I really like this approach, it is basically the approach I took to determine sets of clear frequencies to operate our SRI/WARF OTH radar. Trying to essentially record the entire HF spectrum produces datasets that are totally unmanageable with lots of redundant and/or useless data.
Since what you are interested in is changes in noise level, frequencies should be chosen to minimize the chance that you are recording a signal. There are several algorithms that might be used: first select frequencies in portions of the spectrum known to be "normally" clear. This actually might be enough as a first effort. An improvement on this would be to search +,- an arbitrary number of kHz around a "center" frequency and select the frequency with the lowest noise level. I would think that you might want to sample the spectrum every 2 MHz but that would be TBD. A less expensive (perhaps) and less high tek approach would be to pick up one of many strip chart recorders on the surplus market and use it to record the AGC level out of the receiver. The computer would control the frequency/time sequencing of the receiver and turn on the recorder for several seconds at each sample frequency. This of course would require lots of manual data reduction...hey, I worked my way through school doing just that! Doug W6JD ----- Original Message ----- From: "Rich Lentz" <[EMAIL PROTECTED]> To: "'Elecraft List'" <elecraft@mailman.qth.net> Sent: Sunday, February 13, 2005 6:19 AM Subject: RE: [Elecraft] Automated BPL Interference Data Collection. > I think you are making this to difficult. > > FACTS: > > BPL will cause noise across the entire HF Spectrum. > Hams only use selected portions of this spectrum. > There is no easy way to digitize the entire spectrum. > Radio Jove software will record signal strength based upon the noise level > (don't need to know the S meter reading) for as long as you let it run. 1, > 2, 10, 24, 100, 1000, etc, (there is no set limit) hours. It hooks up like > PSK, rtty, etc to your sound card. > Sampling techniques can prove increased noise at one frequency means > increased noise at other frequencies > > Solution. > > Using the Radio Jove software record 3 to 5 frequencies on each band at > 0000, 0300, 0600, 1200, 1500, 1800, and 2100 for about 1 minute each as a > base. Might want to include local emergency frequencies. > > The output is saved as a data file (read how the software works). > > Do this again once a week (some periodicity) before BPL is installed to > establish a base line. > > Do this again once a week (some periodicity) after BPL is installed. > > As it is all relative any radio will do as long as the same (set of) > frequencies are used (but the frequency only needs to be close, +/- 1 kHz > not +/- 1 Hz). This technique will work with just one frequency. The > additional are only needed to show the uninformed. > > Take the date and put in ACCESS, EXCEL, etc, and plot the before and after. > > Send graphs to FCC, your congressman. > > Rich, > KE0X > > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
