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Add a link to G3WDG doc on using QRA64 for microwave EME.

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git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8060 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
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Joe Taylor 2017-09-01 12:51:42 +00:00
parent bda874be89
commit 0490da3d0c
3 changed files with 18 additions and 18 deletions
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1
doc/common/links.adoc
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@ -104,6 +104,7 @@ d). Edit lines as needed. Keeping them in alphabetic order help see dupes.
:nh6z: http://www.nh6z.net/Amatuer_Radio_Station_NH6Z/Other_Peoples_Software.html[here]
:omnirig: http://www.dxatlas.com/OmniRig/Files/OmniRig.zip[Download]
:osx: http://physics.princeton.edu/pulsar/K1JT/wsjtx-{VERSION}-Darwin.dmg[wsjtx-{VERSION}-Darwin.dmg]
:QRA64_EME: http://physics.princeton.edu/pulsar/K1JT/QRA64_EME.pdf[QRA64 for microwave EME]
:svn: http://subversion.apache.org/packages.html#windows[Subversion]
:win32: http://physics.princeton.edu/pulsar/K1JT/wsjtx-{VERSION}-win32.exe[wsjtx-{VERSION}-win32.exe]
:wsjt_svn: http://sourceforge.net/p/wsjt/wsjt/HEAD/tree/[WSJT Source Repository]

13
doc/user_guide/en/protocols.adoc
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@ -149,13 +149,12 @@ separation is 110250/4096 = 26.92 Hz multiplied by n for JT65A, with n
[[QRA64_PROTOCOL]]
==== QRA64
QRA64 is an experimental mode intended for EME and other extreme
weak-signal applications. Its internal code was designed by IV3NWV.
The protocol uses a (63,12) **Q**-ary **R**epeat **A**ccumulate code
that is inherently better than the Reed Solomon (63,12) code used in
JT65, yielding a 1.3 dB advantage. A new synchronizing scheme is based
on three 7 x 7 Costas arrays. This change yields another 1.9 dB
advantage.
QRA64 is intended for EME and other extreme weak-signal applications.
Its internal code was designed by IV3NWV. The protocol uses a (63,12)
**Q**-ary **R**epeat **A**ccumulate code that is inherently better
than the Reed Solomon (63,12) code used in JT65, yielding a 1.3 dB
advantage. A new synchronizing scheme is based on three 7 x 7 Costas
arrays. This change yields another 1.9 dB advantage.
In most respects the current implementation of QRA64 is operationally
similar to JT65. QRA64 does not use two-tone shorthand messages, and

20
doc/user_guide/en/vhf-features.adoc
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@ -158,15 +158,14 @@ image::JT65B.png[align="center",alt="JT65B"]
=== QRA64
QRA64 is an experimental mode in Version 1.8 of _WSJT-X_. The mode is
designed especially for EME on VHF and higher bands; its operation is
generally similar to JT4 and JT65. The following screen shot shows an
example of a QRA64C transmission from DL7YC recorded at G3WDG over the
EME path at 24 GHz. Doppler spread on the path was 78 Hz, so although
the signal is reasonably strong its tones are broadened enough to make
them hard to see on the waterfall. The triangular red marker below
the frequency scale shows that the decoder has achieved
synchronization with a signal at approximately 967 Hz.
QRA64 is designed for EME on VHF and higher bands; its
operation is generally similar to JT4 and JT65. The following screen
shot shows an example of a QRA64C transmission from DL7YC recorded at
G3WDG over the EME path at 24 GHz. Doppler spread on the path was 78
Hz, so although the signal is reasonably strong its tones are
broadened enough to make them hard to see on the waterfall. The
triangular red marker below the frequency scale shows that the decoder
has achieved synchronization with a signal at approximately 967 Hz.
image::QRA64.png[align="center",alt="QRA64"]
@ -192,12 +191,13 @@ initially, as the QRA64 tones are often not visible on the waterfall.
The box labeled *Tx6* switches the Tx6 message from 1000Hz to 1250Hz
to indicate to the other station that you are ready to receive messages.
TIP: QRA64 is different from JT65 in that the decoder attempts to find
and decode only a single signal in the receiver passband. If many
signals are present you may be able to decode them by double-clicking
on the lowest tone of each one in the waterfall.
TIP: G3WDG has prepared a more detailed tutorial on using {QRA64_EME}.
=== ISCAT
ISCAT is a useful mode for signals that are weak but more or less