Police Frequencies
  · By County

Fire Frequencies
  · By County

EMS Frequencies
  · By County

Various Frequencies:
  · Business/Local
  · Public Works

Other Frequencies
  · Other California Freqs
  · Racing Freqs
  · Railroad Freqs

Aircraft/Airport Frequencies
  · By Airport
  · By Airline

Photo Gallery
  · Photo Gallery

  · Live Scanners
  · SBN TeamSpeak
  · Recorded Audio
  · Online CAD’s
  · Links

Monitoring the LASO

The Radio System:

The Los Angeles County Sheriff’s Department uses what is called a half-duplex radio system. What does this mean? Well, each channel is assigned two frequencies, a transmit frequency (TX Freq) and a receive frequency (RX Freq.) The RX Frequency is the one you want to monitor that is the repeater. For the LASO (and all frequencies between 470-510 MHz), the transmit frequency is 3 MHz higher than the receive frequency. The dispatcher uses the RX frequency, and the units in the field use the TX Freq. When a unit in the field keys his radio/mic, he is transmitting on the TX Freq. The TX Frequency is simplex, which is a direct or line of sight communication, and also means you have to be close to the units talking to hear it. With a half-duplex system the TX Frequency is not Repeated, which means the field units can not me heard over the RX Frequency. However, one unique thing the LASO does, when a unit in the field is transmitting on the TX Frequency, a busy tone is transmitted on the RX Frequency. This is done so the units in the field know when channel is free for use or is being used. Note that the busy tone only applies to the dispatch channels, the Emergency Channel, the LASD Access Channel. All the tactical frequencies, SUD and ABD are repeaters...where field units can be heard on the RX Freq.

Each call is dispatched via voice on the proper dispatch channel depending on the location. Each call is also given a tag number where the field units can use their MDT’s (Mobile Data Terminals or Computers, the LASO now uses full color laptops) to look up any information on any particular call. The field units can also run warrant checks, license checks, run a license plates via their MDT’s. After a call is dispatched, if the unit in the field needs to set up coordination or do a crime broadcast, the field unit unit will ask SCC (what the units call the dispatchers, stands for Sheriff’s Communication Center) for ‘The Patch.’ What SCC will do is ‘Patch’ in the TX Frequency to the RX Frequency allowing the field units to be heard on the RX Frequency therefore allowing the units in the field to communicate with each other without changing channels. The field units will than go about with setting up coordination or putting out a crime broadcast. When the unit is finished, he/she will tell SCC to ‘Release the Patch’ and the RX Frequency will go back to normal using the busy tone when the Field units are transmitting.

For some dispatch audio samples, click here.

Hearing other Cities Dispatched on your local Dispatch channel?

Hearing Century Dispatched on East LA? Altadena on Malibu? Lakewood on Santa Clarita? etc. Nope...the dispatchers are not making mistakes, they are working two or more frequencies at once. How do they do that? Well it goes back to that “Patched in” thing again. The dispatchers have the ability to patch together any frequencies to each other making it like one frequency. They even have the ability to patch their frequencies to other departments, mainly the CHP and departments that use VHF-Lo/Hi and 800 mHz frequencies. There are two main reasons why dispatchers work two or more frequencies at one. First is the number of dispatchers working at a given time. The LASO has 16 separate dispatch frequencies for the different cities/areas they patrol. If there are only 8 dispatchers working at a given time, then each dispatcher will likely be working 2 different dispatch channels. Second is the amount of radio traffic/calls. For instance, between the hours of 00:00 and say 07:00 there are not too many calls...so there is no need to have 8 dispatchers working when a call only goes out every now and then. So the LASO can have 4 dispatchers working 4 channels without the dispatchers getting board/tired (haha) and not getting to busy.

Lets say that a dispatcher is dispatching both Dispatch 5 (SCV) & 15 (LAN/PDL) at once, and Lancaster units go into pursuit, well a the dispatcher can “clear” or release dispatch 5 from that patch and another dispatcher will take and patch in dispatch 5. When the pursuit or other emergency is over the dispatcher will either re-patch in dispatch 5 or take a different dispatch channel. 

The Frequencies/Channels:

The LASO has a total of 66 channels (a channel is two frequencies), 132 frequencies licensed to them. Their FCC license is WII-800 for their 66 channels. 16 channels are dispatch channels (where the the field units can not be heard on the RX Frequency unless ‘Patched In’). These channels are used for dispatching calls and for field units to talk to SCC. 1 channel (SUD) is for special units (ex. K-9 units, SWAT, etc) to be dispatched on. This channel is always ‘Patched in.’ 1 channel (ABD) is for Air units to be dispatched and like SUD is always ‘Patched in.’ 12 channels are L-Tac’s or Local Tactical channels. These frequencies are used for units to do car-to-car communication, to set up coordination, for field units to talk to their station’s Desk, and for small tactical operations. 4 Channels are A-Tac’s or Area Tacticals. These channels are used for medium to large size tactical operations. 2 channels are C-Tac’s or Countywide Tacticals. These channels are used for major tactical operations. 5 channels are M-Aid’s or Mutual Aid Frequencies. These frequencies are not only programmed into all the Sheriff’s radios, but every other Police Department in LA County who use a UHF conventional radio system. These are used for inter-agency communication, major tactical operations where more than one department is involved. These are also used as backup A-Tac’s if a cities A-Tac  and the two C-Tac’s are being used.