User`s manual

100-M0145X2 23 of 36
www.cobham.com/gms
The initial checkout described above is simply to check the basic video operation of the MVRD unit.
Audio can also be checked by enabling audio in the test TX. See the operator’s manual of the TX that
you are using.
Figure 7 – OSD
6.2 Using of the On Screen Display
On Screen Display (OSD) tool, shown in Figure 7, is an extremely useful tool for system set-up and
diagnostic. The displayed diagnostic data includes a spectrum display, signal to noise data, input power
level and frequency. The received spectrum display is useful when checking for interference and signal
quality.
After power up, OSD is available only when unit is locked to incoming RF signal. If the lock is lost
afterwards, OSD still will be available.
When setting a VETA system up, the OSD should be used in the following way.
 Channel is clear. With the transmitter OFF, check that the channel is empty of
interference signals, this is confirmed by ensuring that the reported power in the
channel is at –95dBm or lower and that the spectrum is shown as a rounded dome with
no obvious spikes or tones.
 Check Quality of Link. Switch on the transmitter and confirm that SNR is 6 or greater
and that power level is at least –92dBm or greater. This represents approximately a 5dB
margin. Failure of the link will occur when the power level reaches –97dBm or the SNR
reaches 3dB.