In Japan there are radio-controlled clocks. Time is synchronized by 40khz (in west Japan) and 60khz (in east Japan) radio, which is broadcast from transmission towers. The signal is known as JJY:
After the earthquake in 2011, the tower in the east Japan was collapsed. Time synchronization in the east Japan is affected. Hence, someone Japanese has made a simulators and shared on the Internet.
I am from Hong Kong. I have a radio-controlled watch and clock bought from Japan. I want my devices to be synchronized. There are iOS and Android app JJY-simulators. I have tried some of them. This one works well:
The principle behind is, using time from NTP server, emulating the JJY signal, sending out through 3.5mm audio port.
Now I want to implement the emulator on a Raspberry-Pi. There are some tutorials found on the Internet. Below is the one I am following to:
Instead of the source-code in the tutorial, I use this one: https://github.com/snt/rpi_jjy_server
I have made the circuit following the tutorial:
However, most of the time my watch does not read any signal. If there is signal, the signal status is "low", and eventually the time-sync is failed. (For the Android-app one, my watch can read a "high" signal.)
Note: I am using Toshiba 2SC1815-GR transistor, 30k ohm resistors, which are suggested in the Git-hub article. And a telephone-line made antenna.
I have tried using a 9V battery replacing the 5V Raspberry-Pi power source. But it does not help.
My knowledge on electronic is very limited. Please kindly forgive me if I have asked silly questions or made silly mistakes. Could anyone please point out if I am made anything wrongly? Or, by what means could I boost the signal from the antenna?
Great appreciation for any help!