Reference Qualification And Validation; Broadshield - Spectracom VersaSync User Manual

2.
3.
3.3.2

Reference Qualification and Validation

3.3.2.1

BroadShield

What is BroadShield?
BroadShield is an optional software module for VersaSync that is capable of detecting the pres-
ence of GPS jamming or spoofing in real time.
How BroadShield Works
BroadShield monitors the GPS signal frequency band by applying proprietary error detection
algorithms. If a threshold signal monitoring value level is exceeded, VersaSync will emit a
Major Alarm and – depending on your system configuration – invalidate the GPS reference
causing VersaSync to either transition into Holdover mode (see "Holdover Mode" on
page 167), or go out of sync.
Even if you decide to turn off VersaSync's Auto Sync Control feature, which allows BroadShield
to disable the GNSS reference, BroadShield will still add value to your overall system cap-
ability by telling you (a) if your GNSS receiver is being spoofed, and (b) in the event of a sig-
nal loss due to jamming,
Also, if a normally strong GNSS signal becomes weakened, BroadShield's algorithms are cap-
able of discerning a jamming event from natural events causing the signal to weaken.
BroadShield Requirements
In order for BroadShield to work on your VersaSync system, the following requirements must
be met:
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In the Priority Level text box, enter 1 . This will give this reference the highest pri-
ority.
In the Time field, select "Local System".
In the PPS field, select "GPS".
Check the Enabled checkbox.
Confirm that the first reference in the Reference Priority table has "Local System" as the
Time input and "GNSS" as the 1PPS input.
After a power cycle or reboot, as soon as GNSS is declared valid, the System Time will
automatically be used as-is, with no manual intervention required.
why
the signal is lost.
Note: For an effective jamming detection, and – to some extent – spoofing detec-
tion, a good antenna placement
noise ratio is essential. A strong signal is required to discern between normal sig-
nal fluctuations and a non-natural divergence of signal strength.
3.3 Managing References
with optimal sky view resulting in a high signal-to-
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