KC and I had several back and forth messages through email to determine the scope of the project.  (Lots of detail, but you can see the general thought processes below):

KC -- check this out:

https://github.com/sharkrf/srf-ip-conn-srv

And Openspot 4 by SharkRF:  https://www.sharkrf.com/products/openspot4/learn-more/

On Tue, Jul 19, 2022 at 5:26 AM Kaushlesh Chandel wrote:

Hi, I agree. I am not thinking of starting Mobile first. First, ill work on a raspberry pi and server-side code. I agree with API architecture. The server-side code should be API driven. So, a Pi, microcontroller, PC, Mobile, they call can talk to it alike.  About the headphone jack, most flagship phones are removing that. Though there are lower-end phones still with the jack. We have two options: a Bluetooth-based device or a headphone adaptor for iPhone & Android phones.  Thanks! KC On Mon, Jul 18, 2022 at 9:39 PM Mark Hughes  wrote:

KC -- it occurs to me that much of the initial testing (and getting people excited about the project) might be accomplished with a radio and your regular work computer. Once we demonstrate specific functionality (and we could do that with a $100 refurbished laptop) then we can tackle the harder job of developing an app.  In fact, you could develop the API and let others do the hard work for you. I also thought of a possible complication.  I upgraded phones a few months back and I no longer have an earphone jack.  Are they phasing out industry wide?  I know Apple and Samsung are leaders -- but I have absolutely no idea about what's happening in the other markets. These are all just thoughts -- you of course have the latitude to move in the direction you are most passionate about. On Mon, Jul 18, 2022 at 1:30 PM Mark Hugheswrote:

Ooh -- the discord idea is genius (if we can get it to work). I've not used winlink but I can look into it.  Most amateur radio data happens at very, very slow speeds.  Think dial-up modem or worse. And I will look for apps!   Thanks KC! On Mon, Jul 18, 2022 at 1:23 PM Kaushlesh Chandel  wrote:

Cool! even if we do buy RPi's (or any Arm7-based SBC) the BOM will end up being much higher than just using a good old phone. The phone-based app lets anyone use their existing phone. And we can beacon these phones using APRS style packets. I have some more features in my mind. We can chat over the weekend. We might find a way to link the radio communication to discord or something similar. Thus we don't have to build expensive server-side infrastructure. Though working stand-alone is a must-have requirement. If the mobile phone's hardware can do reliable Audio to text conversion, then it can link up to so many chat-based services. Question... Have you used win-link? Can Winlink send/ receive compressed audio files? Meanwhile, please research the apps out there; that do similar stuff. I'll look as well. I'll talk to some folks specializing in mobile app development. I have built Android & iOS apps, but I am basic.  Thanks, KC On Mon, Jul 18, 2022 at 3:10 PM Mark Hughes wrote:

I like it!  As I mentioned in the call, I'm not married to the RPi idea -- especially with low availability.  That was just one thought of a possible way to solve the problem.  The phone sounds like a better solution! And who knows -- in a few years, maybe we'll have all sorts of integrations / customization options -- RPi, ESP, laptops, etc... So if you think the phone is the best path forward, I'm all in.  Let's go phone! One thing I would like to advise you though -- the cellular signal up here is absolute crap -- very hit and miss.  So definitely want to make use of the onboard wifi for data transfer where possible.   They even apparently make OTS cable assemblies just for this purpose :) https://www.amazon.com/BTECH-APRS-K1-Interface-APRSDroid-Compatible/dp/B01LMIBAZW/ref=asc_df_B01LMIBAZW Great work KC! On Mon, Jul 18, 2022 at 12:52 PM Kaushlesh Chandel  wrote:

Hi Mark, I spent the weekend thinking about the solution. I like your raspberry pi idea, but I feel that it would be easiest to build a mobile app that connects to baofeng radio via a cable. A phone has audio in/ audio out, wifi, Cellular, Bluetooth, processing, storage, GPS, Battery and pretty decent power management, and a display to configure the device Using a raspberry pi based solution will require.

• Input buttons etc.
• Some basic display
• Intelligent power management
• Li-ion battery
• USB soundcard with both audio in/out
• Cables for connectivity with baofengs.
• Wifi Enclosure
• So much more...

