JJY Receivers

Last update: March 30, 2023 19:10 UTC (33276df3b)

JAPANESE

Table of Contents

Synopsis

Address: 127.127.40.u

Reference ID: JJY

Driver ID: JJY

Serial Port: /dev/jjyu; See corresponding receiver

Description

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

Model Mode Language
Tristate Ltd. TS-JJY01, TS-JJY02 1 Japanese only
C-DEX Co.,Ltd. JST2000 2 Japanese only
Echo Keisokuki Co.,Ltd. LT-2000 3
CITIZEN T.I.C. CO.,LTD. JJY-200 4 Japanese only
Tristate Ltd. TS-GPSclock-01 5 Japanese only
SEIKO TIME SYSTEMS INC. TDC-300 6 English and Japanese
Telephone JJY 100 English and Japanese

Mode-1

NTP configuration (ntp.conf)

server 127.127.40.X mode 1

fudge 127.127.40.X time1 0.NNN flag1 0|1 flag2 0|1 time2 H

time1 may specify a constant to be added to the time offset for the time from the receiver, a fixed-point decimal number in seconds. You may specify the time offset from several tens of ms (0.0NN seconds) to a hundred and several tens of ms (0.1NN seconds) for this clock.

time2 may specify a grace period in hours after the adjusted reply of the STUS command stopped coming. This hours is effective when both flag1 and flag2 are set to 1.

flag1 has no effect for time synchronization unless flag2 is set to 1. When flag1 is set to 1, status commands are issued before DATE and STIM commands, and write a response text into the clockstats file.

Value Description
0 (Default) DCST and STUS commands are not issued
1 DCST and STUS commands are issued

flag2 enables the time synchronization only when the reply of the STUS is adjusted. When this functionality is used, flag1 must also be set to 1.

Value Description
0 (Default) Always
1 adjusted only
Interface
RS-232C, 9600 BPS, 8-bits, no parity, 1 stop bit
Time code format
Command Reply
dcst{CR}{LF} valid{CR}{LF} | invalid{CR}{LF}
stus{CR}{LF} adjusted{CR}{LF} | unadjusted{CR}{LF}
time{CR}{LF} HH:MM:SS{CR}{LF}
date{CR}{LF} YYYY/MM/DD WWW{CR}{LF}
stim{CR}{LF} HH:MM:SS{CR}{LF}

The date and time are requested separately. The time is requested before and after the date request to check uncertainty of the date whether it’s before or after midnight.

Mode 2

NTP configuration (ntp.conf)

server 127.127.40.X mode 2

fudge 127.127.40.X time1 0.NNN

Interface
RS-232C, 9600 BPS, 8-bits, no parity, 1 stop bit
Time code format
Command Reply
{ENQ}1J{ETX} {STX}JYYMMDDWHHMMSSS{ETX}

Mode-3

Echo Keisokuki was dissolved. Some business of the company was taken over by FreqTime Co., Ltd. in July, 2015.

NTP configuration (ntp.conf)

server 127.127.40.X mode 3

fudge 127.127.40.X time1 0.NNN

Interface
RS-232C, 9600 BPS, 8-bits, no parity, 1 stop bit
Time code format
Command Reply
C (Mode 2 : Continuous)
(Every second before 0.5 second) YYMMDDWHHMMSS{ST1}{ST2}{ST3}{ST4}{CR}
# (Mode 1 : Request&Send)

Mode-4

The JJY-200 became end-of-sales in 2013.

NTP configuration (ntp.conf)

server 127.127.40.X mode 4

fudge 127.127.40.X time1 0.NNN

Interface
RS-232C, 4800 BPS, 8-bits, no parity, 1 stop bit
Time code format
Command Reply
(Every second) 'XX YY/MM/DD W HH:MM:SS{CR}

Mode-5

This driver supports the Tristate TS-GPSclock-01 in command/response mode, though it is a GPS clock, not JJY radio clock. Using the menus and the onboard switches, the TS-GPSclock-01 should be set to command/response mode and JST time zone.

Besides this driver (Type 40), the generic NMEA GPS driver (Type 20) supports the TS-GPSclock-01 in NMEA mode.

NTP configuration (ntp.conf)

server 127.127.40.X mode 5

fudge 127.127.40.X time1 0.NNN flag1 0|1

time1 may specify a constant to be added to the time offset for the time from the receiver, a fixed-point decimal number in seconds.

flag1 has no effect for time synchronization. When flag1 is set to 1, the status command is issued before the DATE and TIME commands and a response text is written to a clockstats file.

Value Description
0 (Default) STUS command is not issued
1 STUS command is issued
Interface
USB (/dev/ttyACM0)
Time code format
Command Reply
stus{CR}{LF} *R{CR}{LF}|*G{CR}{LF}|*U{CR}{LF}|+U{CR}{LF}
time{CR}{LF} HH:MM:SS{CR}{LF}
date{CR}{LF} YYYY/MM/DD{CR}{LF}

The date and time are requested separately. The time is requested before and after the date request to check uncertainty of the date whether it’s before or after midnight.

