Subject: Re: Calling CQ on PSK-31

[jperelst]

I find I have the same experience, and I typically run 20w on PSK.  I have no clue as to why that happens.  I have pretty good luck at getting QSOs when I respond to CQs, but I rarely see anyone responding to my own CQs.

I have noticed that the longer my CQ string, or the more I repeat it, the more frequently I get a response to the CQ.  I've also noticed a lot of stations that repeat their 3x3 CQs at least two or three times before they get an answer.

>>Panadapter?
>>You can see most of the PSK section of any band on the
software's
>>waterfall....Assuming you're using software ie. MIXW etc.

Just because I can see it on the waterfall doesn't mean that I have any idea if it's a CQ or not.  And if it's a short CQ, by the time I click over to it, it's gone.

A couple of products (e.g., Digipan) show you the text from multiple transmissions at a time, but not all the major products do that (e.g., DM780).

Jon
KB1QBZ

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[Phil Hystad-3]

On May 11, 2010, at 9:14 AM, Jon Perelstein wrote:

> Just because I can see it on the waterfall doesn't mean that I have any idea if it's a CQ or not.  And if it's a short CQ, by the time I click over to it, it's gone.

Which is a good reason to buy an Apple Mac and help to increase my AAPL stock value even more...

The CocoaModem digital interface application that runs only on the Mac has a very nifty feature.  Even if a waterfall trace of a message is over, as long as it is in the displayed buffer you can click on it and see the text of that stream for the amount of the buffer contents that is retained.

This feature allows me to click on any obvious current or previous stream (previous of course is dependent on the buffer history) to interpret the contents.  Often I have caught a CQ call this way and can step right in and respond.

Of course, I  have not used too many other digital interface applications so I am not sure if this particular feature is available elsewhere.
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[Jens Petersen-2]

On Tue, 11 May 2010 09:14:10 -0700 (PDT), you wrote:


>A couple of products (e.g., Digipan) show you the text from multiple
>transmissions at a time, but not all the major products do that
>(e.g., DM780).

In DM780 we have 'SuperBrowser' that can show up to 60 QSOs at one
time.

And in chat mode you can click on the waterfall and have the program
decoding a missed signal.
--
OV1A Jens

 Drive the way you wish your children would.
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[jperelst]

It is available on DM780.  I'm not sure about others.

--- On Tue, 5/11/10, Phil Hystad <[hidden email]> wrote:
Which is a good reason to buy an Apple Mac and help to increase my AAPL stock value even more...

The CocoaModem digital interface application that runs only on the Mac has a very nifty feature.  Even if a waterfall trace of a message is over, as long as it is in the displayed buffer you can click on it and see the text of that stream for the amount of the buffer contents that is retained.
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[Fumiaki Okushi]

The feature described below (playback trace still in the buffer) is also available in Fldigi (which I happen to use for PSK).

Fumi Okushi/KB2KVV

From: Phil Hystad <[hidden email]>
Subject: Re: [Elecraft] Subject: Re: Calling CQ on PSK-31
Date: Tue, 11 May 2010 09:30:44 -0700

> On May 11, 2010, at 9:14 AM, Jon Perelstein wrote:
>
>> Just because I can see it on the waterfall doesn't mean that I have any idea if it's a CQ or not.  And if it's a short CQ, by the time I click over to it, it's gone.
>
> The CocoaModem digital interface application that runs only on the Mac has a very nifty feature.  Even if a waterfall trace of a message is over, as long as it is in the displayed buffer you can click on it and see the text of that stream for the amount of the buffer contents that is retained.
>
> This feature allows me to click on any obvious current or previous stream (previous of course is dependent on the buffer history) to interpret the contents.  Often I have caught a CQ call this way and can step right in and respond.
>
> Of course, I  have not used too many other digital interface applications so I am not sure if this particular feature is available elsewhere.
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[Kok Chen]

On May 11, 2010, at 9:14 AM, Jon Perelstein wrote:

> I have noticed that the longer my CQ string, or the more I repeat it, the more frequently I get a response to the CQ.  I've also noticed a lot of stations that repeat their 3x3 CQs at least two or three times before they get an answer.

With something like PSK31, the receiving station has to achieve phase lock, or at the least frequency lock if it is using a non-coherent demodulator.

Evenn with non-coherent demodulation, the "local oscillator" of the demodulator has to get within 7.8 Hz (90 degree phase resolution at the symbol rate of BPSK31) to get any copy at all, and if your SNR is poor at the receiving end, he really has to get to within 1 Hz.  This means that the receiver could take a large part of a second before it can start decoding you.

Your CQ will have to be at least that long, even assuming that your call sign is the very last thing that you transmit.

Most PSK31 software today have the capability of multiple demodulating (similar to VE3NEA's Skimmer for CW), and this problem is lessened nowadays.  Many people are watching for CQs using the multiple decoders.

