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Hermes Operator Note Page 24 of 32
4.24 Radio Frequency (AT &F)
The Hermes is programmed with a factory set centre frequency that is the
centre of the RF switching band. A new frequency can be entered directly
within the ±99 channels of the centre frequency using this command. The
channel number is re-calculated for the frequency entered using this
command.
The radio frequency of the modem is set as follows:
AT &F=nnn.nnnnnn<CR><LF>
Where: nnn.nnnnnn is the format of the input string for the
frequency in MHz
Default: none
Read: AT &F?<CR><LF>
Read Return: nnn.nnnnnn<CR><LF>
Example: AT &F=458.5<CR><LF> sets 458.5MHz
AT &F=458.500000<CR><LF> sets 458.5MHz
Note that frequencies in multiples of either 12.5kHz or 10kHz only are
acceptable. If a whole number of MHz is entered a “.” must be entered
before the <CR><LF>.
If the frequency entered is outside the ±99 channels, or the frequency is
invalid, the modem responds with the following error message and the entry
is ignored:
ERROR<CR><LF>
4.25 Save parameters (AT &W)
To permanently store any parameter changes, the parameters are saved in
non-volatile memory. The command for this is:
AT &W<CR><LF>
4.26 Restore defaults (AT &Y8)
To quickly check the operation of the modem, the factory settings can be
loaded. If required the AT &W save command can be used to save the
defaults. The command for this is:
AT &Y8<CR><LF>