Confused about LASD radio systems

[SCPD]

As long as everyone is reminiscing I would like to share my impressions of the older low band LASO system. I was living in a remote area of New Mexico in a ranger station housing compound. It was a great location for radio as I could hear some simplex traffic from the Albuquerque PD which was located about 100 miles away, line of sight. This included about half of the simplex from the mobile units who transmitted on the base frequency to a remote base somewhere high on the eastern side of the city. I could pick up traffic from the northern Gila National Forest and most of the Santa Fe National Forest as well as all of the traffic on the Cibola NF where I worked.

During the wonderful solar maximum of 1980-1981 I would pick up skip from California, including the CHP, LAFD and the LASO. I would put my scanner on 33, 39 and 42 MHz limit searches to see if I could beat my distance records for a reception. Some nights, all of a sudden I would hear the LASO "beeps" and dispatchers talking faster than Chick Hern could. You remember "Magic puts Bird in the popcorn machine!"

I don't recall how fast humans can listen and comprehend speech, but it is much faster than the speed that most people talk. Those dispatchers spoke near my own upper comprehension speed. I know deputies were used to it, but I would have a tough time listening to the beeps and trying to keep up with the high speed talking for an entire shift.

 

[Starman918]

SRC had to deal with skip traffic often. On one occasion, a voice came over the air asking for help. Not getting a response, SRC did a roll call of all units. After a few minutes, it was determined that the call for help came from an agency back east.

 

[PaulNDaOC]

During the 39mhz days, I am told that a good number of LASD radio code books were mailed to agencies in many areas of the US also on 39mz so they could better understand what was going on.

Starman918,, just remembered SRC only monitored 470 Freq 9, which served the same purpose the current SCC Access served before Parks..etc.. were placed there as a home dispatch channel.

Here is a tidbit most don't know about the 39mhz days. Avalon/Catalina Is. was dispatched by Aero Bureau desk, not SRC. . SCC absorbed Avalon in 91 or 92 when the station began using the CAD system.

 

[Starman918]

Oh yes....it was channel 9.

 

[jrholm]

During the 39mhz days, I am told that a good number of LASD radio code books were mailed to agencies in many areas of the US also on 39mz so they could better understand what was going on.

Starman918,, just remembered SRC only monitored 470 Freq 9, which served the same purpose the current SCC Access served before Parks..etc.. were placed there as a home dispatch channel.

Here is a tidbit most don't know about the 39mhz days. Avalon/Catalina Is. was dispatched by Aero Bureau desk, not SRC. . SCC absorbed Avalon in 91 or 92 when the station began using the CAD system.

At that time the Catalina station also locked up at 10pm and phone lines were switched to their desk as well. If somebody made a call for service the aero desk had a list of on call deputies to call in from home, which was why living on the island was a requirement. Even in 2003 we had to check in and out when we were leaving the island.

 

[finaldraft151]

C-Code was not brought over to the 480 system when it went live back in the 80's. Other agencies all have the 480 radios in their dispatch centers, so that wasn't the reason.

I was at SCC for 14 years and never heard one word about it, let alone a reason.

Too bad too because it was from at least from an LASD view an easy effective way to quickly furnish outside agencies with important info.

Also, the tones sounded beyond cool on the old 39 mhz system, even better than the old county fire tone-outs IMHO.

Thanks for a great reminder of the good ole days. When police radio was fun.

Hi Paul -

SCC still has full capability to utilize C-Codes across it's system, as the functionality was carried over to the 480 system. How often they are utilized or requested is a totally different beast though. From what I understand they were utilized almost daily on certain crime broadcasts or countywide Bolo's back in the good old days - As of now, they can still be accessed and used, with the ability to choose what talk groups and areas to 'tone' and can be selected and broadcast right from an individual console.

The C Code function lives a pretty quiet and dormant life these days however, but on occasion it still gets dusted off and operated a few times per year. Recently, they were just used as part of a county wide missing person critical broadcast a few weeks back when a silver alert was issued on an elderly gentleman who had gone missing. Every 4 hours SCC put out a county wide 920C broadcast and each time the broadcast went out the RTO brought up and used the C Code function as part of the request in the initial broadcasts special instructions.

