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First cut at replacing QRA64 with Q65 throughout the User Guide.
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@ -27,9 +27,10 @@ our work under terms of the GNU General Public License must display
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the following copyright notice prominently:
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*The algorithms, source code, look-and-feel of _{prog}_ and related
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programs, and protocol specifications for the modes FSK441, FT4, FT8,
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JT4, JT6M, JT9, JT65, JTMS, QRA64, ISCAT, and MSK144 are Copyright (C)
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2001-2020 by one or more of the following authors: Joseph Taylor,
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K1JT; Bill Somerville, G4WJS; Steven Franke, K9AN; Nico Palermo,
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IV3NWV; Greg Beam, KI7MT; Michael Black, W9MDB; Edson Pereira, PY2SDR;
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Philip Karn, KA9Q; and other members of the WSJT Development Group.*
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programs, and protocol specifications for the modes FSK441, FST4,
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FST4W, FT4, FT8, JT4, JT6M, JT9, JT44, JT65, JTMS, Q65, QRA64, ISCAT,
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and MSK144 are Copyright (C) 2001-2021 by one or more of the following
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authors: Joseph Taylor, K1JT; Bill Somerville, G4WJS; Steven Franke,
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K9AN; Nico Palermo, IV3NWV; Greg Beam, KI7MT; Michael Black, W9MDB;
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Edson Pereira, PY2SDR; Philip Karn, KA9Q; and other members of the
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WSJT Development Group.*
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@ -60,7 +60,7 @@ specified response frequency.
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* Checkboxes at bottom center of the main window control special
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features for particular operating modes:
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** *Sh* enables shorthand messages in JT4, JT65, QRA64 and MSK144 modes
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** *Sh* enables shorthand messages in JT4, JT65, Q65, and MSK144 modes
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** *Fast* enables fast JT9 submodes
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@ -69,4 +69,5 @@ features for particular operating modes:
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** *Call 1st* enables automatic response to the first decoded
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responder to your CQ
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** *Tx6* toggles between two types of shorthand messages in JT4 mode
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** *Tx6* toggles between two types of shorthand messages in JT4 and
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Q65 modes
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@ -2,12 +2,12 @@
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=== AP Decoding
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The _WSJT-X_ decoders for FST4, FT4, FT8, JT65, and QRA64 include
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The _WSJT-X_ decoders for FST4, FT4, FT8, JT65, and Q65 include
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procedures that use naturally accumulating information during a
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minimal QSO. This _a priori_ (AP) information increases sensitivity
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of the decoder by up to 4 dB, at the cost of a slightly higher rate of
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false decodes. AP is optional in FT8, JT65, and QRA64, but is always
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enabled for FT4 and FST4 when decode depth is Normal or Deep.
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false decodes. AP is optional in FT8 and JT65, but is always enabled
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for Q65 and for FT4 and FST4 when decode depth is Normal or Deep.
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For example: when you decide to answer a CQ, you already know your own
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callsign and that of your potential QSO partner. The software
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@ -132,25 +132,16 @@ End of line information::
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`d` - Deep Search algorithm +
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`f` - Franke-Taylor or Fano algorithm +
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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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`P` - Number indicating type of AP information (Table 1 or Table 6) +
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Table 6 below shows the meaning of the return codes R in QRA64 mode.
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[[QRA64_AP_INFO_TABLE]]
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.QRA64 AP return codes
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[width="35%",cols="h10,<m20",frame=topbot,options="header"]
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[[Q65_AP_INFO_TABLE]]
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.Q65 end-of-line codes
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[width="45%",cols="h10,<m20",frame=topbot,options="header"]
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|===============================================
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|rc | Message components
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|0 | ?     ?     ?
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|1 | CQ     ?     ?
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|2 | CQ     ?
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|3 | MyCall     ?     ?
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|4 | MyCall     ?
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|5 | MyCall DxCall     ?
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|6 | ?     DxCall     ?
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|7 | ?     DxCall
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|8 | MyCall DxCall DxGrid
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|9 | CQ DxCall     ?
