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author | Eric S. Raymond <esr@thyrsus.com> | 2015-01-27 12:07:08 -0500 |
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committer | Eric S. Raymond <esr@thyrsus.com> | 2015-01-27 12:07:08 -0500 |
commit | 09e5cc69d6599c743d8b8df22d60f6d582b8dc11 (patch) | |
tree | f347ce0ec72dd35e2ca54dff34825ea43737e3a9 /www | |
parent | 89392c9bc88b5615a2f7fccea327e3e53b0041e9 (diff) | |
download | gpsd-09e5cc69d6599c743d8b8df22d60f6d582b8dc11.tar.gz |
Minor date tweaks to Time Service HOWTO.
Diffstat (limited to 'www')
-rw-r--r-- | www/gpsd-time-service-howto.txt | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/www/gpsd-time-service-howto.txt b/www/gpsd-time-service-howto.txt index 427a7980..be4c0c3e 100644 --- a/www/gpsd-time-service-howto.txt +++ b/www/gpsd-time-service-howto.txt @@ -223,9 +223,10 @@ polled in the same order every second. When a device is added it is assigned to one of those 1024 polling slots. It should then be clear that the accuracy of a USB 1.1 connected GPS would be about 1 mSec. -As of late 2013 no USB GPS we know of implements the higher polling-rate -options in USB 2 and 3. When one does, and if it has the Macx-1 mod, -higher USB accuracy will ensue. +As of early 2015 no USB GPS we know of implements the higher +polling-rate options in USB 2 and 3 or the interrupt capability in +USB 3. When one does, and if it has the Macx-1 mod, higher USB +accuracy will ensue. .Summary of typical accuracy |======================================= @@ -322,7 +323,7 @@ are unlikely to be significant to you; flip a coin. == Choice of Hardware == To get 1PPS to your NTP daemon, you first need to get it from a -PPS-capable GPS. As of late 2013 this means either the previously +PPS-capable GPS. As of early 2015 this means either the previously mentioned GR601-W or a serial GPS with 1PPS. You can find 1PPS-capable devices supported by GPSD at <<HARDWARE>>. @@ -356,7 +357,7 @@ is a relatively inexpensive but high-quality navigation GPS. We make a note of this because u-blox also has a specialized timing variant, the LEA 6T, which would be expensive overkill for an NTP server. -Unfortunately as of late 2013 the LEA-6H is still hard to find in a +Unfortunately as of early 2015 the LEA-6H is still hard to find in a packaged RS232 version, as opposed to a bare OEM module exporting TTL levels or an eval kit like the EVK 6H-0-001 costing upwards of US$300. Search the web; you may find a here-today-gone-tomorrow offer @@ -694,7 +695,7 @@ xtime-a.timefreq .ACTS. 1 u 40 64 377 59.228 -8.503 0.516 +SHM(0) .GPS. 0 l 50 64 377 0.000 6.631 5.331 ----------------------------------------------------------------------------- -The line with refid ".GPS." represents the in-band time reportts from +The line with refid ".GPS." represents the in-band time reports from your GPS. When you are getting PPS then it may look like this: ----------------------------------------------------------------------------- @@ -1175,3 +1176,5 @@ Shawn Kohlsmith <skohlsmith@gmail.com> tweaked the Bibliography. 1.3, Aug 2014: Add a note about the GR-601W. 1.4, Dec 2014: Cleaned up Bibliography + +Repository: Minor corrections to dates. |