Gps receiver & ntp
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Have been alternating sources - with varying results.
Agree the USB module will never do PPS - but always connects and then after a few minutes goes to false ticker
The Sure module is erratic - I can always connect to it using GPSD (GPSMON or CGPS) but connection to NTP is not as good - I have had a few occasions when it has connected via the NMEA datastream and then a few minutes later it is unable to connect. No connection via PPS at all - though I believe that the voltages are at CMOS levels not RS232 - have seen a post somewhere about a n extra connection to be soldered onto the board to correct this - next weeks project!
Shame - because on paper this seemed a very cheap way to get very accurate time!
Andrew
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Agree the USB module will never do PPS - but always connects and then after a few minutes goes to false ticker
Just to chime in here: Your issue is using USB. I tried to use a USB GPS on windows, and it always had a 500-600ms delay from the USB driver. No matter what, you're making a virtual serial port, and that will have delay.
What you're seeing is exactly what I saw in windows: You get a good GPS signal first, so your clock resets to that. Then, ntpd notices that all of the other NTP servers listed are constantly 500-600ms faster than your GPS.
It then takes the next logical step: If everyone else has the exact same time, but I have a source that is showing a time far from theirs, then it is a falseticker & will not be used for time sync. I confirmed with them over email that it supports 1pps
As far as a dedicated GPS on the cheap, this is the best one I could find: http://www.usglobalsat.com/store/download/58/mr350p_ds_ug.pdf
I have not bought it yet, but will report back when I do. Note you have to buy the serial adapter separately, or roll your own. They include all the pinout info if you want to save $15 for the cable.
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Update: I bought the GPS I mentioned, and even though I'm using direct serial, I also see a 500-600ms difference from GPS.
This model supports 1PPS, but it doesn't appear PF is picking up on that.
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Another note (and warning) about the MP-350P: The RS232 cableset that you can order with this does not include the 1pps connection according to the manufacturer. I'll need to make my own cable to do that.
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Thanks for the warning.
Better to cut off the custom/PS2 connector and wire on a DB9 plug you think? I guess you still need a 5V supply from somewhere.I'm still not seeing the Google maps link on the ntp status page even during the rare periods it decides to use the GPS signal. Anyone else seeing that?
Steve
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One of the issues with most USB GPS's is they only output NMEA code once per second. I doubt the virtual serial port is adding that much delay all on itself, but there is probably a component related to that.
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I am currently moving from Smoothwall (used for many years) to PFSense. Doing some different stuff with PFSense with multiple WAN and LAN connections such that I built a new box with 6 NICs on it. Its on its own dedicated hardware box right now.
The above said. I have been using an NTP server with a GPS for a few years now. I would like to shut that box down and attach the GPS to the PFSense server.
Over the years have used a variety of GPS hardware devices all serially connected. First one was just mounting a GPS antenna outside and a serial receiver inside (old surplus vehicle one). I then went to the Sure Electronics one (which did OK until it burned up one day) and currently using an older style GPS with a serial connection on it mounted in the attic with a serial wire run some 3 floors into the basement.
Concurrently I am into weather and amateur radio such that I am adding an APRS Station to my setup and playing around a bit with doing direct satellite weather map downloads from NOAA satellites.
Serially right now this is what I see on my NTP box running my some 100 foot serial cable to the comm closet.
$GPGGA,095747.03,4134.4423,N,08800.6293,W,1,08,0.9,00222,M,,,,36
$GPRMC,095747.03,A,4134.4423,N,08800.6293,W,00.0,000.0,220813,02.,W66
$GPGSA,A,3,25,01,32,31,23,14,16,29,,,,,1.5,0.9,1.231
$GPGSV,3,1,10,31,70,029,49,32,62,276,47,14,37,095,44,20,35,304,3677
$GPGSV,3,2,10,25,23,044,36,16,20,184,38,01,13,257,41,23,10,295,3674
$GPGSV,3,3,10,29,06,082,42,22,04,156,,,,,,,,,7F
$GPGLL,4134.4423,N,08800.6293,W,095748.719,A23
$GPGGA,095748.72,4134.4423,N,08800.6293,W,1,09,0.8,00221,M,,,,3C
$GPRMC,095748.72,A,4134.4423,N,08800.6293,W,00.0,000.0,220813,02.,W6F
$GPGSA,A,3,25,01,32,31,23,20,14,16,29,,,,1.5,0.8,1.232
$GPGSV,3,1,10,31,70,029,49,32,62,276,47,14,37,095,45,20,35,304,3676
$GPGSV,3,2,10,25,23,044,36,16,20,184,38,01,13,257,41,23,10,295,387A
$GPGSV,3,3,10,29,06,082,41,22,04,156,,,,,,,,,7C
$GPGLL,4134.4423,N,08800.6293,W,095751.563,A24
$GPGGA,095751.56,4134.4423,N,08800.6293,W,1,09,0.8,00223,M,,,,30
$GPRMC,095751.56,A,4134.4423,N,08800.6293,W,00.0,000.0,220813,02.,W61
$GPGSA,A,3,25,01,32,31,23,20,14,16,29,,,,1.5,0.8,1.232
$GPGSV,3,1,10,31,70,029,49,32,62,276,47,14,37,095,45,20,35,304,3676
$GPGSV,3,2,10,25,23,044,36,16,20,184,38,01,13,257,41,23,10,295,36*74
$GPGSV,3,3,10,29,06,082,41,22,04,156,,,,,,,,,7C
$GPGLL,4134.4423,N,08800.6293,W,095752.875,A2D
$GPGGA,095752.88,4134.4423,N,08800.6293,W,1,08,0.9,00222,M,,,,31
$GPRMC,095752.88,A,4134.4423,N,08800.6293,W,00.0,000.0,220813,02.,W61I am documenting my PFSense build on an automation forum; going really slow with it. That said is there a step by step anywhere here on the forum or wiki such that I can add my hardware GPS to the PFSense NTP server?
Here is where I am posting my PFSense build:
http://cocoontech.com/forums/blog/29/entry-415-from-anyone-using-pfsense-as-a-firewall/
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To enable GPS on pfSense 2.1 it's just a matter of going to Services > NTP, and selecting the serial port on which the GPS sits. Nothing else to it, no knobs or anything.
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How is this installed?
Thanks,
Rick
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Very knowledgeable and very interesting.
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I want one for my SG-2100 a nice little GPS for perfect time keeping
