Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Phase/Magnitude Detector Posted: Sun Oct 14,
2007 10:41 am
Joined: Sun Oct 14, 2007
I am looking for a simple phase
magnitude circuit. I have a few references which have a straight forward
solution for obtaining the magnitude but the phase seems to be overly
complicated (involving a diode ring modulator).
Posted: Tue Oct 16, 2007 3:57 am
Fri Feb 17, 2006 12:07 pm
Location: London UK
If you can down-convert the channels to HF (maybe the signal
frequency is already <50MHz?) then an XOR logic followed by an integrator
will measure phase fairly accurately. With the two channels squared
off to logic levels and fed to a 74LS exclusive OR, the output will
contain a narrow spike when the channels are in phase, and will be a
logic 1 when they are 180 out of phase. Any in-between state gives a
pulse whose width is proportional to the phase difference. The integrator
is a pulse width to analog level low-pass filter.
Post subject: Posted: Tue Oct 16, 2007 4:34 am
Joined: Sun Oct 14, 2007 10:35 am
That's a beatiful solution... very simple!
One more issue
though... this would give a good indication as to when the phase angle
is zero however, it does not give an indication as to wether it's lagging
or leading. I can't think of an easy method to accomplish this. I could
always calculate the time between the voltage and current peak but this
becomes not trivial. Any suggestions?
FYI, the frequency is