A while back I posted some comments on a frequency standard I built using Msf, the Uk version of Wwvb.
The machine works well, and is as accurate as could be expected, after sundown accuracy drops off a little due to ionosphere reflections, and can be a uS or so.
Loran c used to transmit short (200uS) pulses of 100kc, and the rx just 'listened' to the first few cycles of each pulse, the principle reason being that the first few cycles were not affected by atmospheric reflections, and therefore gave very accurate timings & good position fixes.
In the Uk loran has been revived and is now transmitted again, and is very accurate, so I'm toying with building a better frequency standard, not being as affected by atmospherics I should be able to make an improvement on accuracy, or rather be able to use the thing at night time.
I found someone on a Uk forum that is also working on this, he uses a microcontroller, samples the signal & sync's the micro's clock using the osccal register, pretty clever.
I found lots of info on loran c, but not so much on eloran, eloran I believe to be compatible with loran c receivers, the 100kc carrier on loran c was not spec'd to be accurate, eloran I think is however I'd like to find some spec on this.
The machine works well, and is as accurate as could be expected, after sundown accuracy drops off a little due to ionosphere reflections, and can be a uS or so.
Loran c used to transmit short (200uS) pulses of 100kc, and the rx just 'listened' to the first few cycles of each pulse, the principle reason being that the first few cycles were not affected by atmospheric reflections, and therefore gave very accurate timings & good position fixes.
In the Uk loran has been revived and is now transmitted again, and is very accurate, so I'm toying with building a better frequency standard, not being as affected by atmospherics I should be able to make an improvement on accuracy, or rather be able to use the thing at night time.
I found someone on a Uk forum that is also working on this, he uses a microcontroller, samples the signal & sync's the micro's clock using the osccal register, pretty clever.
I found lots of info on loran c, but not so much on eloran, eloran I believe to be compatible with loran c receivers, the 100kc carrier on loran c was not spec'd to be accurate, eloran I think is however I'd like to find some spec on this.