Tagged: heatmap

Creating a Signal Strength Heatmap with an RTL-SDR

Over on Reddit, user tautology2 has linked to his project which is software that can create a heatmap of signal strengths. His software uses the data that is output from RTLSDR Scanner which is a program that will collect signal strength data over any desired bandwidth and at the same time also record GPS coordinates using an external GPS receiver. RTLSDR Scanner can also create a heatmap by itself, but tautology2’s heatmap is much clearer and has good web controls for choosing the heatmap signal frequency.

Tautology2 writes about his program:

Eartoearoak’s rtl-sdr scanner can save GPS location data along with spectrum samples, I had put USB GPS unit and SDR’s antenna on the top of my car, put my notebook with running scanner on the front seat and driven it around.

Then I saved results both as an image sequence (which you can see at the bottom of the map) and as the raw data in json format. My script (scan2web.rb[3] ) parses raw data, filters out redundant samples (which were captured standing at the traffic lights etc) and computes normalized spectrum power for eight 300-KHz bands for each spatial sample. Results are saved in heatmap.json[4] , which is rendered using Google maps v.3 heatmap API.

The Reddit thread discussing his project can be found here.

Tools used for making the heatmap: Laptop, RTL-SDR with stock antenna and a GPS.
Tools used for making the heatmap: Laptop, RTL-SDR with stock antenna and a GPS.
Heatmap of GSM Signal Strengths
Heatmap of GSM Signal Strengths

RTL_POWER Heatmap Viewer

Back in June we posted about DE8MSH’s rtl_power based heatmap viewer which was automatically generated every day from a Raspberry Pi. The browser based heatmap display provides a way to view the frequency and time of where the mouse pointer is allowing you to easily identify signals.

Back then the code was unavailable but now DE8MSH has released his code on GitHub. An example heatmap generated by the code can be found here.

RTL_POWER Heatmap Viewer
RTL_POWER Heatmap Viewer

Automatic Heatmap Logging on a Raspberry Pi using an RTL-SDR and RTL_POWER

Amateur radio hobbyist DE8MSH recently wrote in to let us know about a project he has been working on. His project involves using a Raspberry Pi B and RTL-SDR to automatically log a wide band heatmap using rtl_power. Rtl_power is a command line tool that will log signal strengths to a csv file using the RTL-SDR over a very large definable bandwidth.

To do the automatic logging the Raspberry Pi runs rtl_power for 23 hours constantly writing data to a mounted hard drive. After 23 hours the heatmap image is calculated and then uploaded to a webpage at http://qth.at/de8msh/listheatmaps.php. The scheduling is performed by a cron job.

DE8MSH has also been working on a second related project over at http://www.qth.at/de8msh/hm/pic.html. The heatmap on this page shows various transmissions from weather balloons. As you mouse over those transmissions, the QTH (location) of those weather balloon transmissions is shown as well as the frequency and time of where the mouse pointer currently is.

Raspberry Pi Automatic Heatmap Logging with rtl_power
Raspberry Pi Automatic Heatmap Logging with rtl_power