1. Synopsis

Name: jjy
Reference ID: JJY
Serial Port: /dev/jjyu; See corresponding receiver

2. Warning

Some modes of this driver report only two-digit years, and are thus reliant on the system clock to be near correct before samples will be processed properly. You will not be able to use them to run autonomously, nor will it reliably recover from a trashed or zeroed system clock.

3. Description

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

SEIKO TIME SYSTEMS INC. TDC-300

C-DEX Co.,Ltd. JST2000

Telephone JJY

Echo Keisokuki Co.,Ltd. LT-2000

CITIZEN T.I.C. CO.,LTD. JJY-200

Tristate Ltd. TS-GPSclock-01

  • Tristate Ltd. TS-JJY01, TS-JJY02 https://www.tristate.ne.jp/ (Japanese only)

    NTP configuration (ntp.conf)
    refclock jjy unit X subtype 1 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. You may specify the time offset from several tens of milliseconds (0.0NN seconds) to a hundred and several tens of milliseconds (0.1NN seconds) for this clock.
    flag1 has no effect for time synchronization. When flag1 is set to 1, status commands are issued before DATE and STIM commands, and write a response text into the clockstats file.

    0 (Default)

    DCST and STUS commands are not issued

    1

    DCST and STUS commands are issued
    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.

  • C-DEX Co.,Ltd. JST2000 http://www.c-dex.co.jp/ (Japanese only)

    NTP configuration (ntp.conf)
    refclock jjy unit X subtype 2 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}

  • Echo Keisokuki Co.,Ltd. LT-2000

    NTP configuration (ntp.conf)
    refclock jjy unit X subtype 3 time1 0.NNN
    Interface
    RS-232C, 9600 bps, 8-bits, no parity, 1 stop bit
    Time code format

    Command

    -->

    Reply

    C

    -->

    (Subtype 2: Continuous)

    (Every second before 0.5 second)

    YYMMDDWHHMMSS{ST1}{ST2}{ST3}{ST4}{CR}

    #

    -->

    (Subtype 1: Request & Send)

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

  • CITIZEN T.I.C. CO.,LTD. JJY-200 http://www.tic-citizen.co.jp/ (Japanese only)

    NTP configuration (ntp.conf)
    refclock jjy unit X subtype 4 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}

  • Tristate Ltd. TS-GPSclock-01 https://www.tristate.ne.jp/ (Japanese only)

    This driver supports the Tristate TS-GPSclock-01 in command/response subtype, 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 JUST time zone.

    Besides this driver, the generic NMEA GPS driver supports the TS-GPSclock-01 in NMEA mode.

    NTP configuration (ntp.conf)
    refclock jjy unit X subtype 5 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 a flag1 is set to 1, status command is issued before DATE and TIME commands, and write a response text into a clockstats file.

    0 (Default)

    STUS command is not issued

    1

    STUS command is issued
    Interface
    USB (/dev/ttyACM_0_)
    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}

    time{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.

  • SEIKO TIME SYSTEMS INC. TDC-300 https://www.seiko-sts.co.jp/ (English and Japanese)

    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)
    refclock jjy unit X subtype 6 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 mSec. before second)

    -->

    {STX}{xE5}{ETX}

  • Telephone JJY http://jjy.nict.go.jp/ (English and Japanese)

    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 subtype, the telephone JJY, can not be used with the refclock_modem driver at the same time. Because the phone statement in the configuration file is not involved with the server statement, so the both the refclock_modem and this refclock_jjy (subtype 100 to 180) can not recognize the appropriate phone statement among the phone statements.

    NTP configuration (ntp.conf)
    refclock jjy unit X subtype (100, 101 to 180) minpoll N (N >= 8)

    The subtype 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.

    The subtype 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 Telephone JJY loopback circuit.

    The round trip time through the Telephone JJY loopback circuit is measured 5 times, and each delay time is greater than 700 milliseconds, 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 subtype number) - 100) %, and the adjustment delay time is added to the synchronizing time.

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

    The default polling interval 6 (64 seconds) is too short for this subtype. 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.

    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 the subtype 100 is specified, the time1 may be specified in order to adjust the time offset. When the subtype 101 to 180 is specified, the time1 should not be specified because this driver adds some percentage of the measured loopback delay, depending on the value of the subtype number.

    Table 1. Flag1 is the modem dialing type

    0 (Default)

    Tone

    ATDWTnn...nn

    1

    Pulse

    ATDWPnn...nn
    Table 2. Flag2 is the modem error correction type.

    0 (Default)

    Normal

    AT\N0

    1

    Auto V42, MNP, Normal

    AT\N3
    Table 3. Flag3 is the modem speaker switch.

    0 (Default)

    Off

    ATM0Ln

    1

    On

    ATM2Ln
    Table 4. Flag4 is the modem speaker volume.

    0 (Default)

    Low

    ATMnL1

    1

    Middle

    ATMnL2
    phone 042NNNNNNN

    The phone number is available at http://jjy.nict.go.jp/time/teljjy (Japanese and English)
    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.

    Calling from 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}

    >

    -->

    TIME{CR}

    -->

    HHMMSS{CR}HHMMSS{CR}HHMMSS{CR} 3 times on second

    >

    -->

    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.

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

The user is expected to provide a symbolic link to an available serial port device:

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 with this symbolic link:

ln -s /dev/ttyUSB0 /dev/jjy0

4. 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
Table 5. Mark of the clockstats record

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

5. Driver Options

unit number

The driver unit number, defaulting to 0. Used as a distinguishing suffix in the driver device name.

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.

subtype

Used to select a device type and serial parameters.

mode

Synonym for subtype, retained for backward compatibility.

path filename

Not used by this driver.

ppspath filename

Not used by this driver.

baud number

Not used by this driver. The subtype implies the baud rate.

6. Configuration Examples

See the examples in the Description section.

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