CDM1250/HT1250 MDC1200 issues

[emtprt]

I currently have 25 mobile radios and close to 100 portables all programmed with MDC 1200 IDs. All of the radios have the same settings/frequencies programmed. Four digit IDs are the only variable.

Here are the problems I have been facing on a conventional UHF repeater system MTR2000 with 4 voting receivers and aux MTR2000 backup :

1 The new radios transmit the ID but we are unable to decode at the dispatch center or via other radios on the system.

2 Decoding some of the older radios has been hit or miss going through a voted repeater. The ID will appear on talkaround but intermittant on the repeater. (? receiver issue on voter).

3 I am only using the MDC for ID purposes; no call lists or messages utilized. I have used the same settings for 10 years and these issues are just staring to occur. Are their standarized settings that I should be using (pre-time 500). The console settings are not available (Motorola at 1 center and Zetron at the other)

Mark

[jackhackett]

500 ms pretime is usually enough, but you can do a quick test to see if that's the problem, program a radio for post ID, then you can key up for at least a few seconds and see if the ID dislpays. If it works that way you'll have to play with the pretime to find a long enough delay to compensate for the repeater's delay.

If you can't get the post ID to display even with a long keyup you'll have to look elsewhere for the source of the problem, possibly the level the ID is being sent at.

[Garyf629]

Had the same problem when we installed our JPS voter. Using the trick that Jack mention, and a some trial and error, we had to increase the pre-time to 700 for reliable display.

[Jim202]

Take a try at what Jack suggested. That will point you in the direction of timing if it works. If it doesn't, then I would take a long hard look at system
deviation. By this I mean to start with one of your radios. measure what you get for TX deviation when you bellow into the radio with a steady ahhhhhhh.
Hopefully it is some place like 4.8 to 4.5 KHz deviation on a standard channel. You will have to go into an alignment to try an measure the tone level used
by the MDC. This should be down around 3.5 max for deviation.

If you find the user radio all within spec, then it's on to the repeater. You can probably win a good bet with the old timers on here that most of the radio
shops don't have a clue today on how to set up the throughput audio on the repeater. The best way to do this is to use 2 service monitors. Make sure
you know that they both read close to the same numbers on deviation. Set one monitor to generate a signal into the repeater using 1000 cycles tone.
set the generator level to give 3.5 KHz deviation. Now put this generated signal into the repeater receiver. Let the repeater key up and then measure the
TX output deviation. My bet is you will find it up around the max of between 4.5 and 4.9 KHz deviation. This is way too much compression and will
distort the audio going through the repeater. Yous should see no more than 3.5 to 3.8 KHz max on the TX deviation.

It is common for repeaters to put the incoming audio way into compression. Some people like that high background noise they hear when your rolling
down the highway. Problem is that it causes you to loose the ability to understand the person on the other end. If you are trying to pass any audio
tones through the system, you will be lucky if they can be decoded at all.

Now I will get down off my soap box and say this topic has been covered many times on here. But the problems still keep coming up and people like
your self keep asking what the problem may be.

Jim

I currently have 25 mobile radios and close to 100 portables all programmed with MDC 1200 IDs. All of the radios have the same settings/frequencies programmed. Four digit IDs are the only variable.

Here are the problems I have been facing on a conventional UHF repeater system MTR2000 with 4 voting receivers and aux MTR2000 backup :

1 The new radios transmit the ID but we are unable to decode at the dispatch center or via other radios on the system.

2 Decoding some of the older radios has been hit or miss going through a voted repeater. The ID will appear on talkaround but intermittant on the repeater. (? receiver issue on voter).

3 I am only using the MDC for ID purposes; no call lists or messages utilized. I have used the same settings for 10 years and these issues are just staring to occur. Are their standarized settings that I should be using (pre-time 500). The console settings are not available (Motorola at 1 center and Zetron at the other)

Mark

[emtprt]

We are having a new receiver site installed soon at a school that was just completed. Included in the installation was a general system "tune up". Hopefully this will help some of the issues. The phone lines, voter adjustments and duplexers will be checked and the antenna systems will be inspected along with poly-phaser replacement.

I am just amazed that brand new out of the box radios are giving us trouble compared to 10 year old radios that have been used on a daily basis and only serviced when thay failed.

