Re: [time-nuts] NTP to discipline Raspberry Pi
Le 27 juil. 2013 à 03:18, Julien Ridoux a écrit :
snip
Hi Mike,
Thanks for the interest in the data. You are quite right for everything
regarding data structure, but let me explain what we meant by that comment.
Timespec{} is a 64 bit data structure and support nanoseconds. Yes.
However, it doesn't mean that the digits below the micro-second are actually
representative of anything real.
For the nanosecond digits to be something else than noise you need to make
sure that:
- the hardware counter on top of which the system clock is build has a
frequency of at least 1GHz
- the kernel does not increase the granularity of the counter readings (see
the implementation of 'TSC-low' timecounter on FreeBSD for an example:
http://svnweb.freebsd.org/base/stable/9/sys/x86/x86/tsc.c?view=markup)
In the case of the raspberry pi, the relevant source code can be found around
line 155 in the following kernel source file:
https://github.com/raspberrypi/linux/blob/rpi-3.6.y/arch/arm/mach-bcm2708/bcm2708.c
As you can see, from the comments in the code, the STC counter runs at 1MHz.
Any digit representing a quantity below one microsecond would have to be
interpolated in some way (please don't ask me on how this is done, I am sure
someone will know how the bit stuffing is done better than me).
In any case, I don't see how we can trust anything below the microsecond
resolution on the Raspberry Pi when it comes to assessing the stability of
the actual hardware -- again I am coming from an angle where we bypass all
system clock inner mechanics driven by ntpd or equivalent.
Oh spit.
To illustrate, Hal suggested that I string some calls to clock_gettime().
Here's the result
mike@raspberrypi ~/src $ ./test_clock_gettime_on_RPI
return from 10 succesive calls to clock_gettime(CLOCK_MONOTONIC)
766112 s 68807594 ns
766112 s 68811593 ns elapsed 3999 ns
766112 s 68812593 ns elapsed 1000 ns
766112 s 68812593 ns elapsed 0 ns
766112 s 68813593 ns elapsed 1000 ns
766112 s 68814593 ns elapsed 1000 ns
766112 s 68815593 ns elapsed 1000 ns
766112 s 68816593 ns elapsed 1000 ns
766112 s 68816593 ns elapsed 0 ns
766112 s 68817593 ns elapsed 1000 ns
Looks like I need a new platform.
Thanks for your input Julien
___
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] RS232 cables - thin connectors
wd6...@gmail.com said: Maybe low-profile rs232? Something like: http://www.cablestogo.com/product/52138 Neat. Thanks. I think that's referring to a different dimension. I'm interesting in the thickness of the connector. If you measure a typical connector, it's 0.65 thick 1.3 wide, and 2.1 long long: might be ambiguous. In the case I just measured it includes the end of the shell to the end of the plastic knobs that connect to the screws that hold the connector onto the PC. My problem is the 0.65 vs 0.625 spacing of the connectors on the board. I think your low profile refers to what I'm calling long. The idea is that the connector will fit in a wiring box, or something like that. That web page doesn't include a useful drawing. The only dimension is 1.25 in total depth. I think their depth is my long. -- These are my opinions. I hate spam. ___ 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] NTP to discipline Raspberry Pi
Thanks for that James. Le 27 juil. 2013 à 04:26, James Peroulas a écrit : Date: Fri, 26 Jul 2013 12:27:50 +0200 From: mike cook mc235...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] NTP to discipline Raspberry Pi Message-ID: d7f2de71-32bc-4f54-8fff-5e2027a57...@gmail.com Content-Type: text/plain; charset=windows-1252 Le 25 juil. 2013 ? 05:21, James Peroulas a ?crit : I was hoping to measure the ppm error of a Raspberry Pi's crystal using an NTP client running on the Pi itself. The NTP client reports a ppm correction that I find to be consistently (measurements performed over several days) off by about 10 ppm compared to what I measure using my GPS calibrated frequency counter (HP5328). Specifically, the Pi reports a required ppm correction of -33 ppm whereas I consistenngtly measure a required correction of -43 ppm on my frequency counter. Could you let us know what crystal you were measuring? From the design docs there are 2 on the board , one at 25 MHz and one at 19,2MHz. The 19.2MHz is the one used to derive the ARM clocks. Apparently, the 25MHz crystal is used only for the ethernet port, so I didn't bother with it at all. To measure the 19.2MHz clock, I brought it out to one of the GPIO pins, after dividing by 2. Assuming that the internal divider was working properly, I _should_ have been measuring the crystal's PPM error, but I didn't actually probe the crystal itself... I just added the utility I used for this (gpioclk) to my WSPR fork, in case you find it useful. You can place either the crystal or PLLD (after dividing) on the gpioclk pin using the gpioclk program: https://github.com/JamesP6000/WsprryPi NTP reports the system clock frequency drift ( which I guess is the pll drift), and not the crystal frequency drift, so that may explain what you are seeing. Well, the pll output error would be the same as the crystal error, assuming that NTP was correctly informed of the nominal PLL frequency. What I think might be happening is that the NTP reference clock might have a nominal frequency of (something like) 1.02MHz but NTP was incorrectly told (through kernel headers) that the nominal frequency was 1.00MHz. It would then have to apply a -2PPM correction in addition to the actual PPM error of the crystal in order to discipline the clock. I'm embarrassed to admit it, but I hadn't updated the system on this RPi's SD card. After a dist-upgrade, there is still a bias, but it's only 2.5 PPM or so now, which isn't a problem for WSPR. I'm still going to try to track it down. This does at least show that there is a software issue somewhere... James -- *Integrity is a binary state - either you have it or you don’t.* - John Doerr ___ 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] GPS Spoofing
It seems you can't rely on the human backup. The UK Marine accident Investigation Branch Has recorded numerous accidents due to poor lookout. See http://www.maib.gov.uk/cms_resources.cfm?file=/KarinSchepersReportWeb.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/CoastalIsle.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Beaumont.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Seagate_ReportWeb.pdf for recent examplesThe other problem is that AIS, a significant anti-collision aid, relies on GPS and is susceptable to spoofing. Robert G8RPI. From: Chris Albertson albertson.ch...@gmail.com To: j...@quikus.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, 27 July 2013, 4:18 Subject: Re: [time-nuts] GPS Spoofing I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] GPS Spoofing
If you know your LORAN has a 1/4 mile accuracy then you stay 1/2 mile away from bad things. The trouble with GPS is that it is so good, people don't use common sense and give obstacles a wide berth. Brian On 7/27/2013 04:21, Jim Lux wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether your tax dollars are better spent on LORAN, or on some other precision navigation method or on making jam resistant GPS receivers (which do, in fact exist, and make use of things like direction of arrival of the signal..) Note that a GPS system with 3 antennas (as is common in systems that use GPS to derive attitude/orientation) would be extremely difficult to spoof, and would be VERY inexpensive to implement. Either the carrier phases and code phases are consistent for all the received signals or they're not. A jamming signal coming from the wrong direction will not have the right direction of arrival relative to the platform orientation. One wrong signal might be tolerable (multipath, etc.) but with a multi satellite fix, I suspect it would be hard to do it. Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but that's getting to be a bit noticeable. For what it's worth, I don't know that LORAN has the performance to avoid a Costa Concordia type foul up (assuming they were crazy enough to do the near pass in the fog, so visual navigation didn't work) I seem to recall that LORAN had 1/4 nmi kinds of accuracy. it would get you to the channel or mouth of the harbor, but not get you into your berth. You might be familiar with the local propagation anomalies and get better accuracy with experience in your local waters. -John = I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2242 / Virus Database: 3209/6023 - Release Date: 07/26/13 - No virus found in this
