Joe, Your right the NTR 3 network is very similar to the Austel TS 002 network.
The Austel network I was thinking about was the old one (circa 1991) that had similiar or the same values as U.K. BS 6305 (370 - 620 ohms//310 nF). It has been a while since I've designed an Austel DAA. The network I was thinking of pre-dated TS 002. I don't have those old documents anymore and don't remember the values (I didn't make copies when I left Rockwell). I do remember the terrible time I had getting good return loss and good THL. Regards, Duane _______________________________ On Fri, 21 Feb 1997 [email protected] wrote: > In a message dated 97-02-21, you write: > > << NTR 3 network has little effect on achieving > decent transhybrid loss. It's nothing like the effect the > Austel complex impedance network has on THL. >> > > Duane: > > Thanks for your feedback. I'm surprised that you see any significant > difference between the NTR 3 network (275 ohms, 750 ohms, 150 nF) and the > Austel network (220 ohms, 820 ohms, 120 nF). Are you sure that there is a > difference? > > The old BS 6305 network was a problem (370 ohms, 620 ohms, 310 nF), but this > is now history. > > BTW, I have had the same experience as you with optimizing THL with a complex > return loss termination. It just seems to be easier to get decent results > when the return loss termination is 600 ohms. I'm not sure why. > > