Links
The links on this page will take you to several websites containing audio recordings of a wide variety of sounds recorded on the HF bands. Many of them sound like noise but are actually different forms of commercial and military digital communication. You'll also find recordings of new types of HF radar that are becoming more common, encrypted voice communication and even fishing buoy locator transmitters.
http://www.rfiservices.com/sound.htm -- RFI Services is a company located in Maryland that specializes in locating RFI, primarily from powerlines. Several powerline noise recordings, plus links to some interesting articles.
http://www.kb9ukd.com/digital/ -- An extensive collection of audio files of many digital modes. Many were recorded in the HF bands an most others are found on VHF/UHF frequencies.
http://www.wunclub.com/sounds/ -- A extensive collection of recordings of different digital modes presented by the Worlwide Utility News, a group dedicated to listening to "utility" stations
http://www.grc.nasa.gov/WWW/MAEL/ag/rsounds.htm -- Another collection of sounds of various transmission modes presented by the NASA Mobile Aeronautics Education Laboratory.
http://www.milspec.ca/modems/modems.html -- A collection of sounds of commercial and military digital modes from Richard Lacroix's (VE3UVX) Military Communications Website. Also includes some spectral displays of the files.
http://rover.wiesbaden.netsurf.de/~signals/DIG_intro.htm -- From utility DXer Leif Dehio of Munich, Germany, this is an extensive collection of different digital signals. Besides the audio WAV sample, there is an FFT spectrum display and a short technical description for each signal and its variants.
http://www.nzart.org.nz/nzart/ms/index.html -- From the New Zealand Amateur Radio Transmitters (NZART), this small but carefully selected collection of audio samples represents some of the most common intruders, both analog and digital, in our Amateur bands.
http://www.iarums-r1.org/iarums/sound/main.html -- IARU Region 1 Monitoring System Soundfiles - consists of several samples of military digital communications, several HF Over-the-Horizon radar systems and some others of interest.


Logging Powerline Noise Events -- An article by W4LKE on how he uses a DMM with serial communication capability to record occurrences of powerline noise to provide hard evidence to his local power company of interference he is experiencing.


Links to other websites and documents are greatly appreciated!