Batboard

There is a local repeater here that I've had programmed into the scanner for quite some time. All traffic has been either in the clear or secure (securenet type).
Recently I heard it key up numerous times with just a rapid clicking sound. I've not heard any clear or securenet audio at all since.
It didn't really sound like the astro audio samples I've heard on recordings I've found on the web. The clicks were very short and rapid, like four a second or so and seemed to be all the same.

I don't have a card for the 250d so I can't see if it's astro or not.
I guess I'm just curious if there are any tell tale signs to confirm whether or not it's astro. I did find one other astro signal on another frequency and it doesn't sound the same as that one. I know the other one is legit and has been confirmed by other scanner listeners in the area.
I will try to get a recording of it but I don't know how successful I will be. I never seem to have any luck getting a good recording using the computer.

mancow

OH, also... do astro repeaters have a hang time at the end?

mancow

about the Astro Repeter Hang Time...

From my encounters with LAPD and Anaheim PD On a conventional scanner, i did not hear any repeater tail at the end of the transmittions. Just

_____________**garble**garble**garble**______________

insted of:
_____________**talk**talk**talk**talk**----------__________


___ - no signal
----- - dead air/repeater tail

**sorry about the animation, i am really boarded...**

mancow, normally there is NO hang time on a Quantar, if it is repeating IMBE (of course, there is hang time on a Quantar, if you set it in the the RSS, when it its passing legacy analog FM).

I now have 2 Quantars in operation: one on commercial UHF conventional (supporting my helicopter operations), and one on Ham UHF conventional. On my Ham UHF Quantar, I have interfaced an SCOM 7K repeater controller via the MRTI patch port on the back of my DIU3000. As such, the external SCOM controller holds the carrier up for 2 seconds (fully programmable, of course) after the IMBE input signal drops. I use the "Call Detect" output logic on the DIU3000's MRTI port. "Call Detect" goes logic positive when it "sees" valid COS and Proper PL Detect on analog, and/or when it "sees" valid COR IMBE and ID 293 on digital. Therefore, I have created a hang time on my Ham Quantar, even for IMBE traffic.

The "Call Detect" logic signal on the DIU3000 MRTI port simply goes into the controller's COS Detect port, and I have the controller set to ignore PL. However, Call Detect only goes positive in analog if it sees COS Detect AND proper PL Detect, since I programmed the RSS that way (Call Detect follows the RSS logic). For IMBE, the Call Detect logic goes positive when it sees IMBE cxr and ID 293.

However, to my knowledge, there is no way to create a hang time for IMBE traffic on a stock/non-SP Quantar via the Quantar's standard logic and the associated RSS. The only way I know to do this is via the DIU3000 in the way I lashed it up. My commercial Quantar has no hang time, since it is not using an outboard/aftermarket controller.

To date, every Ham Quantar that I have talked IMBE through has NOT had any hang time with IMBE. My sense is that Hams typically do not want to spend the dough to buy a DIU3000, so it would be a tough job to otherwise somehow try to create a hang time with IMBE. The KEWL thing about using the DIU3000 is that you simply plug your modular jack into the back of the DIU3000 (at the MRTI jack), and hook up the other end to the controller. This way, you are all set to interface the controller to support autopatch, hang time, voice announcements via WAV files, and anything else you might want to do. Simple and very effective!

You could even take this a step further on a commercial Quantar and protect your DTMF commands by signalling over DES-OFB or AES whenever you send DTMF commands in IMBE (they are sent as data signals, of course, when you hit DTMF encoder keys whilst in the IMBE mode). The DIU3000 will decode these encrypted commands and output recovered analog DTMF tones to the outboard controller via the DIU3000's MRTI patch port. This way, no one monitoring the repeater's input and/or output could detect your dialed digits into the autopatch, nor your command tones! The neat thing is that there is no need to go into a special mode, etc. to provide this protection---you would simply turn encryption ON/OFF at the portable/mobile, as desired.

I was motivated to create a way to have hang time in the IMBE mode because my Ham friends vociferously bitched that they would hit their PTT in IMBE mode, and they had no way to know if they were hitting the repeater, unless someone else was listening in IMBE, or unless they switched to analog to see if they were making it.

Bottom line: If you want to get the FULL benefit of a Quantar, you are way ahead of the game if you get a DIU3000 and connect it to the Quantar via a Telco 3002 dedicated line. I found that my local Telco finally dropped the price of 3002 dedicated circuits to where it's quite affordable and allows me to take full advantage of the horsepower of the DIU3000.

