You may need a large array for adequate wave capture.=20 Hard to distinguish between natural source. They communicate with methodica= l wave distortion and clicks, looks just like natural source, I don't know = how you could distinguish? Another page on that same site http://www.vlf.it/cr/differential_ant. Antennex is a great site. http://www.antennex.com/ Its mostly in the antenna tuning for long waves like that. - Sent from my iPhone On Jan 4, 2012, at 10:07 AM, fred jones wrote: >=20 > I appreciate the responses, however it became a discussion as to whether = the US still used 76hz or how communications was being handled. The US sti= ll uses 76hz and the russians still use 82hz to communicate with submarines= .. I do not want to receive and decode what is being communicated. I have = an idea for use of the signal. All I want to be able to do is to receive i= t and measure a signal level. Any ideas how I can do this? It's 76hz, not= Khz. Thanks for any help or ideas. > Thanks, > FJ >=20 >=20 >> From: boattow@hotmail.com >> To: piclist@mit.edu >> Subject: [EE] How to receive submarine signal? >> Date: Mon, 2 Jan 2012 22:12:27 -0600 >>=20 >>=20 >> Hi all, >> I have a question for those analog engineers on the list. I have been se= arching the internet for information on listening to ELF signals. I have fo= und some information but not exaxtly what I'm looking for. For example one = site has a circuit of amplifiers and passive filters utilizing either an an= tenna or just probes stuck in the ground to receive ELF signals below 50Hz.= Another person has a very large coil of wire wound on a spool and just set= s it on the ground. What I would like to do is similar but I'd like to list= en to 76Hz which is the US submarine communications frequency. The Russians= utilize 82Hz. Is it possible to build a circuit that would pickup the 76Hz= signal only? Any information on how to do this if it is possible is apprec= iated. >> Thanks, >> FJ >>=20 >> http://www.vlf.it/kurt/elf.html=20 >> --=20 >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist > =20 > --=20 > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .