Operating instructions

1892 1335 - Orion Radio Modem Operating Instructions - v2.9 / Aug 2009 27
RADIO CONFIGURATION
A number of different radio modules may be fitted to the Orion for different bands, powers etc.
As part of the test and setup routine at the factory, most of the radio parameters will be set up
to suit the module fitted, although you can alter them if necessary with reference to Part Two of
this manual or the AT Command Reference starting on page 63.
Some which you may want to set up yourself are:
Frequency (Centre
Frequency) (ATS155)
This is the frequency (in MHz) which corresponds to Channel 0. It
cannot be set outside the switching bandwidth defined by ATFHB
and ATFLB. Only valid (on-channel) values are permitted.
Channel Number
(ATS157)
The number of channels (of width defined by ATS161) up or down
from the centre frequency. The frequency must lie within the
switching bandwidth.
Operating Frequency
(AT&F)
The absolute operating frequency in MHz. Only valid (on-channel)
values within the switching bandwidth are permitted. See note
below about interaction between this and Centre Frequency and
Channel Number.
Power Level (ATS160) Set to low or high (exact values depend on radio module).
Interaction between Centre Frequency, Channel Number and Operating Frequency
If Centre Frequency (ATS155) and Channel Number (ATS157) are entered, Operating
Frequency (AT&F) takes on the frequency thus defined.
If Operating Frequency is entered later, then the Centre Frequency remains constant, and the
Channel Number changes to accommodate it. If the frequency lies outside the range of
channels -99 to +99, it is not permitted, even if it lies within the switching bandwidth.
Thus the simplest arrangement is usually to leave Channel Number set to 0, use Centre
Frequency to set the frequency, and ignore Operating Frequency.
OVER-AIR PROTOCOL
When using the Orion telemetry modes I, E or L, the over-air protocol is fixed at TU (see
below).
However, when using the data-only mode U, there are four over-air protocols (not to be
confused with serial interface protocols) which allow for different formats of data and different
levels of error correction depending on your application. As you might expect, the more error
correction you select, the lower the maximum throughput.
Protocol can also be selected for a repeater, but must be the same as the network in which it
operates.
Provided there is never any communication between units on the same frequency, they need
not use the same over-air protocol. For example, a Group exchanging data could use Packet
mode (TP) while another Group exchanged telemetry information using FEC (TU).