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was just going to stick this on the end of the other thread but think the info Bill sent me should be on its own.
Thanks for the info. I had already spotted this one on the NESA website and it was included in the Storrar newsletter.
As I am involved with Electro Magnetic testing including interference testing they failed to mention if the jamming signal was also applied to the eLoran frequency? While it is perfectly feasible to jam the GPS signal locally by broadcasting a wide band noise on the operating frequency at a power greater than that from the satellites in a localised area, it is far more difficult to jam the signal world wide. It is also important to point out that the USA GPS and eLoran are unlikely to operate on the same frequency otherwise the signals would interfere with each other [ like ghosting on the TV when two signals are received slightly out of phase with each other due to reflections]. I also think that the systems would require separate receivers [more outlay for an eLoran compatible unit] and we would be carrying two units until a switchable or dual frequency device came in to being.
As the tidal information from the UK must be paid for and is not made available to on line providers of tidal data, it is reasonable to assume that there will be a cost involved with eLoran reception. For wrecking, 8 metre accuracy is good but the USA system can be accurate to less than 3 metres, especially with DGPS. I have worked in the past on ships involved with the oil industry that used sat nav to an accuracy of 1 metre! When equipment goes faulty, and sometimes interferes with aircraft frequencies [as the papers tell us], the range of interference seldom exceeds 1 mile. This usually occurs with faulty radio baby alarms transmitting on the 3rd harmonic [3 times the operating frequency – case in Luton 2007? – distance 2.5 miles]. With satnav units operating in the “hairpin” frequencies, [a hairpin is the length of a ¼ wave antenna], the interference distances rarely extend beyond the end of the street! From this, without using oodles of power it is virtually impossible for faulty domestic equipment to jam GPS systems offshore. Note that microwave ovens have the power but as they used tuned magnetic cavities, it is impossible to transmit beyond the 2.4GHz frequency they operate on and interfere with GPS signals. Hair dryers and the like can interfere with your own TV but rarely if even with the next door TV.
Unless the states do not replace the GPS satellites as they slowly age and stop working, we should have them for at least the next ten years or so. There are around 20 or so and we only require 3 “visible” ones for our purposes. We will just have to wait and see what happens.
Thanks for the info. I had already spotted this one on the NESA website and it was included in the Storrar newsletter.
As I am involved with Electro Magnetic testing including interference testing they failed to mention if the jamming signal was also applied to the eLoran frequency? While it is perfectly feasible to jam the GPS signal locally by broadcasting a wide band noise on the operating frequency at a power greater than that from the satellites in a localised area, it is far more difficult to jam the signal world wide. It is also important to point out that the USA GPS and eLoran are unlikely to operate on the same frequency otherwise the signals would interfere with each other [ like ghosting on the TV when two signals are received slightly out of phase with each other due to reflections]. I also think that the systems would require separate receivers [more outlay for an eLoran compatible unit] and we would be carrying two units until a switchable or dual frequency device came in to being.
As the tidal information from the UK must be paid for and is not made available to on line providers of tidal data, it is reasonable to assume that there will be a cost involved with eLoran reception. For wrecking, 8 metre accuracy is good but the USA system can be accurate to less than 3 metres, especially with DGPS. I have worked in the past on ships involved with the oil industry that used sat nav to an accuracy of 1 metre! When equipment goes faulty, and sometimes interferes with aircraft frequencies [as the papers tell us], the range of interference seldom exceeds 1 mile. This usually occurs with faulty radio baby alarms transmitting on the 3rd harmonic [3 times the operating frequency – case in Luton 2007? – distance 2.5 miles]. With satnav units operating in the “hairpin” frequencies, [a hairpin is the length of a ¼ wave antenna], the interference distances rarely extend beyond the end of the street! From this, without using oodles of power it is virtually impossible for faulty domestic equipment to jam GPS systems offshore. Note that microwave ovens have the power but as they used tuned magnetic cavities, it is impossible to transmit beyond the 2.4GHz frequency they operate on and interfere with GPS signals. Hair dryers and the like can interfere with your own TV but rarely if even with the next door TV.
Unless the states do not replace the GPS satellites as they slowly age and stop working, we should have them for at least the next ten years or so. There are around 20 or so and we only require 3 “visible” ones for our purposes. We will just have to wait and see what happens.