The winds of economic change are starting to have an effect on our online business. Because of that I am spending a lot more time on the computer trying to maintain our search engine positions and think of new revenue streams, with the consequence that I have less time or enthusiasm for blogging and other radio-related activities.

The only noteworthy item of radio news at G4ILO has been the acquisition of an SCS Tracker / DSP TNC for HF APRS packet. It is shown in the picture sitting atop my K2. When I find the time, I will write a review of this TNC for my main (non-blog) website. For the time being, all I will say is that I did a side by side comparison with the best of the PC sound card decoders and it was very quickly apparent that the SCS TNC decoded many stations the sound card software didn’t. Considering what it cost, I’d have been very disappointed if it hadn’t.

Julian Moss, G4ILO, is a regular contributor to AmateurRadio.com and writes from Cumbria, England. Contact him at [email protected].

3 Responses to “DSP TNC”

  • Demetre - SV1UY:

    Hi Julian,

    A hardware solution has always been MUCH BETTER than a software one and this is true for all DIGITAL MODES. Even with todays superfast computers, the O/S takes most of the attention of your CPU, as well as your VIDEO SCREEN, your keyboard, mouse, printer etc, leaving little for the soundcard program that struggles to decode our DIGITAL RADIO Signals.

    Of course this becomes more apparent in PACKET RADIO and in any other DIGITAL MODE faster than RTTY/PSK31 especially in fast synchronous DIGITAL MODES.

    A dedicated HARDWARE MODEM and especially an SCS one, is far more superior in decoding than a crappy soundcard software TNC solution.

    Unfortunatelly there are TNCs that are also crappy, just like a KAM TNC and other pricy TNCs, hence the popularity of soundcard modes today.

    Although I’ve never had an SCS Tracker / DSP TNC, I have a PTC-II at home, a PTC-IIe for my HF portable adventures/holidays and a KAM plus, so I have experimented a lot with HF PACKET and HF APRS in the past. I have come to the same conclusion as you. If you want a good decoder then a good hardware solution is the way to go. My PTC-II and PTC-IIe definately perform superbly on HF/VHF/UHF PACKET radio, HF/VHF/UHF APRS, PACTOR 1/2/3, RTTY and also SSTV. They can do PSK-31 but they are no better than a PSK31 soundcard program, although I feel that these PTC modems decode better RTTY than a soundcard RTTY program, but I have not tested this extensively.

    Good luck with your HF APRS packet experiments.

    73 de Demetre SV1UY

  • Boris UA1CCE:

    Very Good modem!
    73! DX! de Boris UA1CCE, from Russia

  • John kx4o:

    One should bear in mind the SCS Tracker DSP TNC is a software, not a hardware modem. The key benefit in this product is the dedicated DSP to perform the software encoding and decoding. It’s easy to abstract away all this functionality into the box that it is, but we need to understand it can do what is can do thanks to software techniques, not hardware components. This is made quite clear when the Tracker is compared to other TNCs at 1200…


    The SCS Tracker DSP TNC is a marvelous little box full of capability.

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