Re: [time-nuts] RS 232
There are other timing issues involved too. Many radios still use relays to switch from transmit to receive. (PIN diodes only in the more expensive ones). The radio receives a key closure but delays RF output from 8 to 20 ms or more to allow time for relay closure. This time delay becomes particularly important when one is driving a high powered amp (like 1.5 KW). It heavier relay in them need at least 8 to as much as 20ms (even when hot shotted) to go from transmit to receive. Hot switching is to be avoided at all costs. Some top of the line amplifiers do use PIN diodes too but they are not very tolerant of higher than 2:1 SWR's. In the heat of action it is easy to select the wrong antenna or put the amp in a 2:1 SWR situation. Their replacement costs are $100 and up and more than one are used. Yes there are protection circuits which help preserve them most of the time. It only takes one bad zap though. BTW latency/aural feedback issues also affect the acoustic world. Performers in locations with echos need to wear an earpiece which carries non-echo band music to not get totally confused. It is an interesting phenomena to see a performer go totally flaky because of echos. Brian On 7/27/2013 05:05, Didier Juges wrote: Most CW operators use keyers to generate the dits and dahs precisely. The keyer can be controlled directly by the computer or be a software Meyer or be controlled by an iambic key connected to the computer. A few operators still use straight keys like the J38 or a 'bug' like the Vibroplex. The key is the input method, or the keyboard. Some software, like the N1MM contest logging software have an embedded software keyer and also support a separate external keyer. Didier KO4BB Bob Camp li...@rtty.us wrote: Hi ….. but why route the key *through* the computer if you are generating the side tone off of RF… Bob On Jul 26, 2013, at 6:16 PM, Brian Alsop als...@nc.rr.com wrote: Actually computers generate probably 98% of the code during so called radio contests. During a contest weekend it is not at all unusual for individuals to make thousands of contacts. Computers automate the drudgery of sending your call thousands of times and most exchanges. However even during these contests, the manual key has to sometimes be used to provide corrections or handle situations not covered by canned messages. Because of the tremendous adjacent and even on frequency interference, computers have proved incapable of decoding code with the accuracy and speed of a human in real time. Brian On 7/26/2013 22:04, Bob Camp wrote: Hi There's also the time honored approach of generating the side tone off of the generated RF. In that case the latency to the transmitter would matter quite a bit. I have no idea *why* you would run the key through a computer in that case …. Bob On Jul 26, 2013, at 4:52 PM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 12:50 PM, Didier Juges wrote: There is a difference between managing the latency (as in ensuring that sound and video are synchronized, but latency itself is acceptable) and minimizing the latency as in a Morse code keyer where the operator has to manually control the generation of elements that can be as narrow as 20mS (one dit at 60 words per minute) while getting timely aural feedback. That means you need the sound to start and stop within less than about 5 mS following the key closing and opening. It is trivial to do on a microcontroller running at 1MHz but surprisingly harder to do on a 2GHz Windows machine. It is not just a matter of time stamping the key closure, you have to get the sound system starting and stopping. Yep. although, since the propagation path is on the order of 100 milliseconds, providing feedback to the user directly from the interface works quite well (e.g. generating tones directly from the keying). The challenge is trying generate the sidetone through Windows. But really, there's no reason why you can't have a keying box that provides the direct side tone and sends the events to the host computer. Then the issue is more about keeping constant latency (or else the CW will be really, really hard to copy) It's not like an extra 10 milliseconds of delay between keying and the emitted RF waveform makes any difference at the other end. ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2242 / Virus Database: 3209/6023 - Release Date: 07/26/13 - No virus found in this message. Checked by AVG - www.avg.com Version:
Re: [time-nuts] HP Z3801 melted rubber feet. Heads up
I have seen the same problem in the Fluke 5700A and 5720A calibrators on the bottom board quite often and they do not run that hot and are usually in a lab enviroment. Thomas Knox To: time-nuts@febo.com From: hmur...@megapathdsl.net Date: Fri, 26 Jul 2013 19:22:10 -0700 Subject: Re: [time-nuts] HP Z3801 melted rubber feet. Heads up Reversion or not the goo is gone.. ... I thought that problem was well known among Z3801A owners. I think I noticed it many years ago when browsing the web back around the time I got my first one. So far, I'm 3 for 3 on having goo rather than feet when I've opened them up, and I agree that it cleans up easily. Do other HP Z38xxx boxes have the same problem? (Just curious.) -- These are my opinions. I hate spam. ___ 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] GPS Spoofing
About 25 years ago, I bought a bunch of LORAN-C receiver boards at the Appelco bankrupcy auction. Despite zero doc, I got a couple running. They had to 8085 uPs, one to compute the TDs and a second,on a daughter board, to compute Lat/Long. The unit would repeatably hit my location w/in a couple of hundred feet. A trivial uP in a box could easily subtract the GPS and LORAN positions and sound an alarm if they differed by more than a set limit, and sound an alarm. Furthermore, I suspect the cost to operate a set of worldwide LORAN chains is far less than launching a single GPS bird. -John == LORAN can be good to 60 ft. On 7/27/13 12:21 AM, Jim Lux wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether your tax dollars are better spent on LORAN, or on some other precision navigation method or on making jam resistant GPS receivers (which do, in fact exist, and make use of things like direction of arrival of the signal..) Note that a GPS system with 3 antennas (as is common in systems that use GPS to derive attitude/orientation) would be extremely difficult to spoof, and would be VERY inexpensive to implement. Either the carrier phases and code phases are consistent for all the received signals or they're not. A jamming signal coming from the wrong direction will not have the right direction of arrival relative to the platform orientation. One wrong signal might be tolerable (multipath, etc.) but with a multi satellite fix, I suspect it would be hard to do it. Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but that's getting to be a bit noticeable. For what it's worth, I don't know that LORAN has the performance to avoid a Costa Concordia type foul up (assuming they were crazy enough to do the near pass in the fog, so visual navigation didn't work) I seem to recall that LORAN had 1/4 nmi kinds of accuracy. it would get you to the channel or mouth of the harbor, but not get you into your berth. You might be familiar with the local propagation anomalies and get better accuracy with experience in your local waters. -John = I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list --
