King County Metro

[vgabnd]

For those of you who are interested in listening to the KCM day to day activities on UHF they are in the process of switching over to a Motorola 700MHz P25 system. I will update everyone as work continues on this change. Also, you will notice a lot less voice traffic as they'll be utilizing a lot more data traffic with the new system.

 

[AtomicTaco]

Any freqs in particular? I've grabbed everything off WQHJ935 and WQHJ934 and haven't heard a peep out of any of them all day.

 

[Zard0z]

digital?

So they are going digital then on all their buses and everything?

 

[AtomicTaco]

A vendor contract for the replacement radio system was signed in the spring of 2006 and the project is proceeding with design. Federal approval for spectrum licensing should be completed in 2007. Radio site modifications will be completed in early 2008, with the installation of infrastructure equipment completed in 2009. A vendor contract for the On Board Systems project was signed in 2007. The project will proceed with design in 2008 and prototyping and a pilot installation in 2009. Bus installation of radio and On Board Systems equipment will not be completed until 2010.

See the tower they put up on Rattlesnake Ridge here on page 6.


Guess what acronym they're using for it? TRS--for Transit Radio System. Scheduled completion Feb 2011. No mention in any of the many many many documents I've read that it'll be digital, but I know it will be. P25. All the County documents just mention that it's 700 MHz, and that it's going to provide "interoperability." Since it's the first 700 system in King County, I'm not sure who else is going to be on there.

 

[AtomicTaco]

Starting to get some dead air on 775.64375

 

[vgabnd]

They're in process of putting up the towers now. Sometime around the end of the year you'll occasionally hear something but until next year it won't be much. On an interesting note they will be using the XTL5000 for a few months until the full order of APX7500 dual band mobiles comes in.

 

[AlmostHandy]

Alright. I guess I should start saving up for a digital scanner.

If they say that the move to 700Mhz is for interoperability, but they're the only ones using it, does that mean that we should expect to see other agencies in the area follow suit?

Are any other agencies planning a switch to 700Mhz in the area?

 

[AtomicTaco]

The bandsplit on the APX7500 is 764-870 and 136-174 MHz, so that starts to answer my interop question. Here comes multiband trunking! And more voice channels so nobody gets bonked (even though in 2008 all voice channels were in use only 0.000038% of the time).

 

[vgabnd]

Alright. I guess I should start saving up for a digital scanner.

If they say that the move to 700Mhz is for interoperability, but they're the only ones using it, does that mean that we should expect to see other agencies in the area follow suit?

Are any other agencies planning a switch to 700Mhz in the area?

I know Community Transit up in Everett is adding a 700MHz data network. Their voice will stay on 800MHz though... Not sure about Pierce. I heard they were doing something, but it's a different company doing it.

 

[AtomicTaco]

Pierce is already on their own 700 system; I know it does voice and it probably does data. It would make sense to allow CT to roam onto Metro's network since there are a lot of CT buses in various parts of Seattle (mostly the U-District and the CBD).

 

[grishnav]

Seriously? I'm going to need a digital scanner? Right after I finally found one I liked? Ugh!

So uh... what's the P25-capable equivalent of the Pro 164? Anyone? Anyone?

 

[Zard0z]

New Scanner

Yup guess it is time to plan on buying digital soon.

KCM is sometimes entertaining and good snow reports too!

So let me ask this question. the bands that it covers are up to 851 mhz or so. I guess I need
to understand p25 some more.

So is P25 used on a wide spectrum of MHZ?? Meaning you can have a 700 digital and 800 digital
and 1000 digital and so on???

 

[AtomicTaco]

Think of P25 like modulation, not a band. It could go on any band you want. Here's an example of it in use locally.

 

[Zard0z]

ok i see.

That means that they could keep the same bands that they have and just start using P25 when they
start up.

thanks for that info so quick.

 

[AtomicTaco]

Slide 4:
http://depts.washington.edu/itswa/2k8MtgPres/AnnualMtg/KCM_ITS_presentation for ITS WA.ppt

Best to view the whole thing in presentation mode since there's some overlapping text fixed with some animation.

 

[Zard0z]

Thanks for that! Where did you dig that up at? I have been looking everywhere.......

So it looks like the 'paying public' will not be able to listen in on operations anymore once
this is in place? I know TDMA is UNscanable and it sounds like the other is more like
cell phone technology...... or am I wrong on this.

 

[AtomicTaco]

Came from Washington State ITS. Definitely won't be able to listen to voice, at least not with any scanner on the market. Since data will be FDMA, it looks like we'll be able to monitor that, sorta. Should be interesting.

 

[vgabnd]

Who knew!?!?

I didn't even notice in the docs that they were going to a TDMA format. After I saw this I went back and read through the Moto docs and sure enough... TDMA. Sorry!

 

[luminoxs]

It may be possible to listen to TDMA and FDMA but it wouldn’t be practical for listening propose. You can go get a Motorola radio what will decode TDMA/FDMA and program all of the voice output channels; just as long as the DV isn’t encrypted you can listen in. It would be crude like when 800MHz trunking came out or listening to a P25 trunking system with a non-Motorola commercial scanner.... You can program all of the VC in your scanner, but it would be VERY painful! You don’t know what TG was transmitting, you can’t filter out anything and had to hit scan until you found your conversation again. But this is transit so why bother... in my opinion. P25 is a standard for all public service; transit doesn’t fall into that category although the TDMA/FDMA would be more appropriate than the P25 system with its options it offers. What’s interesting is KC Metro Sherriff will be on the PS, while the safety folks will be on the transit system.

 

[AtomicTaco]

FDMA could be monitored (relatively) easily, but to me, TDMA seems nearly impossible with a conventional scanner.

Time division multiple access - Wikipedia, the free encyclopedia



I don't recall seeing anything about Transit PD being on the new system, but it wouldn't surprise me much. TPD is just KCSO under contract. A 700 radio would make interop better--they could talk directly to the operator--but since they're dispatched by KCSO they'll probably have dual band radios. Or KCSO will get a partial major upgrade.