I would love a RTTY skimmer. I can't believe Chen hasn't invented it yet!
The problem with trying to find the QSX these days using a spectrum display (or
even by tuning) is that a lot of people are still calling after the DX has sent
his report or continue to call even knowing the DX is working someone else.
A big problem with RTTY, of course, is that you could be calling the DX, drop
your transmit and not know the DX station had already come back to someone
else, so you call again, basically wasting RF and losing a sense of what's
going on. What we do in New Orleans, is for everyone to monitor the Delta DX
2-meter repeater. The first one to work the DX becomes the person who tells
everyone else when the DX is transmitting so the rest can stop calling, look
for where the DX is working or gear up for the next call. Sunday with ST0R on
17 meter RTTY, I got through first in the group but my 2 meter handheld was not
making the repeater, so I got on the telephone with Mike, W5ZPA, and told him
when the DX started to transmit. Mike quickly made a contact. Then,
the second person to make a contact becomes a "spotter" to tell everyone what
frequency the DX is working AND/OR to find a clear frequency for others to call
on. Another thing the repeater
helps is for everyone to know where the other club members are transmitting so
we don't call on top of each other. This has worked very well through the
years and at one time we had seven members on the RTTY Honor Roll (we presently
have four). On Sunday, I believe every member of the club that tried on RTTY
worked them through this spotting assistance on the repeater.
Other than the W4BVH CW beacon on 18100 on Sunday, I didn't see a lot of
people calling on his frequency and we basically behaved ourselves. I've seen
much worse, so congrats to ourselves to being smart operators on Sunday. I
think everyone has made the mistake of being on the wrong VFO at one time or
another in our pursuit of DX. It seemed on Sunday that those in error figured
it out quickly and got with the program.
Now if we can only do something about that beacon.
73, Don AA5AU
From: Kok Chen <chen@mac.com>
>To: RTTY Reflector <rtty@contesting.com>
>Cc: Tom Osborne <w7why@frontier.com>
>Sent: Tuesday, July 26, 2011 12:39 PM
>Subject: Re: [RTTY] CWSkimmer use in Rtty
>
>
>On Jul 26, 2011, at 9:27 AM, Tom Osborne wrote:
>
>> I wouldn't try to use the 'hole' in between the two traces :-) Not unless
>> you have a narrow enough filter to filter out their mark and space tones.
>
>Heh, heh :-)
>
>Speaking of spectrum holes... those of us who had used waterfall tuning used
>to have a free run with split DX.
>
>All you had to do is to zero beat the station that the DX is working -- that
>takes a second or two at most, especially if your modem implements something
>like the "click buffer" in cocoaModem, where you can print the past signal of
>a station after they have already stopped transmitting.
>
>It used to take a while before the old fashioned knob twiddlers find where the
>DX is listening to, especially if the DX is working a station they can barely
>hear (but sticks out like a sore thumb on a waterfall).
>
>Back then, working split RTTY was like shooting fish in a barrel if you use a
>waterfall based receiver (especially if you have the second receiver parked at
>the DX's signal).
>
>That was 5 years or 6 years ago. Over time, there has been more waterfall
>tuners (I suspect it is the Flex guys). Nowadays, the QSX gets piled on
>almost instantly.
>
>A better technique nowadays is to find a hole right next to the previous QSX
>once the old QSX becomes congested.
>
>Now, if you know that the DX is also using waterfall tuning (for example, the
>VP2MUM and 9X0TL operations), then the "best" technique is a little different.
>
>In this case, you have to guess the bandwidth that the DX is using. In the
>case of DL2RUM operating, you know that he uses a K3 (not a SDR) and his
>waterfall range is limited to about 2 kHz. By watching the stations that he
>answers, you can pretty quickly find the lower and upper bound of his
>waterfall. In this case, finding the cleanest part of the spectrum that he
>watches becomes the key. Especially if you have a puny signal.
>
>You can readily tell if the DX is using a waterfall by seeing him jump around
>very often.
>
>Another interesting trick to crack a pileup is to perfectly "straddle" an RTTY
>signal with another RTTY signal. Place your mark tone (or space tone) right
>smack in the middle of the other guy's shift. If the DX tunes to you, one of
>the QRM tones will be right in middle between your mark and space, and with
>most RTTY filtering (either with matched filters or the "dual-peak" filters)
>the QRM will be depressed by many dB, thus giving you a better chance to print
>cleanly. The same is true if the DX tunes over to the other chap of course --
>his print will be clean and you will barely QRM him. But, in a pileup, there
>is likely to be more that one station at the other frequency, QRMing one
>another.
>
>73
>Chen, W7AY
>
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