San Diego Scanning Primer

If you're new to the area or just got your first scanner, this report will give you the basics to help you understand the ever more complex hobby of scanning in San Diego.

First of all, if you're new to the scanner hobby you should read this section on trunking. 

TRUNKING:

Trunking is a currently popular method of effectively using a set number of frequencies to achieve the maximum number of users.

Trunking breaks the conventional method of frequency utilization by no longer assigning a specific use to any frequency.  The trunking system consists of a pool of shared non-use specific frequencies that are assigned on demand and released back to the pool upon completion of a transmission.  This way, all of the "dead time" almost all frequencies experience can be utilized by other system users thus multiplying the number of users exponentially.

A trunking system radio is dialed to a talkgroup (what we used to call a frequency or channel). The trunking controller uses a frequency called the control channel to control all of the frequency assignments. This channel has a constant data 'buzz' on it and will be what your trunk capable scanner will lock on to in order to track the system.  When a user dials a radio to a specific talkgroup, the radio receives instructions second by second what frequency is currently carrying traffic for that talkgroup. If it is silent, no frequency is used.  If a user pushes the talk button on the radio, the radio sends a request to talk to the controller indicating what talkgroup the radio is dialed on to, a frequency is assigned and send back to that radio to transmit on and all other users on that talkgroup tune to that frequency and hear the transmission.  When the user releases the talk button, the frequency is returned to the pool.  This all happens in a split-second.

Of course it is possible to run out of available frequencies during periods of heavy traffic.  The user making a talk request will get a busy tone and be put into a queue awaiting an available frequency.  The systems are set to prioritize users based on their assignment.  Police and Fire will take priority over street repair crews for example. This way critical communications will bump to the top of the queue immediately.

SAN DIEGO SPECIFIC SCANNING DETAILS:

San Diego it can be reasonably argued, has a very well organized and efficient communication network for local government.  The two main TRUNKING systems in the area are the Regional Communications System (RCS) and the City of San Diego's trunked radio system.  Other smaller systems include National City, UCSD and the Port of San Diego's systems. Each of these systems is separate including each of the RCS Zones and will require a separate bank in your scanner.

All local police and municipal fire agencies, except state agencies, are on one of these systems which are Motorola type II trunking systems.  Older scanners that are not trunk capable will not be able to effectively monitor these systems.  State and Federal firefighting as well as various other state agencies such as the CHP, State Park Rangers and Fish and Game use conventional frequencies that older scanners will pick up just fine.

The City of San Diego's system hosts the San Diego police and fire departments as well as many other departments within the city. 

The RCS system is a type II Smart Zone system. It consists of a North and South Zone, which are easily monitored and an East Zone loop which is less convenient to monitor with a scanner. Each of these zones need to be setup as a Type II Motorola system as well.

The County, as far as the RCS Zones are concerned, is divided roughly at highway 52 to denote North or South Zone. Agencies north of I-52 will be on the North Zone, south of that, they will be on the South Zone.  Agencies in the mountain/desert region of the county will be found on the east zone.  Some Talkgroups are only found in the applicable zone and some are countywide.  What this means is that you cannot program the Talkgroup ID for Oceanside Police in extreme Northwestern San Diego County into your South Zone bank and expect to hear anything.  Only select talkgroups carry countywide. Talkgroups like LAWAIR and MEDAIR to name a few are carried countywide.

All of the cities in the county except San Diego Police, UCSD Police and Harbor Police are members of the RCS.  The San Diego Sheriff covers any unincorporated areas as well as several cities under contract to provide law enforcement.

To further complicate matters for scanner listeners, all most all of the law enforcement traffic on the RCS system is APCO-25 digital modulation.  This means you will need one of the most recent generation of trunking scanners that is capable of digital if you intend to monitor them. This does not apply to the City of San Diego, UCSD or Harbor Police.  There are a few Talkgroups labeled as ENC or encrypted. These cannot be monitored for several reasons, foremost being because it is illegal. You will hear scrambled sounds if you program one in.  There will never be a production model scanner that can monitor encrypted channels because of the legality. Orange County to the north of us has encryption on all law enforcement talkgroups.

While each city or unincorporated region in the RCS has a primary dispatch talkgroup as well as several department specific talkgroups there exists Mutual Aid talkgroups that are brought into play for any incident that involves multi-jurisdictions.  These are as follows: Law South, North, and East Command and Tac's.

When an incident is occurring, for example, a vehicle pursuit, the dispatcher may patch their primary talkgroup to the appropriate LAW COMMAND or TAC.  In this way, units from other agencies nearby can assist in the incident and effectively communicate among themselves.

The same strategy applies to fire incidents.  The RCS provides Mutual Aid Command and Tac channels.

These are the North, South or East COMMAND and TAC talkgroups.

Generally for a large scale fire is underway, the radio traffic will be assigned to these Mutual Aid channels rather than the talkgroups for the community that it is occurring in.  This enables fire departments ease in communicating amongst each other.

The RCS also has a talkgroup called Blue 1 which is used by agencies to notify one another of BOLO's (Be On the Lookout).  If for example, an armed robbery occurred in a city, the dispatch will come on up Blue 1 and advise surrounding agencies to be on the lookout for such and such vehicle, ect.. This way, information on wanted persons can be quickly disseminated to allied agencies in hopes of catching as they flee the area.  Also, officer safety information is broadcast here on armed and dangerous persons.

If you wish to monitor things in both the North and South Zones, you will need to dedicate a separate bank to each of them.  Monitoring the East Zone is a whole different ballgame with many pitfalls to successful listening since each of the numerous sites in that zone are separate and do not carry traffic on them unless a user is affiliated to that site. It is much like a cell phone site.  Affiliation is much akin to "logging on" to a computer.  When a radio is dialed to a talkgroup a data-burst is sent to the controller identifying the radio ID and stating which talkgroup the radio is on. If a radio is dialed to a talkgroup on an East Zone site, that site will carry audio from that talkgroup to that radio or any radios or scanners listening to that site. But only on that site, and since there are about 25 East Zone sites, it will be difficult to hear what you want to.

