PSK31 split operation


Eric KG6MZS
 

What's funny about that George is that the new versions of WJST-X can decode 3 or more signals from the same trace.  I guess the software initially decodes the strongest trace and then subtracts it from the pile and decodes other signals from whats left over.

Very different from PSK in that several signals usually renders all undecodable.  I've noticed that If I want to work a station on PSK that is getting a pileup of responses, just moving over a few hundred hertz will sometimes get me acknowledged from skilled stations.

This underlines another feature of split - the running stations needs to announce they are listening split -- unlike FT8.

73

Eric KG6MZS

On 1/14/22 11:09 AM, George Weller wrote:
That's helpful gents. Thank you.  A pile-up is one thing and I can see the reasoning on that.  On wsjt-x, the rationale is that the Tx signal is narrow band; minor distortion (near the edge of the Tx passband filter) reduces likelihood of a decode, so wsjt-x sets the split and adjusts the audio offset so that the Tx is at the exact same frequency as Rx, but is now in the center of the Tx passband. It seems like the same logic would apply to any narrowband signal. Of course, as was pointed out, the PSK band is usually not crowded and you can pick a frequency in the middle.

73, George KD9PCN

On 1/14/2022 12:56 PM, Eric KG6MZS wrote:
On 1/14/22 9:07 AM, Stephen Melachrinos via groups.io wrote:

The only times I've ever operated PSK split were when I was (semi-)rare DX and I had lots of stations calling.
I'll echo Stephen's sentiments.  I've seldom needed to use split for PSK because the PSK waterfall just isn't that crowded.

In Digital Master 780 it's pretty easy to set up split.  Just set up on a clear frequency and lock it, then move the receive cursor over to the station you want to work.  I usually center my TX frequency in the waterfall.


73

Eric KG6MZS

www.kg6mzs.com









Stephen Melachrinos <melachri@...>
 

George -

Avoiding distortion is always a good thing, but I haven't seen PSK31 get distorted enough near filter-band edges to lose decode. I lose the signal power before I see a distortion.

Perhaps the m-ary FSK underlying the JT modes is more sensitive than PSK.

And remember that with splits in the few hundred Hz, proper positioning of your signal (as Eric suggested) should keep the received signals away from filter-band edges.

Steve
W3HF


-----Original Message-----
From: George Weller <gvweller@...>
To: main@070Club.groups.io
Sent: Fri, Jan 14, 2022 7:09 pm
Subject: Re: [070Club] PSK31 split operation

That's helpful gents. Thank you.  A pile-up is one thing and I can see
the reasoning on that.  On wsjt-x, the rationale is that the Tx signal
is narrow band; minor distortion (near the edge of the Tx passband
filter) reduces likelihood of a decode, so wsjt-x sets the split and
adjusts the audio offset so that the Tx is at the exact same frequency
as Rx, but is now in the center of the Tx passband. It seems like the
same logic would apply to any narrowband signal. Of course, as was
pointed out, the PSK band is usually not crowded and you can pick a
frequency in the middle.

73, George KD9PCN

On 1/14/2022 12:56 PM, Eric KG6MZS wrote:
> On 1/14/22 9:07 AM, Stephen Melachrinos via groups.io wrote:
>
>> The only times I've ever operated PSK split were when I was
>> (semi-)rare DX and I had lots of stations calling.
>
> I'll echo Stephen's sentiments.  I've seldom needed to use split for
> PSK because the PSK waterfall just isn't that crowded.
>
> In Digital Master 780 it's pretty easy to set up split.  Just set up
> on a clear frequency and lock it, then move the receive cursor over to
> the station you want to work.  I usually center my TX frequency in the
> waterfall.
>
>
> 73
>
> Eric KG6MZS
>
> www.kg6mzs.com
>
>
>
>
>
>







George Weller
 

That's helpful gents. Thank you.  A pile-up is one thing and I can see the reasoning on that.  On wsjt-x, the rationale is that the Tx signal is narrow band; minor distortion (near the edge of the Tx passband filter) reduces likelihood of a decode, so wsjt-x sets the split and adjusts the audio offset so that the Tx is at the exact same frequency as Rx, but is now in the center of the Tx passband. It seems like the same logic would apply to any narrowband signal. Of course, as was pointed out, the PSK band is usually not crowded and you can pick a frequency in the middle.

