Hi Yugal,
well, 2-FSK is relatively easy to demodulate, and you'll probably also
be able to use the existing synchronizer blocks to symbol timing- and
frequency-synchronize.
What will definitely require writing code is handling the ax.25 frame
format.
You **should** look at gr-ax25 (it's gr-ax25, by the way, not gr-25)!
It's good to learn from existing resources. And as said, the framing is
definitely to be implemented in code, so you'll end up building an
external module anyways. Best case: you take the existing gr-ax25, and
add the new mode to it.
Now comes something nobody wants to hear, but it's kind of what you're
bound to get when talking to me about the ax.25 standard:
It's a bad frame format. It has a checksum, but that checksum is not
covered by any error correction. That is a terrible idea, and should
have never been designed that way; you can get way, way, way more
reliable and hence, further-reaching communications when you actually
protect *especially* your checksum with forward error correction.
The only redeeming feature of ax.25 is its widespread usage. If you can
help it at all, especially when designing new systems, don't use it, so
that future generations of hams can use less bad frame formats.
Best regards,
Marcus
On 12/08/2020 12.13, Yugal Joshi wrote:
Hey Volker
I understand there are ways to implement it using direwolf.
I am more concern to solve this problem with GRC and mostly with its core.
Can you help me in figuring out the procedural steps to be taken to
implement a receiver in GRC to decode a signal with G3RUH mode Ax25 and
2FSk
Thanks and Regards
Yugal Joshi
On Wed, 12 Aug 2020, 3:30 pm Volker Schroer, <dl1...@gmx.de
<mailto:dl1...@gmx.de>> wrote:
The master branch is for gr3.9, but there is a gnuradio 3.8 branch
Another good starting point for ax.25 could be wb2osz/direwolf on
github.
— Volker
Am 12.08.2020 um 06:31 schrieb Yugal Joshi
<yugaljoshi2...@gmail.com <mailto:yugaljoshi2...@gmail.com>>:
Hello Jeff
Thanks for replying
From what I learned in last two days in GNU Radio, it looks like
gr-25 is an OOT module.
gr-25 works with GR 3.9 and pybinds and I am using GR 3.8.1.0.
Also I want to implement G3RUH 2FSK AX25 using the core modules
of GRC or programming new OOTs so that I can improve my learning
curve.
Any help would be appreciated from the community.
Thanks and Regards
Yugal Joshi
On Wed, 12 Aug 2020, 4:45 am Jeff Long, <willco...@gmail.com
<mailto:willco...@gmail.com>> wrote:
Have you already take a look at this?
https://github.com/dl1ksv/gr-ax25
On Tue, Aug 11, 2020 at 4:13 PM Yugal Joshi
<yugaljoshi2...@gmail.com <mailto:yugaljoshi2...@gmail.com>>
wrote:
Hello all
I am new to the GNU Radio community.
I am starting an effort to implement a receiver using GNU
Radio for the amateur radio whose transmitter operates in
G3RUH mode with 2-FSK modulation and AX25 data format.
I designed the project to learn GNU Radio as well as to
contribute something to the SmallSat Community of my
institution Indian Institute of Space Science and
Technology (IIST).
Is anyone else working on the same configurations ?
Anyone who can guide me through the procedural steps I
should take to design this receiver(G3RUH mode with 2-FSK
and AX25 data format)?
As a background information :
The AX.25 protocol is a standard for encoding the data
that includes a message header,station callsign,
destination callsign, message and a simple CRC-16.
The system is widely used for position reporting of the
amateur stations
Looking for a directive path to move ahead and a positive
response.
Thanks and Regards
--
Yugal Joshi
B. Tech. Electronics and Communication Engineering
Indian Institute of Space Science and Technology (IIST)
Thiruvananthapuram
Kerala
India - 695547