They are comparable to the rotary telephone these days however, since anytime they are mentioned or requested there is usually a look of bewilderment followed up with one of two responses -
Either "Do we even still use C Codes..?" or "What is a C Code..?" -

I think the actual 'C Code' buttons from the consoles should definitely be donated to the Sheriff's museum in Whittier or auctioned off for charity when the consoles finally do get retired as they are part of the history of the LASD radio system.

Take Care -

 

[hpycmpr]

I believe that C-code was actually Secode, a manufacturer of selective calling equipment. And to strain my memory further, I believe this went back to rotary dial days.

Steve

 

[K6CDO]

I believe that C-code was actually Secode, a manufacturer of selective calling equipment. And to strain my memory further, I believe this went back to rotary dial days.

Steve

Steve is correct. "Secode" was the manufacturer, as well as the common name for the technology of using a rotary dial to pulse an otherwise steady tone (1800 Hz, if memory serves me) for over-the-air selective calling. The technology was patented in the 1960s.

L.A. County adopted Secode in the VHF Low-band days to alert monitor receivers at allied agencies and key department facilities, and, it seems, continues to use it today for the same purpose.

Don

 

[SCPD]

Always found the 480 system interesting and other places who use similiar setup to date. Is this old style going to last into the future for lasd or they going to a repeated conventional or 700?

 

[finaldraft151]

I believe that C-code was actually Secode, a manufacturer of selective calling equipment. And to strain my memory further, I believe this went back to rotary dial days.

Steve

Absolutely - Secode became known by and referred to as 'C Codes' as a result of it's function and ultimate purpose. You would bring up the C Code function followed by entering in a two digit number to 'open' up the talkgroup you wanted to broadcast to. Each region/area/bureau and outside agency belongs to a specific talkgroup and one could choose specific groups or all groups by entering a specific C Code number on their console. 'Secode' became 'C Code' on it's own permanent button for use on a dispatcher's console and has gone by that moniker for 35+ years. Here is a pic of the C Code selection/activation button on a LASD Dispatch Console. Right side middle - It's orange is a tad faded but it still gets the mission accomplished.

Thanks for the interesting post on Secode. Are they still around or were they bought out and/or absorbed into another company at some point?

Take Care,

 

[hpycmpr]

I hate to show my ignorance, but I never saw C-Code spelled that way. Probably originated by a whole lot of people who only heard of it and never saw it spelled.

I remember seeing/hearing dial type encoders back when. Perhaps on the state OES and other statewide systems? Don?

I had no success with Google on the history of Secode - long gone I fear. Perhaps some of our historians can comment?

Steve

 

[SCPD]

Absolutely - Secode became known by and referred to as 'C Codes' as a result of it's function and ultimate purpose. You would bring up the C Code function followed by entering in a two digit number to 'open' up the talkgroup you wanted to broadcast to. Each region/area/bureau and outside agency belongs to a specific talkgroup and one could choose specific groups or all groups by entering a specific C Code number on their console. 'Secode' became 'C Code' on it's own permanent button for use on a dispatcher's console and has gone by that moniker for 35+ years. Here is a pic of the C Code selection/activation button on a LASD Dispatch Console. Right side middle - It's orange is a tad faded but it still gets the mission accomplished.

Thanks for the interesting post on Secode. Are they still around or were they bought out and/or absorbed into another company at some point?

Take Care,

I'm confused here. We are talking about the LASD here aren't we? You refer to talkgroups, yet the LASD operated a 39 MHz and now operates a 480 MHz conventional system. When you speak of a "talkgroup" are you actually referring to a frequency?

 

[SCPD]

From what I gather they trunk dispatchers rather then frequencies and patch if needed the channels. Since they operate things a little different one could be confused by the terms LASO or LASD whichever your prefer or is correct, uses for its system. Indeed it Is pretty interesting. It reminds me of NMSP however to my knowledge they never patched anything to date or repeated dispatch to mobiles and never have used the busy channel beeps. Thanks to those who know and explain it. Indeed a unique and different approach from the rest LASD has.

