DSSS modulator COM-1012 -> Dual D/A converter COM-2001 -> L-band modulator COM-4003C/D

This test setup demonstrate the spread-spectrum output spectrum at L-band. 
Modulation rates: 100 Kchip/s, 1 Mchip/s, 9.9 Mchip/s
Connect an external 10 MHz frequency reference to the COM-4003 modulator. 

(a) import the 1012_2001_4003.stn settings into the assembly.

(b) using an oscilloscope, probe the COM-2001 I and Q outputs. The capacitors C3 and C4
are convenient test points. The signals should be a filtered 100 Kchip/s waveform, with amplitude
of 1Vpp.

(c) using a spectrum analyzer, check the COM-4003 output.
The output is a modulated spectrum centered at 1.5 GHz. The level is about -24 dBm.

(d) Using the ComBlock Control Center, change the registers REG0/REG1/REG2 to the following values
and observe the following spectrum outputs:
REG0/1/2/3 = D7 A3 00   selects a 100 Kchip/s direct sequence spread-spectrum modulation
REG0/1/2/3 = 66 66 06   selects a 1 Mchip/s direct sequence spread-spectrum modulation
REG0/1/2/3 = 29 5C 3F   selects a 9.9 Mchip/s direct sequence spread-spectrum modulation

For 100 Kchip/s:
The -6 dB bandwidth is 100 KHz.
Two sidelobes are at -49 dB @ 6.4 MHz away.
Most sidelobes are below -60 dB.

For 1 Mchip/s:
The -6 dB bandwidth is 1 MHz.
Two sidelobes are at -40 dB @ 7.8 MHz away.
Most sidelobes are below -60 dB.

For 9.9 Mchip/s:
The -6 dB bandwidth is 9.9 MHz.
Two spectral spurious lines are at -50 dBc @ 10 MHz away.
Most sidelobes are below -60 dB.