Mode-6

The TDC-300 must be set to the type 3 data format using the front panel menu display and the switches.

NTP configuration (ntp.conf)

server 127.127.40.X mode 6

fudge 127.127.40.X time1 0.NNN

Interface
RS-232C, 2400 BPS, 8-bits, no parity, 1 stop bit
Time code format
Command Reply
{STX}YYMMDDWHHMMSS{ETX}
(5 to 10 ms before second) {STX}{xE5}{ETX}

Mode-100

The telephone JJY is the time service through a public telephone line.

The service is provided by the National Institute of Information and Communications Technology in Japan.

Attention: This mode, the telephone JJY, can not be used with refclock_acts (type 18) at the same time. Because the phone statement in the ntp configuration file is not involved with the server statement, both the refclock_acts (type 18) and this refclock_jjy (type 40, mode 100 to 180) can not recognize the appropriate phone statement among the phone statements.

NTP configuration (ntp.conf)

server 127.127.40.X mode (100, 101 to 180) minpoll N
When mode 100 is specified, this driver does not issue the loopback command in order to measure the delay, and the delay of the telephone line and the system processing is not adjusted.

When mode 101 to 180 is specified, this driver issues the loopback command and measures the delay of the telephone line and the system processing through the Telphone JJY loopback circuit.

The round trip time through the Telphone JJY loopback circuit is measured 5 times, and each delay time is greater than 700 ms, that delay time is ignored during average delay time calculation. Also, if the valid delay time ( <= 700 ms.) is measured more than 3 times, the maximum delay time among the valid delay times is ignored, and if the valid delay time is measured more than 4 times, the minimum delay time among them is ignored, like marking/grading sports judgment.

The adjustment time is calculated by the formula multiply (the measured round trip time) by ( ( the mode number ) - 100) %, and the adjustment delay time is added to the syncronizing time.

If you choose the automatic delay adjustment, in other words, the mode 101 to 180 is specifed, the recommended mode number is 145 to 165.

The default polling interval 6 (64 seconds) is too short for this mode. The minpoll should be set to greater than or equal to 8 (256 seconds, about 4 minutes).

The interval time is given the value in second power of 2. The minpoll value 12 is 4096 seconds interval (about 1 hour), 14 is 16384 seconds interval (about 4.5 hours), 16 is 65536 seconds (about 18 hours), respectively.

fudge 127.127.40.X flag1 0|1 flag2 0|1 flag3 0|1 flag4 0|1
time1 may specify a constant to be added to the time offset for the time from the receiver, a fixed-point decimal number in seconds.

When mode 100 is specified, time1 may be specified in order to adjust the time offset.

When mode 101 to 180 is specified, time1 should not be specified because this driver adds some percentage of the measured loopback delay, depending on the value of the mode number.

flag1 is the modem dialing type.

Value Description AT Command
0 (Default) Tone ATDWTnn...nn
1 Pulse ATDWPnn...nn

flag2 is the modem error correction type.

Value Description AT Command
0 (Default) Normal AT\N0
1 Auto V42, MNP, Normal AT\N3

flag3 is the modem speaker switch.

Value Description AT Command
0 (Default) Off ATM0Ln
1 On ATM2Ln

flag4 is the modem speaker volume.

Value Description AT Command
0 (Default) Low ATMnL1
1 Middle ATMnL2

phone 042NNNNNNN

The phone number is available at https://jjy.nict.go.jp/.

The number of digits of the phone number is checked. If the international access number and the country number are added in order to call from outside of Japan, the number of digits is over the limit.

The first 2 or 3 digits are checked. The emergency service number and the special service number in Japan are not allowed.

When calling from an extension line, the number for an outside line should be prefix 0, (zero comma). The prefix is also checked, and no other outside access number is allowed.

Interface
RS-232C or USB, 2400 BPS, 8-bits, no parity, 1 stop bit

Modem control commands:

ATE0Q0V1, ATMnLn, AT&K4, AT+MS=V22B, AT%C0, AT\Nn, ATH1, ATDWxnn...nn +++, ATH0

Time code format
Prompt Command Reply
Name{SP}?{SP} TJJY{CR} Welcome messages
> LOOP{CR} Switch to the loopback circuit
(One char.) (One char.)
COM{CR} Exit from the loopback circuit
> TIME{CR} HHMMSS{CR}HHMMSS{CR}HHMMSS{CR} 3 times on second
> 4DATE{CR} YYYYMMDD{CR}
> LEAPSEC{CR} {SP}0{CR} | +1{CR} | -1{CR}
> BYE{CR} Sayounara messages

The date and time are requested separately. The time is requested before and after the date request to check uncertainty of the date whether it’s before or after midnight.

The leap second is not handled, and only written in the clockstats file as information.

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 https://www.nict.go.jp/ (English and Japanese) and https://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

Data Meaning
JJY Information message (This refclock starts or stops.)
--> Sent data
<-- Received data
--- Information message
=== Information 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.