As promised.......the Phase Noise Files..... - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st April 2003, 05:21 AM   #1
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default As promised.......the Phase Noise Files.....

Here are some recordings of the phase noise of the oscillator in the SAA7220.......one of my all time favorite parts.

[Snicker, snicker.........]

As I have been ill the last few days, and don't feel like thinking up another clever April Fool's Joke, this will have to suffice. But make no mistake.......these recordings are for real.

Now......if we can get Phred to upload the X-Files theme........

First off.........a recording of the SAA7220 in a CDB-472, stock configuration. The reference oscillator is one of the low-noise jobbies that I have posted here. Note all the line related crap, as this player has tons of ground loops.
Attached Files
File Type: zip 472_a.zip (82.2 KB, 199 views)
  Reply With Quote
Old 1st April 2003, 05:23 AM   #2
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Now......the same chip, but with a 7805, being fed by a 7815 to get rid of the nasty ground loop. Quieter, but you can hear the phase noise on this one.
Attached Files
File Type: zip 472_b.zip (78.1 KB, 114 views)
  Reply With Quote
Old 1st April 2003, 05:26 AM   #3
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
As above, but with the 7805 replaced by a low-noise regulator of my design. A little bit quieter, but not much.
Attached Files
File Type: zip 472_c.zip (78.7 KB, 117 views)
  Reply With Quote
Old 1st April 2003, 05:30 AM   #4
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default For reference...........

Here is the phase noise of one of my oscillators.

It is recoreded at 10 dB higher in level.

Moral of the story:

Use a good oscillator for your clock.

And a quiet regulator.

Get rid of ground loops.

Make a separate distribution scheme. Do not use the internal buffer in the filter chip to distribute the clock signals.

I'm really sick today.......so "forget you guys.....I'm going home......"

Jocko
Attached Files
File Type: zip jocko.zip (76.2 KB, 175 views)
  Reply With Quote
Old 1st April 2003, 11:04 AM   #5
HpW is offline HpW  Switzerland
diyAudio Member
 
Join Date: Mar 2002
Location: Switzerland (Bern)
Default the FFT pictures of the waves above...

red : 472_a
aqua : 472_b
yellow : 472_c
green: Joko

enjoy....

HpW
Attached Images
File Type: gif jocko.gif (16.4 KB, 790 views)
__________________
www.hpw-works.com
  Reply With Quote
Old 1st April 2003, 12:25 PM   #6
ALW is offline ALW  United Kingdom
diyAudio Member
 
Join Date: Jun 2001
Location: UK
Default Excellent stuff

Jocko,

Thanks for taking the time out from your sick bed to post those - excellent stuff.

Were the phase noise measurements made using readily available methods?

I've been thinking about comparing to a known 'good' oscillator (by mixing, and gathering the data via a sound card), but haven't got my head around the effects of non-ideal behaviour in the reference clock on the output signal (mathematically). I think it's simple and will just limit the ultimate measurement noise floor?

I know self-triggered measurements (e.g. on a 'scope) give misleading results based on timebase settings.

Andy
  Reply With Quote
Old 1st April 2003, 02:19 PM   #7
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
The graphs may be somewaht misleading, as the tape recorder used intorduced some noise, and I had to bandlimit things to get the file size under 100k.

The real noise of my oscillator is not even on the scale on my RTA, whereas the SAA7220 stands out like a sore thumb. Remember, I amplified mine 10 dB so that it would not be drowned out by the noise floor of the cheap tape recorder.

The way it is done........a known good oscillator is phase locked to the unit you want to test. Both are then fed into a double-balanced mixer.

I might make some plots on my H-P FFT, but I don't think that they would scan OK.

Yes, I am really am sick today, but I could not let April 1 pass without doing something out of the ordinary. Feel free to ask any questions, but I may not answer right away.

Jocko
  Reply With Quote
Old 1st April 2003, 02:22 PM   #8
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default The more I look at those graphs.......

Yeah, the tape deck has really skewed stuff. The noise hump around 180- 500 Hz on the stock unit doesn't show up as well. I'll have to come up with a better way of displaying this stuff.

Jocko
  Reply With Quote
Old 1st April 2003, 02:58 PM   #9
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default FFT plots......

The top plot is the SAA7220, with the low-noise regulator.

Bottom plot is my oscillator. The hump at 41 Hz seems to be the noise contribution of the PLL, as that is close to the natural frequency that I calculated.

Basically, mine is 20 dB lower noise.

Jocko
Attached Images
File Type: jpg phasenoi.jpg (18.5 KB, 707 views)
  Reply With Quote
Old 1st April 2003, 03:01 PM   #10
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
Default SE Objective Mode

I downloaded the 'jocko.zip' file and I could not hear anything, so therefore you are a fraud Jocko.

Eric / - Only jocking.

What sonic differences do you hear with your arrangement ?.
__________________
I believe not to believe in any fixed belief system.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Article on clocks, jitter, phase noise........ Jocko Homo Digital Source 2 24th December 2005 10:19 PM
Source of low phase noise crystals stolbovoy Digital Source 20 10th April 2005 06:42 PM
PL27TG35 & HDS 164 (phase plug) Measurement files Leffemannen Multi-Way 0 30th December 2004 09:26 PM


New To Site? Need Help?

All times are GMT. The time now is 05:49 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2