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|10 | CQ DxCall
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|11 | CQ DxCall DxGrid
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| | Message components
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|q0 | ?     ?     ?
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|q1 | CQ     ?     ?
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|q2 | MyCall     ?     ?
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|q3 | MyCall DxCall     ?
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|q4 | MyCall DxCall     [<blank> \| RRR \| RR73 \| 73]
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|===============================================
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@ -15,7 +15,7 @@ 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 was designed for EME ("`moonbounce`") on VHF and
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higher bands and is mostly used for that purpose today. Q65 replaces
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an earlier mode, QRA64; it is particularly effective for tropospheric
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an earlier mode, QRA64. Q65 is particularly effective for tropospheric
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scatter, rain scatter, ionospheric scatter, TEP, and EME on VHF and
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higher bands, as well as other types of fast-fading signals. JT9 was
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originally designed for the HF and lower bands. Its submode JT9A is 1
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@ -169,25 +169,25 @@ same as that of the sync tone used in long messages, and the frequency
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separation is 110250/4096 = 26.92 Hz multiplied by n for JT65A, with n
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= 2, 3, 4 used to convey the messages RO, RRR, and 73, respectively.
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[[QRA64_PROTOCOL]]
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==== QRA64
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[[Q65_PROTOCOL]]
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==== Q65
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QRA64 is intended for EME and other extreme weak-signal applications.
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Its internal code was designed by IV3NWV. The protocol uses a (63,12)
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**Q**-ary **R**epeat **A**ccumulate code that is inherently better
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than the Reed Solomon (63,12) code used in JT65, yielding a 1.3 dB
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advantage. A new synchronizing scheme is based on three 7 x 7 Costas
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arrays. This change yields another 1.9 dB advantage.
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Q65 is intended for scatter, EME, and other extreme weak-signal
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applications. Forward error correction (FEC) uses a specially
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designed (65,15) block code with six-bit symbols. Two symbols are
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“punctured” from the code, yielding an effective (63,13) code with a
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payload of k = 13 information symbols conveyed by n = 63 channel
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symbols. The punctured symbols consist of a 12-bit CRC computed from
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the 13 information symbols. The CRC is used to reduce the
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false-decode rate to a very low value. A 22-symbol pseudo-random
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sequence spread throughout a transmission is sent as “tone 0” and used
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for synchronization. The total number of channel symbols in a Q65
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transmission is thus 63 + 22 = 85.
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In most respects the current implementation of QRA64 is operationally
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similar to JT65. QRA64 does not use two-tone shorthand messages, and
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it makes no use of a callsign database. Rather, additional
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sensitivity is gained by making use of already known information as a
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QSO progresses -- for example, when reports are being exchanged and
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you have already decoded both callsigns in a previous transmission.
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QRA64 presently offers no message averaging capability, though that
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feature may be added. In early tests, many EME QSOs were made using
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submodes QRA64A-E on bands from 144 MHz to 24 GHz.
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For each T/R sequence length, submodes A - E have tone spacings and
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occupied bandwidths 1, 2, 4, 8, and 16 times those specified in the
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above table. Full submode designations include a number for sequence
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length and a letter for tone spacing, as in Q65-15A, Q65-120C, etc.
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[[WSPR_PROTOCOL]]
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==== WSPR
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@ -277,8 +277,12 @@ which the probability of decoding is 50% or higher.
