mirror of https://github.com/saitohirga/WSJT-X.git
Starting to remove ISCAT references from the User Guide
Note that remaining QRA64 references need updating to mention Q65.
This commit is contained in:
Bill Somerville
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b7b4ebdb89
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dbc06d226b
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@ -42,7 +42,7 @@ control. The *Sync* control sets a minimum threshold for establishing
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time and frequency synchronization with a received signal.
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* Spinner control *T/R xx s* sets sequence lengths for transmission
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and reception in ISCAT, MSK144, and the fast JT9 modes.
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and reception in Q65, MSK144, and the fast JT9 modes.
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* With *Split operation* activated on the *File -> Settings -> Radio* tab, in
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MSK144 and the fast JT9 submodes you can activate the spinner control
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@ -118,9 +118,7 @@ summarized in the following Table:
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|JT9 | @ | |
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|JT65 | # | |
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|JT65 VHF| # | *, # | f, fN, dCN
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|QRA64 | : | * | R:w
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|ISCAT | | * | M N C T
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|QRA65 | : | | qP
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|MSK144 | & | |
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|===========================================
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Sync character::
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@ -130,14 +128,11 @@ Sync character::
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End of line information::
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`?` - Decoded with lower confidence +
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`a` - Decoded with aid of some _a priori_ (AP) information +
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`C` - Confidence indicator [ISCAT and Deep Search; (0-9,*)] +
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`C` - Confidence indicator [Deep Search; (0-9,*)] +
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`d` - Deep Search algorithm +
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`f` - Franke-Taylor or Fano algorithm +
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`M` - Message length (characters) +
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`N` - Number of Rx intervals or frames averaged +
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`P` - Number indicating type of AP information (Table 1, above) +
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`R` - Return code from QRA64 decoder +
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`T` - Length of analyzed region (s)
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Table 6 below shows the meaning of the return codes R in QRA64 mode.
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@ -8,9 +8,9 @@ as an extended branch of an earlier program, _WSJT_, first released in
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2001. Bill Somerville, G4WJS, and Steve Franke, K9AN, have been major
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contributors to development of _WSJT-X_ since 2013 and 2015, respectively.
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_WSJT-X_ Version {VERSION_MAJOR}.{VERSION_MINOR} offers twelve
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_WSJT-X_ Version {VERSION_MAJOR}.{VERSION_MINOR} offers eleven
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different protocols or modes: *FST4*, *FT4*, *FT8*, *JT4*, *JT9*,
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*JT65*, *QRA64*, *ISCAT*, *MSK144*, *WSPR*, *FST4W*, and *Echo*. The
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*JT65*, *QRA65*, *MSK144*, *WSPR*, *FST4W*, and *Echo*. The
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first seven are designed for making reliable QSOs under weak-signal
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conditions. They use nearly identical message structure and source
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encoding. JT65 and QRA64 were designed for EME ("`moonbounce`") on
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@ -39,14 +39,13 @@ On VHF bands and higher, QSOs are possible (by EME and other
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propagation types) at signal levels 10 to 15 dB below those required
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for CW.
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*ISCAT*, *MSK144*, and optionally submodes *JT9E-H* are "`fast`"
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*MSK144*, and optionally submodes *JT9E-H* are "`fast`"
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protocols designed to take advantage of brief signal enhancements from
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ionized meteor trails, aircraft scatter, and other types of scatter
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propagation. These modes use timed sequences of 5, 10, 15, or 30 s
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duration. User messages are transmitted repeatedly at high rate (up
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to 250 characters per second for MSK144) to make good use of the
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shortest meteor-trail reflections or "`pings`". ISCAT uses free-form
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messages up to 28 characters long, while MSK144 uses the same
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shortest meteor-trail reflections or "`pings`". MSK144 uses the same
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structured messages as the slow modes and optionally an abbreviated
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format with hashed callsigns.
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@ -3,9 +3,9 @@
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[[PROTOCOL_OVERVIEW]]
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=== Overview
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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. JT4, JT9, JT65,
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and QRA64 use 72-bit payloads. Standard messages consist of two
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All QSO modes use structured messages that compress
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user-readable information into fixed-length packets. JT4, JT9, and JT65
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use 72-bit payloads. Standard messages consist of two
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28-bit fields normally used for callsigns and a 15-bit field for a
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grid locator, report, acknowledgment, or 73. An additional bit flags
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a message containing arbitrary free text, up to 13 characters.
