[RTTY] Decoder performance on crowded bands

[Jeff Stai]

I think David has the right idea, this can be handled and improved
algorithmically. And I won't be adding (more) CRLFs to my macros because
there is small incentive for me to do so.

If someone shows up on my QRG and I'm not the expected call, he might still
work me. If he tunes away I've lost nothing, he wasn't going to work me
anyway. If he starts calling the wrong call in response to my CQ, well I
have to correct him and that's the cost of doing business. (That also
happens for lots of other reasons.)

If I am S&P and operating assisted, similarly I will encounter a different
station than I was expecting, but most of the time my band map will tip me
off by showing two (or more) calls in the same slot. And besides I should
listen first before calling.

Fun discussion though! 73 jeff wk6i at W7RN


On Wed, Sep 30, 2015 at 7:32 AM, David G3YYD <g3yyd at btinternet.com> wrote:

> One way of eliminating the problem is to analyse the previous text. So if
> received was CQ M7T M7T CQ AA5AU AA5AU there is sufficient information to
> parse the text to realise the CQ is by M7T and the S&P call is by AA5AU.
>
> Another method would be to have a timer so after identifying M7T as the CQ
> station do not identify a different CQ callsign until 5 seconds has passed,
> which is enough for 30 characters. Could be an even longer time period and
> still not miss a different station calling CQ.
>
> However M7T may be difficult copy with the skimmer and so it may just hear
> in effect noise CQ AA5AU AA5AU in which case AA5AU would be identified as
> the CQ station and M7T would not be mentioned at all. But this will not
> happen very often.
>
> 73 David G3YYD.
>
> -----Original Message-----
> From: RTTY [mailto:rtty-bounces at contesting.com] On Behalf Of Don AA5AU
> Sent: 30 September 2015 13:48
> To: rtty at contesting.com
> Subject: Re: [RTTY] Decoder performance on crowded bands
>
> According to Pete's (N4ZR) post today, "{enter}WW3S WW3S" is suppose to
> break the association from the CQ but it doesn't appear to be true in some
> cases. Putting a C/R L/F {enter} in front of nearly all macros has been
> preached for years and I believe most operators do this already.
> I include a C/R L/F at the start of my macros and I still get spotted
> quite a bit when S&P. Pete's post did make the suggestion of adding {enter}
> after the trailing CQ in the message and although it will make the CQ
> message longer, it might help keep S&P stations from being spotting so I
> think I will try it in JARTS (if I can remember to do so). If there is a
> C/R after the CQ and the S&P station sends C/R at the start of his message,
> perhaps the double C/R will help. I don't know.
> Now all this got me to thinking, and I don't know the answer to this, but
> perhaps if S&P stations wait a little longer before coming back to a CQ
> station, will it help eliminate the S&P station from being spotted? This is
> actually good practice anyway. I like to wait just a half second or more
> after the run stations drops his transmitter to listen to see if anyone
> (that I can hear) else is calling the CQ station at the same time as me. If
> so, I send my call 3 times. If not, I send my call 2 times. I wonder if
> this will also help break the association with the CQ message?
> I don't now how much better the skimmer software can be made. But if the
> operators on this reflector would start implementing changes to our own
> messages and the way we operate, maybe we can make the skimmer experience a
> little better.
> 73, Don AA5AU
>
>
>
>       From: Lee Sawkins <ve7cc at shaw.ca>
>  To: rtty at contesting.com
>  Sent: Tuesday, September 29, 2015 7:58 PM
>  Subject: Re: [RTTY] Decoder performance on crowded bands
>
> Jamie
>
> How sending this. "{enter}WW3S WW3S ". Maybe this would break the
> association between the CQ from AA5AU and you better and not spot you. I
> seem to rarely get spotted during S&P and this is what I do.
>
> 73 Lee
>
> ----- Original Message -----
>
> From: "Gary Senesac" <al9a at mtaonline.net>
> To: rtty at contesting.com
> Sent: Wednesday, September 30, 2015 12:18:03 AM
> Subject: Re: [RTTY] Decoder performance on crowded bands
>
> Quick fix. Don't send the 'DE' before your call. It is absolutely
> unnecessary!
>
> Gary AL9A
> Sent from my Kindle HDX
>
> On September 29, 2015, at 2:57 PM, WW3S <ww3s at zoominternet.net> wrote:
>
> What I think usually happens is the skimmer cannot tell the difference
> between who is who.....so since most people now append their CQ message
> with CQ, it goes like this....
> CQ AA5AU AA5AU CQ
> and then I answer
> DE WW3S WW3S
> ends up looking to the skimmers as
> CQ AA5AU AA5AU CQ DE WW3S WW3S
> and I get spotted on Dons run frequency....
> just a semi educated guess, from a semi educated man....
>
> > On 9/29/2015 7:37:46 PM, Tim Shoppa (tshoppa at gmail.com) wrote:
> > > Wow, thanks for all the responses! Most especially to Lee VE7CC
> > > himself,
> > who helped me figure out how to reset a filter I had apparently
> > applied over a year ago (probably by clicking on the "NE ONLY" button
> > in N1MM). The density of good CW skimmers in NE USA meant that I had
> > never noticed this filter until the RTTY contest, where most of the
> > USA RTTY Skimmers were in 7-land.
> >
> > AA5AU and GU0SUP raised an issue, about how sometimes S
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-- 
Jeff Stai ~ wk6i.jeff at gmail.com
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