Download of THROB 2.5.3.3 was on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. Commonly, this program's installer has the following filename: throb25x3.exe. This free program is a product of DL5SWB, Lionel Sear.
THROB works fine with 32-bit versions of Windows XP/Vista/7/8/10/11. The most popular version among THROB users is 2.5. We recommend checking the downloaded files with any free antivirus. THROB lies within Multimedia Tools, more precisely Editors & Converters.
From the developer:
THROB is a DSP sound card mode that attempts to use Fast Fourier Transform technology (as used by waterfall displays). THROB is actually based on tone pairs with several characters represented by single tones. The THROB program is an attempt to push DSP into the area where other methods fail because of sensitivity or propagation difficulties and at the same time work at a reasonable speed.
You may want to check out more software, such as Drum Station DT-010 or Fldigi, which might be similar to THROB.