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|FT8 |LDPC |(174,91)| 8| 8-GFSK| 6.25 | 50.0 | 0.27| 12.6 | -21
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|JT4A |K=32, r=1/2|(206,72)| 2| 4-FSK| 4.375| 17.5 | 0.50| 47.1 | -23
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|JT9A |K=32, r=1/2|(206,72)| 8| 9-FSK| 1.736| 15.6 | 0.19| 49.0 | -26
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|JT65A |Reed Solomon|(63,12) |64|65-FSK| 2.692| 177.6 | 0.50| 46.8 | -25
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|QRA64A|Q-ary Repeat Accumulate|(63,12) |64|64-FSK|1.736|111.1|0.25|48.4| -26
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|JT65A |RS|(63,12) |64|65-FSK| 2.692| 177.6 | 0.50| 46.8 | -25
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|Q65-15A |QRA|(63,13) |64|65-FSK|6.667|433|0.26| 12.8| -22.2
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|Q65-30A |QRA|(63,13) |64|65-FSK|3.333|217|0.26| 25.5| -24.8
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|Q65-60A |QRA|(63,13) |64|65-FSK|1.667|108|0.26| 51.0| -27.6
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|Q65-120A|QRA|(63,13) |64|65-FSK|0.750| 49|0.26|113.3| -30.8
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|Q65-300A|QRA|(63,13) |64|65-FSK|0.289| 19|0.26|293.8| -33.8
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| WSPR |K=32, r=1/2|(162,50)| 2| 4-FSK| 1.465| 5.9 | 0.50|110.6 | -31
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|FST4W-120 |LDPC | (240,74)| 4| 4-GFSK| 1.46 | 5.9 | 0.25| 109.3 | -32.8
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|FST4W-300 |LDPC | (240,74)| 4| 4-GFSK| 0.558 | 2.2 | 0.25| 286.7 | -36.8
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@ -286,14 +290,18 @@ which the probability of decoding is 50% or higher.
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|FST4W-1800 |LDPC | (240,74)| 4| 4-GFSK| 0.089 | 0.36 | 0.25| 1792.0| -44.8
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|===============================================================================
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Submodes of JT4, JT9, JT65, and QRA64 offer wider tone spacings for
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LDPC = Low Density Parity Check
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RS = Reed Solomon
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QRA = Q-ary Repeat Accumulate
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Submodes of JT4, JT9, and JT65 offer wider tone spacings for
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circumstances that may require them, such as significant Doppler spread.
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Table 8 summarizes the tone spacings, bandwidths, and approximate
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threshold sensitivities of the various submodes when spreading is
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comparable to tone spacing.
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[[SLOW_SUBMODES]]
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.Parameters of Slow Submodes with Selectable Tone Spacings
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.Parameters of Slow Submodes JT4, JT9, and JT65 with Selectable Tone Spacings
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[width="50%",cols="h,3*^",frame=topbot,options="header"]
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|=====================================
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|Mode |Tone Spacing |BW (Hz)|S/N (dB)
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@ -315,11 +323,17 @@ comparable to tone spacing.
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|JT65A |2.692| 177.6 |-25
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|JT65B |5.383| 352.6 |-25
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|JT65C |10.767| 702.5 |-25
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|QRA64A|1.736| 111.1 |-26
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|QRA64B|3.472| 220.5 |-25
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|QRA64C|6.944| 439.2 |-24
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|QRA64D|13.889| 876.7 |-23
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|QRA64E|27.778|1751.7 |-22
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|=====================================
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.Parameters of Q65 Submodes
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[width="100%",cols="h,5*^",frame=topbot,options="header"]
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|=====================================
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|T/R Period (s) |A Spacing Width (Hz)|B Spacing Width (Hz)|C Spacing Width (Hz)|D Spacing Width (Hz)|E Spacing Width (Hz)
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|15|6.67     4.33|13.33     867|26.67     1733|N/A|N/A
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|30|3.33     217|6.67     433|13.33     867| 26.67     1733| N/A
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|60|1.67     108|3.33     217|6.67     433|13.33     867|26.67     1733
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|120|0.75     49|1.50     98|3.00     195|6.00     390| 12.00     780
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|300|0.29     19|0.58     38|1.16     75|2.31     150|4.63     301
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|=====================================
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[[FAST_MODES]]
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@ -89,25 +89,6 @@ You will discover that every possible JT65 message differs from every
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other possible JT65 message in at least 52 of the 63
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information-carrying channel symbols.