Re: [time-nuts] RS 232
Hal, I like your term automagically. Typo or intentional, it describes how most people 'understand' technology. Mike On 7/26/2013 8:07 PM, Hal Murray wrote: ma...@non-stop.com.au said: It you can figure out how to raise DTR while your application has the port open it can be a good source of power for a RS232 device. Most OSes turn it on automagically when you open the file. (and turn it off when you close the file) ___ 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] GPS Spoofing
Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether your tax dollars are better spent on LORAN, or on some other precision navigation method or on making jam resistant GPS receivers (which do, in fact exist, and make use of things like direction of arrival of the signal..) Note that a GPS system with 3 antennas (as is common in systems that use GPS to derive attitude/orientation) would be extremely difficult to spoof, and would be VERY inexpensive to implement. Either the carrier phases and code phases are consistent for all the received signals or they're not. A jamming signal coming from the wrong direction will not have the right direction of arrival relative to the platform orientation. One wrong signal might be tolerable (multipath, etc.) but with a multi satellite fix, I suspect it would be hard to do it. Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but that's getting to be a bit noticeable. For what it's worth, I don't know that LORAN has the performance to avoid a Costa Concordia type foul up (assuming they were crazy enough to do the near pass in the fog, so visual navigation didn't work) I seem to recall that LORAN had 1/4 nmi kinds of accuracy. it would get you to the channel or mouth of the harbor, but not get you into your berth. You might be familiar with the local propagation anomalies and get better accuracy with experience in your local waters. -John = I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] GPS Spoofing
As a (former) Naval Officer, I will tell you that a competent mariner should always be using and cross-checking /all /sources -- GPS, radar, dead reconing, /looking out the window/, and even celestial in open ocean. (I frequently had to remind my junior officers that nobody ever ran aground or collided with another ship from spending too much time looking out the window. Way too easy to get their heads stuck in the radar or the GPS map. 73, Jim wb4...@amsat.org On 7/27/2013 9:43 AM, Scott McGrath wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether your tax dollars are better spent on LORAN, or on some other precision navigation method or on making jam resistant GPS receivers (which do, in fact exist, and make use of things like direction of arrival of the signal..) Note that a GPS system with 3 antennas (as is common in systems that use GPS to derive attitude/orientation) would be extremely difficult to spoof, and would be VERY inexpensive to implement. Either the carrier phases and code phases are consistent for all the received signals or they're not. A jamming signal coming from the wrong direction will not have the right direction of arrival relative to the platform orientation. One wrong signal might be tolerable (multipath, etc.) but with a multi satellite fix, I suspect it would be hard to do it. Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but that's getting to be a bit noticeable. For what it's worth, I don't know that LORAN has the performance to avoid a Costa Concordia type foul up (assuming they were crazy enough to do the near pass in the fog, so visual navigation didn't work) I seem to recall that LORAN had 1/4 nmi kinds of accuracy. it would get you to the channel or mouth of the harbor, but not get you into your berth. You might be familiar with the local propagation anomalies and get better accuracy with experience in your local waters. -John = I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___
Re: [time-nuts] GPS Spoofing
People screw up. Period. The Costa Concordia, that Talgo train driver in Spain, pilots fly into the ground as in San Francisco, just to name a few. IMO, putting all one's eggs in the GPS basket is simply foolish, especially when a continuous cross-check with an independant nav system can be implemented, probably for lest cost than a dinner at the Captain's Table. I was a guest on the bridge of a ship as it went through the Straights of Gibralter and the Captain was using RADAR, Peloris sights, and multiple lookouts. Suspenders and a belt. The modern supertankers and container ships probably don't do that. The highly automated ships don't carry a lot of crew. -John = As a (former) Naval Officer, I will tell you that a competent mariner should always be using and cross-checking /all /sources -- GPS, radar, dead reconing, /looking out the window/, and even celestial in open ocean. (I frequently had to remind my junior officers that nobody ever ran aground or collided with another ship from spending too much time looking out the window. Way too easy to get their heads stuck in the radar or the GPS map. 73, Jim wb4...@amsat.org On 7/27/2013 9:43 AM, Scott McGrath wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether your tax dollars are better spent on LORAN, or on some other precision navigation method or on making jam resistant GPS receivers (which do, in fact exist, and make use of things like direction of arrival of the signal..) Note that a GPS system with 3 antennas (as is common in systems that use GPS to derive attitude/orientation) would be extremely difficult to spoof, and would be VERY inexpensive to implement. Either the carrier phases and code phases are consistent for all the received signals or they're not. A jamming signal coming from the wrong direction will not have the right direction of arrival relative to the platform orientation. One wrong signal might be tolerable (multipath, etc.) but with a multi satellite fix, I suspect it would be hard to do it. Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but that's getting to be a bit noticeable. For what it's worth, I don't know that LORAN has the performance to avoid a Costa Concordia type foul up (assuming they were crazy enough to do the near pass in the fog, so visual navigation didn't work) I seem to recall that LORAN had 1/4 nmi kinds of accuracy. it would get you to the channel or mouth of the harbor, but not get you into your berth. You might be familiar with the local propagation anomalies and get better accuracy with experience in your local waters. -John = I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a
Re: [time-nuts] GPS Spoofing
