L-band DSSS demodulator 
COM-5001 LAN Network Interface 
  -> COM-7001 Turbo code encoder 
    -> COM-1011 DSSS demodulator 
      -> COM-1005 BER measurement
      -> COM-1008 variable decimation
    	-> COM-6001 front-panel display
	-> COM-3002 L-band receiver [950-1450 MHz]

This assembly is to be tested in conjunction with the 70 MHz DSSS modulator.
Modulator settings are as per the 5001_7001_1012_4004_6001.stn settings file.
The assembly input signal is a 950 MHz modulated signal at 166.6 Kchip/s.
Processing gain 127. BPSK modulation.

Take the 70 MHz modulated IF signal. Using a mixer and a 880 MHz carrier, up-convert
the modulated signal to 950 MHz center frequency. Set the modulated signal 
level to -45 dBm at 950 MHz. No need to filter the image frequency. No noise added.

Modify the modulator chip rate to 5 Mchip/s (REG0/1/2 = 00 00 20)

(a) Connect external 10 MHz, LAN, 110VAC power, serial link to host PC, 
and the IF1 port to the input L-band modulated signal.
Turn the power on. 
Using the ComBlock Control Center, enumerate. 7 ComBlocks should be identified.
Import the settings file 3002_1008_1011_1005_7001_5001_6001.stn.

(b) Using an oscilloscope, probe test points TP1 and TP2 on the 
COM-3002 L-band receiver. These test points are at baseband. The IF
AGC should adjust the gain so that the baseband signals prior to A/D conversion
are 1V peak-to-peak.  Because the BPSK modulation uses only one complex axis, 
the received signal is amplitude modulated as it rotates between I and Q due to 
phase differences between transmit and receive.

The PLL_LOC (pll lock) test point on the COM-3002 L-band receiver should be
low to indicate synthesizer lock.

(c) Set the input signal level to about -55 dBm (threshold).
Verify that the COM-1011 DSSS demodulator is locked:
TP1 (carrier lock) is high, TP2 (code lock) is high.
The residual frequency error between tx and rx is on TP3.

Verify lock by triggering on TP4 (bit clock) and comparing TP5 (code replica)
and TP6 (received I channel). Should be the same except for the data bit inversion.

(d) Configure the COM-6001 display as 2A 30 31.
Displays shows 3 green leds and "01".

(e) Ping address 172.16.1.129 from the ComBlock Control Center 
Operations | Communication Setup menu. All four answers should be 
received within 10 ms or less.

(f) establish a hyperterminal connection over TCP-IP 172.16.1.129 port 1026 (receive).
Verify connection is established.
establish another hyperterminal connection over TCP-IP 172.16.1.128 port 1024 (transmit)
Send a text file using the menu transfer | send text file.
Verify that the file is received without obvious errors.
Some data may remain in the tx or rx HDLC buffer.