We have always had licensed software since the UHF system was setup and I have renewed the subscription every 3 years. Radios have had the firmware updated but this issue has never happen. The issue even occurs on simplex channels.

I dusted off my old service equipment and and will check how far off the factory settings are..

Thanks

Mark

[Bill_G]

Good morning Mark - Some of this is not making sense to me. I'm a little confused. In your first post you explain the MDC decode problem as intermittent. In your last post you add that there are new radios of some type, and that the old radios worked fine. What new radios were added? Do the old radios still work 100%? Is it only the new radios experiencing a problem? Have you sent the new radios back in for warranty service, or gotten any support from the vendor?

Side note: Over a year ago I was chasing my tail with improper DTMF encode / decode problems in a new console, and it turned out the new CDM's had a problem with one column of digits. The new HT's plus existing Maxtracs and Spectras worked just fine. We sent the entire batch of CDM's back in for service.

[emtprt]

Sorry for the confusion the older radios are hit or miss through the voter but the new radios have not worked in simplex or through the repeater. I am assuming that there might be a voter receiver that is out of alignment or a phone line issue

I do have a few GM300s and Maxtracs that are used for spare (on wideband channel) and they seem to work through the voter most of the time. Pre time set at 600ms on the older radios.
Thanks again

[emtprt]

The new radios are HT1250s and CDM1250 UHF 40watts 450-512 and the CPS is the latest version (received last month).

Mark

[Bill_G]

Okay. So, even the existing older equipment is not 100%. They just work more often than the new stuff. Definitely sounds like it's time to put eyes on the problem.

[emtprt]

I didn't realize there was an issue until the dispatchers started complaining and I isolated the issue to particular radios (consistantly the new ones and an occasional older radio). The problems wit the older radios I truely believe have to do with the voter and which tower is receiving the transmission. That issue hopefully will be resolved with the new site and the system maintance.

It sounds like other people have had the same type of issues with newer radios. I will send them back to the dealer for service.

[emtprt]

Sorry for the typos (using my phone).

[jackhackett]

Are the new radios programmed for the proper bandwidth? If the system is still 25KHz and they programmed the new radios for 12.5KHz that could cause a problem...

as for there being MDC "issues" with the newer model radios, I haven't seen any and I've done a lot of CDM/HT radios with MDC IDs. I would highly doubt the problem is the radios themselves, either something is wrong in the programming or the system.

[emtprt]

The main repeater is 25KHZ and the radios are programmed on 25KHZ. We have also use talkaround on the same frequency 453.050 DPL and the radios are programmed on 25KHZ. We also have 2 12.5KHZ 460.xxxxMHZ simplex 2 watt channels with MDC and the newer radios have been an issue, the older radios, ranging from 1999-2008 have been fine.

The newer radios has also been a problem on 3 other UHF systems repeater systems 451.550 PL 12.5KHZ, 453.975 DPL 12.5KHZ and 462.975 PL 25KHZ . I have not contacted any of the mutual aid systems regarding encoding of our radios



Mark

[emtprt]

Here is the update

The MDC1200 ID on the radios that never showed an ID were an HT 1250s portable and 2 CDM1250 mobiles that had indiviual ID number 2023 programmed in them.
I changed the ID to 2022 and it worked 0023 worked, 2300 along with every other number that I entered.

I then went to a 10 year old CDM1250 that has not been updated in a number of years and entered ID 2023 and it worked.

Am I missing something with this number or is it a fluke with the newer firmware?

The radio ID's are programmed for a fire department with a standardized system MDC-1200 ID 0180= Truck 18 and ID 0181= Truck 18 portable 1. Officers radios ID 0201 for Company 2 Chief officer...
A volunteer firefighter who is from Company with badge 22 and is issued a radio because he is an EMS first responder has MDC-1200 ID 2022, this system also matches IDs on fire gear, photo IDs and so on.

So I cannot have firefighter 23 from company 2, MDC-1200 ID 2023, use a new radio.

Any ideas

Mark

[jackhackett]

That sounds like something you might want to contact Motorola for.

I get the impression you're the end user and someone else handles programming your radios, but one way to confirm that it was a firmware issue would be to take an older radio that works with that ID, update the firmware to the version in the non-working radios, and see if the radio then stops working with that ID.

[Bill_G]

Like I said earlier I had problems with a single column of DTMF (3,6,9) in new CDM's that had me chasing my tail in a new console.