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Half-baked: remote control head over Ethernet?

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Share your enhancements here! Examples are out of band, scan list increases, other general trickery. What is not permitted is the discussion regarding adding features (aka flash options) which you can still purchase from Motorola for current subscriber products including discussion regarding Depot on current products.
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fogster
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What radios do you own?: HT1250, XTS2500, ASTRO Saber

Half-baked: remote control head over Ethernet?

Postby fogster » Sun Mar 20, 2016 8:13 pm

Has anyone tried to run a remote head and microphone for an XTL5000 or ASTRO Spectra over Ethernet? I'm still at the handwavey details stage, but I think it's possible. My idea is to have something like a Raspberry Pi on either end. TX/RX audio is easy enough with VoIP. (I need to play with Asterisk and app_rpt a bit; I think it can handle keying up the transmitter and I've got the GPIO pins to steer it.)

It looks like the control head and radio communicate over a serial bus called SB9600, which I presume is 9600bps. I spent a while fruitlessly trying to read up on how this works, before I realized -- if it's just remote control, I just need to reliably shuttle bits back and forth, not make any sense of it. Transmitting 9600bps data back over a network isn't exactly a novel problem.

Am I overlooking any major gotchas? Obviously there's a world of difference between the high-level idea and actually getting it working, but I figured I'd toss the idea out here rather than just mulling it over in my mind. The idea is that I could keep the radio drawers upstairs for a short cable run to an attic antenna, while keeping the speaker, mic, and control head a couple stories lower on my desk. Totally not something for a public safety agency to depend on, but a fun thing for me to tinker with for ragchewing on 2 meters...

Jim202
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Re: Half-baked: remote control head over Ethernet?

Postby Jim202 » Mon Mar 21, 2016 5:29 am

Are you looking to have the radio on only one channel and only need to hear and talk over it? If so, it is easy and you don't need the SB9600 control. All you need is a remote adapter at the radio and a remote control unit like a desk telephone style tone remote control. There are a ton of them laying around and should be able to be picked up cheap.

If your looking to change channels and display the control head display information, then your in for some interesting times trying to decode the SB9600 data stream and be able to generate the SB9600 codes to control the radio. As Motorola has been very close to the vest with the SB9600 control codes, you will have to find it yourself. You will also need some sort of computer to generate the required data stream.

With that said, there has been a couple of postings on the Internet with some of this SB9600 information, but it is old and may no longer be available. I did a search some years back on just this subject, but decided it wasn't worth the effort.

You would be much better off running a good piece of coax and have the radio located where your going to be and not try to remotely control it.

Jim

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fogster
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What radios do you own?: HT1250, XTS2500, ASTRO Saber

Re: Half-baked: remote control head over Ethernet?

Postby fogster » Mon Mar 21, 2016 6:37 am

The idea is to have the control head working as well. If I'm connecting a radio to a control head, I think I don't actually need to understand SB9600, right? I just need the computer on either end to emulate a serial cable, shuttling bits back and forth between the control head and the radio. All I'd need to do is have the 9600bps data link available, and the radio and control head are free to exchange whatever codes they wish over it. It's just a lot easier than if it used some wacky DC signaling or something.

Admittedly, the idea has turned into a "because I wonder if I can" thing... I agree that running a bit more coax would probably be the easier solution. (I'm in a condo which makes outside runs trickier, but it's still a solvable problem.)

Wiregeek
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Re: Half-baked: remote control head over Ethernet?

Postby Wiregeek » Mon Mar 21, 2016 9:05 am

Both Jim and yourself are correct, to the best of my knowledge.

SB9600 and some audio isn't the only thing on the control head flex, though.

You know, this is really interesting. If I wasn't running around 100% time commitment in the wood shop, I would like to take a look at this.

Rpi on both ends, sure. Possibly something you could do with an arduino with a wifi or ethernet shield. Latency is a concern. The original design of the radio puts the control head at a maximum of 131 feet (which surprised me, I was expecting ~50), which implies that this is not your grampaw's RS-232 (bog standard RS-232 tops out at 50 ft). Still going to be nothing compared to the latency of a serial to ethernet to ethernet to serial conversion, especially if wifi is in the mix.

