RTL-SDR.com reader Dominic Chen recently wrote in to let us know about a new piece of software he’s created. The software is called d3-waterfall, and is an interactive web based waterfall display. It takes CSV data from the commonly used rtl_power software and produces an interactive labelled waterfall which can be viewed in a web browser. rtl_power is a program that allows RTL-SDRs to produce signal power scans over an arbitrarily wide swath of bandwidth, by quickly hopping between ~2 MHz chunks of live bandwidth.
Dominics software is built using “d3.js” and HTML5. The waterfall axes are automatically labelled, there are multiple color schemes and there is pan/zoom support. The main feature is that it is mouse interactive, so when you mouse over a frequency it shows what the signal is. The default signal frequency data is taken directly from our sister site sigidwiki.com, so it may not be accurate for your particular area. But the labels are editable, so it can be customized.
An example of a previous scan can be seen on Dominic’s website (note that this is a 65mb link so be careful if you are data restricted). The software can be downloaded from its GitHub page.
This is what the admin of the coolsdrstuff.blogspot.com blog has done. The author used the program Chronolapse which was set to take a screenshot every 60 seconds. The waterfall in HDSDR was then set to a speed so that the waterfall would complete one cycle every 60 seconds. Then after collecting images all night he used Irfanview to bulk resize all the images to be 1 pixel high. Finally he then combined all the 1 pixel high images into a nice waterfall image.
The waterfall speed in HDSDR can also be set to a very slow update speed, but the problem with this as noted by the author is that this does not average the data, meaning that data in between waterfall updates is lost.