What is this NOISE? Listen and tell me what it is.

Jim202 · Post by **Jim202** » Thu Apr 24, 2003 6:32 pm

I still haven't heard enough of the tone your talking about. One thought does come to mind. If a repeater is getting desence, you will hear strange sounds at the tail of each input to the repeater.

Many times the repeater will keep itself keyed up if the squelch / CTCSS combination is right. It also covers up weak input signals.

Best way to prove if the repeater has the problem is to go to the repeater. It takes a service monitor generating a weak signal into the repeater with the repeater disabled. The key up the repeater TX and see if the weak signal gets covered up by the interference.

In your case this is probably out of the question. Just keep listening to the system and try to pick out what happens to a weak input signal from a portable.

Jim

nmfire10 · Post by **nmfire10** » Thu Apr 24, 2003 7:00 pm

x1sspic wrote:nmfire10, You sound knowledgeable, so can you explain to me how a parrallel tone-remote base works?

HA HA! My ploy is working excellent. You've been fooled. LOL. Hey, I've learned A LOT of what I know the same way you are... From the folks on this board.

Basicly. a tone remote uses a single audio path to send the voice AND the signals to transmit, monitor, change channels, etc. The voice passes right through like normal. However, added over that voice is the various tones. A Tone Remote decoding control device is attached to the transmitter, wherever it may be. It is interpruts the various tones and controls the transmitter appropriately.

For example, when you key the mic of a tone remote base, several things happen....

1. The high level "Guard Tone" is sent followed by the tone telling the radio what you are want to do.

2. This tone is the "function tone". 99% of time, that function is "F-1 Transmit".

[The above all occurs in a matter milliseconds and is done before you being speaking. It is the beep-boop you heard in my recording]

3. This is followed immidiately by a constant tone in the background for the entire duration you have the mic keyed. That tone however is filtered out of the transmit audio. If you listen to the unfiltered audio, you will hear the dispatchers voice and a really annoying constant tone in the background.

4. When you let go of the TX button, that "background tone" goes away. The transmiter no longer sees that tone and stops transmitting.

Now, what else can you do with it? Well, instead of the "F-1 Transmit" function tone, you can have a "F-2 Transmit", Monitor on/off, repeater on/off, channel select, etc etc. The beauty of it is that it only requires on pair of wires and all it consists of is audio. This allows you to use the public telephone network as your connection from the radio tower to the dispatch center.

Now, PARALLEL BASES. You can connect all the tone remote base units you want to one transmitter. The audio wires (usually phone lines) a connected to the transmitter in parallel, hence "Parallel Base".

RapidCharger · Post by **RapidCharger** » Thu Apr 24, 2003 7:41 pm

RESCUE161 wrote:I thought LAPD's 'sound' went BEEEDAHLAHBOOP???

Am I missing something here?

Scott

LOL.

I've been a member of this board for 2 whole weeks, and I've already had TWO questions that resulted in more than 1 page of replies. This means I'm not as stupid as I had orignially calculated. Woohoo!

Ok, and a MODAT does__________________...???
And aside from LA, it is also used in places such as______________...???

Just go ahead and fill in the blanks. lol

911 monster, listen to that latest file newbird.wav and that's the SQUAAAAK. From the taaaaxi company.

And if anyone wants to put up sound files but don't have anywhere to put them, email them to me if they are small. I will put them on my friend's hosting account! E-mail me for my e-mail address

One other thing, I'm stil having problems with Cool Edit, I don't know if I'm looking in the right place to identify PL codes. I go to ANALYZE then FREQUENCY ANALYSIS. After I connected directly to the sound card, it shows nothing there. Before It was showing 120hz, when I had it running through the amplified speaker's mic jack. Am I looking in the right place?

x1sspic · Post by **x1sspic** » Thu Apr 24, 2003 8:05 pm

thanks for that explanation nmfire10! makes perfect sense to me now!

(and I mean that in a serious, rather than sarcastic, manner)

nmfire10 · Post by **nmfire10** » Fri Apr 25, 2003 2:04 am

Modat was used as an identifier. Each radio had a specific numeric value of Modat. Whenever the the unit would key up, that beep-de-beep-bep would go out. The dispatcher's console can decode that and will show a number. That way, the dispacther always knows who is transmitting, even if there is no voice.

MDC1200, GE-Star, and Kenwood Fleetsync are both similar in use however they are hexidecimal data burts, not specific tones. It can also be used for Panic ID, turning the radio on and off, channel steering, repeater access, status messaging, etc. Again, the dispacther's console decodes these databursts into number and sometimes translates a number combination into an associated word or phrase like "Unit 12" or "In Service".

ExKa|iBuR · Post by **ExKa|iBuR** » Fri Apr 25, 2003 9:21 am

I thought it was 132 at bush.. As in, using a bush for cover..

