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#11
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#12
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On Fri, 14 Dec 2007 22:02:54 EST, Klystron wrote:
You would think that the flat panel multifunction displays (depth, RADAR, fish finder, moving map, etc.) would have LORAN as an option, to back up GPS, but it appears to me that they do not. Don't tell the GPS folks that they need a backup! They are firmly convinced that their system is the greatest thing since sliced bread! ggg -- 73 de K2ASP - Phil Kane From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon e-mail: k2asp [at] arrl [dot] net |
#13
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On Dec 15, 2:05�am, Phil Kane wrote:
On Thu, 13 Dec 2007 20:27:37 EST, (Mark Kramer) wrote: The story I heard is that this started because Collins radios had an IF of 9MHz and only needed one set of (expensive) sideband filters to have LSB below 9 and USB above. Mixing to get the final output: F1+F2 gives same sideband you start with, F1-F2 inverts. That's what I was told. The real story is that it was the Central Electronics (CV ??) exciter that had that scheme. Yes, the CE 10A, 10B and 20A exciters all used a 9 MHz SSB generator. They were quite popular in the 1950s. But they could not be the source of the amateur LSB/USB convention, because that scheme does not invert the sideband on either 75 or 20. 73 de Jim, N2EY |
#14
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Phil Kane wrote:
Don't tell the GPS folks that they need a backup! They are firmly convinced that their system is the greatest thing since sliced bread! ggg Several years ago I had a QSO with a crusty old Navy type who had just retired, somewhat in disgust because the service was no longer teaching things like Morse code and how to use a sextant to do navigation. His contention was that if there was another war the enemy would knock out the US navigation satellites, we would knock out their system, and for the rest of the war both nations' fleets would wander the seas, lost. I wonder how big the solar event would have to be to render GPS unusable. If that or something else took away the capability, it would certainly have a huge impact these days. 73, Steve KB9X |
#15
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#16
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On Sat, 15 Dec 2007 11:26:01 EST, Steve Bonine wrote:
Phil Kane wrote: Don't tell the GPS folks that they need a backup! They are firmly convinced that their system is the greatest thing since sliced bread! ggg Several years ago I had a QSO with a crusty old Navy type who had just retired, somewhat in disgust because the service was no longer teaching things like Morse code and how to use a sextant to do navigation. His contention was that if there was another war the enemy would knock out the US navigation satellites, we would knock out their system, and for the rest of the war both nations' fleets would wander the seas, lost. I wonder how big the solar event would have to be to render GPS unusable. If that or something else took away the capability, it would certainly have a huge impact these days. 73, Steve KB9X That's why the Japanese are teaching there machinists the old way's along with the new. They call those old teachers "super machinists". |
#17
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#18
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![]() "Phil Kane" wrote in message ... On Fri, 14 Dec 2007 06:43:35 EST, Bill Horne wrote: BTW, given a choice between LSB and USB, the military's preference is for Upper sideband, since using USB makes it easy to talk another station on to a net frequency: if his voice sounds high, then so is his frequency. USB was the commercial standard for the 50 years or so that I've been in that business. Even with ISB (Independent SideBand) where each sideband has different information, the "lower" sideband(s) are not inverted relative to the "upper" sideband(s). -- 73 de K2ASP - Phil Kane From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon e-mail: k2asp [at] arrl [dot] net I'm not quite sure what you mean by "inverted". ISB sidebands have the same orientation as normal sidbands, meaning the lower is inverted with regard to the upper sideband and in regard to the freqencies in the original signal, i.e., the higher frequencies in a voice are lower in RF absolute frequency although a greater separation from the "carrier". Single sidband transmission goes back to its early use for intercontental radio links such as the telephone service from the U.S. to England provided by AT&T. I've forgotten the dates but think it was the late 1920's. The equipment was enormously complex compared to later ham SSB stuff. One of the methods used for privacy was sideband inversion applied to both sidebands, that is, the lower voice frequencies were further from the "carrier". If one had a reasonably selective receiver the signals could be heard clearly. This method was used mostly by RCA. ATT used a much more complex system which split the voice base band into several smaller bands and "shuffled" them with or without inversion. One could tell it was voice but not decipher it. -- --- Richard Knoppow Los Angeles, CA, USA |
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