Hi all,

I'm setting up YAAC on a Raspberry Pi 3+ running Rasbian Buster. I've downloaded and setup YAAC and I configured a Tinytrak4 to do KISS mode. The Tinytrak4 is connected to the Raspberry Pi via a USB to serial cable with a null modem. I also have a serial GPS unit plugged into the Raspberry Pi.

YAAC sees the GPS unit. YAAC sees the Tinytrack4 in command mode, I can make config changes and so forth. When I power the Tinytrak4 up and let it go into KISS mode, I see nothing. There are no packets reported even though I can see activity on the radio (a Yaesu FT-60R handheld with the appropriate cable from Byonics). If I unplug the cable from the handheld I can hear packet traffic.

I will be the first to admit I've never really understood how KISS mode works. I've never been able to get it to work and I've always used the text mode. I'm pretty sure I've got something wrong, but I can't figure it out. Does anyone have any thoughts?

Thanks for any help.

Kelley

What exactly do you mean by "let the TinyTrak go into KISS mode"? I also own a TinyTrak4, and one of the annoying features about it is that you can't switch back and forth between KISS and command mode easily. On the other hand, you don't really need to for a continuously-up station. I've tried dynamic switching, but I've found it's easier to configure the TinyTrak4 into KISS mode manually and leave it there, and then configure its Serial_TNC port in YAAC to be a KISS-only device (no switching commands required). Otherwise, YAAC gets annoyed when it doesn't see the TinyTrak acting like a KISS device, and keeps trying to force it, which only works when the TinyTrak has just booted up (i.e., when it says "Press ESC three times to enter command mode", and if you don't do that within about 5 seconds, it's too late).

The other thing to watch out for is your receive audio level. Byonics has directions in the TinyTrak manual for setting the receive amplitude level, which makes a big difference in decodeability for incoming packets (especially if it's at the wrong setting).

Furthermore, the TinyTrak4 is a hardware TNC with an old-style PLL frequency detector for the FSK demodulation, so it depends on good-quality AFSK transmissions, which many stations don't have. Overmodulation and limiter distortion, having amplitudes of the two audio tones inconsistent due to pre-emphasis in the radio (a good reason to use a data port if your radio has one, because that usually bypasses the pre-emphasis and de-emphasis circuits), and being somewhat off-pitch for the two tones; all of these reduce the receivability of the transmissions. And there's not much the receiving hardware TNC can do to make up for a lousy transmission. And that's even before packet collisions, hidden transmitters, and related channel issues contribute to losing packets.

Check these things, and then, with the TinyTrak in KISS mode connected to YAAC, open the Test Port window on the Serial_TNC port. When a packet comes in, you should see a spurt of illegible characters followed by an APRS packet body in ASCII text. The illegible characters is the AX.25 packet header, which for reasons specified in the AX.25 V2.2 protocol specification has the ASCII characters of the callsigns shifted one bit over so they come out as weird characters when the terminal tries to display them as ASCII. If you don't see such spurts of characters, then your TinyTrak is not successfully decoding packets.

What is KISS mode? KISS mode is a way of setting up a TNC so that it just does the HDLC bit stuffing, CRC calculations, and AFSK tone encoding/decoding, and then lets the attached computer do everything else for generating outbound packets and processing inbound packets. Call the TNC a "dumb" modem, with the KISS protocol providing frame boundary control so the HDLC frame boundaries can be seen on a plain asynchronous byte-oriented serial connection (basically, where does one packet end and the next one begin).

Hope this helps.

Andrew, KA2DDO
author of YAAC

开云体育

Hi Andrew,

Thanks for the response. By "let the TinyTrak go into KISS mode", I meant that I put the TinyTrak into KISS mode (AMODE KISS) and left the YAAC KISS command blank. My assumption is that when the TinyTrak powered on that after three seconds or so it would be in KISS mode.

I'll check the receive amplitude level in the TinyTrak when I get home tonight. I've used the TinyTrak as a non-KISS packet device before, and it worked fine for that. I'm using the Yaesu FT-60R as it's the only radio I have a cable that works with the TinyTrak. I also have a KPC-3+ (which I understand has a problem in KISS mode) and an old MFJ-1278 unit, I'd just need to work up some cables if they would work better.

I did open the test port window and watched for any data when the radio and TinyTrak appeared to be receiving (the carrier detect led was on), but after some time of watching, I didn't see anything appear in the window.

What exactly do you mean by "let the TinyTrak go into KISS mode"? I also own a TinyTrak4, and one of the annoying features about it is that you can't switch back and forth between KISS and command mode easily. On the other hand, you don't really need to for a continuously-up station. I've tried dynamic switching, but I've found it's easier to configure the TinyTrak4 into KISS mode manually and leave it there, and then configure its Serial_TNC port in YAAC to be a KISS-only device (no switching commands required). Otherwise, YAAC gets annoyed when it doesn't see the TinyTrak acting like a KISS device, and keeps trying to force it, which only works when the TinyTrak has just booted up (i.e., when it says "Press ESC three times to enter command mode", and if you don't do that within about 5 seconds, it's too late).

The other thing to watch out for is your receive audio level. Byonics has directions in the TinyTrak manual for setting the receive amplitude level, which makes a big difference in decodeability for incoming packets (especially if it's at the wrong setting).

Furthermore, the TinyTrak4 is a hardware TNC with an old-style PLL frequency detector for the FSK demodulation, so it depends on good-quality AFSK transmissions, which many stations don't have. Overmodulation and limiter distortion, having amplitudes of the two audio tones inconsistent due to pre-emphasis in the radio (a good reason to use a data port if your radio has one, because that usually bypasses the pre-emphasis and de-emphasis circuits), and being somewhat off-pitch for the two tones; all of these reduce the receivability of the transmissions. And there's not much the receiving hardware TNC can do to make up for a lousy transmission. And that's even before packet collisions, hidden transmitters, and related channel issues contribute to losing packets.

Check these things, and then, with the TinyTrak in KISS mode connected to YAAC, open the Test Port window on the Serial_TNC port. When a packet comes in, you should see a spurt of illegible characters followed by an APRS packet body in ASCII text. The illegible characters is the AX.25 packet header, which for reasons specified in the AX.25 V2.2 protocol specification has the ASCII characters of the callsigns shifted one bit over so they come out as weird characters when the terminal tries to display them as ASCII. If you don't see such spurts of characters, then your TinyTrak is not successfully decoding packets.

What is KISS mode? KISS mode is a way of setting up a TNC so that it just does the HDLC bit stuffing, CRC calculations, and AFSK tone encoding/decoding, and then lets the attached computer do everything else for generating outbound packets and processing inbound packets. Call the TNC a "dumb" modem, with the KISS protocol providing frame boundary control so the HDLC frame boundaries can be seen on a plain asynchronous byte-oriented serial connection (basically, where does one packet end and the next one begin).

Hope this helps.

Andrew, KA2DDO
author of YAAC