[aprssig] Options for robust digipeaters

[Jason KG4WSV]

Taking it one step further: Depending on usage, some of the techniques to make the file system completely read only may be appropriate. 

-Jason


> On Feb 8, 2021, at 4:36 PM, Curt Mills <Curt.WE7U at gmail.com> wrote:
> 
> Forgot one other: He moves a bunch of things to a tmpfs directory in
> memory to save on writes to the card.
> 
> I personally would also do some Linux tweaks to reduce writes to the
> SDcard, like I do for SSD drives. I don't know if my friend does that.
> 
>> On Mon, Feb 8, 2021 at 2:28 PM Curt Mills <curt.we7u at gmail.com> wrote:
>> 
>> This doesn't directly answer the questions but should apply:
>> 
>> A buddy of mine has been putting Rpi-4 systems onto mountaintops for
>> digipeaters, running Raspian Linux and SVXlink. Before you guys wince
>> and think "I wouldn't use an Rpi for that, they're not reliable
>> enough!"... I had the same thoughts initially.
>> 
>> The keys are:
>> 
>> - Buy very good and fast SDcards which are much larger than what you
>> need (spreads the writes across the card). Like 32 or 64 GB cards that
>> are name brand and fast.
>> 
>> - Use an Rpi UPS board that can control the reset pin.
>> 
>> - Set up scripts that take down the Rpi nicely when the UPS runs out.
>> 
>> - My buddy designed an Rpi board which controls two radios (with a
>> soundcard on there of course and PTT circuitry). He orders/builds more
>> as he needs them, he doesn't market or sell them.
>> 
>> He started deploying with earlier Rpi's and in fact one mountaintop
>> site is still running an earlier Rpi, like maybe a 2? That one will
>> get replaced with an Rpi4 when things warm up again here and he can
>> get to the mountaintop.
>> 
>> Some of these sites have RF links to other repeaters, a bunch have
>> internet links, some of those via HamWAN (another subject entirely).
>> The system works great, and he can adjust the audio in/out of each
>> radio remotely.
>> 
>> Anyway, that's one example of a H/W setup that could easily run
>> Direwolf instead of SVXlink and do what you're asking, 1200-baud-wise.
>> As far as 9600 baud you might need to do some experimentation to
>> figure that out.
>> 
>> Commercial Rpi radio-control boards (not what my buddy is using, but
>> nice boards nevertheless) are available, like the DRAWS boards from
>> Northwest Digital.
>> 
>> He says he's using Sandisk high-endurance 32GB SDcards now, but may go
>> to USB 3 SSD in the future. If he goes to those he may skip the UPS
>> board.
>> 
>> 
>>> On Mon, Feb 8, 2021 at 1:25 PM Jim (List) <jim.list at stuckinthemud.org> wrote:
>>> 
>>> Hi,
>>> 
>>> 
>>> 
>>> I’m looking for advice on current offering for a robust, field-deployable digipeater TNC/modem.
>>> 
>>> 
>>> 
>>> Over the years my go-to device has been the KPC-3+, mainly because when I started out with APRS the sound-modem stuff was rubbish and not easily deployed in the field without needing to be tweaked / set up each time. The KPC-3+ is bomb-proof, out-performs most other hardware, low power and just works (save for the known buffer/timing issues, but they were solved in v9.1). I’ve never had one fail in 25 years (and I’ve had wide-area event systems deployed with a dozen of them spread around the hills!).
>>> 
>>> 
>>> 
>>> The world has moved on and sound-modem stuff is now very good, so looking at what options there are for something that has multi-functionality - i.e. can be used at a centre or in a mobile for situation awareness, perhaps over LAN/Wi-Fi with an appropriate tablet/computer, used as an iGate, as well as “black boxed” with a radio for the hilltop where it can be just switched on and left by someone without any ARPS / computer knowledge.
>>> 
>>> 
>>> 
>>> Units that would reliably handle 9600 would also be useful. Again 25 years ago that was a problem, but radios from the “big three” (and I think some others) have the appropriate connections.
>>> 
>>> 
>>> 
>>> So, any recommendations / thoughts?
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Jim
>>> 
>>> 
>>> 
>>> 
>>> 
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>> 
>> 
>> 
>> --
>> Curt, WE7U        http://xastir.org        http://www.sarguydigital.com
> 
> 
> 
> -- 
> Curt, WE7U        http://xastir.org        http://www.sarguydigital.com
> 
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