M

motorolamonster911 · Post by **motorolamonster911** » Fri Apr 25, 2003 11:34 am

GeorgeJefferson wrote:And if anyone wants to put up sound files but don't have anywhere to put them, email them to me if they are small. I will put them on my friend's hosting account! E-mail me for my e-mail address [/url]

Am I the only one who caught that?...lol

Post by Pj » Fri Apr 25, 2003 11:46 am

Lets see... LAPD used MODAT, Denver, I believe New Orlenes did at one time, and a very other places. For some reason Detriot comes to mind.

Its also used by the COPS crews when using a Smartzone Ominlink system at times

RESCUE161 · Post by **RESCUE161** » Fri Apr 25, 2003 1:39 pm

I've just always found MODAT to be 'easier' on the ears than MDC... I hate the MDC sound...
At least you can hear MODAT as you're transmitting. With MDC, you either have to 'know' to wait, or have an annoying side-tone that gets VERY annoying VERY quickly...

Scott

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Fri Apr 25, 2003 3:20 pm

Let's not forget about DTMF ANI.

I've heard some business freqs back home running DTMF ANI, sounds pretty neat.

Plus, you don't get stuck having to use all Motorola gear [as with MODAT or MDC1200], or all GE gear [as in GE-STAR.]

OX · Post by OX » Fri Apr 25, 2003 5:11 pm

x1sspic wrote:Yep, that one sound sample higher up in this thread is indeed MDC.

nmfire10, your sound sample is the identical sound I hear on the county lowband frequencies here. You sound knowledgeable, so can you explain to me how a parrallel tone-remote base works? This is one area of radio technology that apparently is new to me, and as such, I'd love to understand it

Ugh, I can't believe we're on page 2 now... The sound that this quote refers to is GE Star, definitely not MDC of any sort.

x1sspic · Post by **x1sspic** » Fri Apr 25, 2003 6:29 pm

actually I think you are correct. At first I thought it was a tail-end of an MDC burst, but the more I listened too it, it sounded less like MDC and more 'coarse' like GE star

KH · Post by KH » Fri Apr 25, 2003 6:44 pm

Now that I've heard it, I say it's a comparator. Weirdass tone tho, not 2175. Sounds much higher. But all transmissions are preceded by it, so it isn't isolated to a dispatch point.

nmfire10 · Post by **nmfire10** » Fri Apr 25, 2003 7:01 pm

Why would a voter status tone be heard on the transmit from dispatch? Unless dispatch is using an RF control station and a yagi to talk through the repeater.

Johnny Grep · Post by **Johnny Grep** » Tue Jun 03, 2003 3:40 pm

That newbird sound was definetly not MDC. However, I'm doubting on the fact that it could be GE-Star, I know for a fact that it's GE/Ericsson-based, since one of our client's (real E, not GE) Ericsson Orion mobiles transmit msgs with these bursts. However - I thought GE-STAR sounded like this? http://www.kb9ukd.com/digital/ge-star.wav

Would that one be the slower baudrate (configurable in HT1000 RSS for example) whilst the newbird squawk be the higher baudrate? Keep in mind GE-STAR comes in two speeds, 400 & 800 I think, like MDC600 (never seen it) & MDC1200...

Oh, and speaking of signalling - let's not forget Motorola's MOC (MODAT-on-crack) that is plaguing the FRS band...

n9upc · Post by **n9upc** » Tue Jun 03, 2003 7:19 pm

Lets us not also forget about the new craze that a lot of multi-system users are doing now with remotes: High-speed DTMF remotes.
Where as the remote sends a high-speed DTMF string to the remote/radio interface for keying and un-keying, as well as changing channels, scan, and monitor functions.

We had a customer that had one of these High speed DTMF remotes from CPI interfaced with a Maxtrac. The customer runs on 4 different conventional repeaters in the area and one of the repeaters appears to be DTMF remote programmable (dumb ideal!!!) Anyways when the remote unkeys you hear a quiet high-speed DTMF string and this would cause the repeater tone panel to go nuts until the repeater owner finally listened to us.

I have not heard the tones that started this whole post but from what it sounds and the evidence it appears that it is the standard F1 keying on a tone remote. Also if the repeater is set-up with a comparator and there are quick keyers then he would hear the tones on the base or when people are talking portable to portable.

Try explaining that one to a dispatcher at 2:30am in the morning because they are a quicker keyer and they do not believe they are casuing the issues. Not also mention they call it a systems down when they heard the key-up tones.

N3IVK · Post by **N3IVK** » Wed Jun 11, 2003 9:39 pm

Yup, It's a Tone Remote Command.
But something to think about,
Is his system runnin regular repeat, console repeat or voter repeat ?
I recent rebuilt the Beaver Dam WI VHF system. GE Master 3 repeater, and a JPS voter and a second receive site via a Micor.

