Setting Up a Radio System from Scratch

The reason why you can find these modules is because 434MHz is an ISM band in some parts of ITU Region 1. You won&#x27;t find an garage door opener there in the US. In the US you should use the 315MHz version which allows for license free use.<p>While 434MHz is in the 70cm amateur band you really should have an ID coming out of this thing when it transmits. All you need to do is shove your call sign out at 20wpm Morse code at the end of your transmission.<p>Otherwise it&#x27;s a cool little hack.

This is really great for both the Amateur Radio community (proper) as well as amateurs of radio concepts. Like a lot of things, computers are becoming more and more things in more and more places. Your grandfather&#x27;s crystal set is today&#x27;s DSP with an Arduino. That&#x27;s just fantastic.

Nice post. For a slightly more comfortable setup the Arduino based JeeNode&#x27;s (<a href="http://jeelabs.org" rel="nofollow">http:&#x2F;&#x2F;jeelabs.org</a>) are worth mentioning. Super low power and quite a nice library.

For frame syncing you can also have a look at Hoffman-Neuman sequences, applying convolution between the expected frame sync sequence and the incomming bit stream.

Is it necessary to periodically transmit? What are downsides to only transmitting on state change?

I thought this would be yet another reference to a sci-fi story where someone is marooned on a planet with nothing, and they use their chemistry knowledge to re-implement enough metallurgy to build a spark-gap radio and get rescuced.

Or use Wifi, Bluetooth, Zigbee, :)