A couple of CDM Questions

cfdeng3 · Post by **cfdeng3** » Mon Dec 27, 2004 5:51 am

Hi,
We just installed a CDM1550 LS+ in one of department vehicles and have had a couple of issues...maybe you can help.

1) Bought the heavy duty mic and it was almost inaudible. I replaced it with a regular CDM mic and we are noow readable but it sounds very tinny...What settings can I adjust? I know the mic gains are at the default settings.

2)The MDC ID is not coming over disptaches radio unless the repeater is still active. Do I need to add a delay to the MDC ID?

Thanks!

nmfire10 · Post by **nmfire10** » Mon Dec 27, 2004 6:27 am

You can try fussing with the mic gain settings. Some of the audio experts here might be of better help.

For the MDC, what is the pre-time set for now? I would set it for at least 400ms. I would also set the bitsync packets to 3 or 6. That should get the ID up there no problem. If it still gets clipped, just increase the pre-time until it works. Make sure the sidetone is on!

Post by **alex** » Mon Dec 27, 2004 7:22 am

Also look at the "pre and post" options in the 4th tab of the personality window.

I forget what the settings should be off hand, but this problem has been discussed before.

I think if you goto the last pull down box, and select the last option, you'll find the audio gets better.

It's been a while since I've played with the software for them.

-Alex

jackhackett · Post by **jackhackett** » Mon Dec 27, 2004 9:00 am

Oh lord.. it actually took me straight to the posting thing after logging in.. did someone fix it finally?

Ok, what I was going to say... I've found that on a GR1225 repeater system I've had to set the MDC pre-time to about 500ms, they seem to be slow opening up. Do you know what type of repeater it is?

FDC_100 · Post by **FDC_100** » Mon Dec 27, 2004 9:09 am

Is the dispatchers radio in scan? This could also be the reason for not receiving the MDC. It doesn't drop out of scan fast enough to receive the MDC signal.

thebigphish · Post by **thebigphish** » Mon Dec 27, 2004 9:23 am

first of all, i should hope the disp. is on a console with a dedicated unit per channel / tg.... and second, no dispatcher's radio SHOULD EVER BE IN SCAN! at all!

nmfire10 · Post by **nmfire10** » Mon Dec 27, 2004 9:47 am

You would want it on PRE ID. If it was on post, there wouldn't be a timing problem

cfdeng3 · Post by **cfdeng3** » Mon Dec 27, 2004 11:35 am

Ok Here are some answers:

Pre time was set for 300MS. I changed it to 400ms

PTT Sidetone was on
It is a Pre ID
Quantar repeater
Dispatch is rxing on a CDM1550 with No scan. The get all of our HT1250 ID's fine. This is the CDM we have added to our fleet.

I did not understand about the audio. If anyone has more info on trying to make the Tx audio sound less tinny please let me know.

I am going into work tonight and will program the radio with these updates
Thanks

jim · Post by **jim** » Mon Dec 27, 2004 11:48 am

In the RADIO CONFIGURATION menu, select MICROPHONE.
Adjust MICROPHONE GAIN until you are satisfies with the outcome.

Go into each personality and select ADVANCED. Disable COMPRESSION and the EXPANSION. For EMPHASIS, select DE-EMPHASIS and PRE-EMPHASIS.

I set these radios' delay to 500ms. on all radios that use MDC.

Last, program the console radio so it can't scan!

cfdeng3 · Post by **cfdeng3** » Mon Dec 27, 2004 11:59 am

Ok I set the pretime to 500ms. The settings were already disabled on compresssion.

I did not mess with the mic gain because I believe from messing with that before it justs brings their volume up and down and does not adjust the quality of it.

And the radio at dispatch HAS NO SCAN in it.

Thanks!

The Pager Geek · Post by **The Pager Geek** » Mon Dec 27, 2004 12:23 pm

Here in our system, the optimum timing is 850ms for a voted RX system.

tpg

jackhackett · Post by **jackhackett** » Mon Dec 27, 2004 12:36 pm

yeah, the pretime will vary depending on your system, we just did a UHF system with a VHF link and had to set it at something like 800ms, start at 500 and work your way up til it works.

cfdeng3 · Post by **cfdeng3** » Tue Dec 28, 2004 4:50 am

500ms worked perfect!! Thanks..the audio still is crappy.

Znarx · Post by **Znarx** » Tue Dec 28, 2004 3:23 pm

check to see the channel bandwidth (wide/narrow)...make sure it is matched to your system...Z

jackhackett · Post by **jackhackett** » Tue Dec 28, 2004 10:58 pm

you might also look at the pre-emphasis/de-emphasis settings..
pre-emphasis boosts the high frequencies in the transmit audio, de-emphasis reduces them on receive, so used together they cancel and you get normal audio, but with some noise reduction and a bit better fidelity. If a radio is set for pre-emph and the receiving radio isn't set for de-emph it can sound tinny.

rescuelt · Post by **rescuelt** » Wed Jan 12, 2005 10:58 pm

Go into audio, there is a setting there for flat.. Try that...

jackhackett · Post by **jackhackett** » Thu Jan 13, 2005 6:44 am

The flat audio setting is for the data input, that wouldn't affect the voice audio, and you wouldn't want flat on voice anyway.

Question... is the audio problem on a conventional channel or an LS trunking channel?

There are audio settings for compression and emphasis in both, for conventional they're on the advanced tab, in LS trunking they're under the site settings, advanced tab. I believe the defaults are full compression, full expansion, de-emph and pre-emph.

nmfire10 · Post by **nmfire10** » Thu Jan 13, 2005 7:24 am

Compression is defaulted to off. You wouldn't turn it on unless everyone has it.

A couple of CDM Questions

A couple of CDM Questions

Mic