[Moon] [Moon-Net] FW: QRA 64

Stig Larsson sm4ggc at gmail.com
Thu Feb 14 08:59:42 CET 2019


Great explanation Bob,
I just wonder how good is the red mark is on weak QRA64 signals.
The red marks that appearing on receiving signals are you there to help you
find the beginning of the QRA64 signal. Do they appear on signals below -23
dB? I haven't tested this.
Stig, SM4GGC

Den tors 14 feb. 2019 kl 08:02 skrev Bob Atkins via Moon-net <
moon-net at mailman.pe1itr.com>:

> My take on QRA64
>
> In principle, QRA64 can probably be used on all bands to maximize
> sensitivity. However on really weak signals it's probably more difficult to
> use than JT65 because there is no pilot tone and it's not always possible
> to visually identify the signal. In that case you have to send a constant
> tone so the Dx station can identify your frequency and synchronize with
> it.  If both stations are GPS locked and know their frequency is accurate
> to a few Hz, then you may be able to make a "blind" QSO without first
> synchronizing frequencies, but that's usually not the case.
>
> So while QRA64 is more sensitive, when you really need that sensitivity
> (below around -23), it's hard to visually identify the QRA64 signal by eye.
> That's probably why more people don't use it. When you can easily see the
> signal, JT65 *usually* works just as well!
>
> QRA64 also doesn't use Deep Search or need a table of possible callsigns .
> Some people think Deep Search is "cheating"! I won't get into that
> argument.  QRA64 can/does use AP, but that only uses information actually
> obtained during the QSO. It requires no prior knowledge of possible calls.
>
> I don't know the current status of "AFC" (ability to follow a drifting
> signal and or doppler shift) in QRA64 vs JT65. I'm pretty sure the ability
> of QRA64 to deal with such signals is not better than JT65. It may not be
> as good (it wasn't a while ago, but may have been improved). In the real
> world, with doppler drift, signal instability and birdies affecting the
> signal, I don't know if the  theoretical advantage of QRA64 over JT65 is
> realized.
>
> The submode that works best is the one the other station is using! That's
> usually A on 144, B on 432 and C on 1296.  A is more sensitive than B,
> which is more sensitive than C. However C copes better with signal
> spreading (libration) than B, which copes better than A.  Under conditions
> of minimum signal spreading on 1296 you could certainly use mode B, and
> possibly even mode A and gain some sensitivity (as long as you have a
> stable signal). However that required both stations to know in advance
> which submode is in use.
>
> QRA64 is the mode of choice on higher bands (like 10Ghz) because signal
> spreading is too high for JT65C to be used and the only other choice is
> JT4. QRA64 is significantly better than JT4.
>
> I'm happy to run submode and QRA64 tests on 1296 with anyone interested in
> doing so.
>
> 73
> Bob, KA1GT
> ------------------------------
> *From:* Moon-net <moon-net-bounces at mailman.pe1itr.com> on behalf of Serge
> Szpilfogel via Moon-net <moon-net at mailman.pe1itr.com>
> *Sent:* Wednesday, February 13, 2019 11:24 AM
> *To:* moon-net at mailman.pe1itr.com; moonbounce reflector
> *Subject:* [Moon-Net] FW: QRA 64
>
> Thank you to REX VK7MO & Stig SM4GGC for their detailed explanations on
> how to use QRA64 & why it is more sensitive than JT65B & why for 144Mhz
> QRA64A ought to be used.
> Enjoy
> Serge VE1KG
>
> -----Original Message-----
> From: Stig Åke Larsson [mailto:stig.ake.larsson at gmail.com
> <stig.ake.larsson at gmail.com>]
> Sent: February 13, 2019 15:17
> To: Serge Szpilfogel
> Subject: Re: QRA 64
>
> Serge It is all ok to put it on EME reflector. I have corrected some minor
> spelling here.
>
> Thanks for your appreciation of my video! This video is now 1 and 1/2 year
> old made with WSJT 1.7. I believe there is some improvements and changes
