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Following the COM port selection, the monitoring screen will display the detected signal
in real-time on the graph at right hand side, as seen in Figure 5:
The firmware and serial number fields also fill in automatically when the COM Port is selected.
( Note the firmware version of your Tranisthound may not match the firmware version from the
screen shot below.)
Transit Hound Functional parameters configurable by the user.
1. Threshold – Auto or Manual threshold set by the user determines the signal strength
level used to trigger the internal solid-state relay (SSR). The dry contact of this relay is
connected to the 6-pin Hirose connector and is being used to trigger an external Alarm in
some applications. In the Manual threshold mode, SSR is triggered, when RF signal
exceeds the set threshold. In the Auto threshold mode the user set “Auto Trigger Margin”
determines by how much the current threshold must be exceeded in order to trigger the
SSR.
Transit Hound Auto threshold algorithm:
All uplink cellular frequencies are scanned with a 4 MHz or 20MHz resolution. Signal
strength is sorted along the scan. The maximum value is a “sample”. This process is
continuous and periodic; each period takes approximately 0.6 sec for the US set of
frequencies.
As long as the “new sample” is lower than the current threshold, the latter is calculated as
a moving average of 16 samples increased by the auto threshold margin. It takes up to 16
* 0.6 = 10 sec for the auto threshold to settle after the input signal change.
If the input signal exceeds the current threshold, the threshold stays unchanged for the
next 20 sec. After delay the threshold and each of the 16 entries of the circular buffer are
set to the maximum level of 1000, thus forcing the algorithm to perform step 2., starting
with the next sample.
Figure 5. Monitoring Screen Displaying Real-Time Data
