Spectrum Analysis

How utilized is the amateur radio spectrum?

With a software-defined receiver and a lot of time, we can analyze the utilization of the radio spectrum.

For this experiment, we will use the rtl_power tool, part of the rtl-sdr driver, to monitor power levels across the radio spectrum over a 24-hour period. The data is then compiled into an image with heatmap.py.

The recordings on this page were done in Tacoma, Washington, on a Comet GP-9 at about 20 ft above ground. The dates and times of each recording at printed in the bottom left corner of the image.

The images below are cropped and re-sampled. Click to get the full resolution.

2m band

The US 2m band spans 144 to 148 MHz. For perspective, the 148-160 MHz industrial, public safety, and marine bands were also included in this recording.

The following command was used to record data:

rtl_power -f 144M:160M:10k -i 30 -e 24h -g 30 144.csv

And compiled into a heatmap:

./heatmap.py 144.csv 144.png

2m heatmap


70cm band

The following command was used to record data:

rtl_power -f 420M:450M:10k -i 30 -e 24h -g 30 70cm.csv

And compiled into a heatmap:

./heatmap.py 70cm.csv 70cm.png

70cm heatmap



Filename Size Modified
144.png 5.7MiB 2016-09-08 23:21:50
70cm_cropped.jpg 366KiB 2016-09-08 23:21:51
70cm.png 8.5MiB 2016-09-08 23:21:51
144_cropped.jpg 400KiB 2016-09-08 23:21:50