JJY Receivers

Last update: 15-May-2015 00:00 UTC          ENGLISH   JAPANESE


Address: 127.127.40.u
Reference ID: JJY
Driver ID: JJY
Serial Port: /dev/jjyu; See corresponding receiver


This driver supports the following the JJY receivers and the GPS clock sold in Japan, and the time service through a telephone line.

Tristate Ltd.   TS-JJY01, TS-JJY02
C-DEX Co.,Ltd.   JST2000
Echo Keisokuki Co.,Ltd.   LT-2000
Tristate Ltd.   TS-GPSclock-01
Telephone JJY

The JJY is the radio station which transmits the JST (Japan Standard Time) in long wave radio. The station JJY is operated by the National Institute of Information and Communications Technology. An operating announcement and some information are available from http://www.nict.go.jp/ (English and Japanese) and http://jjy.nict.go.jp/ (English and Japanese)

The user is expected to provide a symbolic link to an available serial port device. This is typically performed by a command such as;

ln -s /dev/ttyS0 /dev/jjy0

Using an RS-232C to USB converter cable, the clock or a modem can be connected to a USB port instead of a serial port. In this case, the typical symbolic link command is as follows;

ln -s /dev/ttyUSB0 /dev/jjy0

Windows NT does not support symbolic links to device files. COMX: is the unit used by the driver, based on the refclock unit number, where unit 1 corresponds to COM1: and unit 3 corresponds to COM3:

Monitor Data

The driver writes sent and received data to/from the JJY receivers, GPS clock, and the modem into the clockstats file.

statsdir /var/log/ntpd/
filegen clockstats file clockstats type day enable

Mark of the clockstats record
JJY Infomation message ( This refclock starts or stops. )
--> Sent data
<-- Received data
--- Infomation message
=== Infomation message ( Start of each polling, and sync. time. )
-W- Warning message
-X- Error message

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 JJY.
flag1 0 | 1
See corresponding receiver.
flag2 0 | 1
See corresponding receiver.
flag3 0 | 1
See corresponding receiver.
flag4 0 | 1
See corresponding receiver.