Re: [time-nuts] OT [GPS Survey grade RX]
A good general purpose reference on GPS surveying is http://140.194.76.129/publications/eng-manuals/em1110-1-1003/toc.htm Title: * Engineering and Design - NAVSTAR Global Positioning System Surveying * *by the Army Corp of Engineering. Full manual is 20 Mb. *On 12/6/2010 1:06 AM, Rob Kimberley wrote: Their measurements are usually referenced to a known survey point via differential methods. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: 06 December 2010 4:40 AM To: j...@quik.com; Discussion of precise time and frequency measurement Cc: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] OT [GPS Survey grade RX] Sure.. That's what all those geodesy folks do. Over sufficient time span, one can relate gps measurements to an eci frame On Dec 5, 2010, at 5:43 PM, J. Forsterj...@quik.com wrote: GPS surveying relative to astronomical reference? I don't think so. -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. ___ 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] Time Code generator
Thanks all for their comments on this topic. Over the weekend I spent much time messing about with the NTP stuff and the NMEAGps application. NMEAGps does just as described and does make a nice IRIG-B signal through a PC's sound card. Unfortunately you cannot specifiy which of several soundcard interfaces you want it to use, it will use the one as set as the default which for my use does not work so well. Set up on a second PC set up as a NTP server and time code generator may just be answer. Some more thought is needed before I figure out how to make it do what I want or to dismiss it. There is also the possibility of adapting tc as suggested by Chris A. Cheers, Graham -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: December 3, 2010 18:03 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Time Code generator You computer can generate time code audio signals and if you are keeping the computer's clock sync'd with NTP then those generated time codes will be reasonably accurate.The time code generator is distributed with the NTP software along with other misc. tools. It's a free download if you don't have it. The code is I think the same as sent by WWV. It is some IRIG version. It hing the name of the time code generator is just tc.There is a good chance you alreasy have this but if not it's in the NTP source distribution OK I just looked it up. The filename is .../util/tg.c and here is a quote from the file * This program can generate audio signals that simulate the WWV/H * broadcast timecode. Alternatively, it can generate the IRIG-B * timecode commonly used to synchronize laboratory equipment. later NTP can read back this time code and sync a clock to it. We do this all the time when recording rocket telemetry at work. It works pretty much exactly the way the OP wanted I thing this implementation in tg.c is good to about 1 millisecond -- = 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] Time Code generator
Would Virtual Audio Cable (VAC) software provide the routing neccessary for your application ? Stan, W1LE On 12/6/2010 8:12 AM, Collins, Graham wrote: Thanks all for their comments on this topic. Over the weekend I spent much time messing about with the NTP stuff and the NMEAGps application. NMEAGps does just as described and does make a nice IRIG-B signal through a PC's sound card. Unfortunately you cannot specifiy which of several soundcard interfaces you want it to use, it will use the one as set as the default which for my use does not work so well. ___ 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] Truetime dc 468 goes sat rcvr simulator basics working
Paul, That is very much appreciated. I have one of these boxes. I didn't realize that the signal was no longer being broadcast, so at this point I'm all for whatever hacks will make it useful. Thanks, -JP On Fri, Dec 3, 2010 at 5:55 PM, paul swed paulsw...@gmail.com wrote: Well I think this puts me in the dangerous zone of time nuttery. I had posted to the group about a month ago about a Austron 2201 gps rcvr and any documents anyone might have. Russell responded and sent me some great documents on the Austron. In a phone conversation with Russell we started talking about the old Truetime dc 468s. Kind of got me thinking. I have been able to design a small single chip goes timecode simulator to drive these older clocks. The dc 468 was always quite attractive with their panelplex 7 segment displays. Have re-purposed the boxes for several other projects on occasion using the supply nd the displays. I find the dc 468s at flea markets still for $5 in the northeast US. Generally no converter assembly though it doesn't matter since the GOES timecode signals been gone since 2005. At the moment the software fits in a small parrallax SXB micro. Its written in basic language and compiled. Runs very fast with a 20 Mhz clock. At this stage the unit puts out a manchester encoded timecode signal and is injected at the very first data stage on the decoder. You have to do this to get the PLLs to lock so things decode correctly. I have not attached a GPS time signal to it yet and associated time decoding to automatically sync the clock. That will be the next item. But I suspect this will be a bit ugly. Like sync once per day type of behavior. Another interesting thing I discovered in this project. That the GOES 100 Hz timecode actually transports a very stable frequency reference. So you need a pretty good 100 hz source. What this means is the clock will only drift as much as that source drifts. Thats why I think a single sync 1 time per day is most likely just fine. Additionally the internal 10 MC clock locks to the 100 HZ and is pretty stable. (Ok now I am in trouble. What on earth does that statement mean in this group?) As with the Loran simulator I will share the information with the group as it shapes up. For now I need to make sure the basic software actually is correctly keeping time. Regards Paul WB8TSL ___ 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] Truetime dc 468 goes sat rcvr simulator basics working