If an android app is built with a custom cable that connects baofeng to the Phone audio jack, we can make it work. A cheap android phone may cost like $150. And we can benefit from its cellular network. I will send you details on the application features and design. if you like, we can talk around the same time this week. Thanks, Kaushlesh (312-363-7664) On Fri, Jul 15, 2022 at 12:01 PM Kaushlesh Chandel wrote:

I am just finishing up... 5 min max. On Fri, Jul 15, 2022 at 11:18 AM markjarrodhughes wrote:

I am, thanks! Sent from my Verizon, Samsung Galaxy smartphone -------- Original message -------- From: Kaushlesh Chandel Date: 7/15/22 9:06 AM (GMT-08:00) To: Mark Hughes  Subject: Re: From Hackchat Hi Mark,  I hope you are still down for the meeting. I have one call just before my call with you. Please hang on if I get a few minutes late. Thanks, Kaushlesh On Thu, Jul 14, 2022 at 11:42 AM Kaushlesh Chandel < wrote:

On Wed, Jul 13, 2022 at 7:18 PM Kaushlesh Chandel  wrote:

Awesome then Friday it is. I’ll send a zoom link  KC On Wed, Jul 13, 2022 at 5:33 PM Mark Hughes  wrote:

Certainly -- I have a webinar runthrough tomorrow -- so perhaps Friday would be better if that works for you.  Also -- I think you have the timezone conversions reversed.  12 pm central should be 10 am pacific.  I'm available at either.Perhaps we could get a grant from the people on hackchat to pay for it all? On Wed, Jul 13, 2022 at 2:40 PM Kaushlesh Chandel wrote:

Hi, You seem to be in California time and I am in central time.  What morning time will work for you. Is 10 AM central time / 12:00 PM your time okay for you? I can send an invite. Thanks, Kaushlesh On Wed, Jul 13, 2022 at 4:00 PM Mark Hughes  wrote:

Hi Kaushlesh,    We could also go with RPi zero wireless, or an RPi 3 or RPi 4 -- I haven't done a feasibility analysis at all. We'd have multiple baofengs.  One for each listening location/frequency.  If we had 20 frequencies of interest, we'd buy 20 baofengs.  That's still only $400.  Scanning would cause the loss of information. It will queue the messages.  I don't know that I fully appreciate the two-generals problem.  But since each radio would have a RPi with it, it could get the time via NTP, correct?  And then we could append a radio-ID to each message too, so even if they have identical time stamps, they'd have different radio-ids, and would still be unique. Regarding the internet.  yes -- I thought of that too.  An external server might become unreliable in an emergency.  It should be possible to create an ad-hoc network that the pis can connect to.  Or in the case of a Pi3 or Pi4, just plug in a cable.  In that  case, you'd need a local server that can accept the information. As far as transmitting -- we wouldn't transmit through SDR.  We'd transmit through a high-power radio (5-50W) -- that's not a problem, we'd just have to key it. What is your availability?j Thanks, Mark KE6WOB On Wed, Jul 13, 2022 at 1:47 PM Kaushlesh Chandel wrote:

Thanks Mark, it's very interesting. And I totally understand the problem. And you also got to deal with Comm Tech ( Joke on Elk river fire incident, where Ham was fined 34K) I do get what you are trying to do. Please allow me to digest this information. Few things I can immediately think of... * Rpi Pico might not be powerful enough. Ill do more research. Recently Raspberry foundation released RPi Pico W, with Wifi module. but there are several options. *  Will you have multiple Baofengs tuned to different frequencies, or does it need some type of auto scan with squelch? * So it will queue the messages;causing an acknowledgment problem ( Two generals paradox) * Needing internet? Can Rpi's do digital mode on quieter frequencies? Maybe some kind of mesh. * Ive done work with SDR's like RTLSDR, hackrf one. they are good to receive radio but very bad at transmitting. Think like a few milliwatts Tx power. Nevertheless, it's a very interesting problem to solve. We should get on a Zoom call. I'd like to understand more about the problem and your proposed solution. What I understand so far, is a way to do some kind of multiplexing, so multiple communications can happen in case of an emergency. Thanks, Kaushlesh On Wed, Jul 13, 2022 at 3:14 PM Mark Hugheswrote:

Hello Haushlesh,     Thanks for replying back so quickly!  You mentioned you were looking for a project -- I have one that is 95% software based (using COTS equipment). I am net controller for the La Habra Heights Fire Watch.  We're in a very dry, very hilly area and I have a need, and an idea of how to accomplish it.  But don't have the time or requisite programming experience to make it happen.  I'm not insistent on the solution -- this is just a proposal.