ComBlock COM-1826 Manual - Página 18

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Troubleshooting Checklist

Receiver is not responsive after power up:
The device typically takes up to 30 seconds
to boot up after power up.
If still not responsive after 30 seconds,
recycle the power. Wait at least 15 seconds
after power off to turn the power on again.
Receiver does not communicate with the ComBlock
Control Center:
Make sure an external 10 MHz frequency
reference is present prior to powering up
the receiver. This applies only when the –B
firmware option (external 10 MHz
frequency reference) is selected by default.
Demodulator can't achieve lock even at high signal-
to-noise ratios:
Make sure the modulator baseband I/Q
signals do not saturate, as such saturation
would strongly distort the modulation phase
information. (this is a phase demodulator!)
Demodulator can demodulate BPSK but not QPSK:
A spectrum inversion may have occurred in
the RF transmission chain. If so, invert the
spectrum inversion flag at the demodulator.

Configuration Management

This specification is to be used in conjunction with
VHDL software revision 0 and ComBlock control
center revision 3.10g and above.
It is possible to read back the option and version of
the FPGA configuration currently active. Using the
ComBlock Control Center, highlight the COM-
1826 module, then go to the advanced settings. The
option and version are listed at the bottom of the
configuration panel.
FPGA utilization
FF: 57673 (45%)
LUT: 51204 (80%)
BRAM: 76
DSP48: 51
BUFG:6
MMCM: 2
PLL: 1
Reference Documents
[1] Space Network Interoperable PN Code Libraries
451-PN CODE-SNIP
ComBlock Ordering Information
COM-1826
TDRSS Spread-Spectrum modem
Options:
1,2 or 3 baseband receivers per 1RU chassis
RF modulator output
TCP-IP modulator input
ECCN: 5A001.b.3
MSS • 845 Quince Orchard Boulevard Ste N•
Gaithersburg, Maryland 20878-1676 • U.S.A.
Telephone: (240) 631-1111
Facsimile: (240) 631-1676
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