I run WSJT-X (2.2.2) and JTAlert (2.16.15).  Recently I have spent quite a lot of time just monitoring 15m, and never transmitting.  I have noticed several times that I get called by a "station" with the right format  eg      "G3UEG  IO6YIP BG06           a2"

How can this happen?  IO6YIP is not on QRZ.COM so is suspect.  How is my callsign known, I have NOT transmitted at all , not even tuned up.

This has happened probably 6/8 times over the last couple of months.  Sometimes the message format is obviously gibberish, but sometimes nearly right as above.

I am perplexed!

73,
Dave  G3UEG

I though I read once that WSJT-X tries and correlate what it can’t quite decode with calls it’s seen before. This is obviously gibberish, as the grid-square is in the middle of the south pacific, and not in Italy.

 

73 Phil GM3ZZA

 

Sent from Mail for Windows 10

 

From: David Gould
Sent: 16 December 2020 15:52
To: main@WSJTX.groups.io
Subject: [WSJTX] Being called when just monitoring and not transmitting

 

I run WSJT-X (2.2.2) and JTAlert (2.16.15).  Recently I have spent quite a lot of time just monitoring 15m, and never transmitting.  I have noticed several times that I get called by a "station" with the right format  eg      "G3UEG  IO6YIP BG06           a2"

How can this happen?  IO6YIP is not on QRZ.COM so is suspect.  How is my callsign known, I have NOT transmitted at all , not even tuned up.

This has happened probably 6/8 times over the last couple of months.  Sometimes the message format is obviously gibberish, but sometimes nearly right as above.

I am perplexed!

73,
Dave  G3UEG

I run WSJT-X (2.2.2) and JTAlert (2.16.15).  Recently I have spent quite a lot of time just monitoring 15m, and never transmitting. I have noticed several times that I get called by a "station" with the right format  eg      "G3UEG  IO6YIP BG06           a2"

How can this happen?  IO6YIP is not on QRZ.COM so is suspect.  How is my callsign known, I have NOT transmitted at all , not even tuned up.

This has happened probably 6/8 times over the last couple of months.  Sometimes the message format is obviously gibberish, but sometimes nearly right as above.

I am perplexed!

73,
Dave  G3UEG

On Wed, Dec 16, 2020 at 11:03 AM, Bill Somerville wrote:
\
Hi Dave,
this happens because of AP decoding techniques, it is a false
decode. In
this case a priori decoding postulates that you might be being
called as
a result of calling CQ and, by assuming messages might be to you, it
can
increase sensitivity to messages where that information may be erased
(missing) due to QSB or interference. Because the reduced number of
bits
being decoded, the false decode probability is slightly raised due to
the smaller set of possible decodes. Check the WSJT-X User Guide for
information on what the "a2" indicates:
https://physics.princeton.edu/pulsar/K1JT/wsjtx-doc/wsjtx-main-2.2.2.html#AP_Decoding
73
Bill
G4WJS.
I've seen what seems to me as an increasing incidence of these types of "out of the blue" false decodes.
Perhaps this exists already and I haven't found it, but I think it would be interesting to have a more granular option to Enable AP - for example, perhaps only enabling a3-a6 where it contains the value of DX Call.
I often hesitate to disable AP completely, because if I am working a weak station I want the advantage, but it sure would be nice to eliminate the obviously false decodes.
73 de KM8V Jon

I'm not sure false decodes have anything to do with it. I think it is more likely someone is watching PSKreporter and seeing a station in an area they are looking for is reporting seeing his call and calls that station.  All a person needs to do is call CQ or otherwise make a transmission for a short time, wait a few minutes, then check PSKReporter for all stations that reported hearing their call. If they see someone in an area they are looking for, like a state or grid square, they take a chance and call that station.

One of the options in WSJT-X is reporting to the Internet, so when you turn on your system and start receiving signals, everything you hear is reported to the PSKReporter database. Some folks leave their equipment on all the time monitoring and reporting, even though they are not at the radio or paying attention. As this is the default setting, many people don't even realize it is happening.

Many times I have left the radio and computer on after operating for a while to come back later and see several stations, especially Japanese stations, have called me while I was away from the radio.

While this may not necessarily be an accepted practice, it is a somewhat common one. Naturally, it is entirely up to you whether you answer these unsolicited calls.

73,
Michael WA7SKG


Jon KM8V wrote on 12/16/20 12:05 PM:

On Wed, Dec 16, 2020 at 11:03 AM, Bill Somerville wrote:

    \
    Hi Dave,

    this happens because of AP decoding techniques, it is a false
    decode. In
    this case a priori decoding postulates that you might be being
    called as
    a result of calling CQ and, by assuming messages might be to you, it
    can
    increase sensitivity to messages where that information may be erased
    (missing) due to QSB or interference. Because the reduced number of
    bits
    being decoded, the false decode probability is slightly raised due to
    the smaller set of possible decodes. Check the WSJT-X User Guide for
    information on what the "a2" indicates:

    https://physics.princeton.edu/pulsar/K1JT/wsjtx-doc/wsjtx-main-2.2.2.html#AP_Decoding

    73
    Bill
    G4WJS.

I've seen what seems to me as an increasing incidence of these types of "out of the blue" false decodes.

