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doc/user_guide/en/protocols.adoc
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@ -227,19 +227,19 @@ For details see Table 3, below.
Standard MSK144 messages are structured in the same way as those in Standard MSK144 messages are structured in the same way as those in
the slow modes, with a 72 bits of user information. Forward error the slow modes, with a 72 bits of user information. Forward error
correction is implemented by first augmenting the 72 message bits with correction is implemented by first augmenting the 72 message bits with
an 8-bit CRC calculated from the message bits. The CRC is used to an 8-bit cyclic redundancy check (CRC) calculated from the message
detect and eliminate most false decodes at the receiver. The resulting bits. The CRC is used to detect and eliminate most false decodes at
80-bit augmented message is mapped to a 128-bit codeword using a the receiver. The resulting 80-bit augmented message is mapped to a
(128,80) binary low-density-parity-check (LDPC) code designed by K9AN 128-bit codeword using a (128,80) binary low-density-parity-check
specifically for this purpose. Two 8-bit synchronizing sequences are (LDPC) code designed by K9AN specifically for this purpose. Two 8-bit
added to make a message frame 144 bits long. Modulation is Offset synchronizing sequences are added to make a message frame 144 bits
Quadrature Phase-Shift Keying (OQPSK) at 2000 baud. Even-numbered bits long. Modulation is Offset Quadrature Phase-Shift Keying (OQPSK) at
are conveyed over the in-phase channel, odd-numbered bits on the 2000 baud. Even-numbered bits are conveyed over the in-phase channel,
quadrature channel. Individual symbols are shaped with half-sine odd-numbered bits on the quadrature channel. Individual symbols are
profiles, thereby ensuring a generated waveform with constant shaped with half-sine profiles, thereby ensuring a generated waveform
envelope, equivalent to a Minimum Shift Keying (MSK) waveform. Frame with constant envelope, equivalent to a Minimum Shift Keying (MSK)
duration is 72 ms, so the effective character transmission rate for waveform. Frame duration is 72 ms, so the effective character
standard messages is up to 250 cps. transmission rate for standard messages is up to 250 cps.
MSK144 also supports short-form messages that can be used after QSO MSK144 also supports short-form messages that can be used after QSO
partners have exchanged both callsigns. Short messages consist of 4 partners have exchanged both callsigns. Short messages consist of 4