Link your Quantar over IP with some crusty old modems for CHEAP!!!!

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mizzotch

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Since you're all chomping at the bit (and rightfully so), I'll post the important pieces of info. I don't have time to write a lengthy post now, but here goes:

Equipment needed to make a Quantar talk over IP:

1) Working Wireline board w/ V.24 daughterboard. Should be running at least SCM R020.010.xxx. If anyone knows what version the V.24 astro connection was well implemented in, please chime in. That's the earliest firmware I had that worked. I tried the V.24 on some crusty old R016 firmware and it didn't work.

2) UDS V.3225 modems. Can be had the 'bay for cheap. Or I imagine some of you guys might have these things lying around. You should definitely opt for the version with buttons and display- easy to configure and run.

3) Obihai OBi-100 VOIP adapters (sells for less than $40 on Amazon)

Basically, you feed the V.24 synchronous serial to the V.3225 modem and then you feed the 2 wire dial line to the OBi-100. I'll post pinouts and settings info later, but this is simple (especially the VOIP adapter part).

Sounds ridiculously easy, and it is! I decided to experiment with the modem on a whim after seeing this specific model mentioned in an old Quantar Infrastructure Planning Guide. This modem is actually very versatile since it will support 2 wire dial, 2 wire leased line and 4 wire leased line.

For the most simple way to make them connect to each other, the VOIP adapters come with a built-in direct dialing number which requires no paid service provider (it actually works with the direct # right out of the box and no configuration). As long as you have a connection to the public internet, the Obitalk service will let the two VOIP adapters call each other direct for free. You set the modem up to dial the the direct Obitalk # of the other end. Have it dial the number, the other end rings and then it's an old school modem training symphony for a bit and voila, synchronous serial over IP! I should note that it can take up to 30 seconds for the modems to train and finally lock on. I think this is because of the high latency of the VOIP transport (roundtrip starts around 260ms and moves up from there, even on same switch). I have successfully had the modems connect routing the call through a provider in LA which the roundtrip time was ~620ms. So, I think linking just about anywhere is possible.

These VOIP adapters are HIGHLY configurable and because they use the SIP protocol, I think it would be fairly easy to get them to use an Allstar/Asterisk server to provide the automatic and configurable connection mechanism. Just think, you could choose what other Quantar you wanted to link up with using Allstar to command it. I don't know enough about Asterisk, but if someone would like to help figure this part out, please post. I have gotten the adapters to the stage where they are registered with the Allstar server as peers, but I don't know the specifics on how to make them virtual nodes and have the server initiate the interconnection.

Before someone asks, I already tried using the DMK USB dongles for Allstar to tie the modems together- NO GO. There seems to be a timing sync issue between the dongles (even when run on the same PC) and the modems complain to no end. It's interesting because you can watch the complaint lights come and go and alternate between the two modems. They get false data and it just plain doesn't work.

I forgot to take a picture of the modem/VOIP adapter combo running, but there's another success story below.

Incidentally, I also have a 24/7 working link using 2x V.3225 modems along with 2x Telex IP-223 boxes. I run the modems in 4 wire lease mode in this scenario and the IP-223 provides the analog to IP conversion. This setup has actually been in service for a month without any hiccups. Here's a picture of the box working. Notice all the status lights (except the QM) on the V.3225 modem are lit. That means it's actively transporting the digital idle link check data and timing.


Will that keep you guys happy for a while?
 

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Mars

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This is fantastic information.

I'm already trying to acquire some of these parts.

We also need to try and come up with a solution for those who do not have the V.24 daughterboard. There's really nothing special about that board; essentially it's just routing certain pins from the mating connector to the RJ-45 plug. There's another thread detailing this/discussion elsewhere on the board.

If TRBO doesn't get its **** together soon, I'm heading back for AES-256/Quantars. This is definitely the way to roll.
 

Okie

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Are you running this setup in mixed mode or P25 only?
 

radio313

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Is this a pure digital link? Or double vocoded? What's the signaling protocol between the modem and the obahai?
 
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mizzotch

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Mars- It would be great if someone could layout a PC board for the V.24. They are so simple and can be made with a few MAX232 ICs as I recall. All you need is for the right connections to be made to the header and then out to the RJ-45.

Okie, all my repeaters are mixed mode. This setup I describe however, is digital only. I use another completely separate link path to handle analog. With the VOIP adapter and V.3225 modem, you can only do digital. I figure most people have already got the analog part handled using another method. The pictures I posted which use a slightly different method with a Telex IP-223 box. IP-223 has two analog channels per box. I use the 'Radio 1' channel for analog and the 'Radio 2' channel for the modem data. Fore some perscpective, I'm using the MRTI port for the external analog controller interface (to the SCOM you see in the photos). The switching between digital and analog is very good if you implement it like I did. I have my PTT priority set to make the digital take over, even when analog is keyed. The Quantar instantly switches over and back.

No, this is not double vocoded. It's V.24 data all the way. The stream is not altered. The link between the modem and obihai is POTS. To be considered double vocoding, I'd have to be using a DIU between, which I'm not. There is no DIU at all in the setup. In fact, I don't own one of those yet....it's on my wish list.
 

Mars

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Yeah, what mizzotch just said. And all embedded signalling (RIDs, Soft IDs, KIDs, etc.) are all preserved in the data stream. This is the ONLY way to link P25. Anything else is welfare.

