Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter - Page 16 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

Digital Line Level DACs, Digital Crossovers, Equalizers, 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 8th November 2011, 06:13 AM   #151
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
Quote:
Originally Posted by iancanada View Post
Impedance matching is very important for all high frequency RF signal transmission as well as clock signal. It's not for video 'only' . Actually S/PDIF signal is not a audio signal. It's kind of bi-phase mark code and should be look upon as a clock signal. If we don't have good impedance matching, the reflecting signal will be added over the clock and introducing more jitter. Ian
What you say may be quite true - I was thinking of an analog signal...
  Reply With Quote
Old 8th November 2011, 06:34 AM   #152
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
Erno Borbely famously terminated all his BNC analogue transmission lines as well.

very nice quality boards, keep me in mind for a set when you look to doing a run. or at least le me know the wallet damage and i'll let you know. if its not under NDA i would have no problems soldering my own boards
  Reply With Quote
Old 8th November 2011, 08:35 AM   #153
diyAudio Member
 
Kurt von Kubik's Avatar
 
Join Date: Feb 2009
Location: Viby, Denmark
Send a message via MSN to Kurt von Kubik
Nice thread
A lot to read and a lot to learn
Keep it up guys.

Btw. reading your discussions I ran into a few things, that might to both you guys and me.

The WM8741 chip from Wolfson is described sounding "not clear"
To that I can say that it actually is like that. Both the 8740 and 8741 which i happened to listen to, are pretty dull and lazy to listen to.
I also think that characterizing that as analog sound is wrong. Good analog sound is much more lifelike than this. And actually it is quita a riddle to me how Wolson managed to get reasonably precise digital recordings to sound like this.
In need of an U out chip I would go for CS or AK instead.

About the whole idea with a FIFO of a certain size to minimize jitter, has always been one of my favourite thoughts about digital audio.
But is there any particular reason why you do not talk about up-sampling?
Up-sampling is as far as I know, seen as a very effective way of managing jitter already present in the signal.
Of course it would be even better if it was not there at all, but still it seems very attractive.
__________________
Just do it
  Reply With Quote
Old 8th November 2011, 05:52 PM   #154
diyAudio Member
 
Join Date: Jan 2007
Very interesting project, Ian.
I second qusp's recommendation for a GB!

Quote:
Originally Posted by iancanada View Post
Working with the FIFO board and clock board, 3 hours bit perfect loop test was passed with up to 192Khz/24 bit setup and for both coaxial and optical connection;
So, Toslink 24/192 is actually feasible using standard Toshiba TORX147/TOTX147 parts? I thought the bandwidth of these parts was not enough and, sadly, the 25Mbps parts (TORX142/TOTX142) have been discontinued.
  Reply With Quote
Old 8th November 2011, 05:56 PM   #155
Turbon is offline Turbon  Sweden
diyAudio Member
 
Turbon's Avatar
 
Join Date: Aug 2011
Location: South
I would also like to see a GB on this.

Brgds
  Reply With Quote
Old 8th November 2011, 08:45 PM   #156
GOR3 is offline GOR3  United States
diyAudio Member
 
Join Date: Jun 2011
Location: Connecticut
Ian,
I think you tried the Crystek CCHD-957. What were your impressions?
BR,
George
  Reply With Quote
Old 9th November 2011, 01:24 AM   #157
jcarr is offline jcarr  United States
diyAudio Member
 
Join Date: Jul 2002
Location: Tokyo, Japan
At least in Japan, it appears that if you contact an official Toshiba distributor and make a custom purchase order for TOSLINK components that are rated for 192kb operation, it is still possible to order and purchase such components from Toshiba.

Do expect to pay for whatever minimum quantities are required.

hth, jonathan carr
__________________
http://www.lyraconnoisseur.com/, http://www.lyraaudio.com
  Reply With Quote
Old 9th November 2011, 01:44 AM   #158
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
are C4 and C9 some sort of capacitor network? they appear to have 4 terminations
  Reply With Quote
Old 9th November 2011, 11:06 PM   #159
diyAudio Member
 
iancanada's Avatar
 
Join Date: Dec 2009
Location: Toronto
Quote:
Originally Posted by qusp View Post
Erno Borbely famously terminated all his BNC analogue transmission lines as well.

very nice quality boards, keep me in mind for a set when you look to doing a run. or at least le me know the wallet damage and i'll let you know. if its not under NDA i would have no problems soldering my own boards
Hi qusp,

Thanks again for the recommendation of the U.FL connectors. I'm very happy with them. It get the signal improved obviously. I use both U.FL conncetors and cables in almost all of my projects now.

Very glad you want the KIT. Once I go through the fully test on all the second edition PCBs and make sure everything is OK with bug free, I will consider setting up a group buy. I could figure out how much work I have to do going a small quantity production. Don't warry about your wallet, I'll give you a surprise .
  Reply With Quote
Old 9th November 2011, 11:59 PM   #160
diyAudio Member
 
iancanada's Avatar
 
Join Date: Dec 2009
Location: Toronto
Quote:
Originally Posted by simmconn View Post

Nice looking board!

Wait... Why would you use a TX since the S/PDIF format is inherent prone to jitter? Shouldn't the output of the FIFO go directly to the DAC?

You know you could implement both S/PDIF RX and TX in the PLD with many benefits.
Thanks simmconn,

The S/PDIF interface board is a very flexible design. Basically, on board, it has a DIR and a DIT which are independent from each other. You can use it as a S/PDIF receiver and feed the I2S signal directly to the DAC form the clock board, which might the way you want; or,you can loop the I2S to the S/PDIF board and make it working as a S/PDIF FIFO; and or, your can make it doing both at same time.

Including the S/PDIF receiver and transmitter into FPGA design is a smrt idea. But my considerations in this project are:

1. Actually I can do this, but the problem is I need more logic cells and other resourses. That means I have to use larger CPLD/FPGA than the CPLD I'm useing now. The DIX9211 is just an $5 chip,the cost would be less then enlarging the CPLD/FPGA;

2. My design idea is kind of open concept. I need to keep the S/PDIF board independent from the FIFO and clock board, in case somebody else want to use their own S/PDIF interface solution, or just don't use it at all;

3. Use a commercial IC like DIX9211 is safer for this project, at least it guaranteed fully tested by the group from TI/BB.

Ian
  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
XMOS-based Asynchronous USB to I2S interface Lorien Digital Source 2113 26th July 2014 06:52 PM
exaU2I - Multi-Channel Asynchronous USB to I2S Interface exa065 exaDevices 1357 3rd March 2014 08:51 PM
DAC chip selection + I2S jitter questions drwho9437 Digital Line Level 2 26th July 2010 12:50 PM
Simple FIFO to I2S CPLD, for MCU players / reclocking KOON3876 Digital Line Level 21 19th September 2008 04:00 PM
asynchronous reclocking and low jitter clocks ash_dac Digital Source 3 8th February 2005 09:22 AM


New To Site? Need Help?

All times are GMT. The time now is 05:48 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