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Building a phase noise measurement system for digital audio
Building a phase noise measurement system for digital audio
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Old 28th February 2018, 08:30 PM   #61
jdlvfr is offline jdlvfr  France
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Location: par la
On the software side I am using Linux, a dirty hack of JAAA from LinuxAudio-Downloads for the FFT analyser. Hacked to have a log display for frequency axis and to extend analysis bandwith down to 0.01Hz.
SISCO : LV2 Plugin Documentation to visualize the signal in time domain.
A PUREDATA patch to remove DC component and Jack the sound server to connect all this together.

If any interest I can give the dirty hacked sources of jaaa.

JoŽl
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Old 28th February 2018, 10:01 PM   #62
gerhard is offline gerhard  Germany
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Mr. Riley is the author of the stable32 program that is the industry standard for analyzing
oscillator stability. Now that he is retired, stable32 is available for free btw.

He also has written some interesting papers on hands-on hardware that can be
duplicated by hobbyists.

< http://www.stable32.com/A%2010%20MHz...L%20Module.pdf >

There is also a homebrew phase noise test set by Bernd Kaa, DG4RBF.
It appeared in UKW-Berichte issue 4/2015, 1/2016, 2/2016 in German.

It probably also appeared in "VHF communications" in English, that is a
sister publication. I have a printout of the german version, that may
stem from a .pdf. Bernd Kaa's web site is
< Messgeršte im Eigenbau - Home-Page von DG4RBF >

Also from this posse:
< http://www.bymm.de/documents/39/Phas...ment_V1_20.pdf >
< Miscellaneous Project documents > (Riley)
< Phasenrauschen von Oszillatoren messen > (German)

I have also done an oscillator board in the Riley style that can sloooow lock an
xtal oven to a, say, GPS reference, It can accomodate MTI 260 ,
Morion MV89A or HP 10811 oscillators.
Also a phase detector board that is not far away from Wenzel, or really HP3048.
Everything is switched with reed relays, that blows up the hardware somewhat,
it looks more difficult than it is.

But it In the last years I had no real interest to finish that since I had excessive
exposure to that stuff in the daytime job and easy access to an E5052B.

regards, Gerhard
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Old 5th March 2018, 07:55 AM   #63
gentlevoice is offline gentlevoice  Denmark
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Building a phase noise measurement system for digital audio
@jdlvfr: Hi JoŽl ... This is just a brief message to say that I have seen your (interesting) posts and would like to give them & this subject more attention in due time. Personally I am, however, in these days looking into some amplifier circuits so I do not have the time to pick up on this right now. But I do look forward to doing so hopefully in not too long.

To this end: Do you have a link to the Morion oscillator (oscillator"s" - more than one I assume?) you used for calibration?

I reckon/assume you may also have posted your ADC design as a reply to my sentence:

Quote:
I a.o.t. need a good-enough ADC to input the DC-Receiver's output to my PC
As it is, however, I have already made a PCM4202 ADC - only the ADC "was lost" due to a mishap - so I am waiting for a replacement. In any case - if you posted your design as a help to me then many thanks

Cheers,

Jesper
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Old 8th March 2018, 02:09 PM   #64
jdlvfr is offline jdlvfr  France
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Hi Jesper,

Morion MV89A comes from ebay, my choice was the cheapest seller. Sellers doesn't measure phase noise!

I think calibration should be done with the final oscillators, MV89A are 10MHz. But it's a good idea to first check the measurement system with known OCXO.

JoŽl
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Old 9th March 2018, 06:37 AM   #65
gentlevoice is offline gentlevoice  Denmark
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Building a phase noise measurement system for digital audio
Quote:
Morion MV89A comes from ebay, my choice was the cheapest seller. Sellers doesn't measure phase noise!

I think calibration should be done with the final oscillators, MV89A are 10MHz. But it's a good idea to first check the measurement system with known OCXO.
Thanks JoŽl ... I will check it out.

Bonne journťe,

Jesper
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Old 9th March 2018, 06:56 PM   #66
gerhard is offline gerhard  Germany
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Quote:
Originally Posted by jdlvfr View Post
Thank you, now I can name the colours! I already knew the sky is yellow and the sun is blue. Or something like that, not really sure, maybe it depends on days...?
There was a French guy some 150 or 180 years ago who deduced that his
color vision was different from that of other people from the color of flowers
as seen by candle light vs. direct sun light.

Impressive achievement.

Gerhard
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Old 9th March 2018, 07:42 PM   #67
gerhard is offline gerhard  Germany
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Quote:
Originally Posted by jdlvfr View Post
Hi Jesper,

Morion MV89A comes from ebay, my choice was the cheapest seller. Sellers doesn't measure phase noise!
The MV89As that I got from ebay are in a quite questionable condition.
Lots of scars, like they have been removed from their old home with
hammer & chisel.

BTW. I have cleaned up the control software for the Agilent 89441A.
It is a 1.9MB zip, including the 89441A GPIB manual. The program itself
is only a few pages of C. Email me if interested.

Having seen the creation date of the phase detector board above, I have
concluded that it's about time to complete my own phase noise tester.
Last weekend I have done most of the mechanical construction. It is quite
large because of the amount of Aircell coax cable needed & the relays
for the switchable delay line. It will be 2 channel so I can use the 89441A
for cross correlation.
The amplifier after the ring mixer is based on an earlier design of mine
using an IF3602 JFET. Ring mixers are SRA-3H since I had them.
The open box in the open box is one of the ring mixer/preamp assemblies.
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"That's right!" shouted Vroomfondel, "we demand rigidly defined areas of doubt and uncertainty!" "We don't demand solid facts! What we demand is a total absence of solid facts. I demand that I may or may not be Vroomfondel!"

Last edited by gerhard; 9th March 2018 at 07:46 PM.
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Old 14th March 2018, 08:34 AM   #68
maxidcx is offline maxidcx  France
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all of that is really good and inspirational. congrats !

jdlvfr, did you mention how you solved the VCXO ? are you using the one proposed by Rutgers or ?
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Old 14th March 2018, 09:13 PM   #69
jdlvfr is offline jdlvfr  France
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Quote:
Originally Posted by maxidcx View Post
all of that is really good and inspirational. congrats !

jdlvfr, did you mention how you solved the VCXO ? are you using the one proposed by Rutgers or ?
No, I build two identical oscillators both with varicap for vfc. One vfc is connected to the pll output, the other one is grounded.

Ideally the reference oscillator should have better phase noise than the dut. If not, measurement gives the values of the worst one or if both are of same phase noise one should remove 3dB to measurement.
So by default I remove 3dB to accommodate worst case.

I have plan for cross correlation, maybe one day...

JoŽl
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Old 18th March 2018, 12:57 PM   #70
andrea_mori is offline andrea_mori  Italy
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Building a phase noise measurement system for digital audio
jdlvfr, jborden, miklos, AverPaul,maxidcx, Gerhard
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