I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously make the system so much more robust. Michael / K7HIL On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether your tax dollars are better spent on LORAN, or on some other precision navigation method or on making jam resistant GPS receivers (which do, in fact exist, and make use of things like direction of arrival of the signal..) Note that a GPS system with 3 antennas (as is common in systems that use GPS to derive attitude/orientation) would be extremely difficult to spoof, and would be VERY inexpensive to implement. Either the carrier phases and code phases are consistent for all the received signals or they're not. A jamming signal coming from the wrong direction will not have the right direction of arrival relative to the platform orientation. One wrong signal might be tolerable (multipath, etc.) but with a multi satellite fix, I suspect it would be hard to do it. Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but that's getting to be a bit noticeable. For
Re: [time-nuts] RS 232
Quite right Bob, Echolink is one such program that doesn't automagically raise DTR when the port is opened. Anyway, I have gone Echo-IRLP now, much more robust running under unix. But I veer of topic.. --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, 27 July 2013 11:16 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] RS 232 Hi If the driving program is written using the standard DLL's / libraries it's directly under control of that program. It's state will depend a lot on what the coder decided was right. Bob On Jul 26, 2013, at 9:07 PM, Hal Murray hmur...@megapathdsl.net wrote: ma...@non-stop.com.au said: It you can figure out how to raise DTR while your application has the port open it can be a good source of power for a RS232 device. Most OSes turn it on automagically when you open the file. (and turn it off when you close the file) -- These are my opinions. I hate spam. ___ 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. ___ 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] GPS Spoofing
Hi Which is why the regulations (air or sea) *require* you to be using at least two nav systems to check each other. If you are depending on only one system, your breaking the rules. It's not a matter of weather there are 100,000 systems available or not. It's a matter of weather they follow the rules. Bob On Jul 27, 2013, at 9:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether your tax dollars are better spent on LORAN, or on some other precision navigation method or on making jam resistant GPS receivers (which do, in fact exist, and make use of things like direction of arrival of the signal..) Note that a GPS system with 3 antennas (as is common in systems that use GPS to derive attitude/orientation) would be extremely difficult to spoof, and would be VERY inexpensive to implement. Either the carrier phases and code phases are consistent for all the received signals or they're not. A jamming signal coming from the wrong direction will not have the right direction of arrival relative to the platform orientation. One wrong signal might be tolerable (multipath, etc.) but with a multi satellite fix, I suspect it would be hard to do it. Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but that's getting to be a bit noticeable. For what it's worth, I don't know that LORAN has the performance to avoid a Costa Concordia type foul up (assuming they were crazy enough to do the near pass in the fog, so visual navigation didn't work) I seem to recall that LORAN had 1/4 nmi kinds of accuracy. it would get you to the channel or mouth of the harbor, but not get you into your berth. You might be familiar with the local propagation anomalies and get better accuracy with experience in your local waters. -John = I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___ time-nuts
Re: [time-nuts] GPS Spoofing
What is the failure rate? The number of failures does not matter unless we know the total number of attempts. Do 1% of the ships that leave a harbor to become involved in an accident or is it more like one in one ten million? I'd bet there are tens of thousands of cases of GPS failures where the user said to himself darn, it's broken turned the thing off and went on his way. On Sat, Jul 27, 2013 at 1:51 AM, Robert Atkinson robert8...@yahoo.co.ukwrote: It seems you can't rely on the human backup. The UK Marine accident Investigation Branch Has recorded numerous accidents due to poor lookout. See http://www.maib.gov.uk/cms_resources.cfm?file=/KarinSchepersReportWeb.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/CoastalIsle.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Beaumont.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Seagate_ReportWeb.pdf for recent examplesThe other problem is that AIS, a significant anti-collision aid, relies on GPS and is susceptable to spoofing. Robert G8RPI. From: Chris Albertson albertson.ch...@gmail.com To: j...@quikus.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, 27 July 2013, 4:18 Subject: Re: [time-nuts] GPS Spoofing I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] GPS Spoofing
The failure rate does not matter a whole lot, if you or a loved one are killed or injured. How much comfort is it to a victim, if 1 person, or 5 million people, survived ? Failure rates only really matter to actuaries and insurance companies. -John = What is the failure rate? The number of failures does not matter unless we know the total number of attempts. Do 1% of the ships that leave a harbor to become involved in an accident or is it more like one in one ten million? I'd bet there are tens of thousands of cases of GPS failures where the user said to himself darn, it's broken turned the thing off and went on his way. On Sat, Jul 27, 2013 at 1:51 AM, Robert Atkinson robert8...@yahoo.co.ukwrote: It seems you can't rely on the human backup. The UK Marine accident Investigation Branch Has recorded numerous accidents due to poor lookout. See http://www.maib.gov.uk/cms_resources.cfm?file=/KarinSchepersReportWeb.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/CoastalIsle.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Beaumont.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Seagate_ReportWeb.pdf for recent examplesThe other problem is that AIS, a significant anti-collision aid, relies on GPS and is susceptable to spoofing. Robert G8RPI. From: Chris Albertson albertson.ch...@gmail.com To: j...@quikus.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, 27 July 2013, 4:18 Subject: Re: [time-nuts] GPS Spoofing I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] GPS Spoofing
Hi Also to the same point - which system is more reliable? You can ask the people who now use GPS how it compares in failure rate to what they used before. I know what kind of answers I get when I ask those questions …. Bob On Jul 27, 2013, at 1:10 PM, Chris Albertson albertson.ch...@gmail.com wrote: What is the failure rate? The number of failures does not matter unless we know the total number of attempts. Do 1% of the ships that leave a harbor to become involved in an accident or is it more like one in one ten million? I'd bet there are tens of thousands of cases of GPS failures where the user said to himself darn, it's broken turned the thing off and went on his way. On Sat, Jul 27, 2013 at 1:51 AM, Robert Atkinson robert8...@yahoo.co.ukwrote: It seems you can't rely on the human backup. The UK Marine accident Investigation Branch Has recorded numerous accidents due to poor lookout. See http://www.maib.gov.uk/cms_resources.cfm?file=/KarinSchepersReportWeb.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/CoastalIsle.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Beaumont.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Seagate_ReportWeb.pdf for recent examplesThe other problem is that AIS, a significant anti-collision aid, relies on GPS and is susceptable to spoofing. Robert G8RPI. From: Chris Albertson albertson.ch...@gmail.com To: j...@quikus.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, 27 July 2013, 4:18 Subject: Re: [time-nuts] GPS Spoofing I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] GPS Spoofing
