Department of the Highway Patrol (CHP) (CA)

A Beginner's Guide to the CHP Radio System:

The CHP employs two frequencies for communications between units in the field and their dispatch centers. One frequency is used by base stations, located at electronic sites, most of which are placed on mountain peaks or other high positions. Cars, or mobile units, use a second frequency to talk with these base stations. On the list below the base frequency is shown as the "frequency" and the mobile frequency is shown as "input." It is important to realize that base stations transmit from higher elevations and at much greater power than mobile units do. For this reason the base frequency can be heard over long distances, while the lower powered ground level mobile units can only be received if they are close by. The dispatch centers use one or more electronic sites to communicate with mobile units. Remember that high locations are ideal for radio reception as they can "see" more territory than ground level sites. This is why the dispatcher can receive most of the mobile traffic, while the scanner listener cannot.

Electronic sites are linked via microwave or 72 MHz frequencies and the dispatcher's console is controlled by a type of computer that chooses the best signal to send to the dispatcher if more than one site is receiving a mobile unit's signal at the same time. This computer is called a voter, as the selection among multiple sites is "voted" for the best signal. When transmitting to a mobile unit the dispatcher can choose the electronic site they want to use, and normally choose the same site the voter chose when replying to a mobile unit. This is why you may hear the base frequency come in well at times when a nearby site is being used and not so well when another, more distant site is being used.

When units want to communicate directly with each other, commonly referred to as "direct" or "car to car", they both switch their radios to another channel where the radio is both receiving and transmitting on the base frequency. The dispatcher can also monitor these transmissions, and may refer to "Channel 2" when using this mode. One disadvantage to this is the cars can have the same experience that scanner listeners have, which is that they cannot hear other mobile units that are located some distance away. The base station transmission may be "simulcast", meaning the same traffic is transmitted simultaneously from multiple sites for greater coverage.

In some locations within the state, mostly in urban areas, and mostly in southern California, the mobile frequency is patched to the base frequency on the most often used electronic site within a dispatch area. Cars are now able to hear each other from longer distances that they could before. This works the best in dispatch areas that are small and mostly urban as in these areas most mobile units can receive the same electronic site. In rural areas the dispatch area can be quite large with as many as 6-12 sites and mobile units may only be in range of one of those sites. Since the advantage of having the other mobile units hear each other is lost, the mobile traffic is not transmitted over the base frequency in rural areas.

Mobile Extender Handheld Radios

When a CHP officer intends to get out of the patrol vehicle or gets out of the patrol vehicle, the officer activates the mobile extender unit to hear radio traffic and transmit radio traffic over the car radio (higher power) via the officer's handheld portable radio.

The mobile extender unit usually operates on 154.905 MHz, and listens for transmissions on that frequency from a nearby handheld portable, which are then re-transmitted through the vehicle-mounted radio out on the lowband car-to-station channel (between 39-47 MHz). When the car radio is receiving traffic on the lowband dispatch channel, that traffic is re-broadcast through the extender unit (if it is enabled) on 154.905 MHz.

The handheld radios are programmed with other frequencies that do not make use of the mobile extender radio, allowing the CHP officer to talk to other CHP handheld portable radios and other non-CHP radio systems. Channels 1 through 6 are listed in the RR database; however, the handheld portable radios also have channels 7-16, which are normally programmed locally to communicate with other public safety systems on the same VHF band within the same geographical area as the radio being used. Beginning in 2010, CHP handheld radios and extenders will be switching to frequencies between 769-775 MHz.

Hint: if you are monitoring 154.905 MHz on a CA highway and you hear traffic (CHP), there is a good chance you are within less than 3 miles of that CHP unit. This is the same technology used in Uniden's Beartracker radios.

