BC250D question

[Beth65]

Our public safety is moving back to analog, which seems odd to me, but anyway, the fire frequency is 151.1750 and I get nothing a "jake brake" sound whenever someone talks. The jake brake thing is the only comparative sound I can come up with. It's like a "RRRRRRRRRRRRRRRRRRRRRRRRRR" type sound. Anyone have any clues why this is happening. Our Sheriff's Office never made the switch to digital and I can hear those channels just fine along with all our area volunteer fire departments.
Thanks in advance!

 

[kb0nly]

By the way you described it that sounds like encrypted. Thats the sound i hear all the time when the local county goes encrypted on their P25.

 

[Beth65]

is that different than the APO-25 card? Sorry, I'm very limited in scanner knowledge.

 

[mass-man]

The radios used to transmit in analog...now if it is an APCO P25 system, it transmits a digital signal. On top of that, it may be encrypted. Without some extra equipment you won't hear the encrypted stuff. Regular P25 probably so.

 

[UPMan]

What specific agency?

 

[Beth65]

The Muscatine Fire Department. I figured since they went back to analog I'd be still be able to hear them. Can anyone advise what kind of scanner I will need to hear them? Apparently the PD is going that way too.

 

[tampatracker]

Where is Muscatine?

 

[UPMan]

I'm guessing Iowa (only Muscatine in the dB). That channel uses MotoTrbo...a type of digital that cannot be monitored by a scanner.

 

[Beth65]

I'm sorry, Yes it's in Iowa. OK Thanks!

 

[Beth65]

What kind of "extra" equipment would we need?

 

[UPMan]

There is nothing you can buy to decode encrypted (which is what that person's comment implied). MotoTRBO is not necessarily encrypted, just encoded using a proprietary format not licensed to scanner manufacturers.

There is some software that hobbiests use that might work. See http://wiki.radioreference.com/index.php/Digital_Speech_Decoder_(software_package).

 

[JRayfield]

MOTOTRBO uses the DMR (Digital Mobile Radio) protocol. It is not 'proprietary'. You can download the specs for the protocol from the European Telecommunications Standards Institute (ETSI) website:

ETSI

However, there are certain aspects to the DMR protocol that were developed by Motorola and Motorola holds the intellectual property rights to that information. So, a scanner manufacturer might have to aquire a license from Motorola in order to use the DMR protocol in their products.

Interestingly, this is exactly the same situation with P25. While P25 is an 'open standard', Motorola holds intellectual property rights to parts of that standard, too, and manufacturers who use parts of the P25 protocol in their products have to be licensed by Motorola.

Here's a Motorola website that explains all of this.

Government & Public Safety Licensing - Motorola

John Rayfield, Jr. CETma

There is nothing you can buy to decode encrypted (which is what that person's comment implied). MotoTRBO is not necessarily encrypted, just encoded using a proprietary format not licensed to scanner manufacturers.

There is some software that hobbiests use that might work. See Digital Speech Decoder (software package) - The RadioReference Wiki.

 

[Beth65]

Thanks a lot for all the help!!! I really appreciate it.

 

[Beth65]

Just wondering if there is any updates on this type of system used by our police and fire departments? Are there products available so we would be able to hear what is going on?
Thank you,
Beth

 

[ka3jjz]

As UPMan mentioned, there is software that will allow you to hear MOTOTRBO - however this requires a scanner with a discriminator tap (this is done inside the radio, and this is something most radios don't have). I should also mention that DSD (the software that can do this) has a learning curve. I see Muscatine police use P25 - DSD will also handle that mode.

There are folks that install these taps for a fee - and if you're a fumble fingers with tight circuitry, this is the way to go. Here is the correct link for the DSD software (the rightmost paren often gets chopped due to a bug in the forum software) and one for someone known to do such modifications...

Digital Speech Decoder (DSD) - the RR Wiki

Discriminator Tap Modification Services

I would get a second hand scanner from a pawn shop or other that's in good shape, and use that to have the tap installed. You then keep your primary scanner for other stuff...HTH...Mike

 

[fredva]

what you need, according to the database

The 151.175 frequency you mentioned in your first post is listed as a sheriff's department frequency, not a fire frequency. The database says it is a MOTOTRBO system. To listen to that sheriff's frequency, you would definitely need a scanner with a discriminator tap and the DSD software.

The county fire dispatch frequency of 154.17500 and the city fire paging frequency of 154.25000 should be monitorable by any type of scanner because they are analog conventional frequencies. To listen to the Muscatine Police department on 857.48750 and the Muscatine Fire Response frequency on 855.48750, you should be able to use a digital scanner. Your Uniden scanner might be able to monitor these frequencies, but given that it is a first-generation digital scanner, I'm not 100% certain.

I only know what is in the RR database. If it is not up-to-date, that's out of my control.

 

[ka3jjz]

As I mentioned, DSD can also handle P25, so that one frequency in Muscatine could also be heard, digital scanner or not...Mike