73, George KD9PCN

On 1/14/2022 12:56 PM, Eric KG6MZS wrote:
On 1/14/22 9:07 AM, Stephen Melachrinos via groups.io wrote:

The only times I've ever operated PSK split were when I was (semi-)rare DX and I had lots of stations calling.
I'll echo Stephen's sentiments.  I've seldom needed to use split for PSK because the PSK waterfall just isn't that crowded.

In Digital Master 780 it's pretty easy to set up split.  Just set up on a clear frequency and lock it, then move the receive cursor over to the station you want to work.  I usually center my TX frequency in the waterfall.


73

Eric KG6MZS

www.kg6mzs.com





 

In Fldigi you do it as Eric explained to do it in DM780, use the lock button which is down at the lower right of the screen.

John  KC3FL


Eric KG6MZS
 

On 1/14/22 9:07 AM, Stephen Melachrinos via groups.io wrote:

The only times I've ever operated PSK split were when I was (semi-)rare DX and I had lots of stations calling.
I'll echo Stephen's sentiments.  I've seldom needed to use split for PSK because the PSK waterfall just isn't that crowded.

In Digital Master 780 it's pretty easy to set up split.  Just set up on a clear frequency and lock it, then move the receive cursor over to the station you want to work.  I usually center my TX frequency in the waterfall.


73

Eric KG6MZS

www.kg6mzs.com


Stephen Melachrinos <melachri@...>
 

George -

I'll tell you my opinion, and how I implement it.

The only times I've ever operated PSK split were when I was (semi-)rare DX and I had lots of stations calling. (I was operating from a large station in KH2 back in 2012 and 2014.) Most of the time I only had one or two replies (at most) for each CQ, so it was easy to pick one out to reply to even on my frequency. Occasionally there would be so many that I couldn't even pick out a callsign fragment, so I'd go split.

I've never had to do that in any other situation, even during contests. Occasionally (like during the PSKfest last weekend) I could pick out two callsigns calling at the same time, and see enough to recognize each. I'd simply reply "two stations calling. First N7WE de W3HF..." and then at the end of that QSO send "73 N7WE de W3HF sk now KD9PCN de W3HF..." 

As to how to implement it, I find the best way is to use the software to split the Tx and Rx audio frequencies (on the waterfall), and leave the radio on a single frequency. Most software that I've seen lets you lock your Tx frequency, but move the receive around. (I use DigiPan, but I'm sure someone can tell you how to do it in fldigi.) Since you can see 2-3 kHz on the waterfall when you only need less than 100 Hz, it's easy to pick them out. My Guam CQs were something like "CQ de W3HF/KH2 up 100-300." Then with my Tx freq locked, I'd move around in the range 100-300 Hz high and find someone to reply to.

73,
Steve
W3HF


-----Original Message-----
From: George Weller <gvweller@...>
To: 070Club@groups.io
Sent: Fri, Jan 14, 2022 11:16 am
Subject: [070Club] PSK31 split operation

I find split operation on wsjt-x useful, and the software automates it. 
It is mentioned in the fldigi manual but looks like one would have to
set it up manually, and it's not clear which fldigi modes to use it on
(makes sense for CW, but...).  Opinion on the internet is all over the
place - some recommend it, others call it stupid.  Is there a consensus
at the 070Club?  73, KD9PCN #2879






George Weller
 

I find split operation on wsjt-x useful, and the software automates it.  It is mentioned in the fldigi manual but looks like one would have to set it up manually, and it's not clear which fldigi modes to use it on (makes sense for CW, but...).  Opinion on the internet is all over the place - some recommend it, others call it stupid.  Is there a consensus at the 070Club?  73, KD9PCN #2879