What is the purpose of heterodyning in radio astronomy?

[NGC]

Hello all,

I'm aware that heterodyning is a radio signal processing technique as kindly explained by the Wiki article on the topic (http://en.wikipedia.org/wiki/Heterodyne).


However I don't understand how radio astronomers use this technique to aid their observations, what sort of analysis can they do with f1-f2 and/or f1+f2?


Thank you in advance,

Peter

 

[Astrofan]

Hello all,

I'm aware that heterodyning is a radio signal processing technique as kindly explained by the Wiki article on the topic (http://en.wikipedia.org/wiki/Heterodyne).


However I don't understand how radio astronomers use this technique to aid their observations, what sort of analysis can they do with f1-f2 and/or f1+f2?

For higher frequencies, it is not directly convertible to electronic (digital) signals, the heterodyne technique lowers the frequency by utilizing the method of mixing. As you can see, by mixing the signal with the local oscillator creates f1-f2 and f1+f2; the f1-f2 term is the one that is being used and the f1+f2 will cause noise so it is just filtered out.

 

[NGC]

For higher frequencies, it is not directly convertible to electronic (digital) signals, the heterodyne technique lowers the frequency by utilizing the method of mixing. As you can see, by mixing the signal with the local oscillator creates f1-f2 and f1+f2; the f1-f2 term is the one that is being used and the f1+f2 will cause noise so it is just filtered out.

Thank you!

Do you know whether heterodyning involve any advantages to processing the data since the technique lowers the frequency?


Peter