Bug with audio TNC

[Scott Currie]

There seems to be some odd things happening with the packet audio TNC (or I don't know what I am doing, which is certainly possible).

I'm testing with a VOX capable DRA from Masters Communications.

I set up a new session to my local gateway station (which happens to be across the room). I selected the audio TNC, and set the audio output to both channels, and set the volume at 100. The session works and connected to my station fine (though responses were a bit slow).

I then decided to take advantage of split audio with data on the right channel and PTT tone on the left channel (or unused channel as it reads). This did not work as expected. The VOX keyed up as expected, but the packets were very quiet. I had to set the transmit gain on the DRA all the way up, and even then they were not really loud enough. I tried swapping channels just see what would happen. That didn't work at all. Even stranger, if I set the session back to both channels and unchecked the PTT tone, it still doesn't work. In fact, if I create a new session with the settings from the original working session, it doesn't work at all. It seems like something has been set in the audio level now that will not change. The original session still works, but I can't create any new session that will.

Am I doing something wrong?

-Scott, NS7C

[Andrew Walker]

Hi Scott,

Sounds like an interesting problem. It would be useful if you could attach the original (working) and new (not working) sessions. They can be exported from the 'Export' item in lower menu when editing the session.

The PTT tone is really designed to be used with devices that explicitly handle it (an example can be found here https://docs.google.com/drawings/d/1phoxb2RhahkpJXXbm_tRh8nsJFb_sZrcZN6WDHDk7_A/edit?usp=sharing). I couldn't find anything in the documentation  for the DRA, but I'm guessing that they handle only a single audio channel and ignore the other.

That said, it sounds like your problem is independent of that.

All the best,

Andrew

VA7YAA

[Scott Currie]

The DRA is a stereo device and for the models that are VOX compatible, you can select which channel is used for VOX/PTT and which channel is used for data. By the way, I tested just using headphones instead of the DRA and the same issue is there, so I think this should be easy to recreate. I will export the sessions and post them here.

-Scott, NS7C

[Scott Currie]

OK, I resolved this issue. I made the wrong assumption about what the "Relative Level" setting was doing. Lesson learned, read the documentation. It is now working properly with the DRA with data on the right channel and PTT tone on the left channel.

I then ran into a problem with connection scripts which I will document and post in a new conversation.

-Scott, NS7C

[Andrew Walker]

Would be great to hear more about the connection scripts problem. Just a heads up that WoAD works a little differently to Winlink here in the way that the steps are defined. Nothing significant, but I think (hope?) the WoAD approach is a little more internally consistent and is hopefully adequately described in the documentation. I suspect that connection scripts get little use in the wild so any problem reports are much appreciated.

All the best,

Andrew

VA7YAA

[Scott Currie]

Sorry Andrew, got pulled away to many other things. I did get it working, but it is different than Winlink Express.

For our local network, I connect to a local node, W6SLO-1, then tell the node to connect to the destination gateway on port 2, c 2 ae6eq-7. The Winlink Express script looks like this:

c W6SLO-1

connected

c 2 ae6eq-7

connected

Using this on WoAD results in some bizarre behavior with the WoAD station getting connected to the node, but then sending many SABM  frames after it is connected to the first station.

What does work with WoAD is:

Set the destination address as W6SLO, SSID 1

Run script after initial connection checked

Script:

connected

c 2 ae6eq-7

!WAITFOR connected

Not sure why the !WAITFOR is needed, but it won't work without it. I'm not sure the first "connected" is needed, I don't remember if I tested with and without it. Is the first connection response ignored or assumed? Is something else needed here?

-Scott, NS7C

[Andrew Walker]

Hi Scott,

Thanks for the update. WoAD operates a little differently from Winlink in how it establishes a connection with a script. In particular:

1) In WoAD the destination address is taken as the first step of the connection, so there is no need to add it to the script.

2) In WoAD (quoting from the documentation) "[t]he final connection request is assumed to terminate at either a Winlink CMS or P2P server, for which no response line is necessary." So if you need to wait for the final connection it would have to be explicitly added using the !WAITFOR command.

This means that a WoAD script should be similar to the WInlink script, but without the first and last lines. 

The script you sent for WoAD is what I would expect given the Winlink script, given that you need to wait for the "connected" response. This all made sense to me at the time I wrote the code, but I am certainly open to changes if needed. 

All the best,

Andrew

VA7YAA