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Tough questions
Tough questions
6:14 PM
@mins
Why not transmit the reference and variable signals as high frequency signals. Why need only 30hz?
 
3 hours later…
mins
mins
8:58 PM
If the two signals have a higher frequency to allow sending them as waves, then to compare the phases (to determine the azimuth) the two signals must have exactly the same frequency. Transmitting two waves on the same frequency is not a valid solution.
This impossibility can be bypassed using complex variants. Measuring a phase difference on high frequency signals is also less accurate. On the other hand modulating a carrier with low frequency signals is straight forward, this is the principle used for almost all transmissions.
 
1 hour later…
mins
mins
9:59 PM
As for why 30Hz, not 70 or 300. Because 30Hz is 60Hz/2 and 60Hz is the public grid frequency in the US. The grid is a very stable reference, it was used to drive a motor with two pairs of poles, thus rotating 30 rounds per second and able to control a variable capacitor to produce the 30Hz sine signal.
 
2 hours later…
Tough questions
Tough questions
11:56 PM
@mins now I got it. Thank you so much.
@mins is the variable signal directional?

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