Fast scanning of frequency ranges

[digitalnull]

Does anyone have a suggestion for software or script that could be used to scan ranges of frequencies and make note or save any over a specific threshold? Something where a complete scan could be done in a few minutes? I know radio and police scanners must have some sort of software to do this (example: seek button on your radio).

Thank you.

[OwlG]

You have a couple options

http://kmkeen.com/rtl-demod-guide/

rtl_fm -M fm -f 154.42M -f 154.75M -f 154.82M -f 154.89M -s 12k -g 50 -l 70

rtl_fm -M am -f 118M:137M:25k -s 12k -g 50 -l 280

Then pipe either of those commands into your favorite player or to a file. The link above has some good info.

[etherxrally]

sdr sharp has some plugins that act like a scanner. more info here....http://www.rtl-sdr.com/sdrsharp-frequency-manager-scanner-v1-31-update/

[james92]

rtlsdr-scanner is good and pretty fast https://github.com/EarToEarOak/RTLSDR-Scanner

[KD6W]

Does anyone have a suggestion for software or script that could be used to scan ranges of frequencies and make note or save any over a specific threshold? Something where a complete scan could be done in a few minutes? I know radio and police scanners must have some sort of software to do this (example: seek button on your radio).

Thank you.

Great question, but is this to survey a range of occupied frequencies or to look for a characteristic signal on more than one frequency? If the criteria is to simply look for RF energy of an amplitude that coincides with the receiver tuned frequency (just like a scanner) then there are some simple programs for analysis that hook into radios with computer interfaces. The radio is programmed to sweep and when the threshold is met the radio stops, and the computer logs the frequency. The primarily usage is for surveys and is best performed with multiple receivers and in multiple locations. But if what you are trying to do is find a specific carrier that jumps all over the place, well then, now we need to talk! The big issue is identifying the suspect (on the fly) in a short dwell time and this is a huge topic in the "sig-int" world. To get over the huge processing requirements, they tend to narrow their search range and record the whole band of interest and then crunch the numbers off-line to find the proverbial needle in the haystack. The best of both worlds is a smart algorithmic search that starts off as a simple sweep but triggers new search ranges as the characteristic of the desired carriers change or doesn't as the case may be. All of this is improved IF you know what you are looking for and IF you know where it is coming from. You my friend just might have a bright future in the worderful world of being a spook! -KD6W