[OZAPRS] Questions about tncs

Max Bainrot mbainrot at gmail.com
Fri Jul 6 12:20:23 AEST 2018

Hi Matt

I will definitely check that out, I have both the radios on open squealch
because it seemed like the squealch control on the wuexon handheld was a
bit slow to open.

I haven’t implemented the leds as they weren’t in the schematic I used but
looking in the source there was allocation for some indicator leds (one of
the tncs uses a different ptt pin because of the non 0.1” header offset so
had to tweak the pin allocations as initially I had stuck ptt issues) I’ll
check tonight

It is sending the acknowledgment though, I had a rtlsdr setup with basic
decoder and I can see the two way traffic but the open squelch might be
what’s slowing it down enough to miss the fast ACK

Max - VK2NMF

On Fri, 6 Jul 2018 at 9:40 am, Matthew Cook <vk5zm at bistre.net> wrote:

> Max,
> Check how your TNC is detecting if the channel is busy.
> Not many TNC's worked well in the day with open mute, in fact we used to
> retrofit a small board to TNC's that would detect the AFSK tones and drive
> the carrier SQ input on our TNC's.    What you describe is classic CSMA
> "hold off" due to a busy channel.  I think you'll find that your TNC thinks
> that the channel is busy, so it's not transmitting.  Since there is no way
> for Xastir or Yaac to know if the packet has left, it retries.
> Does your TNC have a carrier squelch input or software DCD (data carrier
> detect), it may even have a DCD (or RX decoded) LED  if so what is it
> telling you ?
> I'm not familiar with your TNC per se, but can remember back to the time
> where small fury creatures from alpha centari were real small furry
> creatures from alpha centari.
> 73
> Matthew
> On 6 July 2018 at 08:02, Max Bainrot <mbainrot at gmail.com> wrote:
>> Hi all,
>> I’m fairly new to the whole packet radio shenanigans and been tinkering
>> away for the past couple of days and have been running into gremlins
>> I’m currently using a mobilinkd tnc2 firmware on a home brew shield on a
>> 16mhz Arduino which works o.k. but it seems like it has a really long delay
>> between transmitting and receiving, like long enough for default settings
>> xastir (more on that later) to get impatient and retransmit like 6 times
>> before entropy has it that the acknowledgement makes it through.
>> Is this just because the firmware is asking too much of the poor little
>> atmega328p or is it something else? Doesn’t appear to be the radio(s) as I
>> have two radios, wuxeon handheld and a tyt md380 (working 439.100 as there
>> is no local digipeter) and switched radios between the sender and receiver,
>> updated firmware on both Arduinos, the tncs where crashing before I
>> attached ferrites to the cables but that appears to have fixed the issue.
>> I haven’t confirmed beyond all doubt if the tnc is still randomly
>> rebooting or not, going to hook the bus pirate (it has high z serial mode)
>> up to the tnc’s serial lines to see if it’s singing it’s song of it’s
>> people every time it transmits.
>> The reset on connect jumper is enabled btw, is it xastir closing and
>> reopening the serial port?
>> I’m also using default settings in xastir for kiss tnc which could be
>> another mistake I’ve made?
>> Now onto the topic of xastir :) does anyone know where I can find the
>> setting to slow it right down??? It resends wayyyyy too quickly which is
>> both bad form and severely aggrevates the problem. I’m also thinking of
>> rocking YAAC as it’s java based so I can use the latest version on all
>> operating systems and I can slow it right down.
>> Reason I am running down the open hardware and/or diy route is I am
>> intending on cooking up a raspberry pi zero hat/cape, so want to leave
>> options open for my future shenanigans.
>> Many thanks in advance,
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