FSK/MSK/GFSK/GMSK modulator COM-1028 -> dual D/A conversion COM-2001 
-> Dual band 915 Hz / 2.4 GHz RF quadrature modulator COM-4001

Test configuration in 1028_2001_4001.stn settings file:
- GMSK modulation, 9.8 Mbit/s
- modulation index 0.5
- Gaussian filter BT product depends on the COM-1028 firmware version -A: 0.3, -B: 0.5
- RF frequency 2.5 GHz
- external 10 MHz frequency reference
- PRBS-11 sequence is being transmitted.
- No noise. 

(a) connect a serial cable between the COM-1028 and the host computer.
(b) connect a 10 MHz external frequency reference to the EXT_CLK port of the COM-4001.
(c) connect a RF cable from the RF-OUT port of the COM-4001 to a spectrum analyzer. 
Spectrum analyzer window: 100 MHz centered at 2.5 GHz.
(d) apply power to the ComBlock assembly
(e) from the ComBlock control center
- enumerate the Comblocks (2nd button to the left)
- import the 028_2001_4001.stn settings file from the menu File | Import
(f) Make sure the 10 MHz external frequency reference is present before 
recycling power to the ComBlock assembly. Turn the power off and then on. 

(g) Observe the modulated spectrum. 
Power level is typically -10 dBm
spectrum sidelobes are suppressed downto to at least -45 dB
Double-sided 3 dB bandwidth is approximately 5 MHz.

(h) Other debugging:
- COM-4001 SYNC_LOCK test point is low, indicating frequency synthesizer lock
- COM-4001 PLL_REF shows a clean 10 MHz frequency reference, LVTTL 0 - 3.3V