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Edit and add to User Guide.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7284 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
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@ -22,7 +22,6 @@ set (UG_SRCS
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controls-functions-status-bar.adoc
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controls-functions-wide-graph.adoc
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cooperating-programs.adoc
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decoded_lines.adoc
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faq.adoc
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font-sizes.adoc
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install-from-source.adoc
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@ -34,6 +33,7 @@ set (UG_SRCS
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logging.adoc
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make-qso.adoc
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new_features.adoc
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odds_and_ends.adoc
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platform-dependencies.adoc
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protocols.adoc
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settings-advanced.adoc
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@ -1,3 +1,5 @@
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=== Decoded Lines
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Displayed information accompanying decoded messages generally includes UTC,
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signal-to-noise ratio in dB, time offset DT in seconds, and
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audio frequency in Hz. Some modes include additional information such
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@ -33,4 +35,4 @@ End of line information::
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`R` - QRA64 _a priori_ return code +
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`T` - Length of analyzed region (s)
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=== Reference Spectrum
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@ -3,22 +3,50 @@
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All QSO modes except ISCAT use structured messages that compress
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user-readable information into fixed-length packets of exactly 72
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bits. Each message consists of two 28-bit fields for callsigns and a
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15-bit field for a grid locator, report, acknowledgment, or a "`73`"
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sign-off indicator. A 72^nd^ bit flags a message containing arbitrary
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alphanumeric text, up to 13 characters. Special cases allow other
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information such as add-on callsign prefixes (e.g., ZA/K1ABC) or
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suffixes (e.g., K1ABC/4) to be encoded. The basic aim is to compress
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bits. Each message consists of two 28-bit fields normally used for
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callsigns and a 15-bit field for a grid locator, report,
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acknowledgment, or 73. An additional bit flags a message containing
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arbitrary alphanumeric text, up to 13 characters. Special cases allow
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other information such as add-on callsign prefixes (e.g., ZA/K1ABC) or
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suffixes (e.g., K1ABC/P) to be encoded. The basic aim is to compress
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the most common messages used for minimally valid QSOs into a fixed
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72-bit length. To be useful on channels with low signal-to-noise
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ratio, this kind of lossless compression requires use of a strong
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forward error correcting (FEC) code. Different codes are used for
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each mode. Accurate synchronization of time and frequency is required
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between transmitting and receiving stations. As an aid to the
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decoders, each protocol includes a "`sync vector`" of known symbols
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interspersed with the information-carrying symbols. Generated
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waveforms for all of the _WSJT-X_ modes have continuous phase and
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constant envelope.
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72-bit length.
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A standard amateur callsign consists of a one- or two-character
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prefix, at least one of which must be a letter, followed by a digit
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and a suffix of one to three letters. Within these rules, the number
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of possible callsigns is equal to 37×36×10×27×27×27, or somewhat over
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262 million. (The numbers 27 and 37 arise because in the first and
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last three positions a character may be absent, or a letter, or
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perhaps a digit.) Since 2^28^ is more than 268 million, 28 bits are
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enough to encode any standard callsign uniquely. Similarly, the number
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of 4-digit Maidenhead grid locators on earth is 180×180 = 32,400,
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which is less than 2^15^ = 32,768; so a grid locator requires 15 bits.
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Some 6 million of the possible 28-bit values are not needed for
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callsigns. A few of these slots have been assigned to special message
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components such as CQ, CQ DX, DE, and QRZ. CQ may be followed by three
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digits to indicate a desired callback frequency. (If K1ABC transmits
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on a standard calling frequency, say 50.280, and sends "`CQ 290 K1ABC
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FN42`", it means that s/he will listen on 50.290 and respond there to
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any replies.) A numerical signal report of the form "`–NN`" or
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"`R–NN`" can be sent in place of a grid locator. (As originally
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defined, numerical signal reports were required to fall between -01
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and -30 dB. Recent program versions accommodate reports between
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-50 and +49 dB.) A country prefix or portable suffix may be
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attached to one of the callsigns. When this feature is used the
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additional information is sent in place of the grid locator or by
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encoding additional information into some of the 6 million available
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slots mentioned above.
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To be useful on channels with low signal-to-noise ratio, this kind of
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lossless message compression requires use of a strong forward error
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correcting (FEC) code. Different codes are used for each mode.
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Accurate synchronization of time and frequency is required between
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transmitting and receiving stations. As an aid to the decoders, each
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protocol includes a "`sync vector`" of known symbols interspersed with
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the information-carrying symbols. Generated waveforms for all of the
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_WSJT-X_ modes have continuous phase and constant envelope.
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[[SLOW_MODES]]
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=== Slow Modes
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@ -145,10 +145,6 @@ include::vhf-features.adoc[]
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== WSPR Mode
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include::wspr.adoc[]
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[[DECODED_LINES]]
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== Decoded Lines
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include::decoded_lines.adoc[]
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[[COMMAND_REF]]
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== On-Screen Controls
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@ -184,6 +180,10 @@ include::controls-functions-wide-graph.adoc[]
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== Logging
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include::logging.adoc[]
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[[ODDS_AND_ENDS]]
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== Odds and Ends
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include::odds_and_ends.adoc[]
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[[COOP_PGMS]]
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== Cooperating Programs
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include::cooperating-programs.adoc[]
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