LAFD 800 MHz Conv?! WHY?!

[SCPD]

I am in LA taking a vacation, and they are on 800 MHz conventional! Why is this? Why wouldn't they do on UHF like the police? I've never seen 800 MHz conventional systems. Is there a reason they chose 800 over UHF? And also, will they be moving to a digital system like their city partners the police? OK, thanks.

 

[K6CDO]

I am in LA taking a vacation, and they are on 800 MHz conventional! Why is this? Why wouldn't they do on UHF like the police? I've never seen 800 MHz conventional systems. Is there a reason they chose 800 over UHF? And also, will they be moving to a digital system like their city partners the police? OK, thanks.

In the mid 1980s when LAFD needed to expand beyond their 6 UHF-T pairs and 4 VHF lowband simplex channels, there was no additional room in the UHF spectrum inn.

The City was able to get 18 800 MHz pairs. Between the size of the City plus the LAFD operational requirement to be able to talk from the street into multi-level sub-basements (parking garages, etc.), the City obtained a waiver to the 'more than 6 channels must be trunked' rule, as no one City radio site would be equipped with more than 6 channels, and conventional allows for talk-around operation (to get into those pesky basements).

The 6 UHF channels became MDT channels for the LAPD and LAFD.

LAFD is planning on moving to UHF as a part of the LA-RICS regional UHF network.

 

[SCPD]

ok, great thanks for the information! will this system be digital? p25 or?? i dont see it listed in the database ok thanks.

 

[K6CDO]

ok, great thanks for the information! will this system be digital? p25 or?? i dont see it listed in the database ok thanks.

It is a new network, intended to be primarily P25. I suspect that there may be some analog component to it.

 

[scanfan22]

Isn't P25 the only digital protocol that no scanner can decode? It would be so annoying if LAFD switched to that.

 

[mdulrich]

P25 is the one that digital scanners CAN decode.

Mike

 

[scanfan22]

what was i thinking of?

 

[inigo88]

what was i thinking of?

TETRA? OpenSky? MotoTRBO? NXDN? iDEN? VSELP? D-STAR? Need I continue?

 

[LAflyer]

LAFD system might be older analog and mere conventional, but it seems to work quite well imo.

I rarely hear units asking to repeat, or complaining about poor signal.

LACoFD on the other hand with their mixed VHF & UHF system seems to have much more significant reception and comm problems even in the LA metro basin.

 

[Radio_Lady]

LAFD system might be older analog and mere conventional, but it seems to work quite well imo.

I rarely hear units asking to repeat, or complaining about poor signal.

LACoFD on the other hand with their mixed VHF & UHF system seems to have much more significant reception and comm problems even in the LA metro basin.

I can't address LACoFD's system since I don't know anything about it, but LA City Fire's signal quality is probably due mainly to the fact that every duplex transmission is repeated citywide through 9 synchronized transmitter sites around and adjacent to the city, a true simulcast system. There are a number of voted receivers so the best uplink signal from mobiles or portables is always selected, and it will change instantaneously if another site suddenly receives a better signal. Between nine simultaneous transmitters and numerous receiver sites, there aren't too many places for even a 2-watt portable to hide, even up in the 800 band. I believe their radios are all programmed for simplex operation, but it seems to be frowned upon, probably because duplex works so well, even inside buildings.

There is a 10th high-elevation "backup" repeater that is independent of the nine simulcast sites, but it is normally in receive-only mode for their 18 channels.

Unless something has changed in the last few years, LAPD, on the other hand, doesn't use simulcast on their dispatch, division tac, or bureau tac frequencies. The seven citywide tactical frequencies and many of the specialized divisions' frequencies do use simulcast though, since by definition they require coverage throughout the city.

 

[inigo88]

Thanks for the history lesson Don, and Radio_Lady for the specifics. Interesting reading!

Regarding LA County Fire Dept, I recall reading on these forums that the UHF Blue channels are also simulcast with receiver voting. I think the cause for a lot of the LACoFD reception complaints is not a lack of sites but rather multipath propagation interference due to the actual radio waves from several sites reaching the receiver out of phase from each other (often resulting in destructive interference). You may hear a choppiness or crackling to the audio, and I think if I'm not mistaken these are the actual beats from the destructive wave interference.

Potential causes could be center frequency drift on some of the transmitters, or incorrectly set up simulcast delay times. I vaguely recall reading a thread on here where the listener stated that LACoFD does not run any delay on their simulcasting transmitters (which is a pretty important part of simulcast system design if the site coverage areas overlap), and that they got around the problem with the station alerting dispatch audio by giving each station a yagi antenna and pointing it at the closest site (blocking out the rest). That's an ok solution for station alerting, but leaves the mobiles pretty hosed (if true). I'll try to post a link to the thread if I find it.

It's definitely an interesting problem that the 800 MHz LAFD system (on the band with inferior propagation characteristics) sounds much better than the LACoFD 470 MHz system (on the band with superior propagation characteristics), and I think the answer lies in the system design and/or maintenance. i.e. It doesn't matter how well the system was originally designed if the county doesn't have the money to maintain it.

