Telephone JJY: Additional Information
The Telephone JJY service was terminated on March 31, 2024. The information on this page is kept for reference and historical purposes.
Supported commands
The commands listed below can also be seen in the terminal with the HELP or ? command. Send CR by pressing the enter key after the command string. The response will also be followed by CR.
Commands can be abbreviated to the first two or three characters, such that TIME can be sent as TI or TIM. Note that some commands are ambiguous when abbreviated to two characters, such that LO will be treated as LOOP, and executing the LOCAL command requires LOC to be sent. Commands and responses (except for INFO) are ASCII encoded, and commands work in either upper or lower case.
In the response format, hh, mm and ss are the hours, minutes and seconds respectively. DD and MM are the day and month. YYYY is the four-digit year, while YY is the last two digits of the year. 🛆 shows a space. Date and time are returned as Japan Standard Time unless noted otherwise.
| Command | Function |
|---|---|
| TIME | Sends Japan Standard Time for 3 seconds, returns hhmmss |
| JST | Continuous transmission of Japan Standard Time, returns hh: mm: ss continuously until CR is sent. |
| UTC | Continuous transmission of Coordinated Universal Time, returns hh: mm: ss continuously until CR is sent. |
| DATE | Send date,returns YYMMDD |
| UDATE | Sends the date in Coordinated Universal Time, returns YYMMDD |
| DJAP | Send date in Japanese format, returns YY / MM / DD |
| DUSA | Send date in American format, returns MM / DD / YY |
| DEUR | Send date in European format, returns DD-MM-YY |
| 4DATE | Send date, returns YYYYMMDD |
| 4UDATE | Send the date as Coordinated Universal Time, returns YYYYMMDD |
| LEAPSEC | Leap second adjustment. Indicates if standard time will be adjusted by adding or subtracting a leap second at the next 9:00 Japan Standard Time, returns 🛆0 if there is no change +1 if a leap second will be inserted -1 if a leap second will be removed |
| LOCAL | Time difference from Coordinated Universal Time, returns +09 during normal time +10 during daylight saving time |
| SUMMER | Daylight saving time period, returns 0000, 0000 if daylight saving time is not applied, otherwise MMDD, MMDD for start and end of the daylight saving time period |
| LOOP | Enter loopback mode for delay measurement |
| COM | Exit loopback mode |
| INFO | Information display |
| HELP or ? | Display a list of available commands in English |
| BYE or END | Log off. Please use this command to terminate the connection. |
Communication settings
| communication method | synchronous full duplex |
|---|---|
| communication speed | |
| connection mode | non MNP |
| data length (characters) | 8 bit |
| start bit | 1 bit |
| stop bit | 1 bit |
| parity | none |
| flow control | Xon / Xoff |
| local echo | none |
| character encoding | Shift JIS or JIS |
| Enter key sends | only CR, no LF |
| Handle received CR | as CR only, no LF |
In the interest of timing accuracy, the use of error correction protocols is not recommended. However, if poor line conditions result in garbled characters, the following protocols are available. Please note that the following delays will be added in addition to the normal line delay:
| MNP4 | approximately 10ms |
|---|---|
| V.42 | approximately 12ms |
| MNP5 | approximately 52ms |
| V.42bis | approximately 6 to 50ms (varies greatly) |
Transmission control codes:
| CR (return) | 0Dh |
|---|---|
| LF (line feed) | 0Ah |
| Xon (resume) | 11h |
| Xoff (stop) | 13h |
Synchronization with the time signal
The transmitted time data refers to the end of the transmitted signal. The final data frame contains the carriage return code CR, and the trailing edge of the stop bit in this final data frame marks the synchronization point with NICT's internal one-pulse-per-second (1PPS) signal.
The reference point is the input port of the transmission modem, and the receiver needs to correct for the additional delays resulting from the transmission delay and the instrument delays of the transmitting and receiving modems.
