[Moon-Net] Q65 120a QSO's on 2 meter EME.

Joe Taylor joe at princeton.edu
Sun Apr 18 19:46:02 CEST 2021


Hi Earl and all,

Thanks for sharing some comments about your tests with Q65-120A for 2m 
EME.  This submode of Q65 is there, and it's very usable; but as you 
probably understand, it's not recommended for general use.  In most 2m 
EME circumstances Q65-60A (with message averaging enabled) is as good or 
better.

Since you did not send and *.wav files I can't comment on the instances 
you said that "the signal was present on the waterfall but no decode".

As noted in the User Guide and in a WSJT-X Tool-Tip, the RR73 message 
should be used only if you are reasonably confident that no repetitions 
will be required.

As I've said before, we have no plan to introduce two-tone messages for 
Q65, analogous to the shorthand RO, RRR, 73 messages in JT65.  But if 
you need every last bit of sensitivity, you and your QSO partner can 
learn to use and agree to use the single-tone T M R 73 transmissions 
already available in Q65.  Some microwave EME users like find them 
extremely useful.

	-- 73, Joe, K1JT


On 4/17/2021 11:33 AM, Earl Shaffer via Moon-net wrote:
> Hi All
> 
> In keeping with the requirement  of using WSJTx rc4 I am reporting 
> recent activity using that software.
> 
> This is a timeline of my initial QSO with VK2XN.
> I think degradation was something like -5db and 600k noise.
> My noise level was about 4 to 5 db above a dummy load.
> 
> VK2XN  17EL 300 no elevation.
> 
> Q65 120a
> 
> 17Apr 00:47 CQ CQ CQ 1ST 144.144 Q65 120A ====== {WB9UWA/4XP12/1K
> 17Apr 01:06 moon visible @ 0104Z and you magically appear on my 
> waterfall - VK2XN
> 17Apr  0118 -27  2.7 1493 :  WB9UWA VK2XN QF59  q0
> 17Apr  0130 -35  2.7 1502 :  WB9UWA VK2XN R-35  q3
> 17Apr  0132 -27  2.8 1155 :  VK2XN WB9UWA RR73  q3       Thanks Earl..
> 17Apr  0134 -28  2.5 1503 :  WB9UWA VK2XN 73    q3
> 17Apr  -24 your best deepest decode -35 ====== {VK2XN Wayne
> 
> You can see that between 0118 and 0130 there was an extended fade.
> We noted at times that the fade was same at both ends.
> 
> Initial. Many times the signal was present on the waterfall but no decode.
> I could have seen short hand signals in this case shortening up the QSO.
> There were many peaks and fades over this period of time as is usual.
> Of course I am used to adaptive polarization and I have only vertical or 
> horizontal RX with WSJTx rc4 right now. I was monitoring the waterfall 
> from Map65 and comparing it to the waterfall on WSJTx. Any time I saw a 
> better signal on Map65, I would change RX polarity. That works pretty 
> well for me. One thing I like about 2 meter EME is that there are many 
> tropo stations that I can work off the moon. With proper timing I think 
> this QSO could be done on JT65b where the short hand signals would be 
> decoded by eye using the waterfall during the first fade. I have decoded 
> JT65b signals at -27db before on both Map65 and WSJTx. Wayne noted that 
> I was much stronger (speaker copy) after the QSO. Perhaps he had better 
> ground gain at this time.
> 
> JA5EEU   4RP 500
> I worked JA5EEU after this QSO and he was a bit stronger. On another 
> occasion I easily made a quick JT65b QSO with him. This QSO lasted about 
> 20 minutes and as noted in the previous QSO there were many fades and 
> peaks over that period of time.
> There were times that the signal was strong enough that it should have 
> decoded but it was not.
> JA5EEU may have had more frequency drift than VK2XN.  JA5EEU also 
> reported early on that he saw strong but undecoded signals from me.
> These two Q65 120a QSO's reminded me a lot of the old 1 hour CW skeds 
> where you have to ride several peaks and valleys to piece together calls 
> and reports.
> 
> UA9YJM 4X10H 300
> UA9YJM Called CQ after this and I answered his CQ. We had a fast JT65b 
> QSO and his best was -20db which is the strongest I have ever seen him. 
> Generally my noise level was 6db above a dummy load and my moon 
> elevation was 28 degrees by this time.  Any 300 watt station is a great 
> catch for me.
> 
> I really, really wish I could use short hand signals for Q65. At that 
> point I think Q65 120a would make a good DX mode for working very small 
> (initial) stations. There were many times I would have seen the short 
> cut signal on the waterfall but instead was presented with a no decode. 
> This is true especially considering that the sync tone of Q65 is 
> considerably weaker than for a JT65b sync tone. I can see that weak 
> QSO's on Q65 300a could easily go on for over an hour.  Signal fades are 
> often so severe that even more sensitive modes do not make up the 
> difference. Even after all these years, JT65b remains a great DX and 
> contest digital mode. I suspect that Urban noise makes for more QSB than 
> what might be expected by those lucky few that live in a quiet 
> neighborhood. Very strong bursts of noise may take out a digital signal 
> while a simple pattern may still be decoded by eye on a waterfall.  In 
> my mind it is much like digital TV. In the days of analog TV you may see 
> noise bursts or tears in the image, but never lose the picture. Digital 
> TV is all or nothing. When people ask me about what antenna to use for 
> digital TV, I tell them it is easy to pick up digital TV but hard to do 
> it reliably.
> 
> -- 
> Earl Shaffer,  WB9UWA
> My EME array photos
> https://www.dropbox.com/sh/bbn2ktonko8e3az/AACHBBOhf6Djk5Pf2c86Br5ja 
> <https://www.dropbox.com/sh/bbn2ktonko8e3az/AACHBBOhf6Djk5Pf2c86Br5ja>
> Detailed array photos
> http://www.gm4jjj.co.uk/WB9UWA/ <http://www.gm4jjj.co.uk/WB9UWA/>
> Facebook
> http://www.facebook.com/earl.shaffer <http://www.facebook.com/earl.shaffer>
> Linkedin
> http://www.linkedin.com/pub/earl-shaffer/12/881/735 
> <http://www.linkedin.com/pub/earl-shaffer/12/881/735>
> 
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