This article first appeared in the May 2003 issue of Monitoring Times.


The first few months of this year have been busy for Motorola. They've won several contracts for new digital trunked radio systems and have successfully completed the final stages of a replacement system for a county in Florida. They're also selling digital radios to the agency that is tasked to provide security at airports across the United States.

Martin County, Florida

Martin County, Florida is located on the Atlantic coast between Orlando and Miami and is home to more than 130,000 people. In March they officially accepted their new $9.1 million radio system from Motorola, finally replacing a three-site Logic Trunked Radio (LTR) system that was more than ten years old. Agencies on the new system include the Martin County Sheriff’s Office and the Fire/Rescue Department, the towns of Jupiter Island, Sewall's Point and Stuart as well as the Martin County School District. As many as 1,400 subscribers are using the system, with more local agencies expected to join in the future.

Messages are transmitted simultaneously ("simulcast") from four county repeater sites, located in Hobe Sound, Indiantown, Port Salerno and Stuart. Port Salerno is a new site, providing mid-county coverage that was not available with the older LTR system.

An additional selling point of the system was interoperability with other Motorola radio systems previously installed in nearby counties, specifically Palm Beach to the south and St. Lucie to the north. Public safety personnel from all three counties are now able to communicate across county boundaries and speak directly with each other without having to relay messages through a dispatcher.

Frequencies in use in the new system are 866.0375, 866.2250, 866.2625, 866.3750, 866.4125, 866.5375, 866.5625, 866.6625, 866.7875, 866.9125, 867.1750, 867.2375, 867.6375, 867.6750, 867.8875, 868.1750, 868.3250, 868.5375 and 868.5750 MHz.

Talkgroups for this system include

48 003 Mutual Aid Calling
80 005 Mutual Aid Tactical 1
112 007 Mutual Aid Tactical 2
144 009 Mutual Aid Tactical 3
176 00B Mutual Aid Tactical 4
208 00D Mutual Aid Tactical 5
240 00F Mutual Aid Tactical 6
272 011 Mutual Aid Tactical 7
304 013 Mutual Aid Tactical 8
10000 2710 Sheriff Dispatch (North)
10032 2730 Sheriff
10048 2740 Sheriff
10064 2750 Sheriff Dispatch (West)
10096 2770 Sheriff
10128 2790 Sheriff
10192 27D0 Sheriff

County Fire/Rescue has been reported on 12816 (3210 in hex) and 12848 (3230). The Stuart Police Department uses talkgroups 40016 (9C50), 40048 (9C70) and 40080 (9C90). School buses use talkgroups 6288 (1890) and 6448 (1930).

At the present time Fire/Rescue is still being transmitted on 154.010 MHz, so those listeners without digital trunk-tracking scanners should still be able to hear fire and medical rescue activity.

Genesee County, Michigan

In March of this year, Genesee County, in the southeast corner of Michigan's Lower Peninsula, contracted with Motorola for a $10 million SmartZone system. The 14-channel simulcast system is expected to come on-line in 2005, although the county is dependent on the construction and installation schedule for the seven planned repeater sites. Nearly 50 local police and fire departments plan to use the system to serve the county's 300,000 residents across an area of 600 square miles. Genesee County expects to purchase about 1,300 portable and mobile radios.

Since the new system will follow the APCO-25 Common Air Interface (CAI) standard, it will have the capability of interoperating with the Michigan Public Safety Communications System (MPSCS), the state-wide APCO Project 25 network that was first described in this column in the June 2000 issue.

The county plans to use pre-arranged talk groups, although in emergency situations talk groups may be changed dynamically. In such situations some channels may be dedicated to high priority groups, thus ensuring an adequate amount of communications capability.

About 30 local municipalities are already signed up to use the new county system. The cities of Flint and Fenton are considering joining as well.