And engineers. Tom Holmes, N8ZM Tipp City, OH EM79 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: Saturday, July 27, 2013 1:21 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Spoofing The failure rate does not matter a whole lot, if you or a loved one are killed or injured. How much comfort is it to a victim, if 1 person, or 5 million people, survived ? Failure rates only really matter to actuaries and insurance companies. -John = What is the failure rate? The number of failures does not matter unless we know the total number of attempts. Do 1% of the ships that leave a harbor to become involved in an accident or is it more like one in one ten million? I'd bet there are tens of thousands of cases of GPS failures where the user said to himself darn, it's broken turned the thing off and went on his way. On Sat, Jul 27, 2013 at 1:51 AM, Robert Atkinson robert8...@yahoo.co.ukwrote: It seems you can't rely on the human backup. The UK Marine accident Investigation Branch Has recorded numerous accidents due to poor lookout. See http://www.maib.gov.uk/cms_resources.cfm?file=/KarinSchepersReportWeb .pdf http://www.maib.gov.uk/cms_resources.cfm?file=/CoastalIsle.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Beaumont.pdf http://www.maib.gov.uk/cms_resources.cfm?file=/Seagate_ReportWeb.pdf for recent examplesThe other problem is that AIS, a significant anti-collision aid, relies on GPS and is susceptable to spoofing. Robert G8RPI. From: Chris Albertson albertson.ch...@gmail.com To: j...@quikus.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, 27 July 2013, 4:18 Subject: Re: [time-nuts] GPS Spoofing I boat? The backup is a competent captain. He'd see the compass heading move and quickly disengage the autopilot. I had a boat for years I'd notice a 5 degree change. Mine was a sailboat so I'd be more sensitive to heading changes than a power boater but still the human is the backup. Most autopilots don't directly follow GPS, they use GPS to determine a heading, follow it then use GPS to detect drift and re-compute the heading. the heading would be held by a compass sensor in a low-cost setup or in a larger setup a lazer ring gyro backed up by a compass. So a spoofed GPS would cause the autopilot to think there was a bigger crooswnd or current and make a bigger heading change. I bet you could hijack a drone not a manned vehicle the pilot is trained to monitor the automation and he'd very quickly turn it off thinking it was broken. On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote: Prof. Humphry from Texas just reported being able to spoof GPS in the Med and take over the nav system of a luxury yacht. He's done this before with a drone in the US. LORAN as a backup, at least? -John == ___ 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. -- Chris Albertson Redondo Beach, California ___ 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. -- Chris Albertson Redondo Beach, California ___ 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. ___ 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] GPS Spoofing
Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously make the system so much more robust. Michael / K7HIL On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether your tax dollars are better spent on LORAN, or on some other precision navigation method or on making jam resistant GPS receivers (which do, in fact exist, and make use of things like direction of arrival of the signal..) Note that a GPS system with 3 antennas (as is common in systems that use GPS to derive attitude/orientation) would be extremely difficult to spoof, and would be
Re: [time-nuts] GPS Spoofing
When Cape Cod LORAN was functional, I could easily see the pulses with a few turn coil maybe a foot in diameter, roughly resonated, and a scope. -John == Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously make the system so much more robust. Michael / K7HIL On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether your tax dollars are better spent on LORAN, or on some other precision navigation method or on making jam resistant GPS receivers (which do, in fact exist, and make use of things like direction of arrival of
[time-nuts] GPS locked 60Hz?
My Tymeter just clacked over to 50 minutes after, and I had a sudden vision of GPS locking its input to 60 Hz, like in the good old days when the power companies cared about frequency. =) Has anyone actually gone that far in their time-madness? Bob - AE6RV ___ 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] GPS Spoofing
Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously make the system so much more robust. Michael / K7HIL On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard automation/autopilot/autocontrol vendors need to make more sophisticated software (which I suspect they do, particularly on 200+ foot ships.. I would imagine that there are some aspects of this demo that are contrived.) The ship making and driving business is pretty unregulated. It's all about what the owner of the ship is willing to pay (or what he needs to get liability insurance, if he wants). There's nothing even remotely like DO-178 for shipboard stuff. The folks doing stabilized oil rigs probably have sophisticated systems, but they're also using IMUs and other stuff. Ditto for high value things (oil tankers, warships). Molasses tankers? They're probably lucky to have a functioning compass and some old charts. I'm not sure, though, that looking at the big picture, whether
[time-nuts] Trimble Acutime Gold Firmware 1.13.0
Hi, Anyone know where I can get firmware 1.13.0 or greater for the Trimble Acutime gold? --marki ___ 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] GPS locked 60Hz?
http://leapsecond.com/pages/atomic-nixie/ shows a KVARZ CH1-75 Active Hydrogen Maser (5 MHz) through a HP 3325B synthesizer (60 Hz) through a HP 6827A bipolar power supply (100 VAC) to generate a 60 Hz mains. At http://leapsecond.com/pages/mains/ he also shows the 60Hz grid meandering forward and back plus or minus 5 or 10 seconds over a month in 2004. On Sat, Jul 27, 2013 at 1:54 PM, Bob Stewart b...@evoria.net wrote: My Tymeter just clacked over to 50 minutes after, and I had a sudden vision of GPS locking its input to 60 Hz, like in the good old days when the power companies cared about frequency. =) Has anyone actually gone that far in their time-madness? Bob - AE6RV ___ 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] GPS Spoofing
LORAN was/is not perfect geographic features could and did limit reception However an effective jammer would need effective power in the hundred watt range and a efficient antenna system plus a connection to power grid or small Genset. Not amenable to easy concealment and fairly easy to DF using standard techniques especially since location of real station well known and fixed An effective GPS jammer which can take out a few square miles is the size of a trade paperback and runs on batteries and costs under 50 bucks to build Imagine a scenario where a few hundred of these are deployed with hostile intent. Military and Civillian systems are now useless due to nature of signal they are hard to DF Sent from my iPhone On Jul 27, 2013, at 2:09 PM, Bob Camp li...@rtty.us wrote: Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously make the system so much more robust. Michael / K7HIL On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a very convincing reason for something like LORAN. I think it's a convincing argument for a captain who pays attention to the other navigation instruments and doesn't blindly follow the GPS. It's also a convincing argument that shipboard
Re: [time-nuts] GPS locked 60Hz?
