Wierd Honking sounds on our LTR system

2wayfreq · Post by **2wayfreq** » Thu Oct 21, 2004 4:59 pm

Hi all,
Just curious if anyone has run into this before. We have a 7 repeater LTR system at our casino. Often, it will emit an awful Honnnk like a dropped pipe or a wounded goose. Anyone seen/heard this type of thing before? We have MTR-2000 UHF repeaters. Thanks..

Will · Post by **Will** » Thu Oct 21, 2004 5:03 pm

If it were a Motorola Trunking system, that would be normal.

Just a guess, INTERMOD!! you did not want to hear that.

MSS-Dave · Post by **MSS-Dave** » Sat Oct 23, 2004 6:41 am

Intermod sounds like a good guess Will. Just out of curiosity 2Way, do you know if your system is running PTT ID and what kind of portables are you using? I've run into a couple of weird things using HT1250LS on narrowband systems when using Xpand and doing ID.

Dave

apco25 · Post by **apco25** » Sat Oct 23, 2004 7:17 am

Geese??????

(snicker)

Splat · Post by **Splat** » Sat Oct 23, 2004 2:20 pm

Lost any radios lately? Maybe it IS a goose with a stolen radio!

NodrogCop · Post by **NodrogCop** » Sat Oct 23, 2004 3:40 pm

Which would then lead to a (wild) goose chase.

Gordon

KitN1MCC · Post by **KitN1MCC** » Sat Oct 23, 2004 4:24 pm

some one walkign around with a honky horn

Splat · Post by **Splat** » Sat Oct 23, 2004 5:06 pm

Lookin' for a birdie, so to speak!

Post by **batdude** » Sat Oct 23, 2004 5:14 pm

i have always heard this occasionally on some LTR trunks.

i think it's a hung up disconnect tone of some sort

one of the hotel LTR's in vegas honked every time someone unkeyed.

sorta like an edacs honk but worse

doug

Splat · Post by **Splat** » Sat Oct 23, 2004 5:20 pm

That would drive me nuts. Time to go a'huntin' for a goose, IMO!

apco25 · Post by **apco25** » Sat Oct 23, 2004 6:51 pm

AFLAK?

Will · Post by **Will** » Sun Oct 24, 2004 2:27 pm

MSS Dave,

Yes they are running Warez stuff there (That I know about).
Could be just that.

2wayfreq · Post by **2wayfreq** » Wed Sep 07, 2005 4:02 pm

MSS Dave,

HT-1250LS+ LTR Narrowband UHF, Full Expansion/Full Compression. MDC PTT is set to Pre. We have Filtronetics Crystal band stop filters on RX. There have been reports of "Freight Train" sounds from other places that have this repeater. One is in single channel conventional mode. It seems it occurs when a weak signal opens the RX, if a stronger signal from another unit gets in about the same time, thats when it happens.

MSS-Dave · Post by **MSS-Dave** » Wed Sep 07, 2005 7:50 pm

2wayfreq wrote:MSS Dave,

HT-1250LS+ LTR Narrowband UHF, Full Expansion/Full Compression. MDC PTT is set to Pre. We have Filtronetics Crystal band stop filters on RX. There have been reports of "Freight Train" sounds from other places that have this repeater. One is in single channel conventional mode. It seems it occurs when a weak signal opens the RX, if a stronger signal from another unit gets in about the same time, thats when it happens.

I had forgotton about this thread, almost a year old. I think the full compress/full expand is where you will have to start. All starts with what type of controllers used in the system. I use Trident Raiders on RKR 1225 and MTR 2K wide and narrowband. The controllers don't do any internal audio expansion but you can set the RKR and the MTR for XPAND (RKR) and compand (MTR). In my experiences, it has worked best to set the repeaters to NOT compand the audio and let the radios handle it on their own. Next thing, I've NEVER been able to sucessfully (read: satisfy MY ear) run the Waris radios on full expand/full compress. I think the freight train sound is the AGC "pumping" with either LTR data being set too high on the repeater TX or some possible intermod the portable RX is picking up during the hang time and holding the squelch open.

Suggestions.....

1 I don't know if you are the tech that works on the infrastructure so I will start on the portables. If you have access to the CPS, test using the different levels of compression/expansion in the site file (per channel) between 2 radios to find 1 that sounds the best.

2 If you have a service monitor, look at the deviation level on the mod scope. The proper level for LTR data to be transmitted on narrowband (Trident/Moto combo) is 800 Hz. Other controllers may be more or less by 200 Hz or so. If it's much over 1 Khz, the rumble of the data will be heard along with repeat audio. That needs realignment.

3 I think the honking will be some sort of a audio anomaly caused by intermod or your MDC burst overloading the expand circuit and driving the AGC nuts. I don't think I've ever heard the honk on a wideband system, but I had it on 2 narrowband systems from time to time.

4 I actually had better audio and performance using P1225LS and CT450LS on the narrowband systems FWIW.....go figure.

5 Narrowband LTR systems suffer tremendously when the input signals fall below -90 dBm (IMHO....) when using expand/compand. I've heard all sorts of weird things, hiss, crackle, honk that I don't hear using wideband. Alignment is CRITICAL on the repeaters and everything to eliminate intermod and adjacent/co-channel interference needs to be used. Not familar with your filters, are those the ones that down convert UHF to something, filter the crap out of it at a IF type level then Up convert back again? Those things are the Schnizzle as Snoop 'sez...

I went back and read your response again, the conventional repeater having the freight train sound almost for sure points to the LTR TX data being set too high. Since you have a big /\/\ system on LTR I'm 99.9% sure you have Trident Raiders or Marauders if you have interconnect. Let me know. I have additional alignment info available on those for narrowband systems if you like.

Dave

2wayfreq · Post by **2wayfreq** » Thu Sep 08, 2005 5:06 pm

Hi Dave,
Sorry I left that out, I am one of the radio techs here. We have Trident Raider TLCs. Thanks very much

.