CAT Sync - The CAT Tool for WebSDRs

edited March 2018 in KiwiSDR Discussion
Hi All,

Spotted online and may be of interest to some.

I don't know if it's any good - and it's not free, but has a relatively small price.

If anyone who tries it would you care to report back to the forum ?


Martin - G8JNJ

The CAT Tool for WebSDRs

CATSync allows you to control public WebSDR receivers with your real rig connected via CAT control to your computer. It supports the classical WebSDR as well as Kiwi SDR interfaces:

  • Syncronizes any public WebSDR server with your real RIG…
  • Supports a wide number of RIG’s (it uses the popular OmniRig engine)
  • Supports WebSDR and KiwiSDR browser based SDR receivers
  • Tune the VFO of your radio and see the web SDR follow in realtime !
  • Listen to the same frequency as your rig via web SDR
  • Ideally suited e.g. for people suffering from local QRM
  • Can track RX or TX VFO (e.g. to find that split of a DX station) if radio CAT supports both simultanously
  • Can be interfaced with popular logging software using OminRig or via VSPE port splitter
  • This software can help you to bring you back into ham radio when you are suffering from local temporary or permanent high noise levels in an urban QTH location.

The demo has all the functions of the full version, with the exception that it will not retune the web SDR audio in realtime (you only see the web SDR frequency updating, but not the audio). You can only retune the audio to the new frequency manually.

If the demo works on your system and you like the software please consider getting the full version.  The full version is tuning both frequency and audio syncronized in realtime – no limitations!
The Full version costs 9.95€.


  • Hmm, Maybe I spoke too soon............

    It turns out that

    "It only to controls the websdr (as advertised) via CAT not viceversa"

    I think most folks would probably want to use the SDR as a pan-adaptor to click to tune their radio to see if they can hear the signal directly at their own location in order to try for a QSO.

    If they can already hear a signal on their own radio, they would be unlikely to need to use the WEB SDR.



    Martin - G8JNJ
  • I don't understand how this thing can work. Maybe someone can explain it to me.

    If I have a web browser with an open connection to a Kiwi how can this program break into that existing connection and start tuning around in parallel with the web interface? Does it somehow emulate keyboard/mouse events to the browser? I would think that represents a huge security problem and would not be allowed without a special plugin or something.

    It could just open a separate connection to the Kiwi, but that wouldn't influence the UI and audio in the browser of the first connection. This program would have to have its own separate UI for the SDR which I doubt that it does.

  • Hi John,

    The demo version is free so you can try it for yourself. The only demo limitation is that you have to click on the frequency entry box to tune the WEB SDR rather than it being fully automatic in the paid version.

    It is similar to CSVUserlistBrowser in that it has some sort of web browser integrated into the application, which takes in CAT commands and uses them to tune the WEB SDR.

    It's less easy to trap broswer commands and use them to control the radio so this functionality doesn't exist at the moment.

    I've suggested to the author one possible way do it with the KiWi SDR.

    "In the KiWi it has a green button near the frequency display.

    If you click on this button it generates a new URL including the frequency and mode that it uses to open a new browser tab.

    If you could in some way simulate a rapid green button press, and trap the browser URL to stop it opening a new browser screen you may be able to parse the string and derive a tuning and mode command."

    I also suggest that he contacted you for more information regarding possible KiWi control interfaces.


    Martin - G8JNJ

  • Just for information.  I was going to try out this rather large CATSync program, but discovered it gives some positives on multi virus scanners, showing a keylogger (trojanspy.MSIL). Probably false positives from second class virus scanners.Although I can not imagine any malintent from fellow radio amateur DJ0MY I probably hold off until I find an old computer or have a chance to run it sand boxed.

    Best regards, Ben
  • Hi All,

    A new release of CATSync is now available and this one allows tuning of an external radio (or HRD) via a click on the KiWi waterfall. Tuning the radio also sets the KiWi frequency.

    However, tuning by clicking on DX Tags and direct entry of frequencies into the KiWi doesn't work for me.

    The full version costs 9.95€, but the free demo has most of the functionality.


    Martin - G8JNJ

  • Tried out CatSync version V1.11 full version after initially observing it in a sandbox environment and not seeing any suspicious behaviour.

