#1 Re: Hardware » De-emphasized signal poor decoding » 2016-01-19 01:06:08

Hi to all!!!

I'm still thinking to a way to improve decoding... I found "Dire Wolf" (https://github.com/wb2osz/direwolf).
Here the demodulator: https://github.com/wb2osz/direwolf/blob … mod_afsk.c
Here HDLC decoder with error recovering: https://github.com/wb2osz/direwolf/blob … dlc_rec2.c

Maybe some parts of code could be ported....

#2 Re: Hardware » No decode while on (or next to) AC/DC converter » 2016-01-07 09:25:20


you have to check differences in signal using an oscilloscope. If you haven't one you could use a PC soundcard (see http://makezine.com/projects/sound-card-oscilloscope/).
I think that your AC/DC converter introduces too much noise...

#4 Re: Hardware » De-emphasized signal poor decoding » 2015-09-20 10:03:33

Have a look here http://www.febo.com/packet/layer-one/transmit.html here http://wa8lmf.net/TNCtest/ and here https://en.m.wikipedia.org/wiki/Emphasi … nications)

Quick response : a signal without de-emphasis has high tone and Low Tone at the same level. A signal with de-emphasis has high tone at Lowe level than high tone (if trasmitted signal has not pre-emphasis applied )

#5 Re: General discussion » No decode... » 2015-09-19 16:11:21

I already opened a post about this. We need Mark's opinion. You could try to use a rc filter  to decresce the Low Tone level and increase general volume .

The the decode has a Chebyshev low pass filter tuned to 600HZ (afsk.h). So the phase detector already decode  an understated high tone. With a de-emphasis filter on radio side, the high tone is too small to pass the filter.

We have to  redesign the software filter....

#6 Re: General discussion » No decode... » 2015-09-19 12:18:03

Hi, try to adjoust audio level to 2.5 vpp. Also  try to measure level difference between high and Low Tone coming out from baofeng  audio. Maybe that baofeng has a de-emphasis filter. MicroAprs doesn't decode this Kind of signal yet.

#7 Re: Software & Programming » MicroAPRS KISS code Patch » 2015-09-01 11:15:01

I merged together KISS-RESET and SMACK in branch SMACK-FULL.
I still need betatesters...

#8 Re: Software & Programming » MicroAPRS KISS code Patch » 2015-08-28 09:10:31

...KISS-RESET and SMACK branches updated...
Now the code work, but I need betatesters.

Notice About KISS-RESET branch:

To reboot TNC the code enable Watchdog and goes into an infinite loop.
When AVR restart the watchdog enable flag still set, this cause indefinites
reset during bootloader operations.
To avoid this issue standard arduino bootloader need to be replaced.

A good bootloader is Optiboot (https://github.com/Optiboot/optiboot) :

- 100% arduino bootloader compatible
- Smaller than standard bootloader
- Faster than standard bootloader
- WDT safe

#9 Hardware » De-emphasized signal poor decoding » 2015-08-27 21:40:30

Replies: 4


I'm testing Micromodem circuit (MicroAPRS FW)using TNC test CD (http://wa8lmf.net/TNCtest/).

On track 1, 3 and 4 (non-de-emphasized audio) modem has a good packet deconding rate.
On track 2 (de-emphasized audio) modem does't decode any packet.

Are possibles some improvements? Better if software improvements....

#10 Re: Software & Programming » MicroAPRS KISS code Patch » 2015-08-06 13:26:21

Smack can be tested using: agwpe, bpq32 (not sure), linbpq (not sure), standard mkiss linux module, aprx.... and others.... first tests can be made send in raw frames to serial port with wrong and correct crc.

#11 Re: Software & Programming » CSMA on Serial Protocol » 2015-08-01 14:22:41

I think that you have only to enable SERIAL_FRAMIMG_DIRECT in confing.h in MicroModemGP

Try in this way. I didn't studied sources enought to be sure.

#12 Re: Software & Programming » Trying to decode ATIS » 2015-07-29 20:06:16


In AFSK.h you can try change MARK_FREQ, SPACE_FREQ and others parameters.

I don't know exacly how to decode ATIS.

#13 Software & Programming » MicroAPRS KISS code Patch » 2015-07-27 13:54:10

Replies: 12

Hello everyone,
I made some changes to the KISS implementation of MicroAPRS.

On my GitHub fork (https://github.com/IW3IJQ/MicroAPRS) there are two branches: KISS-RESET an SMACK.

SMACK is the implementation of SMACK crc mode in kiss frames (http://www.symek.com/g/smack.html).
Beause I have an application where MicroAPRS is connected to an host through a "long" TTL serial line, so a CRC at
the end of a data packet could be useful.

KISS-RESET do a software reset of TNC when the command 0xFF is sent.
Why a command to reset the TNC?
Because it's the only way to switch back from SMACK to KISS mode.

I'm temporarily lacking hardware and are not able to test the code.
I would be very happy if someone would checkout these changes and give me a feedback.

I will resew code nonhardly will be sure that both branches work properly.
I can upload a specific build if someone need it.


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