San Diago 700 & 800mhz system

[SirJ]

I recently just got back from a trip to San Diago “3 hour drive from my qth “ and while using my HP2 In the hotel on the 40th floor I was able to pick up a lot of activity mainly LE stuff. I have to say the 700 and 800 system sucks especially the 800mhz I believe it’s p25 but it’s also very statically and low volume
It’s as if there using analog radios that’s than converts to p25. It’s really bad. I have recordings from the System.

What’s the story with this system being so bad but used heavily

 

[nick0909]

The 800mhz system is being phased out and should probably not be monitored, the 700mhz system is the primary system. Things are still being bridged over to the 800 as they wind down all the users on that system, but that may be why it sounded bad. I haven't monitored it for a year or more so not sure how it is lately.

The 700mhz system is a simulcast system, and your scanner (and most out there) doesn't support that very well. If you want since you are a subscriber, I provide the Calls feed of the SD 700mhz system here, compare to what you were hearing and see if it is similar or not.

 

[DanRollman]

Things are still being bridged over to the 800 as they wind down all the users on that system, but that may be why it sounded bad. I haven't monitored it for a year or more so not sure how it is lately.

The 700mhz system is a simulcast system, and your scanner (and most out there) doesn't support that very well.

The second part is the more relevant part. Poor reception on a scanner is typically a tale of the scanner, not the target radio system. There's nothing wrong with the system if the system's intended users aren't having the same issue as a cheap scanner toy.

A consumer-grade scanner typically won't work nearly as well as a public safety grade commercial radio. And if that scanner wasn't even designed to properly decode the type of system you're trying to listen to (the HP2 wasn't), all the more so. Uniden sold a bill of goods with pre-SDS scanners marketed as capable of P25 simulcast monitoring. Ironically, given how much trouble cheap consumer-grade P25 scanners have with simulcast P25 systems especially when multiple towers can be heard simultaneously, monitoring from the 40th floor of a building may have hurt rather than helped the OP's cause. In any event, on my BKRadio KNG-P800 scanners the San Diego 700 MHz system sounds fantastic all around the city.

 

[Anderegg]

The 700 system has much less of a working footprint than the 800 system. It is also prone to cell tower interference. My TV station has a cell phone tower on the roof, because they thought that would be a good idea, and the beam shooting at the 94 freeway sprays across our entrance gate, and it literally can fade an APX mobile on SD 700 from receiving while transiting the radiation beam.

Paul

 

[inigo88]

It’s as if there using analog radios that’s than converts to p25. It’s really bad. I have recordings from the System.

What’s the story with this system being so bad but used heavily

You can think of the 700 MHz and 800 MHz as one system because they share a common zone controller / ASTRO system core (if it’s still called that). The talkgroup numbers on the 700 MHz system are the 800 MHz talkgroups divided by 16, because they’re all leading back to the same computer server and the two systems just have two different formats.

The back story is that the analog 800 MHz Motorola SmartZone system used to be the only system.

Motorola stopped supporting the old analog Astro core and they needed to upgrade to the P25 core, but they were able to upgrade the system core backbone only and use hardware at each site to make the system backwards compatible with analog SmartZone operation. Both the dispatchers and mobile units sounded great, but one day when they flipped the switch on the core changeover the mobiles (who were analog) continued to sound great but the dispatchers all started sounding robotic and digital (because they were talking through the new P25 core and then being converted back to analog).

Fast forward many years and they started building out the 700 MHz P25 system using the same Astro core and gradually migrating users over (starting with the garbage trucks lol), and now we’re to the point where most if not all of the police and fire radios are converted over to the 700 MHz P25 system. Therefore what you’re hearing on the 800 MHz system is both the dispatcher and mobiles on the P25 side being converted back to analog, and yes it sucks.

There are a few analog stragglers on 800 MHz I think including random public works, water and sewer department type stuff, and yes they still sound good!