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BY LON ARNOLD Department of Public

A few years ago, the Texas Safety and San

Bernardino County Sheriff’s Department came to me with a problem they had with limited panel space and the need for sev- eral radio direction finders. San Bernardino already had RHOTHETA SAR DF-517 search and rescue radio direction finders. They knew that they performed at a high level for their designed mission; however, they could only track Emergency Locator Transmitters (ELTs), Personal Locator Beacons (PLBs) and Emergency Position Indicator Radio Beacons (EPIRBs). Law enforcement agencies also wanted to track using LoJack and Electronic Tracking SystemsSM (ETS) beacons. Instrument panel real estate being at a

premium, mixed with the weight of adding equipment (not to mention the cost of multiple installations) increased the demand for a single piece of equipment that could perform several different functions. In addition to the panel space neces-

sary for mounting several different direction finders, room for an antenna farm on the belly of aircraft also plays an important fac- tor. Antennas can interact with each other in a negative way, and they all take up space. The RT-600 antenna is a single monopole antenna making the mounting much easier.

The display is a standard 3

1/8” aircraft instrument size. Armed with the request, I contacted

LoJack and ETS and then later AeroComputers. The three companies agreed that a joint cooperation would ben- efit all the customers we serve.


work on a law enforcement version of what was known at the time as the SAR DF-517 radio direction finder. After approximately two years of work, the RT-600 / DF-517 was born and operational testing then started. Early test flights showed that the system did what our customers were asking for.

Several functions were improved upon

based on the test flight findings and imple- mented into the final version. The original SAR DF-517 could

decode and track the COSPAS-SARSAT frequencies that were in use at the time of its release; however, in the past few years new frequencies have been released for use in 406 MHz emergency beacons. Overall there are 19 different frequencies in the COSPAS-SARSAT frequency plan; conse- quently, the changes made to the SAR DF- 517 included the ability to decode and track all planned emergency frequencies. With the cooperation of ETS RHO-

THETA engineers integrated the frequen- cies required to track ETS beacons. ETS, an international provider of wireless asset tracking and location services for nearly 30 years, is the facilitator of hundreds of Community Coalitions designed to reduce crime. These Community Coalitions unite local businesses into a proactive, focused group to help law enforcement capture and arrest bank robbers and other dangerous criminals.

ship has helped financial institutions and communities recognize increased customer and employee safety, a significant reduction in community crime, a strengthened local

business climate, and an overall safer place to work and to do business. Over twenty years ago LoJack

Corporation developed their stolen vehicle recovery system, which has worked with great success. With LoJack Corporations cooperation, the RT-600 is also capable of displaying the LoJack reply code for posi- tive


identification of a transmitter being If there are several LoJack trans-

mitters active simultaneously, an aircrew can select which one they want to track. When a crime is committed, the law

enforcement community has the legal responsibility to respond and bring the bad guys to justice. Both ETS and LoJack have provided technology and equipment to help law enforcement do their job with greater efficiency. In addition to crime fighting, some

agencies have an additional task of provid- ing search and rescue services to their respective

communities. With the

COSPAS-SARSAT system changing from 121.5 MHz to 406 MHz for emergency beacons, the ability to do electronic search- es has gotten even better. Just two years ago if an agency want-

Since its inception, the partner-

ed to track using ETS, LoJack, and emer- gency beacons, they would need to equip their aircraft with a different radio direction finder for each of the systems they wanted to track. Now with RHOTHETA’s RT-600, they can track all the different beacons with one piece of equipment. After the word of the RT-600s abili-

ties got out, customers started asking if it would interface with a moving map system.

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