Austron 2200A/2201A GPS Receivers

Last update: May 4, 2022 17:05 UTC (dbea9b7d4)

Synopsis

Address: 127.127.10.u: Reference ID: GPS; Driver ID: GPS_AS2201; Serial Port: /dev/gps_u; 9600 baud, 8-bits, no parity; Features: tty_clk, ppsclock (required)

Description

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 use the 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.

Monitor Data

When enabled by the flag4 fudge flag, every received timecode is written as-is to the clockstats file.

Fudge Factors

time1 time: Specifies the time offset calibration factor, in seconds and fraction, with default 0.0.
time2 time: Not used by this driver.
stratum number: Specifies the driver stratum, in decimal from 0 to 15, with default 0.
refid string: Specifies the driver reference identifier, an ASCII string from one to four characters, with default GPS.
flag1 0 | 1: Not used by this driver.
flag2 0 | 1: Not used by this driver.
flag3 0 | 1: Enable ppsclock line discipline/streams module if set.
flag4 0 | 1: Enable clockstats recording if set.

Additional Information

Reference Clock Drivers