As a part of Project54, we have a newly formed Radio Testing Lab which is used for performing tests on projects related to the usage of Land Mobile Radios. Currently we are working on two projects that attempt to solve problems associated with the utilization of mobile radios. While the first project provides a solution for the interoperability problem using radio patching, the second project is based on the implementation of APCO Project 25 radio standard.

In the lab, for test equipment, we have more than fifteen radios made by different manufacturers (Motorola, Kenwood, and E. F. Jonson), several digital phosphor oscilloscopes (Tektronix TDS3000B series), a vector signal analyzer (Agilent 89441A with RF section), and a bunch of PCs and laptops. With this equipment and our experience we can assure that our projects are well tested and verified. Below are two pictures from the lab.

Using the radio patching method, we have developed a solution for the radio interoperability problem. It is based on more affordable off-the-shelf devices and represents an adequate solution for small public agencies. The system supports full radio patching with proper PTT functioning and has audio signal latency bellow what is specified by ITU-T standard. It turned out that radio patching is the cheapest and fastest solution to the radio interoperability problem. More information about the system can be found in this technical report, and here about its precursor system.

Project 25 seems a perfect solution to constant growing needs for data communications in cruisers because it supports both data and voice transmissions over radio channels. Also, most public safety agencies already have and use Project 25 compliant radios. However, in order to fully utilize their radios and Project 25 data capabilities those agencies have to purchase very expensive Project 25 data capable base stations. Small public safety agencies usually cannot afford such expensive pieces of equipment. To address this problem, we have developed a software-based Project 25 data base station as an affordable way for small agencies to bring the data into their cruisers. The project is in its final testing stage and very soon will be ready for deployment. You can read more about our base station in this previous post. More technical information about the implementation of the transmission side can be found in Eric’s thesis.

Ivan Elhart

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