Operating instructions

LOCAL OPERATION
3-88
Decoding POCSAG type signals
The POCSAG DECODE option allows signals containing data formatted to the POCSAG
specification to be decoded and displayed.
Decoding of either numeric or alpha-numeric messages is selectable.
The decoder can be set to respond to and display:-
Only messages addressed to a specified RIC number.
Only messages containing the sequence 12345.
All messages.
To configure the Service Monitor to decode POCSAG signals proceed as follows:-
• If the signal is to be obtained by 'Off air' monitoring, select Tx TEST mode or Dx TEST mode
and the BNC (antenna) input. Use a suitable antenna to receive the transmissions.
Set the transmitter frequency (Tx FREQ), of the Service Monitor receiver, to the frequency of
the transmission to be decoded.
• If the signal is obtained from a receiver output, select AF TEST and connect the receiver
output to the AF INPUT socket.
Select the POCSAG option from within the TONES function. If the POCSAG decode option
is not fitted, the
POCSAG ENCODE screen and menu will be displayed, and decoding is not
possible. If the POCSAG decode option is fitted the
POCSAG DECODE screen and menu
will be displayed.
• Set the RIC code, if messages to a specific 'RIC address' only are to be decoded (see response
option selection, below).
• Select the required decode format. The [Decode Format] key toggles the selection between
Numeric and Alpha-numeric.
Response options
Select the required response option. Repeated presses of the [Decode On] key will sequence
through the options of:-
• ALL to respond to, and display, the first incoming POCSAG format message.
• On RIC to respond to, and display, the first incoming POCSAG format message
which is addressed to the set RIC.
• On sequence 12345 to respond to, and display, the first incoming POCSAG format
message which contains the numeric sequence '12345'.
Press the [Clear Sequ] key to remove any data from the decode register and to re-arm the decode
function.
The next message received, if it conforms to the set decode format, will be decoded and the
message displayed.
The following parameters of the signal are decoded and shown on the display:-
Bit Rate: The bit rate of the received signal.
Polarity: Normal or inverted coding.
RIC: The Radio Identification Code
of the addressed pager.
Addr/Alert
Type:
Shows the format of the alerting
signal.
Message
Type:
Numeric or Alpha-numeric.
If a message is included in the transmission, this is shown in the message panel. Messages of up
to 120 characters can be shown.
The decoder detects the codewords of messages with errors and applies error correction. The
number of error codewords received in the message and the number of corrections made is shown.