CONVENTIONAL LISTENING:

To listen to the CHP, take any old scanner, or new, and program a conventional channel to the frequency of interest. The El Cajon (108) office of the CHP is currently on the RCS as a talkgroup but plans are under way for them to return to their state channel called the Gold (39.600) by summer of 2005.

For CDF (California Department of Forestry) firefighting and USFS firefighting, program your scanner in a conventional bank with the frequencies of interest.

If your interest is listening to major brush fires, you most likely will want to listen to CDF Dispatch (151.190 conventional) and whichever CDF Command frequency is assigned to the incident.  In addition, the local fire responders and strike teams will use the appropriate N/S/E Zone Mutual Aid COMMAND AND TAC's for their comms.  Just remember, small fire incidents are usually on the primary departments own COMMAND and TAC's whereas large incidents are on one or more, often many more of the N/S/E Zone mutual aid COMMAND and TAC's.

PROGRAMMING YOUR SCANNER FOR TRUNKING:

First off, I recommend that you do not try to program it by hand from the face place of the scanner. It can be done, however it is a lot of work and will take many hours. 

Here are the basic steps to program a trunk system specific to no brand of scanner. For specific questions regarding your model of scanner, post your questions in the forum for an answer.

Step # 1    Enter the system frequencies into the software. Remember, only put the frequencies of one system in any bank.  Any unused channels are wasted. However, you can put conventional frequencies in the unused places. All but the earliest trunk tracking scanners will scan both the trunked system and conventional in the same bank. Note that this is not very efficient however as you will miss activity on the conventional frequencies or the trunk talkgroups as the scanner switches modes between them.  You will have to identify the bank in the software for the appropriate type of trunking. In San Diego public safety systems it will always be Type II Motorola 800 trunking. (The several military systems in San Diego use 400 Mhz Type II trunking however)

Step # 2    Enter the talkgroups and names of the talkgroups you wish to scan into the scan list area of the scanner.

Step # 3    Connect an antenna and hit Scan.  You will have to become familiar with the scanner's operation to you can learn to toggle in different BANKS and scan lists within those banks.

Remember, you can set up multiple systems using different banks. You can also repeat the same system over 2 or more banks to accommodate custom uses.

If you have questions, please ask on the forum where you will probably get an answer.

ANTENNA SYSTEMS:

Depending on where you monitor from will change what type of antenna you use. If you live near the core of San Diego and have a clear path to one of the radio transmitter sites, you may find that the scanner will hear the City of San Diego system with no antenna connected to the scanner! However, if you are out in the rural areas or deep in a canyon, things can be more difficult.  Most scanners come with a built in antenna. This should work well for most situations. However, if you find that you are rural or in a bad radio reception location, you may have to mount an external antenna on your house.  Since 800 Mhz signals are much more subject to coaxial line LOSS, you will need to pay particular attention to the coax you choose.  The proper coax cable can make your scanner work wonders and the wrong can make it not pick up well at all.  For 800 Mhz you will usually need LMR-400 or Belden 9913 to name a few. This is most important with runs (from scanner to antenna) of more than 50 feet on average.  Most scanner antennas come with RG-58 cable which is very lossy in 800Mhz.  A medium strength 800Mhz signal can almost disappear at the end of 50 feet of RG-58.

If you decide that you do need to mount an external antenna, what you want to listen to will determine which antenna to put up.  If you're only interested in hearing the trunk systems in San Diego and don't care about VHF and 400Mhz UHF stuff, the optimum choice would be an 800Mhz antenna with lo-loss feed line.  If you want to mix the trunk systems with conventional stuff you need an all-band scanner antenna or simply a VHF antenna.  A VHF antenna will work excellent on VHF of course and it will work reasonable well on the 800Mhz signals.  In fact, as far as scanning is concerned, an antenna for lower frequencies will work well enough for anything it is designed for and higher.  The opposite is NOT true.  An 800Mhz antenna will be awful on the CHP frequencies (39 Mhz Lo-band VHF). Also if you have a handheld scanner, most build-in rubber antennas do not perform well in the Lo-bank VHF area.

INTERFERENCE:

If you take your scanner on the road or just to live unfortunately close to a Nextel or paging transmitter site, you may experience one or more types of interference on your scanner.

If you're driving down the road listening to the City of San Diego system, for example, and as you approach a specific area it begins to get scratchy or even drop out altogether, then clears up as you pass that area, you are probably experiencing bleed-over from a Nextel cell phone site.  Currently, the Nextel frequencies are placed in-between the public safety frequencies in 800Mhz.  A real Motorola radio can cope with this much more effectively than your scanner.  Basically what is happening is that your scanner receiver is being overloaded by the much stronger locally generated Nextel signal. Your scanner is not able to tune in a narrow enough window and the adjacent Nextel signal bleeds into your desired signal.  This also affects public safety radios but to a much lesser degree than your scanner.

If your home is located near a Nextel site, and you experience scratchy signals while the scanner's display shows sufficient signal strength bars consider the Nextel problem before you think it's an Antenna problem. If this is the case, get on the forums and ask. There are some remedies that may help lessen the problem.  The same solution doesn't quite work as well in mobile situations and you'll just have to cope with it.  Currently, the FCC is working to relocate the Nextel frequencies.

CONCLUSION:

Trunk scanning can be confusing to someone new to it.  Please jump on the forums of ScanDiego and ask any questions you have. The many experts that can be found there are always helpful with questions.