Anne Arundel County, Maryland

Anne Arundel County, Maryland awarded Motorola a $12.7 million contract in March for an overhaul of their 800 MHz trunked radio system. Besides increasing interoperability, the contract provides for upgrades to the county's four existing repeater sites and the purchase of 1,100 mobile and portable digital radios. Sixteen channels will operate in simulcast mode, meaning the same information will be transmitted from the four repeaters at the same time. The system is expected to be on-line next year, covering 490,000 county residents across more than 400 square miles.

Anne Arundel currently operates a 15-year-old Motorola Type II analog system on the following frequencies: 856.3625, 856.3875, 856.4125, 857.3625, 857.3875, 857.4125, 858.3625, 858.3875, 858.4125, 859.3625, 859.3875, 859.4125, 860.3625, 860.3875 and 860.4125 MHz.

57360 E01 Fire/Medical Dispatch

57392 E03 Medical

57424 E05 Medical

57488 E09 Fireground Operations

57520 E0B Fireground Operations

57552 E0D Command

57584 E0F Mutual Aid (Simulcast on 154.280 MHz)

57616 E11 Mutual Aid

57776 E1B Unit to Unit

57872 E21 County Police (North)

57904 E23 County Police (East)

57936 E25 County Police (West)

57968 E27 County Police (South)

58032 E2B County Police License Information

58320 E3D Detention Center

59120 E6F Prisoner Transport

59728 E95 Annapolis Police Dispatch

59792 E99 Annapolis Police Tactical

Loudoun County, Virginia

Loudoun County's Fire and Rescue Department in northern Virginia passed their one-year anniversary on the new 800 MHz digital trunked system in March, although at last report they continue to operate their old 46 MHz frequencies as dispatch-only channels.

The system was originally awarded to Motorola in December 1998. The Federal Communications Commission (FCC) finally approved system frequencies in January 2001. Construction was essentially complete in June of that year, and coverage testing began in July.

The Sheriff's Department and the police departments for the towns of Purcellville and Middleburg were the first agencies to cutover to the new system, in February of last year. County Fire Rescue moved over in March and the Leesburg Police Department followed in April. Later in the year the county received $4.3 million in Federal emergency preparedness funds, $1.3 million of which was earmarked for mobile data terminals, giving law enforcement and fire department personnel on-scene access to computerized information.

The trunked system uses the following frequencies:

866.5500, 866.5875, 866.8000, 867.0375, 867.0750, 867.3250, 868.0500, 868.6625, 868.7750 and 868.9125 MHz.

Fire talkgroups include 3216 (hex 0C9), 3248 (0CB), 3280 (0CD), 3312 (0CF), 3364 (0D2), 3376 (0D3), 3408 (0D5), 3440 (0D7), 3472 (0D9), 3504 (0DB), 3536 (0DD) and 3600 (0E1).

Other system talkgroups:

1616 065 Sheriff Dispatch (East)

1648 067 Sheriff Dispatch (West)

2096 083 Car to Car (East)

2128 085 Car to Car (West)

2480 09B Leesburg Police Dispatch

2512 09D Leesburg Police Tactical

2672 0A7 Leesburg Police Car to Car

Primary dispatch is simulcast on 46.38 MHz, while fireground operations can still be heard on 46.22 and 46.32 MHz

Fairfax County, Virginia

Nearby Fairfax County is operating a Motorola trunked radio system with both analog and digital traffic. Eight sites cover the county with the following frequencies: 852.9625, 853.1875, 853.3375, 853.4625, 853.4875, 853.6375, 853.7875, 853.9125, 853.9625, 854.1375, 854.2625, 854.2875, 854.4625, 855.9625, 855.9875, 856.2625, 857.2625, 858.2625, 859.2625 and 860.2625 MHz.