> Just because I can see it on the waterfall doesn't mean that I have any idea if it's a CQ or not.  And if it's a short CQ, by the time I click over to it, it's gone.

I had noticed this many years ago.  People were sending CQs that are too short. By the time I see a signal on the waterfall to click on it, he has already stopped calling.  I had to wait until he calls again.

Because of that, I implemented what I called the "click buffer" in cocoaModem.  Think of it as an old fashion tape recorder's tape loop.  The tape allows you to go back in time to replay the signal back.  When you click on a signal, the demodulator attempts to frequency/phase lock on to that signal.  Once the lock is achieved and the local oscillator is locked and not allowed to change anymore, the "tape loop" is played back to the demodulator.  The loop is played back at a faster rate than the normal system, so the decoding catches up with real time very rapidly.  In cocoaModem, this exhibits itself as a short pause right after clicking on the waterfall, and there will be a fast burst of print on the screen, followed by the normal steady BPSK31 character rate.

I extended this concept later to a general "click buffer" (and also to other modes; even the CW decoder has it) where there is a constant 20 second (the height of cocoaModem's waterfall) tape loop running all the time.

When you click on the waterfall spectrogram, I collect both the horizontal position of the click (to get frequency information) and the vertical position of the click (to get "time" information) and use the "time" parameter to determine how far back in the tape loop you play back to the demodulator when you first click on the signal.

With this extended "click buffer," you can actually click on a signal that has stopped transmitting, and if CQ has appeared within 20 seconds of the last time you turned the knob of the rig, you can copy what he sent.  I am sure it is disconcerting to the other end to get a reply to their CQ 20 seconds after they issued them, and they might attribute that to a slow operator, HI.

If you watch the cursor in the waterfall in this movie of the VP2MUM RTTY operation with a K3, you can see Tom (DL2RUM) take advantage of the RTTY click buffer in his RUMped program (RUMped use cocoaModem's demodulator for digital modes) quite often to pull people after they have already stopped calling:

http://dl2rum.de/rumsoft/VP2MUM_RTTY.mov

The text buffer and RTTY waterfall are in the bottom right hand window.  Watch his cursor :-).

With a click buffer, you can get run rates to go pretty high since you seldom have to wait for a slow caller to finish identifying itself.  You just jump to a different trace on the waterfall that has already finished transmitting.

73
Chen, W7AY



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[Julian, G4ILO]

Phil Hystad-3 wrote

On May 11, 2010, at 9:14 AM, Jon Perelstein wrote:

> Just because I can see it on the waterfall doesn't mean that I have any idea if it's a CQ or not.  And if it's a short CQ, by the time I click over to it, it's gone.

Which is a good reason to buy an Apple Mac and help to increase my AAPL stock value even more...

The CocoaModem digital interface application that runs only on the Mac has a very nifty feature.  Even if a waterfall trace of a message is over, as long as it is in the displayed buffer you can click on it and see the text of that stream for the amount of the buffer contents that is retained.

The built in PSK31 modem in KComm for Windows can do that as well. (Actually it is a feature of the PSK31 DLL by AE4JY and not anything clever I did.)

KComm also has a "PSK Browser" that decodes all the signals in the passband (and reports them to PSK Reporter if you want to do that.)

Of course that doesn't help get other people answer *your* CQs. Perhaps an increasing use of PSK Browsers means that people don't tend to bother with weak stations that aren't DX? Adding "QRP" (but please not "/QRP") to your CQ calls might help a bit.

I ran just 4W of PSK31 and an attic antenna for many years with my QRP K2 with quite a bit of success. But there were more sunspots around at the time. I admit that frustration with conditions over the last couple of years was why I got the 100W PA for my K3 (not being able to do anything about the antennas.) It made a heck of a difference to my success rate. No problem getting replies to my CQs now.

If you must run QRP then as others have suggested, replying to other people's CQs is really the way to go.

[lstavenhagen]

Exactly, as well as support Chen so he'll write more cool apps for us, hi hi. Everyone beat me to it tho, I was also going to say cocoaModem's "click buffer" works FB.

There's also a "table" mode in cocoaModem that'll decode multiple streams in the audio bandpass (which I've seen in others like Digipan, I believe). You can also double-click on the streams and the demodulator goes directly to it in the waterfall instantly switching you to that freq. Very nice!

73,
LS
W5QD

[Leigh L. Klotz Jr WA5ZNU]

In addition to having fldigi decode the last few seconds of a qso you left click and move you, you can also right click on another QSO in fldigi and it will display the last few seconds in purple. Finally, you can set up fldigi so that it puts clickable frequency markers in the receive buffer so you can go back to a previous frequency you've left clicked on.  (I had a hand in designing these features and in some of the implementation.)

Leigh/WA5ZNU