 

[Radio_Lady]

I vaguely recall reading a thread on here where the listener stated that LACoFD does not run any delay on their simulcasting transmitters (which is a pretty important part of simulcast system design if the site coverage areas overlap), and that they got around the problem with the station alerting dispatch audio by giving each station a yagi antenna and pointing it at the closest site (blocking out the rest). That's an ok solution for station alerting, but leaves the mobiles pretty hosed (if true). I'll try to post a link to the thread if I find it.

This here one, inigo88?
http://forums.radioreference.com/gr...-areas-discussion/167831-lacofd-blue-8-a.html

 

[inigo88]

This here one, inigo88?
http://forums.radioreference.com/gr...-areas-discussion/167831-lacofd-blue-8-a.html

Exactly! Post #16 is what I was remembering.

Most of the other Blue channels aren't as bad because they're localized command/response channels for various battalion districts (and thus cover a smaller geographic area), rather than trying to cover the whole county at once like Blue 8 does.

 

[Radio_Lady]

And also, will they be moving to a digital system like their city partners the police? OK, thanks.

At the soonest, I wouldn't expect it any time soon if at all, although most of LAFD's frontline apparatus and command officers already are equipped with XTS5000 UHF portables that have both digital and trunking installed and operational, for communications with agencies such as LAPD and with Verdugo as necessary.

But that's only per piece of equipment, not like the 800-band XTL5000 radios that almost all apparatus have, and the 800-band XTS5k portables issued to each firefighter while they're on duty.

I need to backtrack on my Verdugo comment. I hear LAFD and Verdugo agencies communicating especially working vegetation fires between Glendale-Burbank and "the Rock" in Sunland. I don't think I've ever looked at the frequency to see where they are talking, so it could be on Verdugo Talkgroups, a conventional Interop frequency or something else. LAFD's UHF radios definitely have digital in them, and are at least trunking-ready if not already programmed.

 

[landonjensen]

At the soonest, I wouldn't expect it any time soon if at all, although most of LAFD's frontline apparatus and command officers already are equipped with XTS5000 UHF portables that have both digital and trunking installed and operational, for communications with agencies such as LAPD and with Verdugo as necessary.

But that's only per piece of equipment, not like the 800-band XTL5000 radios that almost all apparatus have, and the 800-band XTS5k portables issued to each firefighter while they're on duty.

I need to backtrack on my Verdugo comment. I hear LAFD and Verdugo agencies communicating especially working vegetation fires between Glendale-Burbank and "the Rock" in Sunland. I don't think I've ever looked at the frequency to see where they are talking, so it could be on Verdugo Talkgroups, a conventional Interop frequency or something else. LAFD's UHF radios definitely have digital in them, and are at least trunking-ready if not already programmed.

All Pasadena RA's are equipped with LAFD XTS 800 mhz radios, as well as select Pasadena Engines (31 & 38 if I recall correctly?) & Battalion 3.

LA City Fire also has Verdugo trunked radios, but I am not sure what units were given those.

Glendale Fire is also equipped with XTS 800 mhz portables, which I believe are in every rig...

 

[brianearlspilner]

All Pasadena RA's are equipped with LAFD XTS 800 mhz radios, as well as select Pasadena Engines (31 & 38 if I recall correctly?) & Battalion 3.

LA City Fire also has Verdugo trunked radios, but I am not sure what units were given those.

Glendale Fire is also equipped with XTS 800 mhz portables, which I believe are in every rig...

I also heard Pasadena Fire talking to LACoFD on their analog system the other day. do they use their ICIS radios or just regular analog radios?

 

[landonjensen]

I also heard Pasadena Fire talking to LACoFD on their analog system the other day. do they use their ICIS radios or just regular analog radios?

They have separate radios for each...

800 Mhz & ICIS operate on different bands, making the requirement for 2 different XTS portables for each respective agency (LFD & XLC).

 

[icis_monitor]

I believe that to talk to lacofd the Verdugo people have to just change channels. Lacofd isn't on 800 mhz.

 

[landonjensen]

I believe that to talk to lacofd the Verdugo people have to just change channels. Lacofd isn't on 800 mhz.

LACoFD is on the UHF 470 band, making it just another zone (In scanner terms, a bank) in the XTS5000's that Verdugo uses.

Edit: Just realized the question two posts up was regarding LACoFD and not LAFD.. Sorry!)

 

[karldotcom]

@Radiolady

I have logged 342 LAFD Radio IDs on ICIS......I would be surprised if every front line apparatus didn't have one. As I recall, the Batallion Chiefs and Automatic Aid engines were the first to received them, and there was confusion as to which channels to use onscene....but now it operates more smoothly with say, an LAFD response into Glendale using Verdugo Red 2 or whatever is assigned. Same with Glendale responding into the LA "island" between the LA River and the RR tracks along I-5.