Re: My Raspberry Pi project

Don Ritchie


Thanks for the reply,

I don't understand your comment about "not enough details" ?
I am not a software guy, so I am looking to put together what others may have done
into a package that will do what I need.

REMOTE RADIO~ The GPIO scripts for both PTT and channel change ( it is just a 2 channel radio).

AUDIO ~ We know a bit about VoIP, have been doing it for years for remote monitoring of radios.
we were using old ATA's, but needed a "server" to connect them to each-other. I want to avoid that.

Understand G-711 sounds good, but could use G-729 for smaller UDP packets.

I guess where I am really stuck is in the connecting "together", they are now both running
"headless" on my local network, and I can connect them to each-other with SSH.
From my Windoz machine I "puddy" into Pi # 1 ( which I call 'local")
then I can SSH into # 2.( which I call 'remote')
When I can get this to work on my network, it will be moved 50 miles away to my buddy's QTH
about 50 miles awav, and connected via the internet.

I'm just not sure if SSH is the "answer".
How do I get # 1 to send anything to # 2 ?
It looks like I may use imic and Ispeaker , but still not sure ??

I know I still need to do a lot of work to get this to work the way I need it to work.



On 6/21/2017 10:52 AM, David Ranch dranch@... [Raspberry_Pi_4-Ham_RADIO] wrote:

Hello Don,

Your project idea is definitely possible but you don't mention enough details.  Are you wanting to write all the software yourself or use an existing project?  Programs like Svxlink support the Raspberry Pi for general repeater and optional Echolink functionality.  There is also the IRLP program and network that will work as well.

If writing your own software, where are you getting stuck? 

PTT control:
There are many shell, python, Perl, and other language examples to initialize the GPIO pins.  If you really want to use relays (not required), you'll need to use a simple transistor circuit to drive the PTT line as the Raspberry Pi's pins alone cannot handle that much current.

VoIP transport:
This is a deep area so I would recommend to take in small slices but shouldn't be too complicated.  I would start with recording audio on one Raspberry Pi, encode into a codec like G.711 (64Kbps - old but good sounding or something new like Opus or OGG.  Then sending this data stream over a network connection would most likely be over UDP.  The network transport could be done via existing tools like "socat" or you can choose to write native routines in your chosen programming language.  If this project would be connected to the Internet, don't underestimate what poor security can do to both your Raspberry Pi's and the Internet.  Make sure your IoT devices have proper firewalls configured, the network connections use best practices authentication, sanitize all the input to avoid things like buffer overflows, etc.

Anyway, that's all a start for now.  We need more information from you to understand where we need to point you next.


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