> made in in newer version 2.0.
> I will try to comment on your questions.
>
> 1. The recommended sub mode by K1JT for 144MHz is A. The usage of sub
> modes depends  how much Doppler effect there is on the band you use for
> EME. As max the Doppler only are a couple 100 Hz on 144 MHz is A best. For
> higher bands 70, 23 and so on is B and C better.
>
> 2. In old WSJT 1.7 was audio level 30 good. In the new 2.0 have they
> change how this audio level meter works so I belive 50-60 is Ok as long as
> it is green. I have between 50 and 60 now days.
>
> 3. The sensitivity of QRA64 compared with JT65 depend how you use it look
> at graph. For example JT65 with use of call in Call3 file is some dB
> better.  In answering a CQ call, but QRA64 has better sensitivity when you
> give signal report. If you don't use Call3 file in
> JT65 is QRA64 always better
> image.png
>
>
>
> My Wide graph in WSJT 2.0
> image.png
>
>
> Attached is the presentation from IV3NWV Nico in EME conference Venice
> about his QRA64
>
>
> Best 73 Stig, SM4GGC
> http://www.sm4ggc.se/
>
>
> Den ons 13 feb. 2019 kl 15:06 skrev Serge Szpilfogel <ve1kg at eastlink.ca>:
>
>
>         Stig thank you it is so helpful I wonder if I could ask you
> permission to put it on our reflector??
>         It may help people to understand QRA64 A better. I wonder why
> people do not use it more often??
>         Thank you again dear friend.
>         Serge VE1KG
>
>         -----Original Message-----
>         From: Stig Åke Larsson [mailto:stig.ake.larsson at gmail.com
> <stig.ake.larsson at gmail.com>]
>         Sent: February 13, 2019 08:35
>         To: Serge Szpilfogel
>         Subject: Re: QRA 64
>
>         Good morning Serge!
>
>         Thanks for your appreciation of my video! This video is now 1 and
> 1/2 year old with made with WSJT 1.7. I believe there is some improvements
> and changes made in in newer version 2.0.
>         I will try to comment on your questions.
>
>
>         1. the recommended sub mode by K1JT for 144MHz is A. The usage of
> sub modes depends  how much Doppler effect there is on the band you use for
> EME. As there is only some 100 Hz on 144 MHz is A best. For higher bands
> 70, 23 and so on is B and C better.
>
>         2. In old WSJT 1.7 was audio level 30 good. In the new 2.0 have
> they change how this audio level meter works so I belive 50-60 is it ok as
> long as it are green. I have between 50 and 60 now days.
>
>         3. The sensitivity of QRA64 compared with JT65 depend how you use
> it look at graph. For example JT65 with use of call in Call3 file is some
> dB better i answering a CQ call, but QRA64 has better sensitivity when you
> give signal report. If you don't use Call3 file in
>         JT65 is QRA64 always better
>         image.png
>
>
>
>         My Wide graph in WSJT 2.0
>         image.png
>
>
>         Attached is the presentation from IV3NWV Nico in EME conference
> Venice about his QRA64
>
>
>         Best 73 Stig, SM4GGC
>
>         Den tis 12 feb. 2019 kl 18:15 skrev Serge Szpilfogel <
> ve1kg at eastlink.ca>:
>
>
>                 Good evening Stig I was watching your video using QRA 64
> VERY helpful to me.
>
>                 I have a few questions
>
>                 1) For 144MHZ which submode to use?? QRA/B or QRA/A ?? &
> WHY??
>
>                 2) I notice that your audio level are around 30 mine is
> around 60 not sure what it should be????
>
>                 3) I like the way you have the wide graph set up Which
> shows where the station is
>
>                 Can you send me a complete picture of your wide graph
> please??
>
>                 I thing Stig QRA64 decodes better than JT65B but I am not
> yet convinced
>
>                 Thank you Stig I will watch your video again hi!!!
>
>                 Serge VE1KG
>
>
>
>
>
>
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