I looking to build a phase meter/measurement (even led's lighting up🙂).
Now ideally this would be based around a chip solution.
There is a nice cheap accurate log amp AD8307 but I cannot see how to easily make that into a phase measurement block.
Accurate Gain/Phase Measurement at Radio Frequencies up to 2.5 GHz | Analog Devices
without a multiplier. this is the chip AD8302 AD8302 Amplitude Phase Detection Module 2.7GHz RF/IF Phase Detector 5V-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Groupthey describe but would it be any good in the audio range and are there better ways to do this?
Any chip circuits maybe pulled from ac measurement devices would be good.
Now ideally this would be based around a chip solution.
There is a nice cheap accurate log amp AD8307 but I cannot see how to easily make that into a phase measurement block.
Accurate Gain/Phase Measurement at Radio Frequencies up to 2.5 GHz | Analog Devices
without a multiplier. this is the chip AD8302 AD8302 Amplitude Phase Detection Module 2.7GHz RF/IF Phase Detector 5V-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Groupthey describe but would it be any good in the audio range and are there better ways to do this?
Any chip circuits maybe pulled from ac measurement devices would be good.
Phase of what? Amplifier or loudspeaker phase vs frequency? Phase between voltage and current on the AC line? For each specific task there are separate solutions.
Set a two channel scope to X-Y. Connect one channel to output A the other to output B of the stereo. A mono signal should result in a 45 degree line across the screen. ANy difference between channels will blossom the trace out into patterns. That was one methode of aligning a tape head for azimuth. Adjust azimuth for least deviation from the 45 degree line.
For audio range, and assuming the two signals are reasonably coherent, the phase-comp II of a a CD4046 would be an excellent choice: first remove any amplitude information on the inputs by using clipping limiters, like LM339 comparators, then compare the filtered output of the φ-comp to the voltage of a mid-supply divider. This operation can be done with almost any arbitrary resolution, provided the divider is trimmed according to a known phase source.
The zero will always be inherently calibrated, thanks to the properties of φ-comp II.
Both chips are dirt-cheap commodities, you don't need to pull them out of any equipments: just buy them, they are so cheap that even obsessional fakers wouldn't be interested
Previous replies point to phase comparators used in PLL ( phase locked loops ).
This is definitively in this technology the place to look for to find about how to design phase compare.
So, search for PLL design, application notes and circuit datasheets.
This is definitively in this technology the place to look for to find about how to design phase compare.
So, search for PLL design, application notes and circuit datasheets.
Have a look at the Op/Service manual for the HP3575A Gain-Phase meter. You can download the manual directly from Keysight: https://www.keysight.com/en/pd-3575...r?pm=PL&nid=-536900197.536897310&cc=CA&lc=eng
Tom
Tom
Are we talking about phase between signals that are periodic at the same frequency ?
Because I saw something about two channels may be this relates to delay between audio on different channels. Because audio is non periodic, I do not think phase compare as used in PLL is applicable.
For periodic signals you firstly need some conditionning of those. An appropriate conditionning depends of the kind of signals.
Signals easy to phase compare are square signals of the same amplitude and cyclic ratio, then a XOR function gives a signal that has a mean value representing the phase.
A phase comparator I used for a PLL which required a very low phase noise was based on a ramp derived from the first signal, sampled and held at an edge of the second signal.
A trick was to stop the ramp rise during the sample pulse.
So the DC from the sample and hold was a clean, instant signal giving the phase.
Because I saw something about two channels may be this relates to delay between audio on different channels. Because audio is non periodic, I do not think phase compare as used in PLL is applicable.
For periodic signals you firstly need some conditionning of those. An appropriate conditionning depends of the kind of signals.
Signals easy to phase compare are square signals of the same amplitude and cyclic ratio, then a XOR function gives a signal that has a mean value representing the phase.
A phase comparator I used for a PLL which required a very low phase noise was based on a ramp derived from the first signal, sampled and held at an edge of the second signal.
A trick was to stop the ramp rise during the sample pulse.
So the DC from the sample and hold was a clean, instant signal giving the phase.
Might be useful to know exactly what he thinks he needs to measure and why. Measuring 'phase' between two stereo channels will tell you little more than whether they are in fact stereo or mono.
I've ordered that module £3.20 AD8302-Amplitude-Phase-Detection-Module
and eventually when it arrives I'll get back hopefully with some results. It's dc to 2GHz so its probably rubbish at 1-40khz datasheet shows not much. We'll see in a month or so
and eventually when it arrives I'll get back hopefully with some results. It's dc to 2GHz so its probably rubbish at 1-40khz datasheet shows not much. We'll see in a month or so
There's an SSL phase meter that was a simple pointer style meter that would tell you the relative correlation between the left and right channels. It's an indication of overall stereo width, and it's sometimes useful to a mix engineer to know how 'wide' the mix is, not for any sort of metrology type issue, but again to understand how wide the mix is. It's basically a ratio of L-R energy to L+R energy, and it was built with a few CD4000 series XOR chips and some resistor summing to generate a single voltage to drive the 'phase' meter display. Not such a conceptually complex meter, and it was built only with rectifiers and XOR circuits with some post summing, but it seemed to be useful to put next to the normal L and R level meters.
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