emission designator

Jay · Post by **Jay** » Thu Mar 07, 2002 9:18 am

A little off topic...

What is 20K0F9W ?

I know that F3E is FM - but I assume the above is some data format. Am researching some license data at the FCC website to try and figure out what they are doing on this freq.

Jay

mike m · Post by **mike m** » Thu Mar 07, 2002 10:01 am

If you look up the way the FCC comes up with the designators in rule book CFR 47 sections 2.201 and 2.202 you come up with the following.
20K0 = occupied bandwidth of 99% of the signal IE 20 KHz. F9W the F is Frequency modulation meaning the way the information is applied to the modulator of the transmitter. the 9 means a composite signal consisting of one or more digital channels along with one or more analog channels and the W means a combination of any of the following FAX, video, data, telegraphy or telephony. Quite a mouthful huh ? whats the signal sound like ?

Mike

Twisted_Pear · Post by **Twisted_Pear** » Thu Mar 07, 2002 6:23 pm

http://wireless.fcc.gov/plmrs/faqemsn.html

Jay · Post by **Jay** » Sat Mar 09, 2002 2:43 pm

I'm trying to catch a sound file of this data. It is, ironically, some control data of some sort from a Smartzone 800 Mhz trunking system. Sounds to be faster than 1200 baud.

In several firehouses, there are alerting systems that activate (audible tones) when this stuff is transmitted.

I've seen the inside of the alerting boxes with the PA amps, etc. There is an astro mobile to rx the dispatcher on, and then a VHF GM300 with the 16 pin accessory connector run off somewhere, which activates the tones to wake everyone up.

Seems strange that with such an "advanced" trunking system, there is still the need for a VHF frequency to send this data on. Anyone have experience with this??

Jay

Jay · Post by **Jay** » Sat Mar 09, 2002 4:14 pm

Here is the sound clip of the stuff...

http://www.angelfire.com/amiga/8088/data_2.wav

Will · Post by **Will** » Sat Mar 09, 2002 4:48 pm

The sound link does not work, server says NO.

This may be high speed five tone alerting like most fire departments use. An old protocall, like DigaCom the early MDT.

Bleep and a halfsecond long?

Jay · Post by **Jay** » Sun Mar 10, 2002 7:40 am

Found out that angelfire won't let you link directly to it. Just go here:

http://www.angelfire.com/amiga/8088/

Then click on the link for data file. Hope to hear some feedback, this has me baffled.

Jay

<font size=-1>[ This Message was edited by: Jay on 2002-03-10 20:33 ]</font>

Will · Post by **Will** » Sun Mar 10, 2002 5:26 pm

Jay, it would not work for me. It just said no linking here.
Maybe becuse I do NOT run Windows 9x here?

But I would bet that from the emission designator, and the description it IS five tone paging like most of the fire depts use to trigger the station decoder/bell-out.

Jay · Post by **Jay** » Sun Mar 10, 2002 5:35 pm

Try the revised link....I think its straight.

Jay · Post by **Jay** » Tue Mar 12, 2002 2:19 pm

How about it? Anyone recognize that stuff?

Post by **wavetar** » Thu Mar 14, 2002 1:56 pm

Just sounds like unmuted MDC-1200 to me, definitely not 5-tone.

Todd

Will · Post by **Will** » Thu Mar 14, 2002 4:47 pm

It is data, like runs the MDT, DigaCom, ect; used to alert the individule fire stations.

R F Burns · Post by **R F Burns** » Fri Mar 15, 2002 4:43 am

Just by ear, sounds like 2-tone fsk at about 1200 baud... likely MDC-1200, although I don't hear a recognizeable preamble. Used to trip the horn honk output of the GM300 to flash lights/sound alert buzzer.

-RFB

Jay · Post by **Jay** » Fri Mar 15, 2002 9:45 am

Not sure how this could be MDC 1200...But you guys know more than me. There is no signalling set up in this radio. Just a special accessory connector configuration.

Jay