Hi If you go back into the Frequency Control Symposium papers from the 1980's there are several of them from the power line people on using GPS to track 60 Hz. They have kept at it ever since. Their main interest is in tracking phase across a large network, rather than locking up generators (for accurate time). Knowing phase lets them better balance power flow(s) and thus save money. Bob On Jul 27, 2013, at 3:11 PM, Tim Shoppa tsho...@gmail.com wrote: http://leapsecond.com/pages/atomic-nixie/ shows a KVARZ CH1-75 Active Hydrogen Maser (5 MHz) through a HP 3325B synthesizer (60 Hz) through a HP 6827A bipolar power supply (100 VAC) to generate a 60 Hz mains. At http://leapsecond.com/pages/mains/ he also shows the 60Hz grid meandering forward and back plus or minus 5 or 10 seconds over a month in 2004. On Sat, Jul 27, 2013 at 1:54 PM, Bob Stewart b...@evoria.net wrote: My Tymeter just clacked over to 50 minutes after, and I had a sudden vision of GPS locking its input to 60 Hz, like in the good old days when the power companies cared about frequency. =) Has anyone actually gone that far in their time-madness? Bob - AE6RV ___ 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. ___ 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] GPS Spoofing
Hi A Loran jammer would / could work with a *much* smaller antenna if a local area was the target. Power is easy at 100 KHz. Loran is no easier / harder to DF than GPS. Bob On Jul 27, 2013, at 3:37 PM, Scott McGrath scmcgr...@gmail.com wrote: LORAN was/is not perfect geographic features could and did limit reception However an effective jammer would need effective power in the hundred watt range and a efficient antenna system plus a connection to power grid or small Genset. Not amenable to easy concealment and fairly easy to DF using standard techniques especially since location of real station well known and fixed An effective GPS jammer which can take out a few square miles is the size of a trade paperback and runs on batteries and costs under 50 bucks to build Imagine a scenario where a few hundred of these are deployed with hostile intent. Military and Civillian systems are now useless due to nature of signal they are hard to DF Sent from my iPhone On Jul 27, 2013, at 2:09 PM, Bob Camp li...@rtty.us wrote: Hi Loran can / could easily be jammed over a limited area, just like GPS. Nothing crazy large or expensive would be required. The same sort of malfunctioning this or that took out Loran from time to time over harbor sized areas. Loran had so many issues with dropping out, that they simply were not worth talking about …. Bob On Jul 27, 2013, at 1:35 PM, Scott McGrath scmcgr...@gmail.com wrote: Key Problem with GPS is its easy to spoof on one level and have a complete denial of service on the other. Out in California a while back a malfunctioning TV distribution amplifier jammed a major harbor and surrounding almost 25 sq miles affected all because of a 49.95 TV amp had a problem. The military receivers had the same problem LORAN is virtually jam proof unless you have a very powerful transmitter Sent from my iPhone On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote: I have seen a lot of differing opinions on GPS Spoofing and using back up systems on this thread. Most pretty good, but a couple off the mark a bit. Here are a couple of comments on GPS Spoofing. - There are anti-spoofing GPS receivers available - to authorized users. Typically DOD. Most, if not all, military receivers utilize the encrypted P-Code, while civilians must use the more vulnerable clear text C/A code. The P-Code signals are very difficult to spoof unless you have a-pirori knowledge. The newer satellites (GPS III) will have an even more robust AS methodology. - Note: beware of P-Code, or Military, receivers available on eBay. They are useless without the encryption keys distributed by the US Government. - In the (near?) future there will be four civilian GPS Signals: The government is in the process of fielding three new signals designed for civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, for a total of four civil GPS signals. Users must upgrade their equipment to benefit from the new signals. ref http://www.gps.gov/systems/gps/modernization/civilsignals/ - Receivers utilizing the new civilian GPS frequencies can solve the GPS equations from more than one frequency and see if any one signal is being spoofed. The new civilian frequencies will be more spoof resistant. Comments on using inertial measurement units (IMUs) to back up GPS. - Current IMUs with even a good drift rate of say, 1 degree per hour, available for around a few thousand dollars, will be off 60 nautical miles after an hour of uncorrected operation. That can be reduced by other sensor inputs (GPS, LORAN, pit-log or what ever you have), but the navigation solution will eventually degrade to the accuracy of the external sensor. If my memory serves me for a really deep pocket navigator (having tens to hundreds of thousands of dollars, and a large amount of available mounting space) IMUs with drift rates of up to a thousand times less can be purchased (that's ,001 miles per hour, or around a couple of meters per hour), think submarines, etc. Using a dual sensor navigation system (or timing system! ), such as GPS/eLORAN, would obviously make the system so much more robust. Michael / K7HIL On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com wrote: Key here is how does the captain know that GPS is no longer providing an accurate fix? You need 2 or more independent systems to cross check each other. Sent from my iPhone On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote: On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this is a
Re: [time-nuts] GPS locked 60Hz?
But wouldn't it be easier to set phase if they had a known, good frequency? Oh. Frequency isn't the issue, is it? If you have to supply to the west coast for a few hours and then plug into the east coast to purchase power, you might have to do a large phase shift between the two. And after some arbitrary timeframe doing still more bouncing around you could be off in frequency as measured locally in the long term. This idea just hit me because the Tymeter uses a synchronous clock drive. And giving it some thought, I guess it's not that big a deal if you start with a cheap UPS and a good clock. Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, July 27, 2013 2:42 PM Subject: Re: [time-nuts] GPS locked 60Hz? Hi If you go back into the Frequency Control Symposium papers from the 1980's there are several of them from the power line people on using GPS to track 60 Hz. They have kept at it ever since. Their main interest is in tracking phase across a large network, rather than locking up generators (for accurate time). Knowing phase lets them better balance power flow(s) and thus save money. Bob On Jul 27, 2013, at 3:11 PM, Tim Shoppa tsho...@gmail.com wrote: http://leapsecond.com/pages/atomic-nixie/ shows a KVARZ CH1-75 Active Hydrogen Maser (5 MHz) through a HP 3325B synthesizer (60 Hz) through a HP 6827A bipolar power supply (100 VAC) to generate a 60 Hz mains. At http://leapsecond.com/pages/mains/ he also shows the 60Hz grid meandering forward and back plus or minus 5 or 10 seconds over a month in 2004. On Sat, Jul 27, 2013 at 1:54 PM, Bob Stewart b...@evoria.net wrote: My Tymeter just clacked over to 50 minutes after, and I had a sudden vision of GPS locking its input to 60 Hz, like in the good old days when the power companies cared about frequency. =) Has anyone actually gone that far in their time-madness? Bob - AE6RV ___ 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. ___ 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] GPS locked 60Hz?