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Here's an example using the QRA64 mode:
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C:\WSJTX\bin qra64code "KA1ABC WB9XYZ EN37"
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Message Decoded Err? Type
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--------------------------------------------------------------------------
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1 KA1ABC WB9XYZ EN37 KA1ABC WB9XYZ EN37 1: Std Msg
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Packed message, 6-bit symbols 34 16 49 32 51 26 31 40 41 22 0 41
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Information-carrying channel symbols
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34 16 49 32 51 26 31 40 41 22 0 41 16 46 14 24 58 45 22 45 38 54 7 23 2 49 32 50 20 33
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55 51 7 31 31 46 41 25 55 14 62 33 29 24 2 49 4 38 15 21 1 41 56 56 16 44 17 30 46 36
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23 23 41
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Channel symbols including sync
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20 50 60 0 40 10 30 34 16 49 32 51 26 31 40 41 22 0 41 16 46 14 24 58 45 22 45 38 54 7
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23 2 49 32 50 20 33 55 51 20 50 60 0 40 10 30 7 31 31 46 41 25 55 14 62 33 29 24 2 49
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4 38 15 21 1 41 56 56 16 44 17 30 46 36 23 23 41 20 50 60 0 40 10 30
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Execution of any of these utility programs with "-t" as the only
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command-line argument produces examples of all supported message
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types. For example, using `jt65code -t`:
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@ -11,13 +11,11 @@ higher bands. These features include:
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- *JT65*, widely used for EME on VHF and higher bands
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- *Q65*, for propagation modes including tropospheric scatter, rain
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scatter, ionospheric scatter, TEP, and EME
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- *Q65*, for ionospheric scatter, tropospheric scatter, rain scatter,
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TEP, and EME
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- *MSK144*, for meteor scatter
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- *ISCAT*, for aircraft scatter and other types of scatter propagation
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- *Echo* mode, for detecting and measuring your own lunar echoes
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- *Doppler tracking*, which becomes increasingly important for EME
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@ -177,49 +175,31 @@ image::JT65B.png[align="center",alt="JT65B"]
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=== Q65
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Q65 is designed for propagation paths that produce signals exhibiting fast
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fading, including tropospheric scatter, rain scatter, ionospheric scatter,
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trans-equatorial propagation (TEP), and EME.
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Q65 is designed for propagation paths that produce fast fading
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signals: tropospheric scatter, rain scatter, ionospheric scatter,
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trans-equatorial propagation (TEP), EME, and the like. The following
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screen shot shows an example with submode Q65-30A on a 6-meter
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ionospheric scatter path of about 1100 km.
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EME on VHF and higher bands; its
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operation is generally similar to JT4 and JT65. The following screen
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shot shows an example of a QRA64C transmission from DL7YC recorded at
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G3WDG over the EME path at 24 GHz. Doppler spread on the path was 78
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Hz, so although the signal is reasonably strong its tones are
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broadened enough to make them hard to see on the waterfall. The
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triangular red marker below the frequency scale shows that the decoder
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has achieved synchronization with a signal at approximately 967 Hz.
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image::Q65_6m_ionoscatter.png[align="center",alt="Q65"]
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image::Q65_6m_ionoscatter.png[align="center",alt="QRA64"]
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The QRA64 decoder makes no use of a callsign database. Instead, it
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The Q65 decoder makes no use of a callsign database. Instead, it
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takes advantage of _a priori_ (AP) information such as one's own
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callsign and the encoded form of message word `CQ`. In normal usage,
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as a QSO progresses the available AP information increases to include
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the callsign of the station being worked and perhaps also his/her
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4-digit grid locator. The decoder always begins by attempting to
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decode the full message using no AP information. If this attempt
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fails, additional attempts are made using available AP information to
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provide initial hypotheses about the message content. At the end of
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each iteration the decoder computes the extrinsic probability of the
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most likely value for each of the message's 12 six-bit information
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symbols. A decode is declared only when the total probability for all
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12 symbols has converged to an unambiguous value very close to 1.
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callsign and the message word `CQ`. In normal usage, as a QSO
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progresses the available AP information increases to include the
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callsign of the station being worked and perhaps also his/her 4-digit
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grid locator. The decoder takes advantage of whatever AP information
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is available.