176 00B Fairfax Fire Dispatch

208 00D Fairfax Fire

240 00F Fairfax Fire

272 011 Fairfax Fire

304 013 Fairfax Fireground

16016 3E9 Fairfax County Police Dispatch

16048 3EB Fairfax County Police Tactical 1

16080 3ED Fairfax County Police Tactical 2

16464 405 Parking Enforcement

16496 407 Criminal Justice Academy

16848 41D Fairfax County Police Dispatch (Mount Vernon)

16944 423 Fairfax County Police Dispatch (Franconia)

17040 429 Fairfax County Police Dispatch (West Springfield)

17136 42F Fairfax County Police Dispatch (Annondale)

17232 435 Fairfax County Police Dispatch (McLean)

17328 43B Fairfax County Police Dispatch (Reston)

17424 441 Fairfax County Police Dispatch (Fair Oaks)

17616 44D Fairfax County Police Dispatch (Simulcast on 460.575 MHz)

17648 44F Fairfax County Police (Simulcast on 460.600 MHz)

17680 451 Fairfax County Police (Simulcast on 460.625 MHz)

19760 4D3 Fairfax County Sheriff Tactical 1

19792 4D5 Fairfax County Sheriff Tactical 2

20720 50F Fairfax City Police

20880 519 Vienna Police Dispatch

20976 51F Herndon Police Dispatch

Talkaround frequencies for fireground operations are 866.8625 and 867.7625 MHz while police can make use of 867.2250 and 867.4750 MHz.

Last year Fairfax County received a $12 million grant of emergency preparedness funds, half of which they are spending on three new repeater sites to improve coverage from the current eight.


Major airports within the United States are now protected by the Transportation Security Administration (TSA), an agency created after the terrorist attacks of September 11, 2001. The TSA appears to be using APCO Project 25 radios in the VHF and possibly UHF frequency bands.

For VHF operations, there appear to be three primary active frequencies. The first is 172.150 MHz, which is normally used in simplex mode. This means that each radio transmits and receives on this frequency and communicates directly with other radios.

The other two frequencies, 169.300 and 172.900 MHz, are used with a repeater. Each portable radio transmits to a repeater on 169.300 MHz, which is referred to as the repeater input frequency. The repeater rebroadcasts the input signal on 172.900 MHz, which is the repeater output frequency.

Note that it is possible that either of the repeater frequencies may be used in simplex mode at some airports. So far it is not clear how the frequency and mode of operation selections are made at any particular airport.

These frequencies were originally part of a larger Federal Aviation Administration (FAA) FM radio communications (RCOM) system that has been in use at airports throughout the United States. Channel assignments for the RCOM are:

Channel Repeater Input Repeater Output
1 169.325 172.925
2 169.350 172.950
3 169.375 172.975
4 169.250 172.850
5 169.275 172.875
6 169.300 172.900
7 169.225 172.825
8 172.125 (Simplex)
9 172.150 (Simplex)
10 172.175 (Simplex)
11 166.175 (Simplex)

When tone-controlled squelch is used, it is typically 136.5 Hz.

When used by the TSA, it appears that there are at least four different talkgroups on the 172.150 simplex frequency and perhaps half a dozen talkgroups for the 169.300 and 172.900 MHz repeater frequencies. So far no encrypted traffic has been reported -- everything appears to be in the clear.

Dayton Hamvention

If it's May it must be time for the annual Hamvention in Dayton, Ohio. Starting Friday, May 16 and running through Sunday, May 18, thousands of amateur radio operators and electronics enthusiasts will come from around the world to Dayton's Hara Arena for three days of bargain hunting, radio-related technical sessions, and networking with like-minded friends. The Hamvention is the world's largest amateur radio gathering and is definitely worth the effort to attend. Besides the educational sessions, big-name equipment manufacturers and retailers show off their latest wares inside the arena while thousands of tailgaters sell new and used items in the parking lot outside. My personal favorite is hunting for old calculators and computers, but you can find almost any electronic-related device from the flea market vendors. Lots of fun and highly recommended!

That's all for this month. More information, including updated frequency assignments for public safety digital radio systems, is available on my web site at I also welcome your electronic mail to Until next month, happy monitoring!

Comments to Dan Veeneman

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