WSPRnet map movie

Here's a movie showing the wsprnet map for 40m for a full week. I thought it would be interesting to visually see how propagation changes as the earth turns. The lines are stations that can hear each other.



To capture this I set up an old MacBook with the browser open at the map view. The page has a refresh time of 1200 seconds built in. MacOS has a command line screencapture utility so I created the following cron job to run it every 20 minutes and save the capture to a PNG image named with the date and time. The movie is running at six frames per second.

#!/bin/bash
now=`date "+%Y-%m-%d_%H-%M-%S"`
/usr/sbin/screencapture /Users/marksp/wsprcaps/${now}.png

The cron job looks like this:

*/20 * * * * /Users/marksp/capture.sh

I disabled the screen save and sleep, in the Energy Saver control panel.

After a while images build up in the output directory.



The best way I know to turn the image sequence into a movie is to get a copy of Quicktime 7 for Snow Leopard from the install CD (the current Quicktime Player doesn't have this feature).

Quicktime needs the images to have increasing sequential numbers in the file, a little python does the trick:

import os

START_PATH = '.'

count = 1  # number to start with
for dirname, dirnames, filenames in os.walk(START_PATH):
    for filename in filenames:
        if filename.startswith("2011"):
            newname = "%03d.png" % count
            count += 1
            print filename, newname
            os.rename(os.path.join(dirname, filename), 
                      os.path.join(dirname, newname))

Quicktime 7 (Pro) can open an image sequence and you can set the frame rate.



Then you choose the frame rate.



Finally I saved the movie and uploaded it to YouTube.