King County Metro

[vgabnd]

They are getting the new APX series dual band radios however interestingly the pre-production model I saw last week didn't have the second mini-uhf connector on it. Along the PS side they will be installing a 4.9GHz system throughout downtown, and so they say, along major corridors. Tax dollars at work here!

 

[AtomicTaco]

From what I read 4.9 was for TSP and possibly for AVL.

 

[luminoxs]

After doing to research on the APX radios http://www.motorola.com/staticfiles...ile/APX7000_Portable_Brochure.pdf?localeId=33 It looks like FDMA is a fancy word for Phase 1 P25 that uses an IMBE vocoder while TDMA is a fancy word for Phase 2 P25 that uses an AMBE vocoder (like in ICOM’s D-STAR) and can transmit 2 voice channels on the same frequency. I was under the impression that TDMA was used just for Motorola's motortob's radios http://www.motorola.com/staticfiles...es/MOTOTRBO_Portable_Brochure.pdf?localeId=33. Even though they both use TDMA, they have different protocols... So that being said, it looks like KC Metro Sheriff's will get these radios as they can go on KC TRS along with Metro trans TRS while using only one radio. I doubt they will use the VHF portion of this radio as it has the capable of VHF and 700/800 in the same radio (Maybe KC Metro Sheriff, they can use the VHF LERN and MARS). I think… It’s kind of confusing. So if a scanner had a AMBE vocoder, it should be able to follow the TRS...Now if the control channel is encrypted or the entire system is encripted, then we are all SOL! I think we are going to see more and more TRS encryption as the cost goes down. A good example is the Federal IWN VHF TRS, it's 85% to 95% encrypted.

 

[AtomicTaco]

Learned today that they'll be using proprietary modulation. The only hope for monitoring will be if KCDOT allows citizens to buy a radio and have them program it as receive only. At $5,000 - $7,000 per radio, I doubt they'll have many takers.

 

[joescanner]

Learned today that they'll be using proprietary modulation. The only hope for monitoring will be if KCDOT allows citizens to buy a radio and have them program it as receive only. At $5,000 - $7,000 per radio, I doubt they'll have many takers.

I'd be surprised if the voice paths/channels are using a proprietary modulation - if they are it would likely be ProVoice which MA/COM/Tyco/et. al. for the longest time have said they would not license for receivers. Now that that technology is owned by Harris, who knows.

However, the data/telemetry channels likely will be a proprietary modulation, or at least a proprietary bit-code that wouldn't do much good for anyone to listen to anyway.

The APX radios will do P25 (obviously they could order -SP versions but doubt they'd swallow the cost for that) and I suspect that they are chosing those radios to have a "seamless" transition to P25 Phase 2 (TDMA) when it gets standardized (there is currently NO standard, only the standard that Motorola and all the other vendors have put forward).

 

[AtomicTaco]

It's not Phase 2. Something else Moneyrolla is doing. I forgot exactly what was said.

 

[luminoxs]

From my understanding, it was a next phase of P25 that Motorola was betting on. Kind of like how there was HD DVD and Blue-ray, Blue-ray won. Beta and VHS, VHS won… Well Motorola lost out on the bet but when Metro Transit bid the contract, they had this as an option. So they have to use it per the contract. They can program this proprietary system in the APX radios... I thought I heard it was a flavor of an EDACS system…Could be wrong.

I also found this: http://www.region43.org/documents/700MHz/20090429MeetingSlides.ppt

 

[luminoxs]

It's an TDMA Open Sky trunking system Scanner Frequencies: Snohomish County Public Transit Trunking System, Everett, Washington (ya, I know). Even though it's by M/A-COM M/A-COM Wireless Solutions - Tyco Electronics , it's going to use Motorola radios. I think the WSP looked at this system 3 years ago or so using M/A COM radios... So it isn't the EDACS that I thought it was...

BTW, I want to give Joseph Stein, KD7MLG credit for stating this first!