### Austron 2200A/2201A GPS Receivers

#### Synopsis

Address: 127.127.10.u
Reference ID: GPS
Driver ID: GPS-AS2201
Serial Port: `/dev/gpsu`; 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