Radio Timecode Sync

Generate JJY, BPC, DCF77, MSF, or WWVB radio timecode audio locally to help sync compatible radio-controlled clocks.

Signal
Choose the time signal that matches your clock region.

Kyushu station for Japanese standard time.

Playback: Signal is stopped

Audio output
Start low and raise only as needed for the clock receiver.
30%

Adjust in milliseconds if your system clock or audio path needs correction. (ms)

Carrier
60,000 Hz
Output tone
15,000 Hz
Low pulse level
10%
Live preview
Preview follows the selected station and local system clock.
Station time
01/01/2000, 09:00:00
Time zone
Asia/Tokyo
Current symbol
M

Next symbols

+0sM
+1s0
+2s0
+3s0
+4s0
+5s0
+6s0
+7s0
+8s0
+9sM
+10s0
+11s0
Operating notes
  • Keep output volume low and do not wear headphones while transmitting; high-frequency square-wave audio can be uncomfortable.
  • The signal is generated offline from this device's system clock.
  • The browser emits a lower-frequency harmonic approximation, so results depend on the speaker or wired headphone driver, clock model, antenna alignment, and placement.
  • JJY voice call sign minutes are not simulated.

What Radio Timecode Sync Does

Radio Timecode Sync generates browser audio that follows common long-wave radio time signal formats: JJY, BPC, DCF77, MSF, and WWVB. It is useful when a compatible radio-controlled clock cannot receive the real transmitter indoors, or when you want to test how a clock reacts to a known station format.

How to Use It

Select the station that matches the clock, then place the clock’s antenna area close to the device speaker or a wired headphone driver. Start with the built-in speaker; if the clock does not detect the signal, try over-ear headphones and rotate the clock to improve coupling. Keep the volume low and do not wear headphones while transmitting.

Accuracy and Limitations

The generated time comes from this device’s system clock plus the optional offset, so synchronize the device clock before using the tool. Browsers cannot emit the real long-wave carrier directly; this tool uses a lower-frequency square-wave approximation that may work through harmonics on some devices. Hardware, speaker or headphone driver placement, antenna alignment, and clock firmware all affect results, and JJY call sign audio is intentionally omitted.