Selecting a Satellite
Setup Procedure
7-8
Ocean TRx™ 4500 Installation and Operations Manual
7.3.3
Defining Channels (Tracking Signals)
7.3.3.1
Criteria for Selecting the Tracking Signal
A good-quality signal strength – defined as the highest possible signal-to-noise ratio – is
required to perform step-tracking of the antenna. The tracking signal received from the
satellite may be one of the following:
Satellite Beacon
– Typically an un-modulated CW
Customer Data Channel
– Typically
occupying a few hundred KHz to a few MHz of
bandwidth, with digital modulation (QPSK or 8PSK)
Wide-band TV transponder
– Digital only
The OceanTRx
TM
4-500 system uses a narrow-band tracking receiver (NBR) to receive
each of the above signals. To achieve optimal performance, the following specifications
are recommended:
Satellite beacon
– 50 KHz filter
Customer data channel
– 150, or 300 KHz filter, according to the channel’s
occupied bandwidth
Wide-band TV transponder
– 300 KHz filter
The selected tracking signal should be unique to the selected satellite or received on a
considerably lower level from adjacent satellites. Otherwise, the system may lock onto
the wrong satellite.
In general, a unique tracking channel is preferable to a satellite beacon (which may be
the same for multiple satellites of the same type), and the latter is preferable to a data
channel.
