For many years, Communications Research Centre Canada (CRC) provided a free online tool call CovLab Web that would generate FM coverage using the Longley-Rice terrain-sensitive propagation model.  It was extremely handy for doing quick plots, giving insight into terrain obstacles, and allowing the user to do some quick comparisons of different transmitter sites or power levels.  Unfortunately, the web-based tool joined its desktop brethren CovLab in the land of non-distribution.

Since this free tool performed a valuable task to some, I’ve been asked if there’s anything else like it.  Now as a broadcast engineer, I can be forgiven for occasionally putting aside other hobbies, just to play around with other web-based radio coverage tools, right? <crickets chirping>.

Well, here’s a couple options that I was test-driving while still using CovLab Web from time to time.

First, transmitter manufacturer Nautel has a free RF Toolkit that has a radio coverage planning tool.  Use of the tool requires you to sign up for an account, which is free.  The radio coverage tool uses the same Longley-Rice model as CovLab Web.  The interface feels a little simplistic, but it does get the job done.  Coverage maps are generated on a Google Map background.

Next, there’s an offering from CloudRF.com .  I like the interface and background maps.  There’s a lot of knobs and switches in the input parameters, which can be a good and a bad thing depending on your level of comfort.  This is definitely a freemium type offering.  On this page you can get see what you can get for free, and browse other paid options.  The free version limits a few things, most notably the maximum radius to calculate coverage is 10 km which would basically limit the free use of this tool to low power stations.  Also the number of calculations that can be performed per month is also limited.

Are there other options out there?  Quite possibly.  I don’t use either of these tools a lot because I have other commercial software to generate coverage contours and do terrain-sensitive coverage analysis.  One thing that’s definitely missing from these free tools is the ability to assess any kind of interference.  For many stations, that’s not an issue, but in a region that has more spectrum congestion, it’s a problem.  When I was test driving CloudRF a few years ago I reached out to the developer to see if this was possible.  Possible yes, likely to implement in the near future, no.

If you know of another tool besides these two that can generate FM coverage maps, please comment below.  If you need help plotting FM or TV coverage maps for your stations, please contact me.