Charles County School Buses

[terrancedjr]

I have 46.540 programmed and I get very scratchy communication. It seems like they have changed all the antennas on the buses could this mean they upgraded. I just took a break from driving a Charles County bus but would like to keep up every now and again.

[ka3jjz]

The fact that you're receiving something scratchy doesn't necessarily mean they've upgraded anything. It's much more likely that your receiving setup doesn't do well at 46 Mhz. If you're listening on a handheld just with the little duckie, you should be thankful you can hear anything at all - these little antennas are very inefficient at 46 Mhz.

A little more information on your receiving setup is in order here...Mike

[WA3CSX]

I use to work for a two way radio company and we did Charles county school buses,that was always a common problem.I can ask and see if they has changed or upgraded.

[dtscho]

Charles County does have a pending application for two MOTOTRBO repeaters on 152.3075 and 152.9825. I'm assuming they will eventually be moving the school buses to this system.

ULS Application - Industrial/Business Pool, Trunked - 0005375161 - Charles County Public Schools

Dave

[terrancedjr]

I think they are using these Freqs now. Are they allowed to use them while their application is pending approval ?

Thanks for the Info All !

[JRayfield]

Yes. Operation can begin on a frequency 10 business days after the FCC ULS system shows a file number assigned to the application.

John Rayfield, Jr. CETma
W0PM

Originally Posted by terrancedjr

I think they are using these Freqs now. Are they allowed to use them while their application is pending approval ?

Thanks for the Info All !

[ka3jjz]

Note that MOTOTRBO cannot be decoded by any scanner - however with a discriminator tap and some software called DSD, it's possible. This is extensively discussed in this sub-forum...

Digital Voice Decoding Software - The RadioReference.com Forums

Mike

[terrancedjr]

There goes my hopes of keeping up with the school bus world lol. I am not advanced enought to all of the decoding etc etc !

[N1508J]

Greetings Mike!

Exactly what is MOTOTRBO all about? I assume it is a digital encoded signal but what is the modulation method that digital scanners like the 996 can't decode? It appears that there is software available to decode MOTOTRBO and I saw a comment regarding a discriminator tap for that purpose.
What do you recomment as a method to decode Charles County BOE bus communications, if any?
Lastly, do you have any idea why this mode was chosen when the pre-existing system was working?

TNX & 73

de n1508j

[ka3jjz]

From our glossary

MOTOTRBO - The RadioReference Wiki

Yes, DSD would require a discriminator tap on a scanner to work - you can read about DSD a bit here...

DSD - the RR wiki

You can find the link for the forum that discusses this mode in a previous message in this thread.

I have no idea why the County changed - I don't live there...HTH...Mike

[N1508J]

TNX Mike for the information!

I am confused however regarding the six items under the "download" title in the RR DSD wiki.

Am I supposed to download each one in order to decode MOTOTRBO or just one? My goal is obviously to obtain the software necessary to decode MOTOTRBO.

Your time appreciated,

73 de n1508j

Originally Posted by ka3jjz

From our glossary

MOTOTRBO - The RadioReference Wiki

Yes, DSD would require a discriminator tap on a scanner to work - you can read about DSD a bit here...

DSD - the RR wiki

You can find the link for the forum that discusses this mode in a previous message in this thread.

I have no idea why the County changed - I don't live there...HTH...Mike

[ka3jjz]

The first 2 links are for UNIX systems. The other 4 are for Windows. It looks like they've added some additional software filtering - for what purpose I'm not sure. I don't run DSD - but the forum I gave in message 7 of this thread would be the place to ask for more support.

Before you go investing time and energy into this, I'd try plugging the 2 freqs Dave listed in message 4 of this thread and see if you hear some wierd sounding digital junk on these freqs. Don't be too disturbed if you can't tune them precisely on your scanner, as these look like narrowband assignments.
(what scanner are you using, anyway?). If you can hear this, then it may be time to look around for an older scanner that can be modified (you don't want to do that to your only scanner, after all...)

HTH...Mike

[N1508J]

Hi again Mike!

Ok on the tips! I am using a HP Touchsmart 300 which has Windows 7...therefore I suppose that the last 2 programs you mention should be downloaded. I plugged in both of your suggested frequencies and found a real strong signal on 152.3075mHz. I have a PRO 2053 and Uniden 996 to choose from. I know where the discriminator tap is for the 996 but not for the 2053. I would prefer to install the tap in the 2053 first to see if the programs work. Also need to see if the HP sound card is sufficient for this application.

Really appreciate your time educating me on this subject!!!!!

best of 73 de n1508j

Originally Posted by ka3jjz

The first 2 links are for UNIX systems. The other 4 are for Windows. It looks like they've added some additional software filtering - for what purpose I'm not sure. I don't run DSD - but the forum I gave in message 7 of this thread would be the place to ask for more support.

Before you go investing time and energy into this, I'd try plugging the 2 freqs Dave listed in message 4 of this thread and see if you hear some wierd sounding digital junk on these freqs. Don't be too disturbed if you can't tune them precisely on your scanner, as these look like narrowband assignments.
(what scanner are you using, anyway?). If you can hear this, then it may be time to look around for an older scanner that can be modified (you don't want to do that to your only scanner, after all...)

HTH...Mike

[ka3jjz]

You would do well to check this out on another site like mods.dk, but it looks like the tap point for a 2053 is TP (test point) 4

Pro2053 tap - The RadioReference Wiki

Mike

[N1508J]

Hi Mike!

TNX again for your tip and other info.!

de n1508j