AM mode seems now suport TDoA (??)

zachliangzachliang
in TDoA topics
Hello this is my first ever mesage in this group
Two days ago i experimented with 153 kHz a station from Romania with my android tablet . Forgot to change the mode from AM into IQ but the results were very good and very fast . Just 30 seconds were enough to identtify the trasmitter site with 3 spots

Comments

  • G8JNJG8JNJ
    I suspect that when you select TDoA it defaults to I/Q for sampling ?

    I seem to remember asking John to so this some time ago, as I got fed up remembering to select I/Q each time I ran a TDoA session, but I'm not 100% sure if it got implemented.

    Regards,

    Martin - G8JNJ
  • zachliangzachliang
    edited June 2019
    I made several tests today using AM mode in the main reception spot.
    As understood from the files produced by the kiwi spots after the TDOA analysis , inherent IQ mode is used that cant be played in standard PD players
    Something other I noticed , ifyou try to use non kiwi spots , ie time signals , they immediately change the SDRs frequency to theirs > I can’t still understand on how you can use them for analysis
  • WA2ZKDWA2ZKD
    AM is not workable... FWICT
  • jksjks
    When the kiwirecorder.py scripts are launched for each of the sampling stations IQ mode is forced. The current mode on the Kiwi running the TDoA extension is ignored. I will update the TDoA "help" button text and remove the mention that IQ mode must be selected.

    What is important is the setting of the passband. It should be symmetrical about the carrier (what you get by default in AM or IQ mode) and no wider than the signal of interest.

    When you say "non kiwi spots" what do you mean exactly? If, while the TDoA is open, you tune the Kiwi manually and then click the TDoA "submit" button it should use the manual frequency you entered. When you click on a "reference" station on the map (green label) then current frequency will be tuned to the frequency of the reference if one is defined.

    If you select a time station from the "select band" menu, and then click TDoA submit, the frequency of the time station should be unchanged.
  • zachliangzachliang
    JKS
    Two non kiwi sports for example as noticed in the European part of the map
    • Hungary HGA32 EFR teleswitch 135.6kHz
    • Bekgium DFF 77 time station 77.5 kHz
    You cant use them for TDoA .If you click at their labels the frequency is immediately changed
    I cant understand on how they are used for...
  • jksjks
    I'm sorry, I don't understand the problem you are describing. On the TDoA map when I click on the green "DCF77" pin (located in Germany) the Kiwi frequency is changed to 77.5 kHz, the mode to IQ and a custom (optimal) 1000 Hz wide passband set. Does this not happen for you? People TDoA DCF77 successfully all the time. I did it just now:

    image

    image

    Attachments:
    https://forum.kiwisdr.com/uploads/Uploader/37/6ab7e4e6d53074c324450e494b4267.png
    https://forum.kiwisdr.com/uploads/Uploader/ff/e2afbfce231f8803f1221cff636a16.png
  • zachliangzachliang
    Yes this is exactly what i wrote . You cannot use a time signal a s direction finding service for TDoA process.
    I made this mistake many times when i tried to DF positions of some standard AM stations on LW and MW for the time. . I m now more careful in selecting only kiwis !
  • jksjks
    Okay, I see what you are saying now.

    There are two different kinds of markers on the map. Kiwis that can be used as sampling stations are shown in blue and change to yellow when selected to be used in a TDoA measurement. Reference stations with well-known positions are shown in green. When you click on these they are not entered in the sampling station list like Kiwis, but rather entered into the reference station box at the bottom right of the TDoA control panel. And also the Kiwi is tuned to the frequency/passband appropriate for the reference station. This is intended to make it easier to practice TDoA on a known signal.

    You can disable the display of reference stations in the list to the right of the map (also select based on reference station type). And also disable display of the TDoA Kiwis. This is useful because there are so many markers on the map now.
  • zachliangzachliang
    >>Update TDoA help button panel to indicate current mode setting is ignored (IQ data is always used).
    From the yesterdays change log in github
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