On 1/16/14 2:04 PM, julius wrote:> On Thursday, January 16, 2014 1:13:20 PM UTC-5, glen herrmannsfeldt wrote: >> >> In an optics class some years ago, I was told about the system >> for communicating with submarines using a 7Hz carrier. >> >> More specifically (and maybe not exactly 7Hz) the EM resonance >> frequency of the earth. >> >> Also, another submarine communication system at about 15kHz where >> the index of refraction of water is about 9. >> > > Stay calm and don't panic, but we use<1 Hz carrier, and sometimes carrierless with bandwidth<0.1 Hz. It all depends on the signal generator and the propagation channel. > > I laugh at the notion of ELF (Extremely Low Frequency) which is at 3-30 Hz according to Wikipedia. > > I suggest today we launch two new terms: RLF (Ridiculously Low Frequency) for anything 0.125-12 Hz carrier. And ULF (Unbelievably Low Frequency) for symbol rates less than 0.1 symb/sec.i remember something in the 80s, i think, where there was a big underground ELF array somewhere in Wisconsin. and i thought it *was* able to send very low bit rate but very secure messages. -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."
Error correcting codes for extremely high error rates
Started by ●January 14, 2014
Reply by ●January 16, 20142014-01-16
Reply by ●January 16, 20142014-01-16
On Thursday, January 16, 2014 5:47:53 PM UTC-5, robert bristow-johnson wrote:> On 1/16/14 2:04 PM, julius wrote: > > > On Thursday, January 16, 2014 1:13:20 PM UTC-5, glen herrmannsfeldt wrote: > > >> > > >> In an optics class some years ago, I was told about the system > > >> for communicating with submarines using a 7Hz carrier. > > >> > > >> More specifically (and maybe not exactly 7Hz) the EM resonance > > >> frequency of the earth. > > >> > > >> Also, another submarine communication system at about 15kHz where > > >> the index of refraction of water is about 9. > > >> > > > > > > Stay calm and don't panic, but we use<1 Hz carrier, and sometimes carrierless with bandwidth<0.1 Hz. It all depends on the signal generator and the propagation channel. > > > > > > I laugh at the notion of ELF (Extremely Low Frequency) which is at 3-30 Hz according to Wikipedia. > > > > > > I suggest today we launch two new terms: RLF (Ridiculously Low Frequency) for anything 0.125-12 Hz carrier. And ULF (Unbelievably Low Frequency) for symbol rates less than 0.1 symb/sec. > > > > i remember something in the 80s, i think, where there was a big > > underground ELF array somewhere in Wisconsin. and i thought it *was* > > able to send very low bit rate but very secure messages. > > > > -- > > > > r b-j rbj@audioimagination.com > > > > "Imagination is more important than knowledge."http://en.wikipedia.org/wiki/Project_Sanguine
Reply by ●January 16, 20142014-01-16
On 1/16/14 6:28 PM, John wrote:> On Thursday, January 16, 2014 5:47:53 PM UTC-5, robert bristow-johnson wrote: >> On 1/16/14 2:04 PM, julius wrote: >> >>> On Thursday, January 16, 2014 1:13:20 PM UTC-5, glen herrmannsfeldt wrote: >> >>>> >> >>>> In an optics class some years ago, I was told about the system >> >>>> for communicating with submarines using a 7Hz carrier. >> >>>> >> >>>> More specifically (and maybe not exactly 7Hz) the EM resonance >> >>>> frequency of the earth. >> >>>> >> >>>> Also, another submarine communication system at about 15kHz where >> >>>> the index of refraction of water is about 9. >> >>>> >> >>> >> >>> Stay calm and don't panic, but we use<1 Hz carrier, and sometimes carrierless with bandwidth<0.1 Hz. It all depends on the signal generator and the propagation channel. >> >>> >> >>> I laugh at the notion of ELF (Extremely Low Frequency) which is at 3-30 Hz according to Wikipedia. >> >>> >> >>> I suggest today we launch two new terms: RLF (Ridiculously Low Frequency) for anything 0.125-12 Hz carrier. And ULF (Unbelievably Low Frequency) for symbol rates less than 0.1 symb/sec. >> >> >> >> i remember something in the 80s, i think, where there was a big >> >> underground ELF array somewhere in Wisconsin. and i thought it *was* >> >> able to send very low bit rate but very secure messages. >> > > http://en.wikipedia.org/wiki/Project_Sanguineso it's shut down now? i wonder why. did it not work to the expected spec? -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."
