Hi.
To measure phase noise of crystal oscillators by using two generators.
Signals from the test oscillator and heterodyne oscillator are fed to the mixer. The difference between the frequencies of 20-40 kHz generators optimally. The signal output from the mixer is input to the sound card. The figure in the upper window, the spectrum of the signal of the crystal oscillator in the lower window range phase noise. Alternative to expensive devices for measuring phase noise.
Hello Sergei,
Very interesting stuff.
I love also the oscillometerz software, a pity that the eval version work only few seconds.
Could you explain a little more your setup, and if possible post some pictures ?
would be very interested to try this.
What do use as heterodyne oscillator ? I suppose his own phase noise must be very clean.
Could you give some details ? I'm sure that many here will be very interested.
Best regards.
Frex
Very interesting stuff.
I love also the oscillometerz software, a pity that the eval version work only few seconds.
Could you explain a little more your setup, and if possible post some pictures ?
would be very interested to try this.
What do use as heterodyne oscillator ? I suppose his own phase noise must be very clean.
Could you give some details ? I'm sure that many here will be very interested.
Best regards.
Frex
Hi.
The oscillator circuit is very simple. One element UN-buffered logic. Required selection of the capacitors and resistor on the fact minimum phase noise.
The figure scheme of the mixer. I like this scheme including for measuring intermodulation distortion. The mixer may be different.
The measurement technique was tested on a reference Agilent E5052B. Measured phase noise of the same generators. Compare the link.
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In the program menu You can select the measurement function phase noise or amplitude noise of the signal. Good luck.
The performance of your simple oscillators is close to the current state of the art. Here is an example: BTULN | You will see -148 at 100Hz and -168 at 1 KHz for a 23 MHz oscillator. I'm really impressed. More info on the crystal may help understand how you got such performance from a very simple oscillator.
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Hi.
I will try to explain. As the active element of the selected inverter with a very small intrinsic noise.
http://www.onsemi.ru.com/pub/Collateral/NC7WZU04-D.pdf
Recommendations for use recommended chip resistors 2-10 Mω and capacitors 20-30 pF. As a result of experiments picked up the resistors to 3 K Ohm, capacitors 180 - 1500 pF, depending on the type of quartz. In the result, the phase noise is reduced to -10 to -30 dB from the initial variant. In the photo the generators.
http://www.cqham.ru/forum/attachment.php?attachmentid=137368&d=1365179326
To check ADC AK5394A used generators in operational amplifiers 10 kHz. In the figures the spectra of phase noise in green, the spectrum of the amplitude noise in red.
http://www.cqham.ru/forum/attachment.php?attachmentid=268672&d=1502614050
http://www.cqham.ru/forum/attachment.php?attachmentid=268673&d=1502614260
I hope that the measurements of phase and amplitude noise signals will help participants to improve their designs.
AndrewT
Hi.
Board ADC/DAC imposed on the long cable and shielded. Bought three copies of the E-MU 1212m. Sound card V1 had a smaller -6 dB of dynamic range compared to V2 . Measurement with a sound card V2. Most likely I don't have a map better than others, and test signals generated by the quartz oscillators may be better ratio signal/noise than generated by the operational amplifiers. Do you think that it is better to create a new topic on the issues?
Hi.
Board ADC/DAC imposed on the long cable and shielded. Bought three copies of the E-MU 1212m. Sound card V1 had a smaller -6 dB of dynamic range compared to V2 . Measurement with a sound card V2. Most likely I don't have a map better than others, and test signals generated by the quartz oscillators may be better ratio signal/noise than generated by the operational amplifiers. Do you think that it is better to create a new topic on the issues?
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Here are some relevant threads
The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
Building a phase noise measurement system for digital audio
I read through some of the Russian thread on oscillators. it was quite interesting.
The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
Building a phase noise measurement system for digital audio
I read through some of the Russian thread on oscillators. it was quite interesting.
I used 1212m for measurements of intermodulation distortions of RF mixers. The frequencies are 7 MHz.
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What I use is as follows:
One strip for input routed directly from hardware to input wma or asio. Set gain to 0 and the link is direct. Bypass soft limiting.
Do the same for output. The hardware gain setting shifts between -10 and +4. Inputs are differential so you can minimize ground noise. Opamp upgrades to lme497xx do help. There are other potential mods but without docs i would hold off.
The RTX6001 is better but its not a simple task to improve on the 1212m or 1616m.
One strip for input routed directly from hardware to input wma or asio. Set gain to 0 and the link is direct. Bypass soft limiting.
Do the same for output. The hardware gain setting shifts between -10 and +4. Inputs are differential so you can minimize ground noise. Opamp upgrades to lme497xx do help. There are other potential mods but without docs i would hold off.
The RTX6001 is better but its not a simple task to improve on the 1212m or 1616m.
