LACOFD Blue 8

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kenjicam

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Their repeaters are not timed, so the simulcast transmissions over lap and cause interference if the sites are to close. That's way they don't run a "PL" tones on the output.

If my memory serve me correctly, this was another cost cutting measure back when they were building the new all "Blue" dispatch system back in the early 90's. In the old days they used to dispatch on one of three VHF (remember "LA", Valley & Antelope" dispatch) frequencies, and simulcast on Blue channels, which were more of a fire ground tactical channel back then.
When they went to the new "Command and Control TRO" system and one Blue channel for all dispatches, they started running into problems. The quick fix was to turn off the RX PL.

Like I said that's what I remember, I could be wrong, and if I am please let me know!

Kenji Luster
 

scanfan22

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Thanks for the info. I was wondering where the simulcast repeaters are located? From the callsign in the database I see that the local repeaters to my area would be Oat Mt and Castro Peak so they would definitely stomp on each other at my location. Some days the interference is worse than on other days. This may be due to? Any ideas? I wish they would do something about it because I know the signal is strong but the audio is almost too bad at times to monitor.
 

scanfan22

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updated observations

even with an elevated base antenna the signal is solid but the audio is garbled at times but not all the time. It's unfortunate that they can't improve the channel. The other blue channels don't give me this issue.
 

monitor142

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I think that Kenji is dead on. There seems to be really bad simulcast distortion on Blue 8. As conditions change, it gets worse. The transmitters are out of phase which make the audio poor. Unless you right against a site that can capture your radio, we will need to live with it. It's a Countywide channel so there are probably close to a dozen transmitters if not more. Maybe as they prepare for narrowbanding, a better simulcast timing system will be added, that is if there equipment won't go 12.5 and it needs a forklift upgrade.

-M142
 

zerg901

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If you can, try to put attenuation on the signal.

I think that their 2 countywide channels use approx 8 common synchronized sites each. Their other channels use 1 to 3 synchronized sites each IIRC. In North Hollywood, you might get signals from their East LA site and the Palos Verdes site also.

If you are sitting halfway between 2 sites, it can be tough to get a good signal - although I have read that if the signals are timed correctly, the overlap area actually gets a better signal than the non overlap areas.

Peter sz
 

code3cowboy

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One would assume they would have a better simulcast system. In my home system the voting cards for each simulcast channel are $19500 per channel, but the simulcast quality is wonderful. I would presume and hope they are familiar enough with their system to be working out a plan to tune and upgrade their simulcast and multicast systems.
 

K6CDO

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One would assume they would have a better simulcast system. In my home system the voting cards for each simulcast channel are $19500 per channel, but the simulcast quality is wonderful. I would presume and hope they are familiar enough with their system to be working out a plan to tune and upgrade their simulcast and multicast systems.
They are. It is called LA-RICS.
 

zz0468

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It's quite possible for a simulcast system to sound just fine inside it's designated coverage areas, and sound really bad just outside the intended coverage area. Just a possibility to keep in mind.
 

code3cowboy

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It's quite possible for a simulcast system to sound just fine inside it's designated coverage areas, and sound really bad just outside the intended coverage area. Just a possibility to keep in mind.
Yay multipath.
 

zz0468

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Yay multipath.
It doesn't have to have anything to do with multipath, in the usual sense of the word. One attempts to control the arrival time of the signal in the areas where it's needed, and doesn't worry about it at all outside those areas.
Outside the designed coverage area, signals can arrive from the simulcast sites, and be spread so far out in phasing that it's completely unintelligible.
 

judas12

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How can i just listen to a couple of stations only? like Station 30, 35 from Cerritos? without listening to D-8 for 10 hours waiting for a call to hit in Cerritos
 

zerg901

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judas 12 - I dont think there is any easy way to listen for just 1 or 2 stations. The local response channel would be quieter than Blue 8. And listening to the input of your local response channel would be quieter still. (473 Mhz vs 470 Mhz).

If your scanner has "fire tone out" capability, maybe you can listen for just your local battalion chiefs tone. See this thread for more info. http://forums.radioreference.com/greater-los-angeles-inland-areas-discussion/179099-lacofd-quickcall-ii-tones.html

Peter sz
 
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judas12

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judas 12 - I dont think there is any easy way to listen for just 1 or 2 stations. The local response channel would be quieter than Blue 8. And listening to the input of your local response channel would be quieter still. (473 Mhz vs 470 Mhz).

If your scanner has "fire tone out" capability, maybe you can listen for just your local battalion chiefs tone. See this thread for more info. http://forums.radioreference.com/greater-los-angeles-inland-areas-discussion/179099-lacofd-quickcall-ii-tones.html

Peter sz
ok thanks
 

spectr17

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We use yagi antennas on the LACFD stations to capture just one repeater site on Blue 8. Some FS even have panel antennas to prevent getting torn up by the simulcast from the back side.

Put a UHF yagi up with rotator if you can. LACFD mtn sites to aim the yagi at from Cerritos would be Rolling Hills (Rancho Palos Verde), Mt. David (above Pasadena), Blackjack on Catalina.
 

PaulNDaOC

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You would think that after all this time that the Radio Techs at the bottom of the hill would have fixed this phase distortion by now. (If this is indeed the problem). I can't beleive how bad this has gotten.

ISD has the people to send up to the mountain tops to fix. They did a great job on LASD problems after they decided to fork over the money.

Thats all fire has to do too.

If it is phase distortion sometimes a band-aid approach can help a bit by turning down the power out some sites.

I think LASD under 40 watts on most of their sites.
 

K6CDO

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You would think that after all this time that the Radio Techs at the bottom of the hill would have fixed this phase distortion by now. (If this is indeed the problem). I can't beleive how bad this has gotten.

ISD has the people to send up to the mountain tops to fix. They did a great job on LASD problems after they decided to fork over the money.

Thats all fire has to do too.

If it is phase distortion sometimes a band-aid approach can help a bit by turning down the power out some sites.

I think LASD under 40 watts on most of their sites.
Why should the County invest any $ in maintaining operating 1980s infrastructure when they are evaluating proposals to replace the entire system (LA-RICS)?

All of the existing equipment MUST be out of service by FCC regulations before 1-1-2013.
 

SCPD

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Fire management units on the Angeles National Forest, most especially patrol units and batt chiefs, listen to Blue 8 most of the time. The dispatchers at Fox Field listen to it quite a bit of the time, but they also have the MDT looking device at their consoles that the county has. It would drive me nuts to have it on because of the distortion as well as having to listen to so much traffic. In my time with the USFS I learned to listen to multiple radios and tune out traffic I didn't need to hear, but listening to Blue 8 all the time would drive me nuts.
 

scanfan22

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Why should the County invest any $ in maintaining operating 1980s infrastructure when they are evaluating proposals to replace the entire system (LA-RICS)?

All of the existing equipment MUST be out of service by FCC regulations before 1-1-2013.

How are they going to pay for the new system?
 
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