Mobilinkd TNC4 and AX.25 Packet Length Bug #mobilinkd

RadioMail
1

My devices:
iPhone 8+ on iOS 16.3.1
Mobilinkd TNC4 Rev B - Firmware 2.5.9 - and they sold me the cable to connect this to my HT.
Yaesu FT5D

Things that work:
I can use the iOS aprs.fi app to send position beacons and messages through the TNC4 using the FT5D. No problem. Of course, I don't really NEED this, because the FT5D already does this with its built-in stuff anyway (though the interface for writing APRS messages is HORRID).

I can connect to a Packet gateway 4 miles away. This is quick and snappy.

What doesn't work:
I can't send an email. It acts like it's STARTING to, but it ends on the following screen/log/console
;PR: ********
; N0DZQ-10 DE N0MQL (EN35ld)
FC EM GA2DMODFMQYW 222 205 0

69 (and it hangs here a minute or so, transmitting briefly every several seconds, but not progressing, then eventually...)

*** Error: Unexpected AX.25 protocol error, code e. (and I can't see the rest because there's no scrollbars on an iPhone screen for some unexplained reason)

I posted a pic of this on Mastodon, to a handful of dudes with whom I'm trying to sort this stuff out. One of them ordered the Mobilinkd almost the same day I did. Received it one USMail day before I did (Sat vs Mon).

Someone from Mobilinkd said this:
"set the frame size to 128 or 64. RadioMail has a bug where it can corrupt longer packets sent via Bluetooth LE."

I took that to mean
Radiomail
- Settings
  - Packet KISS TNC Modem
    - Max length
It was set to 255. I reduced it to 128 and retried.
Same response. Exact same Error message.
I reduced it to 64 and retried.
Same response. Exact same Error message.

Is there any validity to what the Mobilinkd dude said? Does Radiomail have a bug with regard to BLE connections and packet-size/frame-size/bytes-per-packet/whatever-you-call-it?

Is there some OTHER setting I should be adjusting in Radiomail to improve the chances I could actually pass mail over the radio?

73 de n0mql

2

Is there any way to set the delay? I had similar issues with connecting to an RMS node from my 705 and it turned out that the delay needed to be set much longer.

I was using the Windows winlink with software modem so not quite apples to apples.

I'll try using the TNC4 with Radiomail when I have time later to see if I can reproduce your findings.

73 de K6EF

3

Kelvin, sorry to hear you're having issue sending mail. The AX.25 protocol error code E means RadioMail received a DM (Disconnected Mode) response from the server while it was trying to exchange information. This is akin to the server hanging up on you (so very rude). There are many things that could cause that to happen. Here are a few steps that might help pinpoint the cause:

1) Can you receive emails with your setup?

2) Is the squelch fully open, audio level setup properly, etc.?

3) Can you try sending against another Winlink gateway?

4) Regarding the possibility of packet corruption on BLE, yes, there is a possibility that could happen. Rob from mobilinkd alerted me to this recently. In practice, I've tested sending 50KB of data back and forth without problem on the mobilinkd V3 & V4, so it may be only manifesting under particular circumstances. Regardless, I have a fix that now properly takes into account the max frame size that the BLE device can handle. Happy to invite you to testflight if you want to test it out and see if that solves your problem.

5) You can enable server logging by going to iPhone settings -> RadioMail -> Log to Remote Server. Try to reproduce the problem and let me know afterwards so I can analyze the logs. After reproducing the problem, remember to turn off logging as it can send a lot of data.

4

1) RX emails? Not yet. It seems we can ID to each other, then it hangs.
2) Open squelch? Oh really... I must've missed that when I skimmed the documentation. It wouldn't have dawned on me that wide-open-hiss is the OK way to go, but if it ain't makin' noise in the house, who cares? Will give that a crack.
2b) Audio levels were set by making the RX graph tickle the right edge, then listening to mine do APRS blurps and comparing that to the many other APRS blurps I can hear from the rooftop antenna that runs to the radio that handles the N0MQL-1 2-way iGate. Since I've gotten APRS to go both ways with it, I think it's probably good. (I could be wrong.)
3) I have tried. The close guy is 4 miles. The next guy is 19 miles. Even from the roof, I can't hit that 2nd guy. Although, over the weekend or something, I might drive over that way, get lunch from Zantigo, and see if I can hit that one from the truck. That'd be a good test.

I'm gonna try open squelch, and then fiddle with the timing settings (as mentioned by another respondent), see if I can get over the hump. If not, will consider annoying you with logs.

Tnx, & 73 de n0mql

5

Opened squelch and tried Receive Mail only, to see if I could get a complete "No soup for you!" anyway.
Oh, that worked, and quick!
OK, let's try sending mail.
BOOM! Worked! This is fanTAStic!!
Oh, wait... I'm on telnet. D'OH.

Switch back to N0DZQ. Now I don't even get a response. Like, they're 100% offline today.

Thunderstorms last night. He may've unplugged overnight. May've been struck.

Definitely tempted to drive closer than 16 miles (I remembered the number upside-down) to the 2nd closest gateway over the weekend.

Dorkishly yours,

6

I’m only 2 miles from the packet station, but live in a valley. I get the same type error message & behavior when I have a poor connection to the packet station. I tried both a Yagi and my home antenna and the problem disappeared. Once you get past the initial setup details, RadioMail is phenomenal. Good luck. N4DPH

7

Thank you. That's encouraging.

It's possible that even with the antenna at 30' or so, with the meager amount of fire the HT can put into the wire, I could be marginal on his RX.

Tomorrow, able to drive to that neighborhood, and to another gateway's, I hope to learn much more.

8

I had thought that if the problem might be BLE related, I should dust off my Field Day Linux Laptop and update all the things, and try to get PAT to do it's thing using a USB-connected Mobilinkd.
That, I tell you, was a horrid bugaboo. Many hours lost. It theoretically could work, but the person at the keyboard and screen deciding what to install and how to configure it would need to know what they were doing. I do not.

Frustrated, thought I'd try the iPhone RadioMail BLE Mobillinkd to nearest gateway again.

I feel it was slightly closer to success.

*** Finding device TNC4 Mobilinkd
*** Connecting to N0DZQ-10 with PACKET @ 145.010 MHz
Welcome to the Washington County Gateway
[WL2K-5.0-B2FWIHJM$]
;PQ: 44889623
CMS via N0DZQ >
;FW: N0MQL
[RadioMail-1.1.1-B2FHM$]
;PR: ********
; N0DZQ-10 DE N0MQL (EN35ld)
FF
*** Error: AX.25 protocol time out, code i

Code 'i' is short for "idiot, stop doing this."

9

:smile: Code i is "N2 timeouts: unacknowledged data". So probably means the station does not hear you anymore or you're not getting the response it's sending.

10

Yesterday, drove East and parked about 1.5mi from that nearest node. Still no joy.

Today, thought about how I'd done the Twist adjustments. Re-did them.

Used auto-adjust for RX, with HT tuned to 144.39 - there's much APRS traffic nearby. That bumped Twist up to +6dB.

For TX, I went out to my truck, where the "other radio" that I could listen to has much better fidelity (basically flatter EQ sort of). Moved Twist significantly 'cuz the 2200Hz tone was too low (sounded OK on other very crappy sounding radio).

Repeated send/receive email with nearest gateway. Worked without error thrice in a row.

I consider it all sorted, now.

73 de n0mql

11

What were the TNC4 audio output settings that ultimately worked?