This is an image of a 1 MHz bandwidth slice within the 2-Meter Band of the Radio Frequency spectrum in San Jose, CA. The image is built from logged data over a period of 12 hours on 2 January 2015.
More specifically, this image illustrates 145.000 MHz through 146.000 MHz. Left to right represents increasing frequency. Top to bottom represents passed time. 145.390 MHz is highlighted between the green lines. On this frequency in San Jose, CA you will find “Bay-Net 4”: a San Jose, CA ham amateur operated repeater (bay-net.org). It’s often said this repeater is busiest during commuter hours. It appears to be illustrated now as well.
A bit about the image. The .csv log file was 99.7 megabytes. The original output image from the log file was rendered in 65 seconds, and ended up being 1434 x 8639 pixels @ 518 kilobytes. After applying some notations and resizing the image for the web, I ended up with the 830 x 5000 pixel @ 497.5 kilobytes image below. If you’re interested in seeing how I achieved the original data, start here.