Reply by ●January 17, 20142014-01-17
John <sampson164@gmail.com> writes:> [...] > http://en.wikipedia.org/wiki/Project_SanguineFascinating! -- Randy Yates Digital Signal Labs http://www.digitalsignallabs.com
Reply by ●January 17, 20142014-01-17
On Thursday, January 16, 2014 9:56:20 PM UTC-5, robert bristow-johnson wrote:> > so it's shut down now? i wonder why. did it not work to the expected spec? >It's not the functionality of that system as much as the vulnerability of a single large facility. Everybody knows exactly where that facility is, therefore it is hard to keep it safe from attack or sabotage. In turn, this defeats the purpose of that facility. If the US government were able to conceal its existence then the consideration will have been different. Or, build dozens of them for redundancy.
Reply by ●January 17, 20142014-01-17
julius <juliusk@gmail.com> writes:> On Thursday, January 16, 2014 9:56:20 PM UTC-5, robert bristow-johnson wrote: >> >> so it's shut down now? i wonder why. did it not work to the expected spec? >> > > It's not the functionality of that system as much as the vulnerability > of a single large facility. Everybody knows exactly where that > facility is, therefore it is hard to keep it safe from attack or > sabotage. In turn, this defeats the purpose of that facility. > > If the US government were able to conceal its existence then the > consideration will have been different. Or, build dozens of them for > redundancy.And they couldn't have figured that out BEFORE they spent billions? -- Randy Yates Digital Signal Labs http://www.digitalsignallabs.com
Reply by ●January 17, 20142014-01-17
On Friday, January 17, 2014 9:27:43 AM UTC-5, Randy Yates wrote:> julius <juliusk@gmail.com> writes: > > > > > On Thursday, January 16, 2014 9:56:20 PM UTC-5, robert bristow-johnson wrote: > > >> > > >> so it's shut down now? i wonder why. did it not work to the expected spec? > > >> > > > > > > It's not the functionality of that system as much as the vulnerability > > > of a single large facility. Everybody knows exactly where that > > > facility is, therefore it is hard to keep it safe from attack or > > > sabotage. In turn, this defeats the purpose of that facility. > > > > > > If the US government were able to conceal its existence then the > > > consideration will have been different. Or, build dozens of them for > > > redundancy. > > > > And they couldn't have figured that out BEFORE they spent billions? > > -- > > Randy Yates > > Digital Signal Labs > > http://www.digitalsignallabs.comThe same can be said about a very large number of things. Hindsight is 20-20.
Reply by ●January 17, 20142014-01-17
On 1/17/14 8:58 AM, julius wrote:> On Thursday, January 16, 2014 9:56:20 PM UTC-5, robert bristow-johnson wrote: >> >> so it's shut down now? i wonder why. did it not work to the expected spec? >> > > It's not the functionality of that system as much as the vulnerability of a single large facility. Everybody knows exactly where that facility is, therefore it is hard to keep it safe from attack or sabotage. In turn, this defeats the purpose of that facility. > > If the US government were able to conceal its existence then the consideration will have been different. Or, build dozens of them for redundancy.listen, i grew up in North Dakota. we all knew where the missile silos were. and there were nondescript buildings out in the middle of nowhere. i think the Rooskies knew what to bomb. it's the zillion of megawatts of power that intrigued me about this project. like we're trying to send ELF all the way to the planet Zog. -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."
Reply by ●January 17, 20142014-01-17
julius <juliusk@gmail.com> writes:> [...] > On Friday, January 17, 2014 9:27:43 AM UTC-5, Randy Yates wrote: >> And they couldn't have figured that out BEFORE they spent billions? > [...] > The same can be said about a very large number of things.In this specific instance, I disagree with you, Julius. IMO, this is pretty obvious even in foresight. It doesn't take a mentalist to figure it out.> Hindsight is 20-20.That's always true, yes. Many times it's relevent. But not here, IMO. -- Randy Yates Digital Signal Labs http://www.digitalsignallabs.com
Reply by ●January 17, 20142014-01-17
On Fri, 17 Jan 2014 10:27:02 -0500, Randy Yates <yates@digitalsignallabs.com> wrote:>julius <juliusk@gmail.com> writes: >> [...] >> On Friday, January 17, 2014 9:27:43 AM UTC-5, Randy Yates wrote: >>> And they couldn't have figured that out BEFORE they spent billions? >> [...] >> The same can be said about a very large number of things. > >In this specific instance, I disagree with you, Julius. IMO, this is >pretty obvious even in foresight. It doesn't take a mentalist to figure >it out. > >> Hindsight is 20-20. > >That's always true, yes. Many times it's relevent. But not >here, IMO. >-- >Randy Yates >Digital Signal Labs >http://www.digitalsignallabs.comI think when it was originally done it wasn't that well known for long enough to be useful. Like most things of this type, I always figured they shut it down because they had come up with a better substitute and didn't need it any more. Eric Jacobsen Anchor Hill Communications http://www.anchorhill.com
