[time-nuts] Loran-C Anthorn Down Time
To anybody else attempting to use Loran-C from Anthorn in the UK for timing or frequency calibration purposes, I have just found out the hard way that it's scheduled to be off air every day from today until 6th April inclusive between the hours of 0700 and 1900 UTC :-( Other stations in the Lessay chain should still be available during this period. Regards Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran-C Anthorn
EB4APL wrote: A word of caution here: Don't trust Google maps coordinates for any technical / serious work, they can have errors in the 100´s meter class. And also don't use the copyright date of the maps and images as a time reference, they normally are older than that. If you live in an area under urban development you can check what I mean. Take in account that this is a beautiful thing for locating a restaurant or a route, and can be classified as a geomarketing tool, not a measuring one. For that matter, what ellipsoid is google maps using? GPS is WGS84, but many (if not all) topographic maps in the US are still NAD27 (the corrections are in the bottom left corner). The difference in horizontal position around where I live is some 30-40 meters. Google has to reconcile their imagery, their map data, and their topography somehow, and I imagine they take it all to some common ellipsoid, but it's possible they don't. (That is, nobody is using Google earth to fly a plane across oceans) Especially if you are using digital elevation models (DEMs) (e.g. to do propagation path analysis), you can be off by 50-100 meters comparing the topography in the DEM to the feature on the ground. A "3 second" DEM has horizontal control comparable to a 1:250,000 map. If you see that phrase at the bottom of a USGS map "Meets national map accuracy standards" it helps to know that the standard is basically "positions are accurate to the diameter of a pencil point or about 1/50th of an inch: 0.5 mm)" 0.5mm on a 1:250,000 map is 125 meters. Google is my friend, and I turned up the following with respect to Google Earth (which is NOT the same as Google Maps, apparently) "We represent the earth as a sphere (special case of an ellipsoid). The surface of our sphere corresponds to 0 meters sea level. As far as the KML coordinate system, we consider 0 meters altitude to be sea level, and we draw KML and terrain in a way that's consistent with that. Specifically, the EGM96 geoid is our sea level, a potato-like shape that's smoothly varying but not perfectly smooth, and represents mean sea level around the globe. The geoid (and therefore sea level) is offset from the ideal WGS84 reference ellipsoid by as much as 200 meters or so in some places. " ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran-C Anthorn
A word of caution here: Don't trust Google maps coordinates for any technical / serious work, they can have errors in the 100´s meter class. And also don't use the copyright date of the maps and images as a time reference, they normally are older than that. If you live in an area under urban development you can check what I mean. Take in account that this is a beautiful thing for locating a restaurant or a route, and can be classified as a geomarketing tool, not a measuring one. You can verify this yourself easily comparing your GPS antenna location with the coordinates given by the program and also looking for roads, etc. mismatches in the image seams. I had to explain this a lot of times to guys trying to do shortcuts for technical projects. Regards, Ignacio, EB4APL Peter Vince wrote: Hello Antonio, Looking at the aerial photographs on Google Maps, the transmitter building can be seen at 54.91224°N, 3.27831°W - nearer Cardurnock than Anthorn! Which are the actual aerial masts though, I don't know. Might I suggest you contact Peter Whibberley at the National Physical Laboratory (peter.whibberley (at) npl . co . uk) - if he can't tell you, he will certainly know who can! Regards, Peter Vince On 12 July 2010 00:40, wrote: Greetings to the group. I would like to have the exact (and trustworthy...) WGS84 coordinates of the Anthorn Loran-C antenna. Searching the net I got at least three different sets of LAT/LONG. It seems to me that exactitude is not a cult anymore, except for us the nutties... I would also appreciate to have the exact Coding Delay for that transmitter. (Not the Emission Delay, which is known to be 27,300.00 uS). Thanks in advance. Antonio CT1TE ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com __ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran-C Anthorn
note that at 54,9 degrees, one least significant decimal digit in the latitude/longditude is approx 11cm/6cm . That might well explain why there are multiple references. Le 12/07/2010 11:46, Peter Vince a écrit : Hello Antonio, Looking at the aerial photographs on Google Maps, the transmitter building can be seen at 54.91224°N, 3.27831°W - nearer Cardurnock than Anthorn! Which are the actual aerial masts though, I don't know. Might I suggest you contact Peter Whibberley at the National Physical Laboratory (peter.whibberley (at) npl . co . uk) - if he can't tell you, he will certainly know who can! Regards, Peter Vince On 12 July 2010 00:40, wrote: Greetings to the group. I would like to have the exact (and trustworthy...) WGS84 coordinates of the Anthorn Loran-C antenna. Searching the net I got at least three different sets of LAT/LONG. It seems to me that exactitude is not a cult anymore, except for us the nutties... I would also appreciate to have the exact Coding Delay for that transmitter. (Not the Emission Delay, which is known to be 27,300.00 uS). Thanks in advance. Antonio CT1TE ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com __ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran-C Anthorn
Hello Antonio, Looking at the aerial photographs on Google Maps, the transmitter building can be seen at 54.91224°N, 3.27831°W - nearer Cardurnock than Anthorn! Which are the actual aerial masts though, I don't know. Might I suggest you contact Peter Whibberley at the National Physical Laboratory (peter.whibberley (at) npl . co . uk) - if he can't tell you, he will certainly know who can! Regards, Peter Vince On 12 July 2010 00:40, wrote: > Greetings to the group. > > I would like to have the exact (and trustworthy...) WGS84 coordinates > of the Anthorn Loran-C antenna. Searching the net I got at least three > different sets of LAT/LONG. It seems to me that exactitude is not a cult > anymore, except for us the nutties... > > I would also appreciate to have the exact Coding Delay for that transmitter. > (Not the Emission Delay, which is known to be 27,300.00 uS). > > Thanks in advance. > > Antonio > CT1TE > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > __ > This email has been scanned by the MessageLabs Email Security System. > For more information please visit > http://www.messagelabs.com >__ > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Loran-C Anthorn
Greetings to the group. I would like to have the exact (and trustworthy...) WGS84 coordinates of the Anthorn Loran-C antenna. Searching the net I got at least three different sets of LAT/LONG. It seems to me that exactitude is not a cult anymore, except for us the nutties... I would also appreciate to have the exact Coding Delay for that transmitter. (Not the Emission Delay, which is known to be 27,300.00 uS). Thanks in advance. Antonio CT1TE ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