That's one big Pocket Watch HI HI 73, Dick, W1KSZ On 7/27/2013 12:11 PM, Tim Shoppa wrote: http://leapsecond.com/pages/atomic-nixie/ shows a KVARZ CH1-75 Active Hydrogen Maser (5 MHz) through a HP 3325B synthesizer (60 Hz) through a HP 6827A bipolar power supply (100 VAC) to generate a 60 Hz mains. At http://leapsecond.com/pages/mains/ he also shows the 60Hz grid meandering forward and back plus or minus 5 or 10 seconds over a month in 2004. On Sat, Jul 27, 2013 at 1:54 PM, Bob Stewart b...@evoria.net wrote: My Tymeter just clacked over to 50 minutes after, and I had a sudden vision of GPS locking its input to 60 Hz, like in the good old days when the power companies cared about frequency. =) Has anyone actually gone that far in their time-madness? Bob - AE6RV ___ 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. ___ 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] GPS locked 60Hz?
Hi The guys who put up the original papers were from Quebec Hydro. Their issue was trying to set things up independent of the grid and dispatch power to where ever it was needed. Once they demonstrated it was possible a lot of other people became interested. Oddly enough at dinner I brought up the possibility of using Loran-C to them. Their commit was have you ever tried to get 100 KHz past the field of a hydro station --- no way!!!. Actually the last part of it was in French, but that's as close as I an get …. Bob On Jul 27, 2013, at 4:10 PM, Bob Stewart b...@evoria.net wrote: But wouldn't it be easier to set phase if they had a known, good frequency? Oh. Frequency isn't the issue, is it? If you have to supply to the west coast for a few hours and then plug into the east coast to purchase power, you might have to do a large phase shift between the two. And after some arbitrary timeframe doing still more bouncing around you could be off in frequency as measured locally in the long term. This idea just hit me because the Tymeter uses a synchronous clock drive. And giving it some thought, I guess it's not that big a deal if you start with a cheap UPS and a good clock. Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, July 27, 2013 2:42 PM Subject: Re: [time-nuts] GPS locked 60Hz? Hi If you go back into the Frequency Control Symposium papers from the 1980's there are several of them from the power line people on using GPS to track 60 Hz. They have kept at it ever since. Their main interest is in tracking phase across a large network, rather than locking up generators (for accurate time). Knowing phase lets them better balance power flow(s) and thus save money. Bob On Jul 27, 2013, at 3:11 PM, Tim Shoppa tsho...@gmail.com wrote: http://leapsecond.com/pages/atomic-nixie/ shows a KVARZ CH1-75 Active Hydrogen Maser (5 MHz) through a HP 3325B synthesizer (60 Hz) through a HP 6827A bipolar power supply (100 VAC) to generate a 60 Hz mains. At http://leapsecond.com/pages/mains/ he also shows the 60Hz grid meandering forward and back plus or minus 5 or 10 seconds over a month in 2004. On Sat, Jul 27, 2013 at 1:54 PM, Bob Stewart b...@evoria.net wrote: My Tymeter just clacked over to 50 minutes after, and I had a sudden vision of GPS locking its input to 60 Hz, like in the good old days when the power companies cared about frequency. =) Has anyone actually gone that far in their time-madness? Bob - AE6RV ___ 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. ___ 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. ___ 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] GPS locked 60Hz?
The guys who put up the original papers were from Quebec Hydro. Their issue was trying to set things up independent of the grid and dispatch power to where ever it was needed. Once they demonstrated it was possible a lot of other people became interested. Oddly enough at dinner I brought up the possibility of using Loran-C to them. Their commit was have you ever tried to get 100 KHz past the field of a hydro station --- no way!!!. Actually the last part of it was in French, but that's as close as I an get . How far away would you have to get before reception would be reasonable? What are the EMI rules for things like power stations? -- These are my opinions. I hate spam. ___ 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] Rockwell/Conexant Jupiter(?) 10kHz Output Off Frequency
The Jupiter (TU-30) board in my homebrew GPSDO has died. A friend gave me some unmarked Jupiter-like boards with Conexant chips that he had been told were Jupiter compatible. The boards are mounted on an aluminium plate that has a puck-type antenna on it. One of the chips has a sticker with ZOD8 V1.83 printed on it. The boards have the same connections as a Jupiter, and I've been able to connect one to my GPSDO in place of the dead Jupiter. It eventually starts outputting sensible messages with location etc. and the homemade display on the GPSDO shows that everything is supposedly normal. However, the PLL will not lock. Even though there's 10 kHz from the board (which I can only measure to 1 Hz accuracy), the PLL keeps hunting for lock. The 10kHz is in sync with the 1pps also from the board. However, when I compare the 10kHz to 10 MHz from another GPSDO, it doesn't appear synced to GPS - it must only be fractions of a Hz off, though. At the moment, I'm thinking there are 3 possibilities: - I need to send a command to the board to configure the 10kHz/1pps somehow. The Jupiter doco doesn't show any command like that and seems to assume the 10kHz and 1pps are always there. - There are components for the 10kHz/1pps syncing missing. I've already had to add a jumper wire where bits for supplying active antenna power were missing (from factory). - The firmware doesn't support 1pps / 10kHz. Perhaps the boards were meant for navigation only. Does anyone recognise these boards and have experience with extracting 10kHz from them? Regards, David Smith ___ 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] GPS locked 60Hz?
