Goldquest v Ship's Radar ??

[Anonymous]

Eric,
Could a large ship, with it's radio communications and/or radar produce a regular strong "ping" on my Goldquest?
No amount of adjustment to the REJECT setting could get rid of the interference. The ping was very regular in it's timing and strength, about once every 2 seconds. The interference started as a large container ship moved inshore to it's anchorage. I guess it was about 4 km's offshore from where I was detecting. As there were about 10 large ships in the general area, I thought that maybe the regular 360 degree sweep of it's radar was producing these strong, regular pings.
Unfortunately, I had to put up with it for about 4 hours <img src="/metal/html/shocked.gif" border=0 width=15 height=15 alt=":shock"> ....but it was worth it for the recent beach drops over the weekend <img src="/metal/html/smile.gif" border=0 width=15 height=15 alt="">
Regards,
Tony.

 

[Anonymous]

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[Anonymous]

Hi Tony,
It's possible that the radar could make your Goldquest ping. There are many unknowns regarding rf interference, particularly when the rf frequencies are so far removed from the PI bandwidth. Portable transmitters, as Max mentioned, seem to affect PI's when they are keyed on or off. The rf seems to cause an offset at the output of the first amplifier, and is likely the carrier being rectified by the input protection diodes. Hard to understand how it gets through the lead shielding of the coil. Still, at microwaves, even a ground can look like an antenna if you are not careful.
There is a discussion of PI wobblies on the Nuggetshooter.com forum at the moment. Looks like solar flares are another candidate. Or maybe a pulsar in a far distant galaxy <img src="/metal/html/glasses.gif" border=0 width=15 height=15 alt="">
Eric.

 

[Anonymous]

[No message]

 

[Anonymous]

Thanks Eric,
It's the only prolonged interference I've had since using the detector. I forgot to mention that after I left the beach, I drove about 2 kms away from the coast, switched the detector on, and the "pinging" had gone...just a smooth threshold.
I'm fairly convinced the interference was from "out to sea".....we have the Australian Navies submarine fleet based over here now, and they can regularly be seen prowling out to sea <img src="/metal/html/frown.gif" border=0 width=15 height=15 alt=""> <img src="/metal/html/frown.gif" border=0 width=15 height=15 alt=""> Radar/Sonar/Comms.... <img src="/metal/html/cry.gif" border=0 width=40 height=15 alt=":cry">
Tony.

 

[Anonymous]

Every two or three seconds is a very common sweep period for a marine radar. From what you've said, it seems quite likely that your theory that it was a radar on that tanker is correct.
The smaller radars one sees on fishing boats and motorboats are X-band (about 9.4 GHz), with kilowatt pulses; while the larger radars likely on a tanker are S-band (about 3 GHz), with 3 to 75 kilowatt pulses; both having pulses one tenth to ten microseconds wide at a pulse repetition frequency in the kilohertz range.
As you can see, these are powerful radars, and unless a metal detector were designed to handle such pulses, interference is likely. Nor would it make sense to harden most detectors against marine radars; the problem doesn't come up that often.
Shipboard equipment is quite another matter, and mutual interference between shipboard equipment is a major issue.
Joe

 

[Anonymous]

Joe,
Great information, thanks.
Everything seemed to point towards the container ship as being the culprit. Other sources of interference (mobile phones, CB, handheld radios, lighting, power lines, etc, etc) seem to be irregular and always temporary in their strength and timing.
Regards,
Tony. <IMG SRC="/metal/html/ausflag.jpg" BORDER=0 width=32 height=17 ALT="au~">