Justin, I might think quite a few time Nuts have these. So making progress have build a gps sat message decoder for the GPRMC sentence that gives time and data. I believe most GPS units put that sentence out. Have it decoding time and next is date. Maybe tonight. Then I have to glue this code into the simulator to set the clock. Next will be a update subroutine which is quite tricky as to how the updates done. Lastly the dates a pain. Always has been. Its the number of days from new years. But it seems that the system doesn't actually care what those digits are. S I am thinking of using the LSD 2 as the day of the month and the single 3rd digit as a hex month. I know cheeky. I can calculate days as the system originally used. Maybe you can't use the 3rd digit for Hex months. But I do know the other digits support hex numbers. So thats were I am at. Lastly I may use a seperate SX28ac as a 20 mc to 100hz divider would save about 8 external divider chips. Just not sure I can make it accurate enough to appease the dc468 gods. Regards Paul WB8TSL On Mon, Dec 6, 2010 at 3:44 PM, Justin Pinnix jus...@fuzzythinking.comwrote: Paul, That is very much appreciated. I have one of these boxes. I didn't realize that the signal was no longer being broadcast, so at this point I'm all for whatever hacks will make it useful. Thanks, -JP On Fri, Dec 3, 2010 at 5:55 PM, paul swed paulsw...@gmail.com wrote: Well I think this puts me in the dangerous zone of time nuttery. I had posted to the group about a month ago about a Austron 2201 gps rcvr and any documents anyone might have. Russell responded and sent me some great documents on the Austron. In a phone conversation with Russell we started talking about the old Truetime dc 468s. Kind of got me thinking. I have been able to design a small single chip goes timecode simulator to drive these older clocks. The dc 468 was always quite attractive with their panelplex 7 segment displays. Have re-purposed the boxes for several other projects on occasion using the supply nd the displays. I find the dc 468s at flea markets still for $5 in the northeast US. Generally no converter assembly though it doesn't matter since the GOES timecode signals been gone since 2005. At the moment the software fits in a small parrallax SXB micro. Its written in basic language and compiled. Runs very fast with a 20 Mhz clock. At this stage the unit puts out a manchester encoded timecode signal and is injected at the very first data stage on the decoder. You have to do this to get the PLLs to lock so things decode correctly. I have not attached a GPS time signal to it yet and associated time decoding to automatically sync the clock. That will be the next item. But I suspect this will be a bit ugly. Like sync once per day type of behavior. Another interesting thing I discovered in this project. That the GOES 100 Hz timecode actually transports a very stable frequency reference. So you need a pretty good 100 hz source. What this means is the clock will only drift as much as that source drifts. Thats why I think a single sync 1 time per day is most likely just fine. Additionally the internal 10 MC clock locks to the 100 HZ and is pretty stable. (Ok now I am in trouble. What on earth does that statement mean in this group?) As with the Loran simulator I will share the information with the group as it shapes up. For now I need to make sure the basic software actually is correctly keeping time. Regards Paul WB8TSL ___ 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] Truetime dc 468 goes sat rcvr simulator basics working
There are also a lot of GPS hockey pucks that send the NMEA codes to map software in a laptop that are rapidly becoming obsolete. NMEA is adequate for the 468 display. Have three of them, to go with three NIB (except for the manual) DC 468 receivers. Don't need any of them. Bill Hawkins -Original Message- From: paul swed Sent: Monday, December 06, 2010 3:13 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Truetime dc 468 goes sat rcvr simulator basics working Justin, I might think quite a few time Nuts have these. So making progress have build a gps sat message decoder for the GPRMC sentence that gives time and data. I believe most GPS units put that sentence out. Have it decoding time and next is date. Maybe tonight. Then I have to glue this code into the simulator to set the clock. Next will be a update subroutine which is quite tricky as to how the updates done. ___ 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] Truetime dc 468 goes sat rcvr simulator basics working
Well indeed progress the dc468 is now sync'ing to gps on start. Have a dirty fudge factor to get the seconds exactly synced. Don't like it but does work. Did try to use hex as a month indicator and that did not work. As an example Nov would be A and Dec B. But looking at the driver ckts its doesn't look like anything stops you from doing it. I have seen the clock put out a-d in the digits when I had the info feeding them wrong. Need to tinker with that a bit more. I just don't find 100s of days to be useful though easily implemented now that I can get the date. Regards Paul. On Mon, Dec 6, 2010 at 4:38 PM, paul swed paulsw...@gmail.com wrote: I am using a hocky puck unit On Mon, Dec 6, 2010 at 4:35 PM, Bill Hawkins b...@iaxs.net wrote: There are also a lot of GPS hockey pucks that send the NMEA codes to map software in a laptop that are rapidly becoming obsolete. NMEA is adequate for the 468 display. Have three of them, to go with three NIB (except for the manual) DC 468 receivers. Don't need any of them. Bill Hawkins -Original Message- From: paul swed Sent: Monday, December 06, 2010 3:13 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Truetime dc 468 goes sat rcvr simulator basics working Justin, I might think quite a few time Nuts have these. So making progress have build a gps sat message decoder for the GPRMC sentence that gives time and data. I believe most GPS units put that sentence out. Have it decoding time and next is date. Maybe tonight. Then I have to glue this code into the simulator to set the clock. Next will be a update subroutine which is quite tricky as to how the updates done. ___ 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.