What's the voice latency like? If I keyed up my radio and said "oh ****", how long before you hear it on your end? Are we talking about one second, under normal Internet latency? (50-200ms)
 
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Since this seems to be based on the dialing Point A to Point B principle {as explained by the OP}.

Q1: how long does the direct dial link stay up before having to reestablish a dial connection?
Q2: Can you link more then two quantars or no?
 
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mizzotch

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Yeah, what mizzotch just said. And all embedded signalling (RIDs, Soft IDs, KIDs, etc.) are all preserved in the data stream. This is the ONLY way to link P25. Anything else is welfare.

What's the voice latency like? If I keyed up my radio and said "oh ****", how long before you hear it on your end? Are we talking about one second, under normal Internet latency? (50-200ms)

Funny you mention that Mars- With the latency, you definitely hear the tail end of your transmission when I routed through LA (with the 600+ms roundtrip). If you said "oh sh**" then unkeyed, you'd hear the sh** coming back. When I did the test, I had the link going from Astrotac to Quantar and played with the voice latency for a bit as I found it mildly amusing. :cool: If the two obihais are on the same LAN, you'll hear maybe the last syllable at most. Usually you hear just the brief moment of silence between when you stop speaking and unkey.

123: The direct dial link will stay up for as long as the internet between the two obihais is constant. I ran overnight tests and when I came back in the morning, they were still solid.

You could link more than two Quantars if you use an Astrotac with a modem & obihai for each channel. Remember, this is active bi-directional data handshaking we're doing here. It's a 1 to 1 setup. If you don't have an Astrotac, you're limited to linking two Quantars total using the RT/RT config.
 

kayfox

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Mars- It would be great if someone could layout a PC board for the V.24. They are so simple and can be made with a few MAX232 ICs as I recall. All you need is for the right connections to be made to the header and then out to the RJ-45.

Ive made a semi-working protoboard for it, but I kinda want to know what is the exact circuit on the V.24 board before going to far, unfortunately this board does not seem to ever be included in service manuals, I have revisions -C and -E and neither have the V.24 board.

EDIT: If someone has the chance - even without any schematic I can use high-resolution photographs of both sides of the board. If I can get something going I will post the Gerber files for people to order PCBs with or something.
 

Mars

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kayfox: I still have a Quantar boxed up, with V.24 board installed. I'll pull it and take some high-res pics for you. Macro lens, proper lighting, etc. I'll see if I can get it done tomorrow. The Quantar isn't at my home QTH.
 

iam4thapack

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Ive made a semi-working protoboard for it, but I kinda want to know what is the exact circuit on the V.24 board before going to far, unfortunately this board does not seem to ever be included in service manuals, I have revisions -C and -E and neither have the V.24 board.

EDIT: If someone has the chance - even without any schematic I can use high-resolution photographs of both sides of the board. If I can get something going I will post the Gerber files for people to order PCBs with or something.


Check your PM's.
 
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moetorola

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Mizzotch, Do you have piouts and settings?:D Excited!!!!
 
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mizzotch

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Here is the manual for the V.3225 modem and an Excel sheet with the pinouts for the interface cables. Now get to work!

And, seriously, if there are any Asterisk experts out there, I could use your help.
 

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Mars

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Excellent interfacing chart. Could you please clarify which gender the DB25 connectors (cable side) need to be? Thanks
 

kayfox

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I have the circuit diagrams for the V.24 board and I'm working on a PCB.
 
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mizzotch

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Excellent interfacing chart. Could you please clarify which gender the DB25 connectors (cable side) need to be? Thanks
You need MALE connectors on your cables. The modem data port and Quantar J14 MRTI are DB25 females.

Also, you have to do some wildcard programming to make the RDstat output work on the telco interface. I found that the COS signal on the MRTI port will also indicate when receiving a P25 signal, so that's no good for mixed mode operation with external controller
 

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Thanks! I'm going to make some cables up. Already have a pair of modems/VoIP adapters on the way.
 

moetorola

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You need MALE connectors on your cables. The modem data port and Quantar J14 MRTI are DB25 females.

Also, you have to do some wildcard programming to make the RDstat output work on the telco interface. I found that the COS signal on the MRTI port will also indicate when receiving a P25 signal, so that's no good for mixed mode operation with external controller

I found that problem also with the COS. I ended up using Relay 7 and set wildcard as (State and condition settings is State: RX PL DETECT) (Under action I have SET OUTPUT 7) (Under Inaction I have CLR OUTPUT 7). So this output RLY7 goes to the extrnal controller.

I have access to probably 6 or 7 v.3225 and a couple v.3229 modem's. I want to play with this, but do not have a second quantar:(. Really want to play with some IP-223's there are 2 on ebay know for sale if any one is interested, they are not being sold by me, if so they would not be for sale, LOL


Also on page 103 of PDF, Could you use Factory option set #3 for the VOIP device or Factory option set#4 if you use an IP-223? Would those factory settings be fine? depending of course which type of device you used weather OBi-100 or IP-223.

I also assume you can use many of the telephone over IP units avaliable as long as they are unlocked from a provider, like vonage for example.
 
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MattSR

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I'm kind of amazed that running a MODEMs audio over a VoIP adaptor works!
 
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