    It starts up a CefSharpBrowserSubprocess as interface to the selected web Kiwi and listens to Omnirig CAT commands. As far as I see it works well bi-directional although sometimes clicking on the waterfall does not result in tuning of the rig. In the case an old ICOM 725 rig data transfer gets restored after going form VFO to memory tuning and back.

    So far I have used it for scanning 2G ALE channels, transmission tests and interfacing it with various decoders and frequency data bases such as CSVUserlistBrowser.

    To share the rig com port I use VSPE as portsplitter and browser audio transfer via "audio router" which helps out in diverting audio from the computer standard audio card to which it is tied to in seemingly all HTML5 browsers.

    An obvious drawback with CatSync is that an actual rig connection is required but not always desired. In case of scanning thru a list of frequencies you end up with the rig following and endlessly clicking its bandswitch relays. So I am still thinking about somehow a fake transceiver connection to Omnirig just echoing the CAT commands.


    best regards, Ben
  • Thanks Ben for the explanation of how it works. I had no idea existed.
  • Hi Ben,

    I've had some discussions with Oskar (the software author) about various aspects of CATsync and I've already asked if he could add CAT radio emulation, like the CAT to HDSDR option in HDSDR, so that other stand alone programs with CAT control outputs could drive it like a normal hardware radio without having to have one physically attached in order to echo back the CAT commands.

    Fingers crossed :-)


    Martin - G8JNJ
  • I finally saw Oscar's latest YouTube video. Pretty neat. I've added CATSync to the list of Kiwi recommended accessories. To support the effort I bought a copy for myself even though I don't use Windows and don't own a traditional rig at present.
  • edited June 2018
    Hello. I do not speak English. Translates Google :-). I do not have to talk. Video speaks for me :-) Remote KIWI via CATSync - CSVUserlistBrowser
  • I worked on a few Kiwi problems for Oscar and he now has a new download of CATSync available. From the release notes:

    The next release version 1.12 of CATSync is now available.

    Version history V1.12:

    – Fixed KiwiSDR mode change (was broken after KiwiSDR firmware update of 7th July 2018)
    – New support for clicking on Kiwi SDR station database labels (it will switch frequency and mode)
    Important: This new feature requires a KiwiSDR with firmware v1.231 or later
    – Update radio via CAT when manually entering a frequency and hit enter (on WebSDR and KiwiSDR).
  • I just received this announcement from Oscar about a new CATSync release:

    Hello dear OM,

    The long awaited next major release of CATsync is here.

    This is reflected in a major version number increase due to significant feature increases.
    The new version is V1.2.

    Version history V1.2:

    – Fixed one major bug breaking the link to the SDR website after loading a second site
    – New Feature: CAT Radio Emulator. This allows CATsync to behave like an external radio. Elecraft K3 is being emulated.
    (e.g. this way you can connect e.g. external decoder programs like WSJT-X or FLDIGI or others to the emulated K3 radio in CATsync)
    This new feature may still be buggy with some untested programs and CAT emulator supports only frequency and mode reading/setting.
    To use this feature you need to install a third party virtual serial port driver.
    – Browser cookies are now supported, allowing memorizing e.g. last frequency, mode, memories, etc.
    – Mouswheel tuning in WebSDR is now also syncing CAT (KiwiSDR does not support mousewheel tuning as it uses it for zooming)
    – Audio recording functions in WebSDR and Kiwi now working. Audio files are automatically saved into CATsync application path.
    – RX / TX switching of your local radio can be now also controlled via CATsync GUI button.
    – Introduced unmute delay (200ms for WebSDR and 1500ms for Kiwi) for “Mute on TX” to reduce hearing your own echo at end of TX.
    – Various smaller bugfixes (based on user reports)

    Thanks for supporting my software.

    73 de Oscar DJ0MY
  • More news from Oscar:

    Hello dear OM,

    Today I release a very quick bugfix release of CATsync due to some faulty behaviors in V1.2.

    The new version is V1.21.

    Version history V1.21:

    – Fixed the broken JavaScript injection preventing KiwiSDR with newest firmware to react on “Click&Tune” – works now OK.
    – Fixed flickering database labels while retuning.
    – Introduced Browser Zoom with CTRL + and CTRL – hotkeys (same as normal browsers use)
    – Saving of audio recordings may not be working properly due to limited access rights to Windows default application install path
    Now a “Save as” file dialog is shown with your Windows documents folders shown before saving, which should give you full flexibility

    Thanks for supporting my software.

    73 de Oscar DJ0MY
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