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MESSAGE RCVD
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Page B-8 Appendix B:
Communication Formats
DESCRIPTION
EXAMPLE 1:
first round
Another round follows, which will be compared to this
message.
second round
This round compares with the preceding one; no more
activity is required, and the verification (or kissoff) tone is
subsequently sent back to the account.
EXAMPLE 2:
first round
Another round follows, which will be compared to this
message.
second round
An error in the way the message was received prevents it
from comparing with the previous round; another round is
required.
third round
This is the correct message, but it fails to compare with the
previous round; another round is required.
fourth round
The correct message compares with previous round; no
further messages are required and kissoff will be sent. If a
"compare" was not achieved here, the communicator would
hang up and redial the Central Station and submit up to four
more rounds.
EXAMPLE 3:
first round
Another round follows, which will be compared to this
message.
second round
An error in the way the message was received fails to
compare with the previous round; another round is required.
third round
This is the correct message, which compares with the first
round; no further messages are required and kissoff is sent.
If a compare was not achieved here, the communicator
would have one more opportunity to send a message to
compare with any of the previous rounds; if no compare
was then achieved, the communicator would hang up and
redial the Central Station and submit up to four more
rounds.
The chief disadvantage of the Double-Round Comparison
method is that at least two rounds of messages must be
sent – resulting in an expenditure of time that can restrict
the Central Station's "throughput," especially during busy
times of the day. The Parity Checking methods,
discussed on the following page, are speedier simply
because they provide accurate error-checking in just one
message round.
COMMENTS
CP-220A Central Station Receiver
Hook-Up and Installation Manual
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