Value
RPR 550IS Series
TM1188 Issue 1 Page 3A - 9
Figure 10: Binary Message Codeword
31. Some paging sites have multiple encoder channels controlling sequential transmitters.
If a paging receiver is located mid-way between two transmitters it may receive the
same call twice. To assist the paging receiver's call comparator in determining
whether the second call is the same call or a new call, a Message Stamp codeword
may be inserted before the message.
32. The Message Stamp codeword is a binary codeword (see Figure 10) where bits b0 to
bF comprise a checksum of the message that follows it. The Message Stamp
codeword is not used in calls other than Tone Only or Tone plus Speech calls.
Speech Messages
33. A speech message is initiated by a Type 1 message codeword `<DC1><DC1>'. This
switches the paging receiver into speech mode after the pre-programmed autospeech
delay and allows other paging receivers to be alerted prior to sending the same speech
message.
34. The paging receiver is switched out of speech mode by a short preamble (32 bits)
followed by the speech terminator sequence. The short preamble minimises the
amount of digital data output heard over the speech channel. If there are other
messages to be transmitted (including a Time-of-Day or In-Range transmission) a full
preamble is then transmitted after the shutdown sequence, in order to recapture any
paging receivers which have reverted to the battery economy mode.
GROUP ADDRESS
35. Groups of pagers can be called simultaneously when programmed with a second
address. This can be related to the individual address or can be entirely different. The
following groups are possible:
a) 1,000 groups of ten
b) 100 groups of one hundred
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