bit rate: 293 Kbits/s
modulation: BPSK
data stream: PRBS-11 pseudo-random binary sequence, period 2047 bits.
external 10 MHz frequency reference.


a) connect the transmitter assembly to the receiver assembly using a 20-40 dB attenuator.

b) connect a serial link between the tx assembly (COM-1001) and a PC. power up. Import the 
1002_2001_4003_3003A_1001_tx.stn configuration using the ComBlock Control Center
File | Import menu.

c) connect a serial link between the rx assembly (COM-3003A) and a PC. power up. Import the 
1002_2001_4003_3003A_1001_rx.stn configuration using the ComBlock Control Center
File | Import menu.

d) using an oscilloscope, connect probe1 to the COM-1002 BPSK modulator test point TP10 (start of PRBS11
pseudo-random sequence). Probe1 signal consists of a single pulse every 2047 bits, i.e. ever 6.986 ms.
Set the oscilloscope trigger on this signal.

e) connect oscilloscope probe2 to the COM-1001 BPSK demodulator test point TP5 (demodulated I-channel).
Preferred time setting: 25us/div.
Verify that the demodulated PRBS-11 sequence is fixed with respect to the trigger. 
In particular, verify that 11 '1s' are located between 69us and 106us after the trigger.
One can use the oscilloscope persistent mode to verify that no bit errors occur.

f) change the modulator center frequency by 0.5% of the symbol rate (1.5 KHz) by
setting COM-1002 REG3/4/5 to E0 53 00. Cycle power to force re-acquisition.
Repeat e).