The old time (stone age) method of setting the phase of a power generator was easy: Get an ordinary light bulb and connect it between the grid and your generator, Adjust the phase of your generator until the bulb goes dim. When the bulb is 100% dead out then flip the switch and connect the load. They had it a lot easier before there were computers and good instruments. On Sat, Jul 27, 2013 at 2:52 PM, Bob Camp li...@rtty.us wrote: Hi The guys who put up the original papers were from Quebec Hydro. Their issue was trying to set things up independent of the grid and dispatch power to where ever it was needed. Once they demonstrated it was possible a lot of other people became interested. Oddly enough at dinner I brought up the possibility of using Loran-C to them. Their commit was have you ever tried to get 100 KHz past the field of a hydro station --- no way!!!. Actually the last part of it was in French, but that's as close as I an get …. Bob On Jul 27, 2013, at 4:10 PM, Bob Stewart b...@evoria.net wrote: But wouldn't it be easier to set phase if they had a known, good frequency? Oh. Frequency isn't the issue, is it? If you have to supply to the west coast for a few hours and then plug into the east coast to purchase power, you might have to do a large phase shift between the two. And after some arbitrary timeframe doing still more bouncing around you could be off in frequency as measured locally in the long term. This idea just hit me because the Tymeter uses a synchronous clock drive. And giving it some thought, I guess it's not that big a deal if you start with a cheap UPS and a good clock. Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, July 27, 2013 2:42 PM Subject: Re: [time-nuts] GPS locked 60Hz? Hi If you go back into the Frequency Control Symposium papers from the 1980's there are several of them from the power line people on using GPS to track 60 Hz. They have kept at it ever since. Their main interest is in tracking phase across a large network, rather than locking up generators (for accurate time). Knowing phase lets them better balance power flow(s) and thus save money. Bob On Jul 27, 2013, at 3:11 PM, Tim Shoppa tsho...@gmail.com wrote: http://leapsecond.com/pages/atomic-nixie/ shows a KVARZ CH1-75 Active Hydrogen Maser (5 MHz) through a HP 3325B synthesizer (60 Hz) through a HP 6827A bipolar power supply (100 VAC) to generate a 60 Hz mains. At http://leapsecond.com/pages/mains/ he also shows the 60Hz grid meandering forward and back plus or minus 5 or 10 seconds over a month in 2004. On Sat, Jul 27, 2013 at 1:54 PM, Bob Stewart b...@evoria.net wrote: My Tymeter just clacked over to 50 minutes after, and I had a sudden vision of GPS locking its input to 60 Hz, like in the good old days when the power companies cared about frequency. =) Has anyone actually gone that far in their time-madness? Bob - AE6RV ___ 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. ___ 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. ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] GPS locked 60Hz?
Hi Apparently if you are generating hydro station type levels and sending it out over long distance lines, the EMI is pretty fierce. They tried various LF and HF solutions and could not get a good enough signal to be useful. Bob On Jul 27, 2013, at 6:38 PM, Hal Murray hmur...@megapathdsl.net wrote: The guys who put up the original papers were from Quebec Hydro. Their issue was trying to set things up independent of the grid and dispatch power to where ever it was needed. Once they demonstrated it was possible a lot of other people became interested. Oddly enough at dinner I brought up the possibility of using Loran-C to them. Their commit was have you ever tried to get 100 KHz past the field of a hydro station --- no way!!!. Actually the last part of it was in French, but that's as close as I an get …. How far away would you have to get before reception would be reasonable? What are the EMI rules for things like power stations? -- These are my opinions. I hate spam. ___ 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.
[time-nuts] More pictures of the mystery Collins Ru
https://plus.google.com/u/0/photos/111617808980322733757/albums/5890266601277045697 The board with the edge connector was inside the same bag the connector was in, the bag was taped to the unit. I pulled the ends off first, but was immediately stopped with foam, it is glued in place. Then when I finally got the lid with all the screws off, all there is, is one board covered in potting compound. The compound breaks away pretty easily. One can see where a couple parts were replaced and there soft RTV was used. There are two precision resistors in that area. The biggest surprise is the General Radio logo on the board ! goo.gl/1XGG2F ___ 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] GPS locked 60Hz?
Greetings, Actually it requires TWO light bulbs in series (or one bulb with a twice the voltage rating). They usually use TWO standard bulbs in series for EACH phase line. This gives an immediate indication that the phase rotation is correct. I have actually seen it done about 12 years ago to sync three emergency generators with each other and then the power grid and then take over the load and disconnect the grid. All done by hand and very carefully. It was a US Navy hospital situation. Gordon WA4FJC -- Message: 6 Date: Sat, 27 Jul 2013 16:46:01 -0700 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] GPS locked 60Hz? Message-ID: CABbxVHvZc6hQYmWWP_=ptbzgojwga95yszj1blwou-yyuzm...@mail.gmail.com Content-Type: text/plain; charset=windows-1252 The old time (stone age) method of setting the phase of a power generator was easy: Get an ordinary light bulb and connect it between the grid and your generator, Adjust the phase of your generator until the bulb goes dim. When the bulb is 100% dead out then flip the switch and connect the load. They had it a lot easier before there were computers and good instruments. ___ 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] GPS locked 60Hz?
Hi It turns out that if you have a network with a *lot* of sources and a *lot* of loads and a *lot* of interconnects, you would need a *large lot* of light bulbs…. Bob On Jul 27, 2013, at 9:32 PM, Gordon Batey gpba...@wildblue.net wrote: Greetings, Actually it requires TWO light bulbs in series (or one bulb with a twice the voltage rating). They usually use TWO standard bulbs in series for EACH phase line. This gives an immediate indication that the phase rotation is correct. I have actually seen it done about 12 years ago to sync three emergency generators with each other and then the power grid and then take over the load and disconnect the grid. All done by hand and very carefully. It was a US Navy hospital situation. Gordon WA4FJC -- Message: 6 Date: Sat, 27 Jul 2013 16:46:01 -0700 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] GPS locked 60Hz? Message-ID: CABbxVHvZc6hQYmWWP_=ptbzgojwga95yszj1blwou-yyuzm...@mail.gmail.com Content-Type: text/plain; charset=windows-1252 The old time (stone age) method of setting the phase of a power generator was easy: Get an ordinary light bulb and connect it between the grid and your generator, Adjust the phase of your generator until the bulb goes dim. When the bulb is 100% dead out then flip the switch and connect the load. They had it a lot easier before there were computers and good instruments. ___ 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.
