Reference ID: GPS
Driver ID: GPS-AS2201
/dev/gpsu; 9600 baud, 8-bits,
This driver supports the Austron 2200A/2201A GPS/LORAN Synchronized
Clock and Timing Receiver connected via a serial port. It supports
several special features of the clock, including the Input Buffer
Module, Output Buffer Module, IRIG-B Interface Module and LORAN Assist
Module. It requires the RS232 Serial Interface module for communication
with the driver. It requires the
ppsclock streams module
described in the Line Disciplines and Streams
Drivers page. It also requires a gadget box and 1-PPS level
converter, such as described in the Pulse-per-second
(PPS) Signal Interfacing page.
This receiver is capable of a comprehensive and large volume of statistics and operational data. The specific data collection commands and attributes are embedded in the driver source code; however, the collection process can be enabled or disabled using the flag4 flag. If set, collection is enabled; if not, which is the default, it is disabled. A comprehensive suite of data reduction and summary scripts is in the ./scripts/stats directory of the xntp3 distribution.
To achieve the high accuracy this device provides, it is necessary to
ppsclock feature of the xntp3 program distribution
or, alternatively, to install the kernel modifications described in the
README.kern. The clock can be wired to provide time to a single CPU or
bussed in parallel to several CPUs, with one CPU controlling the
receiver and the others just listening. Fair accuracy can be achieved in
the single-CPU configuration without use of the 1-pps signal, but in
multiple CPU configurations accuracy is severely degraded without it.
When enabled by the
flag4 fudge flag, every received
timecode is written as-is to the
flag1 0 | 1
flag2 0 | 1
flag3 0 | 1
flag4 0 | 1
clockstatsrecording if set.