S/PDIF transmission with RS422/485 tranceiver over twisted pair with SN75176 - 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 17th July 2004, 05:10 AM   #1
diyAudio Member
 
Join Date: Jan 2004
Location: US
Default S/PDIF transmission with RS422/485 tranceiver over twisted pair with SN75176

Guys,

I have done it! I got the idea from a web site that I forget the URL too. I built some conversion circuits, toslink and coax to TTL, which I fed into an SN75176. It was fed over twisted pair telephone wire using RJ-11 jacks and connectors to interconnect. At 10ft, the sound is perfect. The receiver circuit has an SN75176, it's received output connects to a circuit with converts TTL to coax, which then is fed into jwb's DAC. With a good tranceiver (I'm getting SP1485ECP which operates up to 20Mbps on Monday) reflection and jitter is minimized, and allows transmission of S/PDIF over thousands of feet with no noise or degradation. At work, we have over a mile of cable run that transmits data at 9600bps. Even though S/PDIF uses much faster transmission rates, I am almost positive it will work well. Why hasn't this method of transmission been used? I think it works pretty damn well.
  Reply With Quote
Old 19th July 2004, 04:47 AM   #2
diyAudio Member
 
Join Date: Jan 2004
Location: US
No replies? I'm sure someone would have found some sort of error with it. Anyone have any input? I had the circuit running pretty much all day and jwb's DAC is still sounding good. The transmitting IC gets slightly warm, but still pretty much perfect operation. I'm looking fot your input because I'm a new commer to S/PDIF transmission, and don't really know much about it.
  Reply With Quote
Old 19th July 2004, 05:44 AM   #3
diyAudio Member
 
Join Date: Oct 2001
Location: .
If you are happy with it and it works well, why worry about what anyone else thinks?
  Reply With Quote
Old 19th July 2004, 06:08 AM   #4
diyAudio Member
 
Join Date: Jan 2004
Location: US
Well, I'm just wondering if anyone else did it. It works too well to be as simple as soldering in an 8 pin DIP socket and connecting lines to it, then connecting it to a transmission line. Because of it's operation, I'm wondering why no one ever tried this before.
  Reply With Quote
Old 19th July 2004, 06:21 AM   #5
diyAudio Member
 
Join Date: Oct 2001
Location: .
I once wanted to stick a CD player on a BTS router and I stuck a 75176 in a Technics player drove drove a 100ft drum of coax. With a Prismsound DSA-1 on the other end, doing the testing, there were no problems. The chief engineer wasn't too keen on them though, he felt they died too easily.
  Reply With Quote
Old 19th July 2004, 06:43 AM   #6
diyAudio Member
 
Join Date: Jan 2004
Location: US
Really? Odd. For the life of me I can't kill one. At work we use them for long distance serial transmission, and they get lightning transients and high voltage spikes, shorts, ESD, and even with atleast 8 years of operation, I never had one die. They seem quite resilliant to me. I can probably go thousands of feet and still get good transmission. I think everyone should use them.
  Reply With Quote
Old 19th July 2004, 06:53 AM   #7
dhaen is offline dhaen  Europe
diyAudio Moderator Emeritus
 
dhaen's Avatar
 
Join Date: Jun 2002
Location: U.K.
Modern Rs422 tranceivers are slew rate limited, and will not be able to transmit even the fundamenal.
Twisted pair is used for a similar audio standard described in AES / EBU spec's. This runs for "miles" though proper cable, and quite a distance through "improper cable" (RS422)
  Reply With Quote
Old 19th July 2004, 07:10 AM   #8
diyAudio Member
 
Join Date: Oct 2001
Location: .
Quote:
Originally posted by dhaen
Modern Rs422 tranceivers are slew rate limited, and will not be able to transmit even the fundamenal.
Twisted pair is used for a similar audio standard described in AES / EBU spec's. This runs for "miles" though proper cable, and quite a distance through "improper cable" (RS422)
I once worked at place that needed to move audio around the building in the days when your choice of AES rx was the BBC AESIC or some unobtainable Sony device. Proper AES/EBU spec cable was used and the stuff was hideous. Halfway through the building A4 size eq/boosters had to added. In contrast the 270MHz SDI over coax was a breeze.
  Reply With Quote
Old 19th July 2004, 07:29 AM   #9
diyAudio Member
 
Ouroboros's Avatar
 
Join Date: Dec 2003
Location: Nottingham UK
Not all RS485 drivers are slew-rate limited. Have a look on the Maxim site for parts with digital pre-emphasis for high bit-rates over fairly long cables.

It is certainly possible to carry SPDIF over CAT5 twisted pair for 100 metres. (As a comparison I am running 2.048M bits/sec over a single CAT5 pair here at work over 500 metres, although I am using a simple first-order C-R equaliser at the receiver).
  Reply With Quote
Old 19th July 2004, 07:43 AM   #10
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Since you asked.............

Quote:
With a good tranceiver (I'm getting SP1485ECP which operates up to 20Mbps on Monday) reflection and jitter is minimized.
And you can prove this I suppose?????

Hard to convince me that anything with Schmitt trigger inputs will have low reflections.

Jocko
  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
Twisted Pear - S/PDIF 4:1 MUX/Receiver Module (new, unused) n_maher Swap Meet 3 19th February 2009 04:57 PM
twisted pair wiring on a tube amp jarthel Tubes / Valves 15 16th March 2007 02:24 AM
How does Twisted pair work? Pbassred Everything Else 39 29th March 2006 10:21 PM
Video on twisted pair Olen Pulassa Everything Else 1 29th December 2003 05:28 PM
Twisted Pair fmak Digital Source 51 22nd May 2003 07:42 PM


New To Site? Need Help?

All times are GMT. The time now is 09:47 AM.


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