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@ -14,7 +14,7 @@ Special cases allow other information such as add-on callsign prefixes
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aim is to compress the most common messages used for minimally valid
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QSOs into a fixed 72-bit length.
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Information payloads for FST4, FT4, FT8, and MSK144 contain 77 bits.
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Information payloads for FST4, FT4, FT8, Q65, and MSK144 contain 77 bits.
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The 5 additional bits are used to flag special message types used for
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nonstandard callsigns, contest exchanges, FT8 DXpedition Mode, and a
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few other possibilities. Full details have been published in QEX, see
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@ -325,46 +325,6 @@ comparable to tone spacing.
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[[FAST_MODES]]
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=== Fast Modes
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==== ISCAT
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ISCAT messages are free-form, up to 28 characters in length.
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Modulation is 42-tone frequency-shift keying at 11025 / 512 = 21.533
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baud (ISCAT-A), or 11025 / 256 = 43.066 baud (ISCAT-B). Tone
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frequencies are spaced by an amount in Hz equal to the baud rate. The
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available character set is:
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----
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0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ /.?@-
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----
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Transmissions consist of sequences of 24 symbols: a synchronizing
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pattern of four symbols at tone numbers 0, 1, 3, and 2, followed by
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two symbols with tone number corresponding to (message length) and
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(message length + 5), and, finally, 18 symbols conveying the user's
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message, sent repeatedly character by character. The message always
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starts with `@`, the beginning-of-message symbol, which is not
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displayed to the user. The sync pattern and message-length indicator
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have a fixed repetition period, recurring every 24 symbols. Message
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information occurs periodically within the 18 symbol positions set
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aside for its use, repeating at its own natural length.
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For example, consider the user message `CQ WA9XYZ`. Including the
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beginning-of-message symbol `@`, the message is 10 characters long.
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Using the character sequence displayed above to indicate tone numbers,
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the transmitted message will therefore start out as shown in the first
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line below:
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----
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0132AF@CQ WA9XYZ@CQ WA9X0132AFYZ@CQ WA9XYZ@CQ W0132AFA9X ...
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sync## sync## sync##
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----
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Note that the first six symbols (four for sync, two for message
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length) repeat every 24 symbols. Within the 18 information-carrying
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symbols in each 24, the user message `@CQ WA9XYZ` repeats at its own
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natural length, 10 characters. The resulting sequence is extended as
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many times as will fit into a Tx sequence.
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==== JT9
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The JT9 slow modes all use keying rate 12000/6912 = 1.736 baud. By contrast, with
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@ -419,8 +379,6 @@ and your QSO partner ± 200 Hz.
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|=====================================================================
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|Mode |FEC Type |(n,k) | Q|Modulation Type|Keying rate (Baud)
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|Bandwidth (Hz)|Sync Energy|Tx Duration (s)
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|ISCAT-A | - | - |42|42-FSK| 21.5 | 905 | 0.17| 1.176
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|ISCAT-B | - | - |42|42-FSK| 43.1 | 1809 | 0.17| 0.588
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|JT9E |K=32, r=1/2|(206,72)| 8| 9-FSK| 25.0 | 225 | 0.19| 3.400
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|JT9F |K=32, r=1/2|(206,72)| 8| 9-FSK| 50.0 | 450 | 0.19| 1.700
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|JT9G |K=32, r=1/2|(206,72)| 8| 9-FSK|100.0 | 900 | 0.19| 0.850
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@ -11,7 +11,8 @@ higher bands. These features include:
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- *JT65*, widely used for EME on VHF and higher bands
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- *QRA64*, another mode for EME
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- *QRA65*, another mode for EME, also used for tropo-, and
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iono-scatter propagation on VHF and higher bands
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- *MSK144*, for meteor scatter
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@ -216,14 +217,6 @@ waterfall.
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TIP: G3WDG has prepared a more detailed tutorial on using {QRA64_EME}.
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=== ISCAT
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ISCAT is a useful mode for signals that are weak but more or less
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steady in amplitude over several seconds or longer. Aircraft scatter
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at 10 GHz is a good example. ISCAT messages are free-format and may
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have any length from 1 to 28 characters. This protocol includes no
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error-correction facility.
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=== MSK144
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Meteor scatter QSOs can be made any time on the VHF bands at distances
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