Field Report: RFSoftware RFInvestigator

April 1, 2004

Throughout the years, I have filed hundreds of FCC applications. In the old days (20+ years ago) I had to use whatever tools I could piece together to perform the allocation studies, find open channels, plot the terrain graphs, create contour maps and crunch the numbers. It took several days to do all of the calculations and obtain the topographic maps, and then sometimes a few weeks more if there was a complicated set of protections to be figured into the mix. Non-commercial applications were even more difficult, because those applications required spacing and contour interference studies, which needed timely license and application data from the FCC reference room. That meant gathering the data by hand in person or using a Washington, DC, service to gather, copy and mail the countless paper files required to provide a detailed and timely source for the study.

Those old days are gone. There are some powerful software tools now available that do most everything that is required to search for new allocations, and also provide the ability to modify and upgrade any existing AM or FM station.

I was given the opportunity to evaluate the RFInvestigator 2.0 suite of programs, and it is an impressive package. Included under the hood of this powerful set of programs are a group of software tools that can be used to complete commercial and non-commercial channel allocation searches. All of the tools I need are here, including open channel searches and studies, contour maps, automatic directional antenna pattern design, terrain profiling and other helpful features. In short, everything that I need to gather, analyze and prepare the data for FCC applications for clients is right here at my fingertips.

By purchasing the optional DB-Builder, I can download the FCC database from the FCC website myself and use it directly with the programs. This alone pays for itself quickly because the FCC downloads don't cost anything.

Making it easy

To test the program, I used my 2.4GHz PC notebook and the supplied CD from the company. The program comes with a short movie that explains a typical set of tasks for the program and provides a glimpse at some of the features. The manual is helpful as well, and after a few minutes the software was loaded and configured. I was ready to try my hand at an FM class upgrade for one of my commercial FM clients. For the most part, the program suite is fairly intuitive and easy to follow. After a few more minutes, I had the station of interest up on the screen, and the open allocation spacings around the station were plainly in view. A couple more mouse clicks and I had an answer for the upgrade question. The answer was yes, but the station would require contour protection and a directional antenna. This might take some time, I thought. But a few more mouse clicks and something I thought impossible was created before my eyes. A directional antenna pattern meeting FCC rules concerning minimum two-degree variation and power levels was finished and waiting for my inspection before I could even begin to think about all of the calculations needed to do it by hand.

As a test, I decided to try moving one of my client's stations to an adjacent site to determine if the situation would be better or worse from a coverage and interference basis. Once again, I found it fairly easy to compare the sites using the array of tools available within the program. By examining the sites using the Terrain Profiler, I determined that the alternate site had a problem with terrain blocking the signal from full line-of-sight coverage to the city of license. To confirm my results, a mouse click provided a color terrain view that confirmed the size and locations of the hills that would be a problem.

So not only did I quickly figure out a way to upgrade the station, but I also saved valuable time in researching the viability of the alternate site, and all without having to switch between different programs and operating platforms.

In thinking about finding a site for another client to relocate, a new tower would need to be constructed. With another mouse click, the software showed the locations of all the nearby AM broadcast towers, which was handy for determining if a collocation was possible, or if the new tower would be close enough to an existing AM broadcast tower to require a de-tuning network to be added. In short, every time I came up with a seemingly difficult question, the software seemed to have the answer ready and waiting.

It is obvious that the company has brought some considerable engineering expertise and experience to this set of programs. Much of what I am used to doing, even with the assistance of various software programs I have on hand, was made faster and easier to accomplish using the RF Investigator. For the serious allocation consultant, or the group engineer or owner seeking to maximize the facilities of any station, the RF Investigator is a fully-loaded and powerful tool to accomplish everything needed to get the most out of any facility.

I only wish I had this wonderful suite of programs to use back when I was doing applications and studies by hand.

Mussell is a consulting engineer in Bonny Doon, CA.

Performance at a glance

Analyzes STL microwave paths
Calculates population within contours and contour overlaps
Includes 30-second terrain data
Three-second terrain data is available
Antenna pattern tool to design DAs
Performs free-space and Longley-Rice path loss calculations


P 352-336-7223
F 352-367-1725

Editor's note: Field Reports are an exclusive Radio magazine feature for radio broadcasters. Each report is prepared by well-qualified staff at a radio station, production facility or consulting company.

These reports are performed by the industry, for the industry. Manufacturer support is limited to providing loan equipment and to aiding the author if requested.

It is the responsibility of Radio magazine to publish the results of any device tested, positive or negative. No report should be considered an endorsement or disapproval by Radio magazine.

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