If the setup ends up being "latency tolerant", it would be kinda awesome to have a project box with an Rpi in it, an 05 CH mounted to the top, and a power supply at work, using your radio at home...

http://www.radioparts.com/motorola-hkn6164a 131 ft control head cable.

...seeing that, it may be easier to run the control head cable, instead of extending coax or implementing CHoIP.

I do want to see this working though! Anyone have any more data on SB9600 and other signalling on the CH -> Radio lines?

Wiregeek
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Re: Half-baked: remote control head over Ethernet?

Postby Wiregeek » Mon Mar 21, 2016 9:19 am

even more delicious when you start looking at O-style XTL or APX, that's non-standard CANBus in there.

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tuckerm
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Re: Half-baked: remote control head over Ethernet?

Postby tuckerm » Mon Mar 21, 2016 9:35 am

There was a guy either here or P25 forums that was parsing data from it to show Channel and Radio IDs on a console. I don't recall where I saw it, but it was recent.

This company is doing something similar and when I asked about an XTL, he said they were working on it for another customer. http://www.softradio.se/softradio.htm
An Alt radio, from parts unknown

Bigfella237
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Re: Half-baked: remote control head over Ethernet?

Postby Bigfella237 » Mon Mar 21, 2016 7:29 pm

There's been a lot of work done with Automotive CAN Bus hacking and they run much faster (up to 1000kbps) so 9.6kbps should be a walk in the park.

Looking at the rear J2 connector on mid-power XTL radios, I see a twisted pair CAN Bus on pins 2 & 3 (CAN+ & CAN- respectively)

Image

Most automotive CANs use either a 11-bit or 29-bit address (or header) with a 64-bit payload, although there are no guarantees seeing as Motorola have just invented their own protocol?

It should be a simple (although certainly not trivial) matter of "sniffing" the CAN Bus, logging PID and message IDs, filtering and then identifying what's what? For example, pressing a button on the CH (other than a W series) should send a message over the CAN with that button's ID plus a payload of data, if you then use the terminal software to send that same message from your PC it should mimic that button press!

Very interested in this project if anyone has the time to get into it?

Andrew

Jim202
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Location: Radio Land

Re: Half-baked: remote control head over Ethernet?

Postby Jim202 » Tue Mar 22, 2016 5:45 am

Bigfella237 wrote:There's been a lot of work done with Automotive CAN Bus hacking and they run much faster (up to 1000kbps) so 9.6kbps should be a walk in the park.

Looking at the rear J2 connector on mid-power XTL radios, I see a twisted pair CAN Bus on pins 2 & 3 (CAN+ & CAN- respectively)

Image

Most automotive CANs use either a 11-bit or 29-bit address (or header) with a 64-bit payload, although there are no guarantees seeing as Motorola have just invented their own protocol?

It should be a simple (although certainly not trivial) matter of "sniffing" the CAN Bus, logging PID and message IDs, filtering and then identifying what's what? For example, pressing a button on the CH (other than a W series) should send a message over the CAN with that button's ID plus a payload of data, if you then use the terminal software to send that same message from your PC it should mimic that button press!

Very interested in this project if anyone has the time to get into it?

Andrew


Sorry to break the bad news to you but the BUS + and the BUS - on pins 2 and 3 on the XTL radios are not CAN bus connections. They are SB9600.

Jim

Wiregeek
Posts: 57
Joined: Thu Nov 06, 2014 9:53 am

Re: Half-baked: remote control head over Ethernet?

Postby Wiregeek » Tue Mar 22, 2016 2:35 pm

Well, Fogster is looking at a transparent Control Head over IP transport, I'm just interested. IF SB9600 is on the J2... can a CH be connected there?

Wiregeek
Posts: 57
Joined: Thu Nov 06, 2014 9:53 am

Re: Half-baked: remote control head over Ethernet?

Postby Wiregeek » Tue Mar 22, 2016 3:49 pm



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