CHPERS CHP Enhanced Radio System

The CHP is undergoing a major radio system update. This is a multi year program to upgrade and enhance the statewide system. Here is the brief summary from the program update as of 2009: "The CHPERS project is a five year effort which will provide for the development and implementation of an enhanced statewide radio communications system in support of CHP’s mission to provide safety, service and security to the public." The full status update file can be found here:CHPERS Project Status 2009

This program includes upgrading of transmitter sites, field office radio equipment, addition of new frequencies, new 700/800 MHz handheld radios and new vehicle radio systems. It will include capabilities for 700/800 MHz transmission as needed, incorporation of repeater function primarily in urban areas and a revision to the vehicle extenders to operate in the 700 MHz range. In addition, the new vehicle systems called Consolidated Patrol Vehicle Environment (CPVE) will include GRE-PSR 600 Scanners on a remote control head(GRE stated that the PSR 600 does not have a remote head capability, the CHP reference may be premature or refer to a 3rd party modification) along with additional radio equipment in different bands to meet federal interoperability standards for communication with adjacent agencies. This includes the ability to access various regional conventional and trunked systems throughout the state.

The program is being implemented gradually throughout the state. As of November/December 2009, all existing CHP radios have been reprogrammed with updated code plugs to prepare for upcoming changes. As remote transmitter sites are upgraded, new and revised frequency plans are being implemented on a division by division basis. Divisional updates will continue through 2010 and into 2011. CPVE installations are tentatively scheduled to begin in 2010 and continue over a 3 year period. Once all the systems have been purchased and installed, the final configuration will be implemented state wide.

Several California forum threads have links to updated maps and other documents outlining changes and updates as well as field observations of changes being implemented.

As with any capital improvement program in California, delays are occurring. The state has continued to fund the program for 2010, but delays have occurred for different reasons. Information provided on schedules are tentative and expected to slip. Any additional information that can be provided by users can be posted in the applicable divisions below.

Divisional Updates & Status

Please feel free to complete, update and reformat this info. Users should provide field observations of changes here prior to completion. Depreciated frequencies will be listed in the CHP Database. Please see the links below to RR forum topics related to CHP Upgrades. Addtional files and user submitted observations are available through the related California forum topics.