BTW, an older ASTRO DIU (predecessor to the current production DIU3000) will do just fine if you 1) uplift it to the current firmware, and 2) put in the IMBE firmware, rather than the VSELP stuff that the ASTRO DIUs originally shipped with. Once you do this, you essentially have a DIU3000 in a plastic case, rather than the metal case (big deal!). Also, Motorla has recently introduced a nice desk top metal case (with rubber feet, etc.) for the new DIU3000 so it can sit on your desktop, rather than be rack mounted in a Quantar style cabinet.

Larry

We've got two IMBE ham Quantar ham repeaters up running exxternal repeater controllers without DIU's. Both have courtesy beep and hang time when in IMBE mode (the courtesy beep is only heard if the subscriber is mixed mode receive as it is going out analog).

You DO NOT need the DIU but for the way we have it configured you do need the MRTI option.

George

All the Quantars I've ever worked with had the adjustable "Drop Out Delay" setting in the RSS, which is a hang-time of sorts. It keeps the repeater transmitter keyed after mobile unkeys for the specified time. The Quantar seems to send frames containing only the Network ID--no talkgroup, unit ID, or other parameters. About all it does is cause the mobile/portable busy light to stay on during the "Drop Out Delay", which does let you know if you hit the repeater. In P25, it's essentially like an analog repeater that drops the PL after the mobile unkeys, but keeps the transmitter keyed for a time. In analog, the transmit PL/DPL is sent for the duration of the "Drop Out Delay", with the reverse burst/turn off code at the end. This is all with no DIU.

I see Larry's point about the advantages to having a DIU. It seems like the way he has it set up with the S-COM, the Quantar would be transmitting full "silent" frames for the hang-time, as opposed to the ones containing only the Network ID that just cause the busy light to illuminate. This way, if an Astro mobile/portable is scanning, it can stop on the hang-time of the Quantar. This doesn't happen on the standard "Drop Out Delay".

If you were listening to a Quantar repeating P25 on an analog receiver, you should hear the regular P25 "rumble" whenever a mobile is keyed up. As soon as the mobile unkeys, the "rumble" turns into more of a "buzz" sound, which is the Drop Out Delay.

RocketNJ, in the IMBE mode, how does the controller handle DIGITAL voice, since there is no vocoder in the Quantar?! I assume you would want to route both analog FM and digital IMBE voice (after the DIU decodes the IMBE voice into analog) through the ANALOG controller so you can use the delay line, and also to be able to cover your IMBE DTMF data control codes while you are in the IMBE mode.

Again, how do you route digital voice and digital data signalling for DTMF in IMBE through an analog controller (without the vocoder in the DIU)?!

With the DIU3000, it has an internal vocoder so that BOTH analog and digital voice are routed through the controller (in analog, since the DIU's internal vocoder decodes IMBE into analog BEFORE it hits the ANALOG controller), all automatically, of course. And, in the IMBE mode, the voice traffic comes in and goes out digitally, completely transparently. I'd sure like to know how you do this, RocketNJ, with your Quantar in IMBE mode since you have no vocoder and therefore no way to make full use of a controller (such as IMBE delayed voice, delayed/covered DTMF tones, etc.) without the DIU.

For example, suppose you have WAV tracks to play voice IDs, WAV announcemsnts, etc. that your controller plays at given time intervals based on pre-programmed conditions. In the IMBE mode, your controller would have no way to play these WAV tracks in IMBE. With a DIU3000, these WAV tracks are played into the DIU3000, wherein its internal vocoder digitizes the voice stream and sends it out in IMBE.

I don't see where an external controller hung on the MRTI jack of a Quantar can do anything at all in the IMBE mode, except to cause PTT! It would only be useful to support typical control functions in the old legacy analog FM mode. If this is the case, then why use an expensive Quantar and not be able to have the controller, autopatch, etc. be able to transparently handle all operations and functions in analog and/or the digital IMBE mode? With no DIU3000, and the external controller hooked up to the Quantar via the Quantar's MRTI port, I suppose you could support analog ops with the controller, but certainly not in the IMBE mode. That was my point about the DIU that it is ABSOLUTELY NECESSARY to support the full capabilities of the Quantar, which include the old legacy FM stuff (Ugh!!!) and IMBE (LOVE that ASTRO!).

My understranding is that the MRTI jack on the Quantar is for ANALOG use ONLY, since there is no vocoder in the Quantar. The controller should only work in the old analog legacy FM mode. So would the MRTI. But, in IMBE, there is no way the controller can provide any useful controller functions, except to maybe hold up the PTT.

If you look in the Motorola sales catalog (dated July, 2003), the DIU3000 is presented as an interface device that allows analog control equipment to be interfaced to the Quantar Repeater and/or Base Station so as to fully support the old analog FM legacy mode, AS WELL AS the modern IMBE mode. All transparently, of course.

