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
This commit is contained in:
Joe Taylor 2016-11-03 19:14:07 +00:00
parent cdaa64324a
commit 4d0c6c4466
4 changed files with 51 additions and 21 deletions

View File

@ -22,7 +22,6 @@ set (UG_SRCS
controls-functions-status-bar.adoc
controls-functions-wide-graph.adoc
cooperating-programs.adoc
decoded_lines.adoc
faq.adoc
font-sizes.adoc
install-from-source.adoc
@ -34,6 +33,7 @@ set (UG_SRCS
logging.adoc
make-qso.adoc
new_features.adoc
odds_and_ends.adoc
platform-dependencies.adoc
protocols.adoc
settings-advanced.adoc

View File

@ -1,3 +1,5 @@
=== Decoded Lines
Displayed information accompanying decoded messages generally includes UTC,
signal-to-noise ratio in dB, time offset DT in seconds, and
audio frequency in Hz. Some modes include additional information such
@ -33,4 +35,4 @@ End of line information::
`R` - QRA64 _a priori_ return code +
`T` - Length of analyzed region (s)
=== Reference Spectrum

View File

@ -3,22 +3,50 @@
All QSO modes except ISCAT use structured messages that compress
user-readable information into fixed-length packets of exactly 72
bits. Each message consists of two 28-bit fields for callsigns and a
15-bit field for a grid locator, report, acknowledgment, or a "`73`"
sign-off indicator. A 72^nd^ bit flags a message containing arbitrary
alphanumeric text, up to 13 characters. Special cases allow other
information such as add-on callsign prefixes (e.g., ZA/K1ABC) or
suffixes (e.g., K1ABC/4) to be encoded. The basic aim is to compress
bits. Each message consists of two 28-bit fields normally used for
callsigns and a 15-bit field for a grid locator, report,
acknowledgment, or 73. An additional bit flags a message containing
arbitrary alphanumeric text, up to 13 characters. Special cases allow
other information such as add-on callsign prefixes (e.g., ZA/K1ABC) or
suffixes (e.g., K1ABC/P) to be encoded. The basic aim is to compress
the most common messages used for minimally valid QSOs into a fixed
72-bit length. To be useful on channels with low signal-to-noise
ratio, this kind of lossless compression requires use of a strong
forward error correcting (FEC) code. Different codes are used for
each mode. Accurate synchronization of time and frequency is required
between transmitting and receiving stations. As an aid to the
decoders, each protocol includes a "`sync vector`" of known symbols
interspersed with the information-carrying symbols. Generated
waveforms for all of the _WSJT-X_ modes have continuous phase and
constant envelope.
72-bit length.
A standard amateur callsign consists of a one- or two-character
prefix, at least one of which must be a letter, followed by a digit
and a suffix of one to three letters. Within these rules, the number
of possible callsigns is equal to 37×36×10×27×27×27, or somewhat over
262 million. (The numbers 27 and 37 arise because in the first and
last three positions a character may be absent, or a letter, or
perhaps a digit.) Since 2^28^ is more than 268 million, 28 bits are
enough to encode any standard callsign uniquely. Similarly, the number
of 4-digit Maidenhead grid locators on earth is 180×180 = 32,400,
which is less than 2^15^ = 32,768; so a grid locator requires 15 bits.
Some 6 million of the possible 28-bit values are not needed for
callsigns. A few of these slots have been assigned to special message
components such as CQ, CQ DX, DE, and QRZ. CQ may be followed by three
digits to indicate a desired callback frequency. (If K1ABC transmits
on a standard calling frequency, say 50.280, and sends "`CQ 290 K1ABC
FN42`", it means that s/he will listen on 50.290 and respond there to
any replies.) A numerical signal report of the form "`NN`" or
"`RNN`" can be sent in place of a grid locator. (As originally
defined, numerical signal reports were required to fall between -01
and -30 dB. Recent program versions accommodate reports between
-50 and +49 dB.) A country prefix or portable suffix may be
attached to one of the callsigns. When this feature is used the
additional information is sent in place of the grid locator or by
encoding additional information into some of the 6 million available
slots mentioned above.
To be useful on channels with low signal-to-noise ratio, this kind of
lossless message compression requires use of a strong forward error
correcting (FEC) code. Different codes are used for each mode.
Accurate synchronization of time and frequency is required between
transmitting and receiving stations. As an aid to the decoders, each
protocol includes a "`sync vector`" of known symbols interspersed with
the information-carrying symbols. Generated waveforms for all of the
_WSJT-X_ modes have continuous phase and constant envelope.
[[SLOW_MODES]]
=== Slow Modes

View File

@ -145,10 +145,6 @@ include::vhf-features.adoc[]
== WSPR Mode
include::wspr.adoc[]
[[DECODED_LINES]]
== Decoded Lines
include::decoded_lines.adoc[]
[[COMMAND_REF]]
== On-Screen Controls
@ -184,6 +180,10 @@ include::controls-functions-wide-graph.adoc[]
== Logging
include::logging.adoc[]
[[ODDS_AND_ENDS]]
== Odds and Ends
include::odds_and_ends.adoc[]
[[COOP_PGMS]]
== Cooperating Programs
include::cooperating-programs.adoc[]