OFFICE NAME			UNIT PREFIX			BASE	INPUT	-
101 NORTHERN DIVISION - REDDING
Blue						42.34	42.18
HUMBOLDT DISPATCH CENTER
Crescent City			95		Green	42.54	42.24	107.2
Humboldt			16		Green	42.54	42.24	107.2
Garberville			105		Green	42.54	42.24	107.2
REDDING DISPATCH CENTER
Red Bluff			36		Red	42.44	42.28	107.2
Redding			37		Red	42.44	42.28	107.2
Trinity River			90		Red	42.44	42.28	107.2
SUSAN VILLE DISPATCH CENTER
Susanville			38		Amber-2	42.08	42.76	107.2
Quincy			20		Amber-2	42.08	42.76	107.2
Alturas			60		Amber-2	42.08	42.76	107.2
YREKA DISPATCH CENTER
Yreka	145		41		Purple	42.4	42.16	107.2
Mt. Shasta			52		Purple	42.4	42.16	107.2
UKIAH DISPATCH CENTER
Ukiah			18		White	42.56	42.72	107.2
Clear Lake			7		White	42.56	42.72	107.2
201 VALLEY DIVISION - SACRAMENTO
Blue 2						44.84	42.36	173.8
SACRAMENTO DISPATCH CENTER
Auburn			45		Green 2	45.36	42.64	173.8
Grass Valley			42		Green 2	45.36	42.64	173.8
Placerville			44		Green 2	45.36	42.64	173.8
North Sacramento			46		Gold 2	44.62	42.38	173.8
South Sacramento			112		Black 2	44.66	42.28	173.8
Rancho Cordova			58		Black 2	44.66	42.28	173.8
Woodland			47		Black 2	44.66	42.28	173.8
TRUCKEE DISPATCH CENTER
Gold Run			70		Gray 2	45.6	42.88	173.8
Truckee			80		Gray 2	45.6	42.88	173.8
South Lake Tahoe			13		Gray 2	45.6	42.88	173.8
CHICO DISPATCH CENTER
Oroville			35		Brown 2	44.7	42.4	173.8
Chico			104		Brown 2	44.7	42.4	173.8
Yuba-Sutter			43		Brown 2	44.7	42.4	173.8
Williams			39		Brown 2	44.7	42.4	173.8
Willows			93		Brown 2	44.7	42.4	173.8
STOCKTON DISPATCH CENTER
San Andreas			49		White 2	44.92	42.32	173.8
Stockton			62		White 2	44.92	42.32	173.8
Tracy			103		White 2	44.92	42.32	173.8
Amador			94		White 2	44.92	42.32	173.8
301 GOLDEN GATE DIVISION - VALLEJO
Blue						42.34	42.18
GOLDEN GATE COMMUNICATIONS CENTER
Contra Costa			19		Maroon	42.92	42.74	131.8
Napa			21		Grape	42.42	42.66	131.8
Redwood City			91		Amber	42.08	42.82	131.8
San Francisco			32		Pink	42.44	42.76	131.8
San Jose			24		Ruby	42.5	42.28	131.8
West San Jose			119		Ruby	42.5	42.28	131.8
Hayward			25		Aqua	42.62	42.84	131.8
Castro Valley			143		Aqua	42,62	42.84	131.8
Marin			34		Violet	42.16	42.64	131.8
Santa Rosa			17		Emerald	42.8	42.2	131.8
Solano			22		Turquoise	42.6	42.02	131.8
Oakland			96		Bronze	42.12	42.4	131.8
Dublin			118		Khaki	44.94	42.78	131.8
401 CENTRAL DIVISION - FRESNO
Blue						42.34	42.18
BAKERSFIELD DISPATCH CENTER
Bakersfield			69		Brown	42.5	42.82	146.2
Buttonwillow			117		Turquoise	42.6	42.02	146.2
Fort Tejon			102		Turquoise	42.6	42.02	146.2
FRESNO DISPATCH CENTER
Fresno			65		Silver	42.08	42.28	146.2
Hanford			68		Pink	42.44	42.76	146.2
Visalia			67		Pink	42.44	42.76	146.2
Porterville			40		Pink	42.44	42.76	146.2
Coalinga			88		Pink	42.44	42.76	146.2
MERCED DISPATCH CENTER
Sonora			61		Yellow	42.52	42.3	146.2
Madera			66		Orange	42.88	42.66	146.2
Mariposa			63		Orange	42.88	42.66	146.2
Oakhurst			63		Orange	42.88	42.66	146.2
Merced			64		Orange	42.88	42.66	146.2
Los Banos			30		Orange	42.88	42.66	146.2
Modesto			48		Yellow	42.52	42.3	146.2
501 SOUTHERN DIVISION - LOS ANGELES
Blue 2						45.42	42.78	186.2
LOS ANGELES COMMUNICATIONS CENTER
Baldwin Park			81		Orange 2	45.02	42.58	186.2
South Los Angeles			77		White 2	39.22	42.88	186.2
East Los Angeles			82		Yellow 2	45.5	42.82	186.2
Newhall			78		Tan 2	45.7	42.9	186.2
