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

So a couple weeks ago, my colleague Ivan Elhart and I got to join Dr.Miller and Dr.Kun on a journey to Colorado for the National Institute of Justice (NIJ) conference. What can I say, it was a fabulous time. We arrived on Wednesday at 11pm (local time), so we just had time to grab some really late dinner, then head to bed. Thursday morning from 9am-12pm was the demonstration time, where TWG members were to walk around to each exhibit and take notes. Well, towards the end, it was actually cut short which made last minute rush through presentations even more hectic.
All in all, I was pretty pleased with our booth. In the morning, we got up early, and set everything up. As you can see here, we were pretty eager to get started.

Here we are all set up with the Project25 demo on the left (presented by Dr.Miller and Ivan), and the handheld demo on the right (by Dr.Kun and myself).

Ivan took some pretty good pictures during the demonstration. The room was pretty small with all the equipment and people walking around I was glad I didn’t need to wear a formal jacket.

After the demo session, the 15 minute presentations of people’s demonstrations started. There were some pretty interesting projects explained in more detail. Dr.Kun’s presentation was the next day, so we got to sit around, relax and enjoy other’s presentations.
On Friday, Dr.Kun gave his talk on the research we do here. It was tough presenting effectively, because of the limit of 1 slide for the presentation which could be divided into 4 subsections. Thus effectively reducing the distance the slides could be clearly seen from, and in essence bringing down the usefulness of the slide itself.

Other than these small details, the conference was enjoyable. The food was good, the hotel rooms were nice. Boulder is a beautiful city, for those of you who have never been there, I strongly suggest you go. Ivan and I stayed an extra few days to enjoy some snowboarding in the mountains about 1hr from Boulder.
Overall, it was a good time, and it was very educational for (I think) all of us.

András Fekete & Ivan Elhart

The Project 25 standard allows for both voice and data communications on digital radios. However, commercial manufacturers have implemented the data communications portion of the standard using very expensive equipment. While large agencies may have the resources to purchase and maintain this equipment, small agencies, such as e.g. a town police department with a few cruisers, just cannot afford to do so. Project54 has set out to create a low cost Project 25 data-capable base station that will allow small agencies with limited resources to implement data communications between headquarters and mobile units.

This picture below shows a laboratory demonstration of our Project 25 data-capable base station. On the left is a laptop connected to a Project 25 digital radio. On the right is a PC connected to an analog radio. We have created PC software that sends and receives Project 25 waveforms via the analog radio. The waveforms are received and sent via the PC’s sound card. Our software implements a digital signal processing algorithm that can decode Project 25 waveforms received by the analog radio. The software can also encode information as Project 25 waveforms.

In the video below you can see a demonstration of the Project 25 base station. In the demo the laptop, which runs the widely-deployed Project54 software, initiates a database query by sending out data packets over the Project 25 digital radio. The packets are received by the analog radio. Instead of connecting the analog radio to speakers, we connect its audio output to the PC’s sound card. The DSP software we’ve created then reads the packets (that is the Project 25 waveforms that encode the packets), and extracts the query. The query is sent to a server (in this demo the server resides on the same PC). The server response is encoded as a Project 25 waveform and this waveform is sent to the audio input of the analog radio, via the sound card. The analog radio transmits the Project 25 waveform, which is received by the Project 25 digital radio. Finally, the Project54 software receives the response to the query from the digital radio and provides an output to the user. 

Ivan Elhart