Hi Philip,
Our policy is to report all decodes that include a grid square, as we
receive them. Multiple decodes of the same transmission by the same
receiving station are most frequently caused by:
1. Low-level sidebands offset in frequency by multiples of the
power-line frequency. Usually the offset signals are at +/- 100 or 120
Hz, and usually they are down by 20 to 30 dB from the main signal.
2. Multipath propagation with different Doppler shifts. Most commonly
these are aircraft reflections; they are often seen at 50 and 144 MHz.
Frequency offsets are typically a few tens of Hz at 50 MHz.
I suppose we could suppress multiple reports of the same transmission --
say, by reporting only the strongest one -- if you thought that was
important.
These are not program errors. The multiple signals truly exist in the
received data.
-- 73, Joe, K1JT
On 1/20/2019 10:33 PM, Philip Gladstone wrote:
I notice that I am getting a bunch of duplicates in the packets (as seen
in the raw packet captures) being sent to pskreporter. For example:
WE6Z reported seeing KG7VOR twice at Jan 21, 2019 03:03:29. The only
differences were:
One entry had Frequency 1841279 with snr -15
Another had Frequency 1841400 with snr of 13
In fact there were 9 spots of KG7VOR in the same packet (at five
difference timestamps).
This is not limited to a few cases, but it appears a fair amount.
At the same time, I'm getting comments from people that not all of their
spots are being reported -- so I'm wondering if this duplication is
actually a symptom of something more serious....
Puzzled
Philip
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