# Crestar remote control operating frequency

I have tried very hard to find the frequency that my remote is using. I've took pictures of the inner board and the remote. Please help or guide me on how I could find the frequency.

• What are you going to do when you find the frequency? Do you have the ability to reverse engineer the communications protocol? – Transistor Aug 30 '17 at 18:48
• 1) Why would you need to know this frequency 2) There's a 4.00 MHz crystal (X1) and an IC (U3). Since that IC will contain a PLL, almost any frequency can be made. 3) Devices like this must operate in a certain frequency band otherwise they could violate regulations. The most used frequencies for these kind of devices is 315 MH, 433 MHz and 868 MHz so take your pick. Also: the transmit frequency should be mentioned in the manual so why not look that up. – Bimpelrekkie Aug 30 '17 at 18:49
• Hey there, well it's for home automation. I'm trying to duplicate the signal with a receiver. And transmit it with my arduino. However, I need to know the specs to know what receiver and emitter I need to get. As for the manual, I can't find the manual. – user859385 Aug 30 '17 at 19:14
• Is there an RF module on the other side of the PCB? – Brian Drummond Aug 30 '17 at 20:00

The 1/4 wave antenna is connected to L2 looks to be about 0.25m long with my ballpark estimate being 200MHz using $\dfrac{2/3c}{ \lambda /4} =f$ for the ballpark estimate.