The way this works and is quite comman in a repeater system with multiple receive sites,
The repeater is a full blow full duplex repeater...except it doesnt repeat. Everything it hears it sends down the phone line (4 wire remote) to the voter. The voter is then setup to repeat, which it then sends the 2175/1950 HZ keyup command to the repeaters transmitter. (I wont explain pilot tones)

So it's very possable that when mobiles use the system, you can hear 2175 squeaking through if they time thier transmissions just right. Usually if they keyup just as the "hang time" expires"

Another version of this squeaking 2175 is this....
The repeater is a normal stand alone repeater with a 2 or 4 wire tone remote on it (ie console). When a mobile uses the system and he unkeys, there will usually be a delay or "hang time" until the repeater unkeys. usually you will hear the 2175 sqeak through is the dispatcher replies before the hang time expires. This varies with make/model of repeater or tone termination panel. Motorola always seem to let 2175 squeak through if you take a tone remote and hammer the PTT several times a second. However, the CPI units seem to mute all TRC tones no matter what. kinda a buzzkill as I like the 2175 squeaking through :)

Clear as mud ? I learned it the hard way, new radio tech and was handed keys to my service van and sent to repair the Beaver Dam system at 2:30 AM after a JPS board went thermonuclear.

As for the tone not quite sounding 2175, My MTR2000 repeater allows you to use whatever tone ya want to key up. Doesnt need to be 2175. It's programmable via RSS. Maybe they use 2175 for somethign else ?

Usually voter "tones" are heard when a mobile unit unkeys his mike and you hear the very breif sucking sound. I'd say that's the remote receiver's COR closing and resending pilot tone and the voter passing it through the audio path before it mutes pilot tone and unkeys. That's another whole ball of wax :)

My interest in radio was always repeaters, tone remotes, voters, etc..you know, all the goodies :)

Have a good one y'all
Matt Orr
N3IVK
Ex tech for Evan's Ind Communications

RADIOMAN2002 · Post by **RADIOMAN2002** » Mon Jun 16, 2003 6:52 pm

That is definitely Key Up tones. All motorola and most GE have filters to remove the 2175 key up tone. But the function tone is outside the range of the filter. These tones can be anywhere from 1050 to 1950 in 100hz increments, used to control PL, multi-frquency or even encryption on/off. The filter removes the HLGT (hi level guard tone) and the LLGT (low level guard tone) or keep up tx tone, but fails to remove the function tone, which is sandwiched in between the HLGT and LLGT.

Hightower · Post by **Hightower** » Tue Jun 17, 2003 1:21 am

GeorgeJEfferson wrote:
KH wrote:
Same you hear on "Cops" intro? "529 I have him at gunpoint" DEEDUL! 529 10-4......
DUH! Yes, he's right. That's the one.

But here's the zinger. I have a similiar (if not the same noise) recorded today from a taxi company. I'm assuming it's a taxi co, because it's all en espanol. It doesn't sound like a deedul, it sounds like a kasquaaaak.

And anyone wonder what that dadeedulkasquaaak is that you hear on cops, on the LAPD system, because they are using the latest digital crap and you can hear it on their radios. I haven't heard this anywhere but lapd, and absolutely gotta know why that is.

I figured out why the machine is making the hum, just don't use the mic jack if you have amplified speakers with a mic jack. This is of course a pain, because I have to move a lot of heavy stuff to access the back of the computer.

Here is the new file, a lot smaller & no hum.
http://www.conceptflooring.com/newbird2.wav

newbird2.wav sounds like MDC-1200 - not to be confused with MDC-600.

RapidCharger · Post by **RapidCharger** » Tue Jun 17, 2003 7:50 am

I'm surprised to see this one still floating around here but I'm glad it is because over my weeklong trip in the northeast, I heard that on a HAM repeater.

Microwave Mike · Post by **Microwave Mike** » Tue Jun 17, 2003 6:53 pm

Sounds like a voting system that needs to have a tune up. The tone used for voting should be notched out with analog notch filters. They need to be adjusted often. It could be a tone remote tone also for the remote base.
I think that the techs need to get off the donut wagon and get to work.

mm

OX · Post by OX » Wed Jun 18, 2003 3:01 am

Check out this site to help you figure out what you're hearing:
http://kb9ukd.com/digital/

It seems to have almost everything EXCEPT tones from tone remotes....

Johnny Grep · Post by **Johnny Grep** » Sat Dec 13, 2003 12:35 pm

I finally found the answer to GeorgeJefferson's data burst in newbird2: It's Kenwood FleetSync. However, some GE Orion radios can be programmed with a Futurecom external module to send similar MSK packets. Hope this ends the search.

What is this NOISE? Listen and tell me what it is.

a

Odd noise