Hi Well, designing jammers on a public forum is an “interesting” thing to do…..
With WWVB, you are fine with a “near field” solution. You don’t need something that propagates for miles and miles. The other thing you have in your favor is that coming up with a KW at 60 KHz is quite easy. All those 60 KHz switchers we complain about … there’s your dirt cheap source of parts. The next part of the “solution” is to feed your signal into the local power grid. Your switcher is happy with a low impedance load. The power line looks fairly low impedance at 60 KHz. It goes the RF and out and about it flows. Indeed it works pretty well over a good chunk of ground. At least as good as your typical GPS jammer and no more expensive. Been there end done all that, though not for a WWVB jammer. Bob > On Aug 30, 2018, at 5:20 PM, Brooke Clarke <bro...@pacific.net> wrote: > > Hi Bob: > > I would disagree in that ease of jamming/spoofing is strongly related to > wavelength. That's because antenna efficiency goes down as the size of the > antenna gets smaller than 1/4 wave. > So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 wavelength > is a few inches, something that you can hold in your hand. > It's harder to make a WWV jammer (.5, 5, 10, 15, 20 MHz) since a 1/4 > wavelength in in the range of 500 to 12 feet, something that can be mounted > on a vehicle for the higher frequencies. > But it's extremely hard to make a jammer for WWVB (60 kHz) where a > 1/4wavelength is over 4,000 feet. This means an antenna that can be vehicle > mounted will be very inefficient. Note this also means that it's extremely > hard to make a Loran-C jammer. Note that the WWVB and LORAN-C transmitters > run very high power and the antennas are massive. > > This also means that if someone makes a WWVB simulator for their house the > signal at the next door neighbor's house is probably going to be too small to > effect their clocks. > > PS. Some decades ago I maintained a beacon transmitter "LAH" on 175 kHz where > the rules for unlicensed operation limited the input power to 1 Watt and > total antenna length to 50 feet. Under these conditions the effective > radiated power might be 2 milliwatts, orders of magnitude less if a portable > system. > http://www.auroralchorus.com/pli/1750meter_antennas.pdf > > -- > Have Fun, > > Brooke Clarke, N6GCE > https://www.PRC68.com > https://www.end2partygovernment.com/2012Issues.html > axioms: > 1. The extent to which you can fix or improve something will be limited by > how well you understand how it works. > 2. Everybody, with no exceptions, holds false beliefs. > > -------- Original Message -------- >> Hi >> >> When infastructure GPS *does* get jammed these days that source gets tracked >> down a lot faster >> than a month or so. Anything that goes on for more than a day gets booted up >> pretty high >> pretty fast. Indeed I’ve been in the middle of that more than I would have >> wished to be ….. >> >> The same sort of RFI issues that take out GPS from a TV preamp can equally >> well take out WWVB or WWV. >> With WWVB, there are a *lot* of 60KHz switching power supplies out there to >> create problems. There is nothing >> unique about any of these services in terms of being jam immune. >> >> The bigger issue with any of them is spoofing. A proper GPSDO will go into >> holdover when RFI jammed. I would >> *assume* the same would be true of a fancy WWVB device. I’m not at all sure >> that’s true of a real WWVB standard, >> they haven’t been for sale new for a really long time. If your time source >> is in holdover, you can go out and track down >> the issue. If it simply locks to the new signal …. not so much. >> >> There is a subtle distinction in some of this. Newer systems do indeed want >> time. Older systems were generally after >> frequency. The only WWVB standards I’ve seen were aimed at frequency (and >> frequency holdover) rather than time and >> time holdover. Getting reasonable (1 to 10 ppb) frequency from WWVB is a >> very different task than getting the sort of time >> that modern systems are after. >> >> Bob >> >>> On Aug 30, 2018, at 2:46 PM, Scott McGrath <scmcgr...@gmail.com> wrote: >>> >>> The port of Long Beach CA was jammed wrt GPS for several months by a >>> malfunctioning 29.95 TV preamplifier on a boat. >>> >>> GPS was completely unusable when this unsuspecting guy was watching TV on >>> his boat. >>> >>> He had quite the surprise when the coasties with guns showed up. >>> >>> The fact is civillian GPS Is trivial to jam and jammers can be bought >>> ‘under the counter’ at any truckstop along with illlegal linear amplifiers. >>> >>> >>> >>> On Aug 30, 2018, at 12:58 PM, Peter Laws <pla...@gmail.com> wrote: >>> >>> On Mon, Aug 13, 2018 at 8:52 AM Peter Laws <pla...@gmail.com> wrote: >>> >>> >>>> I have yet to hear anyone make a case for retaining the HF system that >>>> isn't backed by nostalgia. >>> Still looking for this. Most of the "OMG IF WWV GOES AWAY MILLIONS >>> WILL DIE" posts (elsewhere, not here ... quite ...) are the type of >>> hysteria that is usually reserved for, I don't know, the EMP folks. >>> :-) >>> >>> >>>> As for solar flares taking out the various GNSSs ... wouldn't a solar >>>> flare only take out the vehicles that were on the "sunny" side of the >>>> Earth? Wouldn't the (approximately) half of the SVs that are in the >>>> Earth's shadow be unaffected? Serious technical question - I have no >>>> idea. >>> One of the responses to my initial message pointed out that the >>> effects of solar flares and CMEs take a while to get from Sol to Sol >>> III and don't arrive all at once, so potentially all GNSS spacecraft >>> could be affected. >>> >>> Since then, I've been poking around for papers on the effect >>> (observed, potential, theoretical) of these events on the Navstar or >>> other GNSS constellations but am not having much luck. I assume it's >>> because I'm not putting the right magic incantation into the google >>> machine. >>> >>> Anyone got some cites? Looking for the effect of solar flares and >>> CMEs on the spacecraft themselves and not how the GNSSs can be used to >>> measure the effects on the ionosphere, etc (those seem plentiful). >>> IOW, I'm curious about the resiliency of the systems to solar events. >>> >>> I did note that at the time of the 1989 solar event that took out a >>> lot of Hydro Quebec's grid, only the "Block I" experimental GPS "SVs" >>> were in orbit. Well, maybe a couple of the later ones - the >>> operational constellation started launching about a month before that >>> flare. >>> >>> As I said initially, I'll be sad if WWV* goes away but it won't affect >>> my life in any measurable way that I can see. I mean, other than the >>> mantle clock slowly losing time. >>> >>> -- >>> Peter Laws | N5UWY | plaws plaws net | Travel by Train! >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> >> > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.