16/07/05: Is there an easier way to find Aliens?
The SETI project works by using software to search for signals. This is pretty complex stuff as you not only need to tune into a specific frequency but you also need to take account of the Earth’s rotation and the rotation of any planet the signal is originating on. As the world rotates any signal will move up or down in frequency (Doppler-shift) depending on whether we are rotating towards or away from the source.
I think there might be an another way:
Rather than looking for a specific signal at a specific frequency, just look for the presence or absence of any signal.
You do this by taking the original signal and flipping all the negative components so they become positive, a process called “full-wave rectification”. To then use a filter to search the signal looking for DC components.
This process has a number of advantages:
Because the system is not looking for an exact frequency, it will pick up any signal. This means you do not need to test at different frequencies.
Rotation of the planets is no longer an issue as the system is not looking for exact frequencies, they can drift as much as they want as it simply doesn’t matter.
This system requires vastly less computation power than searching for exact frequencies and trying to find an exact match with an exact Doppler shift.
Such a system could be used to make communication easier, you could broadcast the same signal on multiple frequencies simultaneously and the system will effectively sum them for you making detection of weak signals much easier.
Listening to: Jeff Wayne: War of the Worlds