Hi Bill
I have noticed similar problems with sending just RRR on its own on 10
and 24 GHz aircraft scatter where RRR often comes out as RRT or RRS. We
have also tried sending R R R as you did and this does seem to solve it
but at the expense of extra time which we often don't have on very short
aircraft scatter bursts. Your finding that SSS works well is useful and
might give a clue as to what is causing this and what might be the
solution but as it does not happen all the time it will be worthwhile
your testing that the SSS result is always consistently good. David
VK3HZ and I commented as below in a DUBUS article 2015 vol 1 (it might
have been 2014 vol 4 as I don't have it with me) on 10 and 24 GHz
aircraft scatter. It would certainly be good to find out the reasons
and any solution that still allows the use of the shortest messages.
*6. Decoding of RRR*
We often see RRR decoded with only two of the Rs correct such as RRS.It
seems this error is due in some way to having three of the same tones in
a row together with Doppler shift in the signal.In addition to the RRR
one also sees the length of the message in the first column as 4.As it
is unlikely that any message with two RRs and a length of 4 would be
other than RRR (i.e. beginning-of-message plus 3 characters) we have
taken the view that two RRs in a message of length 4 is sufficient to
confirm that RRR is being transmitted.It is also possible with some
experience to decode RRR and 73 by ear.
73 Rex VK7MO
On 18/06/2015 5:30 AM, Bill Ockert - ND0B wrote:
Good afternoon,
Several of us playing with ISCAT on 6m have noticed that it has a
difficult time decoding the RRR message regardless of signal
strength. This is occurring both with the standard RRR message in
WSJT 10 and with alternate messages in an experimental version of WSJT
we are using. Typical non decode is as follows, note the consistency
180545 4 -3 3.1 -43 0 * ND0B W5LDA -6 14 10
10 2.2
180615 3 -2 11.5 -43 0 * ND0B W5LDA RRT 15 5
10 1.1
180645 6 -2 12.6 -43 0 * ND0B W5LDA RRT 15 5
10 2.2
180715 3 -2 11.5 -43 0 * ND0B W5LDA RRT 15 5
10 1.1
180745 2 -5 2.6 -43 0 * ND0B W5LDA RRR 15 6
10 2.2
180815 6 -2 14.3 -43 0 * ND0B W5LDA RRT 15 5
10 2.2
180845 2 -3 4.2 -43 0 * ND0B W5LDA 73 14 10
10 1.1
As an experiment we put spaces between the Rs, this decoded every time
181045 8 -2 9.8 -43 5 * ND0B W5LDA R R R 17 5
10 4.5
181115 8 -2 9.3 -43 5 * ND0B W5LDA R R R 17 5
10 4.5
181145 8 -2 11.5 -43 5 * ND0B W5LDA R R R 17 4
10 4.5
As a further experiment we changed it to SSS... again decoded every time
182115 3 -2 9.8 -43 0 * ND0B W5LDA SSS 15 9
10 1.1
182130 0 -20 0.0 0 0 0 0 0 0.0
182145 3 -2 2.0 -43 0 * ND0B W5LDA SSS 15 10
10 1.1
182200 0 -20 0.0 0 0 0 0 0 0.0
182215 3 -2 1.5 -43 0 * ND0B W5LDA SSS 15 10
10 1.1
Any thoughts on where I might start looking for this issue would be
greatly appreciated.
This is happening on 10.0 5490 release as well as the experimental
version I developed. It also happens with just the RRR message.
Thank you!
73 de Bill ND0B
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