• When did this WEBSDR started ?
    • This websdr went live on Wednesday may 13, 2020


  • Which bands do we support  ?
    • 80m, 60m, 40m, 30m 20m, 17m, 15m, 12m, 10m (upper and higher part separate receiver) and the 2m, also 2 parts).
    • All bands complete with CW segment.


  • Do we have a chat box ?
    • No, this WebSDR has no chat box. Our hobby is radio.
      Internet is only the channel to receive the signals by from the remote location.


  • Latency ?
    • Different browsers have different overall latency in the audio.
      Firefox has the lowest latency contribution of the browsers we measured.
      The latency of Chrome (and CATSync) is 80msec higher and that of Microsoft Edge 65msec higher.
      Also external sound cards will have short but different latency contributions.
      Even with CADSync the overall latency should be <=500msec.


  • CATSync and the RIT (Receiver Incremental Tuning) on the transceiver.
    In CATSync we see (in some rigs) RIT which is double the value as set in your rig. The reason is that OmniRig adds the RIT offset to the main frequency, which was also done in your rig, ending up in two times the RIT added to the frequency in CATSync.

      A work around is modifying the corresponding OmniRig .ini file for the transceiver.
      (These files are in: Program Files(x86)/Alfreet/OmniRig/Rigs)
      For the FTDX5000 and FT-950 the line starting with Value1 in [STATUS1] is modified:

            Value1=13|5|vfText|0.00005|0|pmRitOffset         <========== here is the change

      The RIT offset is now multiplied by 0.00005 instead of a 1 ("0" didn't work).
      See also: http://dxatlas.com/OmniRig/IniStru.txt


  • Increasing noise level at sun set.
    This is not local man-made noise, but received sky wave noise.
    A good reference is the thesis of Ben Witvliet PE5B:


     On page 67 the noise level on 60m is plotted vs. time. It is measured with a low dipole and calibrated equipment.
     The radiation pattern of a low dipole is practically the same as that of the small receiving loop.

  • Pocket RxTx is not supported anymore
    Reason is that our websdr is fully free and no commercial activities are involved with


  • Websdrmaasbree.nl is not responding on CATSync

     I once experienced that websdrmaasbree.nl was not giving any response in CATSync. I could solve the problem

     by searching the debug.log file in the CATSync directory and emptied the file (first change the permissions,.....). It helped....

     But, after a few logins, the problem came back. I started looking for files used to remember things like cookies, or cache files

     and found in the CATSync directory the folder "cache". In there another folder "Cache" was found. In that directory a lot of

     files were found, like data_0, etc. I empties this directory completely, and restarted the CATSync Full.exe app.

     After a week the problem was still solved.

  • Websdrmaasbree.nl is not responding to Safari or other browsers?

      In all reported cases we could solve the problem with clearing the history files in the browser. Cookies, history files, etc.

  • Hick ups in audio/waterfall

      There are many situations that can create hick ups in the fluent stream of audio and video.

      - The websdr PC is too slow. But this is not the case up to over 200 users.

      - The internet is is having trouble with band with. This will certainly happen sometimes, but is most of the time not the cause

      - Routers can also get mixed up. An occasional reset can do wonders in your house.

      - If you experience other reasons, please let me know,....... (admin).

  • DXCC, see Operation chapter
  • CATSync is not muting my PC in TX mode. See next FAQ about Ominirig.
  • Omnirig

      Omnirig is a small free program which is an universal interface between apps on your pc/laptop and a lot of different   

      transceivers. It uses .ini files for all different sets for proper handling the several command sets.

      But, unfortunately we found a bug in the .ini file of Yaesu transceivers (confirmed for the FT-950, FT-991A and the 5000).

      The consequence of this bug is that CATSync can not read the TX status of the set correctly, and therefor can not MUTE

      the sound in TX mode.

      Luckily it can be solved easily. Look in the .ini file (for example for the FT-950) and look for the following code in the "set"





     The TX command is set to TX1. This is good, don't change it.


     A little further in the .ini file look for the following code in the "read" section:



    Here the Flag2 is set to "..1."  and this is not correct. It should be "..2." . So change the 1 into 2 and it is

    corrected  (Flag2=(..2.)|pmTX).  The reason it should be 2 is that the FT-950 is sending the "TX2-command" in TX mode when     

    inquired,   and not the "TX1-command".

    Load the corrected .ini file and restart CATSync. The MUTE on TX function should be working now, at least when you tick the box

   in CATSync of course. Also you see the text "TX VFO" in the upper left of CATSync turning RED.

   For the FT-991A, it looks like






  • USB-serial convertors (Prolific gives problems sometimes)

     There are several convertors on the market. I worked with Prolific convertors and FTDI convertors.

     With the Prolific convertors, I experienced strange behavior. Connections were not reliable. I.e. Using CATSync the CATSync

     parameters were not updated correctly, or with delay. Or not at all,...sometime turning on the sets freq knob had no effect in

     CATSync. I changed to FTDI convertors, and the problem has been solved. 

     A lot of info on serial ports and connecting rigs to pc's can be found in




  • Using Audacity for recording
    can be used to record the audio from the WebSDR directly when selecting
    "Windows WASAP":


    After recording you can select, cut, etc. etc. and save in your format of choice