COM-3004 20-90 MHz receiver -> Variable Interpolation COM-1008

The baseline configuration in the 3004_1008.stn settings file is as follows:
70 MHz center frequency
Internal 10 MHz frequency reference.
-61 dBm input level threshold for full scale 10-bit A/D conversion.
External PLL-STROBE frequency hopping signal disabled.

Purpose: test the RF receiver module in presence of an input sinewave. 
Check the AGC (the COM-1008 controls the RF gain so that the signal 
prior to the A to D converter is 1V peak to peak.)
Check the ability to tune to extreme tuning frequencies: 20 MHz and 90 MHz.
Check the internal and external reference clocks.


(a) Turn the power supply on. Import the 3004_1008.stn setting file into the assembly 
(from the ComBlock Control Center  File | Import menu).

(b) Sensitivity: connect an RF frequency generator to the RF-IN input. 
Set the frequency to 71 MHz, level -61 dBm.

(c) using an oscilloscope, verify that test points TP1 and TP2 are 
1 MHz sinewaves of amplitude 1Vpp.
The sinewaves represent the frequency difference between the RF signal generator 
and the COM-3004 external frequency reference.

(d) Verify AGC operation over 40 dB dynamic range: increase the input level to -21 dBm. 
Verify that TP1 and TP2 remain at 1Vpp.

(e) verify low-pass filter frequency cutoff.
Program the signal generator in sweep mode between 70 and 110 MHz.
Set the signal generator output level to -65 dBm so that the receiver gain is always maximum.
Using a spectrum analyzer, observe test points TP3 and TP4 (I/Q baseband signals).
Set the spectrum analyzer trace mode to max hold.
Observe that low-pass filter frequency response. 
Check that the 3 dB filter cutoff frequency is around 10 MHz on both I and Q channels.
Check that the out of band rejection at 40 MHz away is greater than 25 dB.

(f) Verify external 10 MHz operation:
Connect an external 10 MHz frequency reference 
(generally available from a spectrum analyzer or RF signal generator) 
to the COM-3004 10 MHz input port.


Modify REG04 from 0x00 (internal clock reference) to 0x01 (external clock reference). 
Modify REG05 from 0x05 to 0x14 (20 decimal).
Check TP1 and TP2 again. 

(g) Frequency selection
REG6  
0x00 	RF frequency 0:	70 MHz
0x20	RF frequency 1: 20 MHz
0x40	RF frequency 2: 90 MHz

Change the center frequency by modifing the upper 4-bit of REG6 from the ComBlock Control Center.
Change the signal generator frequency accordingly.
Using an oscilloscope, verify TP1 and TP2 are near-zero frequency signals.