Perhaps this exists already and I haven't found it, but I think it would be interesting to have a more granular option to Enable AP - for example, perhaps only enabling a3-a6 where it contains the value of DX Call.

I often hesitate to disable AP completely, because if I am working a weak station I want the advantage, but it sure would be nice to eliminate the obviously false decodes.

73 de KM8V Jon

Michael,
he false decode reported by the OP was:
G3UEG  IO6YIP BG06
this is clearly a false decode as gridsquare BG06 is nowhere near Italy, also I am not sure that IO prefixes are even issued.
BTW PSKReporter spotting is no the default, you have to enable it.
73
Bill
G4WJS.
On 16/12/2020 20:33, Michael WA7SKG wrote:

I'm not sure false decodes have anything to do with it. I think it is more likely someone is watching PSKreporter and seeing a station in an area they are looking for is reporting seeing his call and calls that station.  All a person needs to do is call CQ or otherwise make a transmission for a short time, wait a few minutes, then check PSKReporter for all stations that reported hearing their call. If they see someone in an area they are looking for, like a state or grid square, they take a chance and call that station.

One of the options in WSJT-X is reporting to the Internet, so when you turn on your system and start receiving signals, everything you hear is reported to the PSKReporter database. Some folks leave their equipment on all the time monitoring and reporting, even though they are not at the radio or paying attention. As this is the default setting, many people don't even realize it is happening.

Many times I have left the radio and computer on after operating for a while to come back later and see several stations, especially Japanese stations, have called me while I was away from the radio.

While this may not necessarily be an accepted practice, it is a somewhat common one. Naturally, it is entirely up to you whether you answer these unsolicited calls.

73,
Michael WA7SKG


Jon KM8V wrote on 12/16/20 12:05 PM:

On Wed, Dec 16, 2020 at 11:03 AM, Bill Somerville wrote:

    \
    Hi Dave,

    this happens because of AP decoding techniques, it is a false
    decode. In
    this case a priori decoding postulates that you might be being
    called as
    a result of calling CQ and, by assuming messages might be to you, it
    can
    increase sensitivity to messages where that information may be erased
    (missing) due to QSB or interference. Because the reduced number of
    bits
    being decoded, the false decode probability is slightly raised due to
    the smaller set of possible decodes. Check the WSJT-X User Guide for
    information on what the "a2" indicates:

https://physics.princeton.edu/pulsar/K1JT/wsjtx-doc/wsjtx-main-2.2.2.html#AP_Decoding

    73
    Bill
    G4WJS.

I've seen what seems to me as an increasing incidence of these types of "out of the blue" false decodes.

Perhaps this exists already and I haven't found it, but I think it would be interesting to have a more granular option to Enable AP - for example, perhaps only enabling a3-a6 where it contains the value of DX Call.

I often hesitate to disable AP completely, because if I am working a weak station I want the advantage, but it sure would be nice to eliminate the obviously false decodes.

73 de KM8V Jon

On Wed, Dec 16, 2020 at 11:03 AM, Bill Somerville wrote:

\
Hi Dave,

this happens because of AP decoding techniques, it is a false decode. In
this case a priori decoding postulates that you might be being called as
a result of calling CQ and, by assuming messages might be to you, it can
increase sensitivity to messages where that information may be erased
(missing) due to QSB or interference. Because the reduced number of bits
being decoded, the false decode probability is slightly raised due to
the smaller set of possible decodes. Check the WSJT-X User Guide for
information on what the "a2" indicates:

https://physics.princeton.edu/pulsar/K1JT/wsjtx-doc/wsjtx-main-2.2.2.html#AP_Decoding

73
Bill
G4WJS.

I've seen what seems to me as an increasing incidence of these types of "out of the blue" false decodes.

Perhaps this exists already and I haven't found it, but I think it would be interesting to have a more granular option to Enable AP - for example, perhaps only enabling a3-a6 where it contains the value of DX Call. 

I often hesitate to disable AP completely, because if I am working a weak station I want the advantage, but it sure would be nice to eliminate the obviously false decodes.

73 de KM8V Jon

On Dec 16, 2020, at 13:33, Michael WA7SKG <wa7skg@...> wrote:

While this may not necessarily be an accepted practice, it is a somewhat common one. Naturally, it is entirely up to you whether you answer these unsolicited calls.