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previous: moocow Nope, the coils are off by 180 degr... -- 9/19/2004 6:14 PM view thread

Re: Phase Angle

9/24/2004 1:34 AM
Joe Gwinn
Re: Phase Angle
One can implement 90-degree phaseshifts with passive components, if one gives up on mathematical exactitude. The typical design is a number of RC networks in series, or what is called an "all-pass" network. It cannot be done in a single stage, which is what the mathmeticians are talking about. Nobody uses Hilbert transforms to do this in analog hardware. For more information, look into the Radio Amateur's Handbook chapter describing the "phasing" method of SSB (single-sideband) signal generation, in the part describing how to generate the 90-degree shifted voice signal. Practical phaseshift networks and circuits are described.