 

[K6CDO]

I hate to show my ignorance, but I never saw C-Code spelled that way. Probably originated by a whole lot of people who only heard of it and never saw it spelled.

I remember seeing/hearing dial type encoders back when. Perhaps on the state OES and other statewide systems? Don?

I had no success with Google on the history of Secode - long gone I fear. Perhaps some of our historians can comment?

Steve

Steve,

Secode was used on the 3 statewide CalOES systems through the 1970s, but had been phased out in favor of DTMF by the time I arrived at OES in 1984. I suspect Secode was bought out by someone else.

For Exsmokey, with regards to the talkgroup, he means the two digit code was either a shortcut for the code, or the code itself, to open a group of receivers at other agencies. Not the term I would use, but it does fit.

Don

 

[SCPD]

Semantic discussions aside I'm confused about what he is saying. I assume the following: the C-Code or Secode was a system to open up special receivers that the news media and other agencies had. Those receivers monitored one or more LASD frequencies. The C Code could be used on one frequency or a group of frequencies.

Is this correct?

A frequency or group of frequencies is not a "talkgroup" when radio systems are being discussed. I'm familiar with how the LASD utilizes their "dispatchers" and you could liken it to "trunking," however, that does not mean the radio system they transmit on is a trunked system. I've often read posts where people confuse the term talkgroup with frequency or channel and I can only assume that is what has happened here. If the LASD operated a trunked system then the term would fit. If my assumption is not correct then I'm more confused than I thought.

When I've visited L.A. and monitored the CHP's Blue frequency I've heard some type of audible tone used when a "Sigalert" is transmitted. I think it was a DTMF tone. How does this differ from the C-Code or Secode?

 

[motobot213]

LASO's Frequency Charlie is still in use - It's what LA County uses to transmit Emergency Alert System messages to the various news media outlets.

You will hear very little traffic on it. There is a weekly test and a monthly test.

What frequency is this broadcasted on?

 

[finaldraft151]

Semantic discussions aside I'm confused about what he is saying. I assume the following: the C-Code or Secode was a system to open up special receivers that the news media and other agencies had. Those receivers monitored one or more LASD frequencies. The C Code could be used on one frequency or a group of frequencies.

Is this correct?

A frequency or group of frequencies is not a "talkgroup" when radio systems are being discussed. I'm familiar with how the LASD utilizes their "dispatchers" and you could liken it to "trunking," however, that does not mean the radio system they transmit on is a trunked system. I've often read posts where people confuse the term talkgroup with frequency or channel and I can only assume that is what has happened here. If the LASD operated a trunked system then the term would fit. If my assumption is not correct then I'm more confused than I thought.

When I've visited L.A. and monitored the CHP's Blue frequency I've heard some type of audible tone used when a "Sigalert" is transmitted. I think it was a DTMF tone. How does this differ from the C-Code or Secode?

I never mentioned a trunked system. Concerning 'talkgroup' - Perhaps it's inaccurate to say 'talkgroup' is not a frequency or group of frequencies when radio systems are being discussed, but to clarify and clear up any confusion, I was referring to the 'talkgroup' features and options available specifically within the C Code function built into the radio and cad system operated by LASD.

C Code function is initiated on 1 channel, The Countywide 'SRC Access' channel and then per the C Code instructions, a dispatcher then chooses what 'talkgroup' they wish to 'open' up via SRC Access Channel - One may choose any combination or opt to open and broadcast over the entire 'talkgroup' - This is done by entering a 2-3 digit code to select the desired are or 'talkgroup' - (Various LASD regions, bureaus, specific stations, outside agencies, or a combination of all or both) The program refers to this as talkgroups - The system is broke down into various 'talkgroups' and again, the user chooses what 'talkgroups' to broadcast the radio traffic to.

Here is a quick reference guide on using the C Code operation, activation, options and use. The 400+ page manual goes into greater detail and puts more reference on 'talkgroup' functions. Hope that helps clear up your confusion. Just two different definitions and use of the term 'talkgroup' - Same word with different (yet legitimate) descriptors.

 

[riccom]

What frequency is this broadcasted on?

39.480mhz

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