gps jamming dover etc
- Thread starter ianabc
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nimbusgb
Well-Known Member
“We are picking up significant modes of jamming in the U.K. including in the Dover area,” Mr. Last said.
Well then do something about the cause you plonker! Fit a couple of spinning roofracks to some boats and go and hunt the causes down. Don't just come up with an expensive piece of equipment for us to pay for.
Well then do something about the cause you plonker! Fit a couple of spinning roofracks to some boats and go and hunt the causes down. Don't just come up with an expensive piece of equipment for us to pay for.
sarabande
Well-Known Member
given the real and proven threat to a system upon which many YBW users place considerable reliance, is it not about time that the MCA insisted that every boat carries relevant charts, alternative position-fixing apparatus, and someone on board who has proven capability to use them ?
This is NOT a troll; it's an expression of genuine concern that our pastime is at risk of electronic disruption, and that every person in charge of a raggie or mobo should be ready and able to use alternatives to GPS.
This is NOT a troll; it's an expression of genuine concern that our pastime is at risk of electronic disruption, and that every person in charge of a raggie or mobo should be ready and able to use alternatives to GPS.
ChrisE
Well-Known Member
Hmm, when I hear of a single instance of this happening in the waters that I play in I'll take it seriously and not before ....
Looks more like an add for Loran which, btw being a radio based system can also be jammed.
Looks more like an add for Loran which, btw being a radio based system can also be jammed.
Jaramaz
Active Member
jamming?
Well, eLORAN is developed/maintained as a back-up system. Not as easy to jam as GPS:
GPS transmitter is satelite based, which considerably limits output power, sometimes said to be about 25 W. Carrier frequencies 1.2 and 1.5 GHz. Signal strenth on the earth is low; in the infancy of GPS some manufacturers had difficulties in designing recievers with sufficient sensitivity.
LORAN transmitt on a much lower frequency, around 2 MHz, and much much higher output power (~1 MW). It is much more difficult to jam a low frequency signal, in particular a very high power signal.
However, LORAN does not give the same accuracy as GPS. Expect 50-100 m as best, whereas GPS accuracy is in the order of 1 m.
LORAN is probably not of interest for yachts (as too expensive). Better to use traditional methods as back-up: charts, compass and eyes.
/J
Well, eLORAN is developed/maintained as a back-up system. Not as easy to jam as GPS:
GPS transmitter is satelite based, which considerably limits output power, sometimes said to be about 25 W. Carrier frequencies 1.2 and 1.5 GHz. Signal strenth on the earth is low; in the infancy of GPS some manufacturers had difficulties in designing recievers with sufficient sensitivity.
LORAN transmitt on a much lower frequency, around 2 MHz, and much much higher output power (~1 MW). It is much more difficult to jam a low frequency signal, in particular a very high power signal.
However, LORAN does not give the same accuracy as GPS. Expect 50-100 m as best, whereas GPS accuracy is in the order of 1 m.
LORAN is probably not of interest for yachts (as too expensive). Better to use traditional methods as back-up: charts, compass and eyes.
/J
rotrax
Well-Known Member
Dont go OOT! I am sure that most leisure sailors who use this site are like me-I use local knowlege in familiar waters, the plotter when visiting somewhere new-along with channel markers and other hard information available visually-and a combination of plotter and chart when offshore. If due dilligence is observed when passage planning and hazards identified and noted and the chart marked with the vessels position half hourly or hourly as required-and attention paid to any deviation from the expected track-all should be OK. As Andrew Edwards addmitted in PBO some years ago coastal sailing around our coast is often a matter of keeping the land on the left-or right-as required. Not so in all cases but a rather neat summary of what happens in practice when sailing familiar waters. The area around the Thames Esuary is one I am not familiar with so I would be on top of my game when planning and passage making in that area. Electronic aids are a usefull tool but are not essential for safe sailing-as has been agreed on these pages many times!
Otter
Well-Known Member
What - like they used to before GPS was invented? I well remember the days when every yacht skipper had to hold a certificate in advanced dead reckoning and you couldn't buy a Leisure 17 without signing a declaration that you were proficient in astro navigation.
temptress
Well-Known Member
Is this actually happening?
So how real is GPS jamming? The loran system has been in the works for years and years.
However I would like to understand if this is real and see evidence of actual deliberate GPS jamming by non-military sources. It is technically possible to jam ANY radio signal but it this really happening
So how real is GPS jamming? The loran system has been in the works for years and years.
However I would like to understand if this is real and see evidence of actual deliberate GPS jamming by non-military sources. It is technically possible to jam ANY radio signal but it this really happening
David2452
Well-Known Member
Have noticed some odd GPS behaviour in harwich harbour a couple of times, very localised close to the terminal. I assume there are containers with cars "destined for foreign climes" in containers, it was as I say very localised though.
richlear
Well-Known Member
GPS suffers from the effect of multipath resulting in ambiguities especially when operating around buildings, bridges and so on. Normally these are transient effects rather than anything permanent and tend to go away before you even notice what has happened.
'Jamming' a GPS carrier is normally achieved by introducing a timing jitter into the carrier which will simply degrade accuracy, much like the SA before that was removed.
Dont forget, todays receivers are typically 12 channel and are receiving 8 or more satellites.
Bottom line is - there is significant reliance on GPS these days and it is difficult to jam multiple signals on different frequencies.
'Jamming' a GPS carrier is normally achieved by introducing a timing jitter into the carrier which will simply degrade accuracy, much like the SA before that was removed.
Dont forget, todays receivers are typically 12 channel and are receiving 8 or more satellites.
Bottom line is - there is significant reliance on GPS these days and it is difficult to jam multiple signals on different frequencies.
geoid96
Well-Known Member
The GPS satellites all transmit different codes on the SAME frequency, 1575.42 MHz.
richlear
Well-Known Member
Geoid, you are right of course, my mistake!
lw395
Well-Known Member
Actually each signal has its spectrum spread over the same 2MHz band.
I would have thought a few jammer detecting receivers in the port would do the trick, and possibly catch a few shipments too.
But if big brother was doing that, he wouldn't tell us would he?
Vara
Well-Known Member
In my frequent observations of GPS in the Dover area I have noticed no evidence of jamming.
If it was occurring I'm sure somebody would have mentioned it.
If it was occurring I'm sure somebody would have mentioned it.
geoid96
Well-Known Member
Of course. Every modulated radio signal takes up some bandwith. The point I was making was that all GPS satellites broadcast their L1 signal on the same central frequency not a different one for each satellite as had been implied.
Rossynant
Well-Known Member
"Ships will need to install receiver equipment. " I'd risk to say: this is all there is 
Going out without at least the general chart?
Used Loran aboard, it was popular on yachts, also a Decca - this was better here. But then those are not much more usefull or accurate then sextant and eye sight; backup is a must be anyway.
Going out without at least the general chart?