Chip based TNCs (NinoTNC, TNC-Pi, PK232) vs software (Direwolf/Soundmodem)

Discussion in 'Working Different Modes' started by KK6QMS, Nov 10, 2021.


Do you operate APRS/packet with hardware or software modem?

  1. Hardware modem/TNC

    11 vote(s)
  2. Software modem/TNC

    8 vote(s)
Multiple votes are allowed.
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  1. KK6QMS

    KK6QMS XML Subscriber QRZ Page

    I have exp using hardware modems for 1200 baud packet ie TNC-Pi, PK232, etc. They seemed to always work adequately. I have heard some say Direwolf and/or Soundmodem are far superior. Any evidence/testing/analysis to support the latter opinion?
  2. WA9UAA

    WA9UAA Ham Member QRZ Page

    Don't know about superior, the easiest software setup for me has been UZ7HO Sound MODEM It runs well under windows. I used it to monitor and connect with HF packet on 20M. MODEMS are included for VHF packet as well. I'd still run my old PK-232 if I could get the original software to run with modern Operating Systems.
  3. KB0MNM

    KB0MNM Ham Member QRZ Page

    No testing, but realize that the hardware solution already contains the HDLC ( High-level Data Link Control ) protocol needed for AX.25 in firmware. What that means is that you are not using an external program to generate the packets as would a software-only solution. Thus, an external program to put your data into that AX.25 data-stream is not burdened with the packetization rules- simply availabity of the channel(s). Some folks suspect the 'computer-only' solution gives the advantage of using a faster micro-processor than the Z-80 setup within the PK-232. Since timing is typically either 1200 or 9600 bps ( most amateur packet products ), any illusion that an external program not using a dedicated TNC is 'faster' would seem very unlikely. The external TNC approach means that station operators seldom worry about software corruption- firmware is more permanent than software. The exception is the parameter-storage battery condition.
    N8VIL likes this.
  4. WA9UAA

    WA9UAA Ham Member QRZ Page

    I leave the battery disconnected in my PK-232. Recently I've been running a program called Lan Link Lite, free ware BTW, it runs an initialization file ( updatable ) on boot up so I don't have to worry about the battery. The program is the handiest thing since the original, although there is no way to address each individual setting as with PCPakratt for DOS. There was a time when I was running a very early laptop, the kind of thing that sold for $30.00 used. The modem program connected me to the PK-232 and it was possible to upload a file when not connected and in Command Mode that would up date the settings.
    KB0MNM likes this.
  5. N1ZZZ

    N1ZZZ Ham Member QRZ Page

    For VHF packet, you aren't going to see much of an advantage with either hardware of software TNCs. With FM it's either there or not for the most part. The big advantage of software TNC's is cost. Typically most people already have a soundcard interface, so it's only a time investment. The disadvantage is that they are fairly simple TNC's and need the computer to be running to use them. They usually also lack mailbox drops if that is important.

    Hardware TNC's run independently of a computer and can digipeater and have memory for store and forward messaging. Of course they cost more, but can be had fairly cheaply at hamfests. I have a number of brands and don't seem much performance difference between them.

    I use both, and sometimes simultaneously. I often have the hardware TNC on my DM-710 decoding the APRS network near me, and use a soundcard modem to display the raw packets. With one of my KAM TNC's I sometimes run a packet node that allows for digipeating and access to the local packet network. I store a number of messages in my memory for people to download (mostly ASCII art and short articles). Sometimes people link in and drop me an email. I just have to have the TNC and my radio powered on and I can use my soundcard interface for other work.

    The choice often comes down to budget, interest, and what you are planning on doing with packet radio.

    Jeremy N1ZZZ
  6. KK4GGL

    KK4GGL Premium Subscriber QRZ Page

    For my packet node (FM) I use a TNC. For APRS, I'm using a freed up Signal Link. For things like FLDIGI, WSJT-X and QSSTV, I'm using the sound card in my 991a.

    You might want to add "Both" to your poll. :)
  7. WB9TEN

    WB9TEN Ham Member QRZ Page

    For my VHF, it's a Kenwood TR-7950, Pi 3, Dire Wolf, and a totally homebrew interface made with 20-20kHz transformers for a Crown tape deck.
  8. KA2DEW

    KA2DEW Subscriber QRZ Page

    The software-only TNCs are not software-only. They require audio and PTT coupling to the radio, plus your radio needs to have a PTT timeout if there is any chance of the computer getting stuck. There used to be such a chance. I don't know if that is still a problem. Please find out.

    The NinoTNC is not all that expensive compared to the audio+PTT coupling. That said, Direwolf is a very good modem. NinoTNC is very close. The balance between a hardware TNC and a software TNC may not be that easy to judge. How much do you have to pay for the added features of the hardware TNC? And are those features missing from the software? It depends on how you look at it.

    The NinoTNC is really easy to operate with easy-to-access switches, knobs, and LEDs for config and diagnostics. This is a considerable improvement over many of the solutions. It seems like having more things to change would be a problem, but you can see all of the adjustments and you don't have to go digging through configuration files.

    NinoTNC does 1200, 2400, 4800, and 9600 with no software updates/upgrades. If you set it, then move it to another computer, it still has the same configuration. This aids in getting newbs set up for your data-over-ham project.

    The NinoTNC is a great kit and can be built for about $40 USD including shipping.

    The NinoTNC can be used in quantity on the same computer. If you have a radio for WinLink, one for APRS, another for the local BBS network, you can leave them all on the same computer at the same time and let the individual applications run continuously. It's a heck of a lot easier to configure a NinoTNC in quantity than the software TNCs. Which TXDELAY did you change? Oh, the one on the front of the TNC near the WinLINK radio. That was easy. Also, you have receive-volume-too-high light right on the front of the TNC (rx-overdrive) along with Good-packet vs CRC-error lights. It's actually fun to watch.

    Check out the documentation and especially the assembly instructions. You'll like it.
    The NinoTNC has its own email reflector/group/list. That's also available from the web page. See the web page at

    Last edited: Jan 1, 2022
    KE6DUY and N3RYB like this.

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