[RTTY] RTTY skimmer observations - long

[Robert Chudek - K0RC]

Hello Wes...

I know you have put a lot of time, effort, and money into building your 
RTTY Skimmer. Please take my comments below as a 'positive' feedback 
experience, offered to help identify and find solutions to some of the 
issues I am reporting.

The first issue I noticed this past weekend was that when I (KØRC) was 
spotted, the spot frequency was consistently 100 Hz too low. That's not 
a huge discrepancy so I don't feel this is a major problem. As you know, 
the cluster system rounds off frequencies to the nearest 0.1 KHz 
increment. In many cases this is a plausible explanation for the 
mismatch. This isn't the case I am reporting though. I am reporting that 
my Mark frequency is perhaps 14085.5 and the spot comes through as 
14085.4. There should not be any rounding error in that scenario. That 
minor frequency error is not enough to miss a CQing station and I am 
reporting the issue only as a data point.

The second observation was that I was not picked up on 10 meters. Maybe 
you didn't have a receiver scanning that band or maybe there was no 
propagation between our locations. Were you scanning 10 meters over the 
weekend?

The third observation was on the other bands I was being spotted almost 
immediately, which is good, but is not good when I am in S&P mode! I 
think this is the issue that is being reported by others and hopefully 
can be reviewed and resolved.

As you know, during contests many stations (who are running a frequency) 
will end their transmission with _CALLSIGN_CQ_ (where the underscore is 
the space character in these examples).

I answer with my call sign only. The actual Baudot code would be: 
CR/LF_KØRC_KØRC_  (with the FIGS/LTRS codes either side of the number Ø).

I answer a CQing station, immediately on their frequency. Typically 
within +/- 10 Hz. In addition, I might start my transmission prior to 
their carrier dropping. To a third-party listener, who is receiving us 
both at the same strength, there might not be any detectable "dead air" 
separating the two transmissions. It is possible the frequency could 
sound like a continuous transmission from one transmitter.

Other times when I answer a CQing station, the RUN station will have 
some unexpected trailing "garbage" so I cannot anticipate when to hit my 
TX, and in those cases, there WILL be dead air between our transmissions.

In either case, if you were CQing and I answered you, the sequence might 
look like this:  ...WZ7I_WZ7I_CQ_CR/LF_KØRC_KØRC_

I send the CR/LF_ to start a fresh line and one space character to 
provide extra synch time for your decoder. On the other hand, some 
fellows go CR/LF 'happy' at the end of their transmissions (which I 
never understand WHY!) sending a half dozen CR/LF codes. My sample above 
is the most abbreviated example of a S&P station calling a RUN station 
and the S&P call sign getting spotted incorrectly.

If you check your RTTY Skimmer log for KØRC, you will want to know that 
I ran on 280084.0 for the first 10 minutes of the contest only. The rest 
of the weekend was strictly S&P mode so my call sign should not show up 
anywhere other than between 1800z ~ 1810z the first day on 10 meters.

It was nice to know that my signal was being decoded and posted (and I 
could see how strong I was being received). But I felt "guilty" that I 
was being spotted numerous times on someone else's run frequency. Of 
course that scenario was not unique to me. I am anticipating you and 
Walter will figure out a better method to determine whether a RTTY 
station is a RUN or a S&P station.

My own personal thought is to delay posting of any spot until a higher 
level of RUN vs S&P has been determined. On 40 meters (where I think 
there was very good propagation between us) my call sign was posted 
almost immediately after making my first call to a CQing station. The 
logic that determines who is the RUN station was obviously fooled. I 
recall that specifically happening because I was startled to see my call 
sign pop up in big red letters in the Info window of N1MM Logger!

I visited DXWatch.com to look for my spots but apparently it does not 
store RTTY spots. Is there a place to view the spot history online?

73 de Bob - KØRC in MN

------------------------------------------------------------------------
On 1/6/2014 8:57 AM, Wes Cosand wrote:
>> I also noticed that some of the most prolific running stations, had a long
>> trail of skimmer spots for their callers, and this was with my packet
>> timeout of 10 minutes.
>>
>
>> Also all the skimmer spots seem 300-400Hz too low. The manually entered
>> spots seemed to be within 100Hz. Not a big deal for me (as I know to
>> inspect spot source) but I'm sure it confused some others.
>>
>>   I would welcome this discussion as I am certain Walter, DL4RCK would.  I
> am certainly motivated to find solutions to these issues.  I thought I had
> a definitive way of calibrating my spot frequency but it obviously isn't
> working.  I will spend some time this week looking at the W1AW RTTY
> frequency.
>
> Wes, WZ7I
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