My Motorola sales guy told me years ago when I mentioned that I needed a MRTI at the Quantar site and I wanted to operate patches in the old FM analog mode AND in IMBE (otherwise why the heck buy a Quantar if you don't run IMBE?!) and he said I'd need a MRTI with a DIU3000 at the site to support analog FM and IMBE patch operations. In fact, at the time (several years ago) this lash up (MRTI2000 with DIU3000 in the same Quantar cabinet) was an SP. Now it's standard, although 99% of systems with MRTI and Quantars lash up the MRTI at the DIU3000 at the control point site, and not in the Quantar remote cabinet. This way, the encryption remains end-to-end.

Also, that's the other point for using a DIU3000, at least for commercial ops. The system can go encrypted completely transparently, including encrypted autopatches and encrypted DTMF data commands. There is NO WAY that a hacker can discover the control codes with a DIU and encryption since a wise operator would ONLY send DTMF data control codes in DES-OFB and/or AES, and NEVER in the clear. Even the Ham approach of sending clear analog DTMF tones on the repeater input (with the output delayed and thus covered) is very easy to discover by simply monitoring the input, or listening to the control channel.

Is the DIU3000 Expensive? Yes! Powerful? Absolutely! The expensive aspect is why I commented that most Hams don't have DIUs lashed up to their Quantars. However, these things DO show up on eBay. I bought an ASTRO DIU at this years Dayton Hamfest for little more than a song and a dance. I simply put the new firmware chips in it (latest operating firmware, plus converted it from VSELP to IMBE and it's as good as new!). BTW, the DIU employs the old EEPROM chips for its firmware uplifts, as opposed to the newer FLASH. But, this actually makes it more bulletproof and easy to uplift.

My point about the DIU3000 was (and still is) that to get full use out of the Quantar (in both analog and IMBE modes) you MUST have either a DIU3000, or the older ASTRO DIU.

Larry

Never said we had full bells and whistles but I did say that you DO NOT need the DIU to hang a controller off a mixed mode Quantar. Without the DIU it does not decode IMBE DTMF or allow IMBE transmissions to be decoded and passed to the external controller. I am VERY familiar with the DIU and it's functions, just that I have not come across a DIU3000 for the "right price".

We do not use phone patch on the repeater. We use these things called cell phones.

In the amateur service P25 encryption is not allowed as per FCC rules.

As far as control of the repeater, a control receiver on another band works just fine, especially when the frequency is not published and not used very often. Also a dial-up modem on the controller RS-232 port works well.

The nice part of hanging the controller off the Quantar MRTI port is program the repeater for in cabinet repeat on IMBE and no repeat for analog. This way when you disable repeat on the external controller the repeater goes into IMBE only mode.

Another advantage of not having the IMBE audio get decoded/encoded by a DIU is one less A/D - D/A conversion.

There are benefits and drawbacks of each method. I just pointed out your initial assesment of needing a DIU to connect an external controller was not true.

George

RocketNJ, what I said was:

"Bottom line: If you want to get the FULL benefit of a Quantar, you are way ahead of the game if you get a DIU3000."

I think my explanation will suffice for anyone wanting to use an external controller on a Quantar, and wanting to have FULL analog and IMBE controller capabilities.

Yes, one can hang an external controller on a Quantar without a DIU3000 IF you only want to support controller operations on the old legacy analog FM side, with no controller functions (except maybe PTT) on the IMBE side of things.

RocketNJ, if you are patient, you can definately find good deals on DIUs. I have 2 DIU3000's as well as an ASTRO DIU and I can tell you that if you are patient, these things do come up, and they are very affordable, IF you have the time to wait for a good deal. I see them somewhat regularly at local Hamfests and the like for pretty darn good prices.

Good luck on your Ham Quantar. We need more of 'em on P25 Ham.

Larry

I've been reading the posts and they are quite interesting. The bad part is I don't know 1/2 of what the hell you guys are talking about, but I'm trying.

What was said about the drop out delay having just the timing information seems to follow what I'm hearing. Heck, it may be nothing more than just a repeater problem that hasn't been addressed, but what I'm hearing does sound like some sort of timing hack.

BTW, it's a Fed agency repeater, so P-25 would make sense. I just thought it was interesting that all I hear are clicks and no rumble of data or anything else. Maybe they are in a trasition period and are still testing.

I'm still trying to get a wav of it.

Thanks for the replys.

mancow

Normally, a Quantar in IMBE mode will not have any cxr tail once the PTT on the input transmitting unit drops. As soon as the guy dumps PTT, the Quantar should go instantly silent. Whatever you are hearing is probably an anomoly.

Oh, well, it's probably not going to stop the earth from revolving!

Larry

Nah, just made me curious, plus I wanted to know so I could decide whether or not to go get a card for the BC250d.

mancow