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For EME QSOs some operators use short-form QRA64 messages consisting
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of a single tone. To activate automatic generation of these messages,
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check the box labeled *Sh*. This also enables the generation of a
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single tone at 1000Hz by selecting Tx6, to assist in finding signals
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initially, as the QRA64 tones are often not visible on the waterfall.
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The box labeled *Tx6* switches the Tx6 message from 1000Hz to 1250Hz
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to indicate to the other station that you are ready to receive messages.
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For Q65 EME QSOs, particularly on the micriowave bands, some operators
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use short-form messages consisting of a single tone. To activate
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automatic generation of these messages, check the box labeled *Sh*.
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This also enables the generation of a single tone at 1000Hz by
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selecting Tx6, to assist in finding signals initially. The box
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labeled *Tx6* switches the Tx6 message from 1000Hz to 1250Hz to
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indicate to the other station that you are ready to receive messages.
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TIP: QRA64 attempts to find and decode only a single signal in the
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receiver passband. If many signals are present, you may be able to
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decode them by double-clicking on the lowest tone of each one in the
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waterfall.
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TIP: G3WDG has prepared a more detailed tutorial on using {QRA64_EME}.
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// TIP: G3WDG has prepared a more detailed tutorial on using {QRA64_EME}.
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=== MSK144
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@ -332,21 +312,28 @@ image::echo_144.png[align="center",alt="Echo 144 MHz"]
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=== Tips for EME
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Current conventions dictate that digital EME is usually done with
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JT65A on the 50 MHz band, JT65B on 144 and 432 MHz, and JT65C on 1296
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MHz. On higher microwave bands typical choices are JT65C or one of
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Until the advent of Q65, digital EME has mostly been done using JT65A
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on the 50 MHz band, JT65B on 144 and 432 MHz, and JT65C on 1296 MHz.
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On higher microwave bands typical choices have been JT65C or one of
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the wider QRA64 or JT4 submodes, depending on the expected amount of
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Doppler spread. JT4 and JT65 offer message *Averaging* -- the
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summation of subsequent transmissions that convey the same message --
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to enable decodes at signal-to-noise ratios several dB below the
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threshold for single transmissions. These modes also allow *Deep
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Search* decoding, in which the decoder hypothesizes messages
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containing known or previously decoded callsigns and tests them for
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reliability using a correlation algorithm. Finally, JT65 and QRA64
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offer _a priori_ (AP) decoding, which takes advantage of naturally
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accumulating information during a QSO. The following tutorial aims to
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familiarize you with these program features, all of which are of
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special interest for EME and other extreme weak-signal conditions.
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Doppler spread. We now recommend a suitable submodes of Q65 for EME
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on all bands: for example, Q65-60A on 50 and 144 MHz, -60B on
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432 MHz, -60C on 1296 MHz, and -60D on 10 GHz.
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JT4, JT65, and Q65 offer *Message Averaging* -- the summation of
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subsequent transmissions that convey the same message -- to enable
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decodes at signal-to-noise ratios several dB below the threshold for
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single transmissions. JT4 and JT65 also allow *Deep Search* decoding,
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in which the decoder hypothesizes messages containing known or
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previously decoded callsigns and tests them for reliability using a
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correlation algorithm. JT65 and Q65 offer _a priori_ (AP)
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decoding, which takes advantage of naturally accumulating information
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during a QSO.
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////
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The following tutorial aims to familiarize you with
|
||||
these program features, all of which are of special interest for EME
|
||||
and other extreme weak-signal conditions.
|
||||
|
||||
As a starting point, configure _WSJT-X_ as follows:
|
||||
|
||||
@ -434,3 +421,5 @@ You might wish to experiment with other combinations of entries for
|
||||
options of the *Decode* menu on and off. For best sensitivity, most
|
||||
users will want to use *Deep* decoding with *Enable averaging*,
|
||||
*Enable deep search*, and *Enable AP* all turned on.
|
||||
|
||||
////
|
Loading…
Reference in New Issue
Block a user