Antelope Valley			89		Tan 2	45.7	42.9	186.2
Santa Fe Springs			83		Gold 2	39.4	42.14	186.2
West Los Angeles			79		Pink 2	44.62	42.7	186.2
Altadena			98		Brown 2	44.74	42.46	186.2
West Valley			56		Teal 2	45.52	42.84	186.2
Central Los Angeles			15		Black 2	44.94	42.54	186.2
601 BORDER DIVISION - SAN DIEGO
Blue						42.34	42.18
EL CENTRO DISPATCH CENTER
Winterhaven			116		Maroon-1	42.92	42.64	162.2
El Centro			85		Maroon-1	42.92	42.64	162.2
BORDER COMMUNICATIONS CENTER
San Diego			87		Orange-1	39.4	42.66	162.2
Oceanside			92		Tan-1	39.8	42.84	162.2
El Cajon*			108		Gold-1	39.6	42.2	162.2
Temecula			115		Tan-1	39.8	42.84	162.2
INDIO DISPATCH CENTER
Indio			76		Red	42.44	42.28	162.2
San Gorgonio Pass			97		Red	42.44	42.28	162.2
Blythe			6		Red	42.44	42.28	162.2
ORANGE COUNTY COMMUNICATIONS CENTER
Santa Ana			86		Purple-1	39.44	42.16	162.2
Capistrano			113		Green-1	39.36	42.24	162.2
Westminster			55		Gray-1	39.72	42.68	162.2
701 COASTAL DIVISION - SAN LUIS OBISPO
Blue						42.34	42.18
MONTEREY DISPATCH CENTER
Santa Cruz			26		Green	42.54	42.24	167.9
Hollister-Gilroy			23		Green	42.54	42.24	167.9
Monterey			27		Black	42.46	42.7	167.9
King City			8		Black	42.46	42.7	167.9
SAN LUIS OBISPO DISPATCH CENTER
Templeton			9		White	42.56	42.72	167.9
San Luis Obispo			28		White	42.56	42.72	167.9
Santa Maria			14		White	42.56	42.72	167.9
Buellton			3		White	42.56	42.72	167.9
VENTURA DISPATCH CENTER
Santa Barbara			29		Green	42.54	42.24	167.9
Ventura			31		Purple	42.4	42.16	167.9
Moorpark			137		Purple	42.4	42.16	167.9
801 INLAND DIVISION - SAN BERNARDINO
Blue						42.34	42.18
Blue 1						39.14	42.18
INLAND COMMUNICATIONS CENTER
Riverside			74		Turquise-1	39.68	42.02	118.8
Rancho Cucamonga			123		Beige-1	39.88	42.08	118.8
San Bernardino			75		Copper-1	39.26	42.74	118.8
Arrowhead			101		Copper-1	39.26	42.74	118.8
BISHOP DISPATCH CENTER
Bridgeport			71		Gold	42.12	42.2	118.8
Bishop			72		Gold	42.12	42.2	118.8
Mojave			59		Gold	42.12	42.2	118.8
BARSTOW DISPATCH CENTER
Needles			114		White	42.56	42.72	118.8
Barstow			73		White	42.56	42.72	118.8
Victorville			12		White	42.56	42.72	118.8
Morongo Basin			106		White	42.56	42.72	118.8
STATEWIDE
Border Tac						39.92	42.64
Clemars 6/7						39.46	45.86
Tac-1						45.02	42.26
Tac-2						39.42	42.06
Tac-3						45.94	42.1
Tac-4						39.92	42.28
Tac-5						42.92	42.62
Tac-6						45.06	42.38
Tac-7						45.02	42.08
Tac-8						39.14	42.22
Clemars-1						154.92
Clemars-2						154.935
Clemars-3						155.475
High-Band
Lima-3						460.025	465.025
Lima-4						460.25	465.25
Lima-5						460.375	465.375
Lima-6						460.45	465.45
Lima-7						453.2	458.2
Lima-8						453.825	458.825
Lima-9						453.85	458.85
Tactical-1						460.0875
Tactical-2						460.2125
Tactical-3						460.3375
Tactical-4						465.0875
Tactical-5						465.2125
Tactical-6						465.3375
Aircraft
BLUE						42.34
VHF (Primary)						122.85
VHF (Secondary)						122.875
Helicopter Air to Air						123.025
Fixed Wing Air to Air						122.75

Additional

CHP Offices & Frequencies
CHPERS Update File PDF
Cleaned Up Version of CHP Freqs from Wayne H
Link to Forum Threads for CHP Updates

External Links

• [1] CHP map with color divisions
• Southern California Frequency Directory
• CHPERS Project Update 2009
• GRE Press Release on CHP Purchase of PSR-600 for Patrol Vehicles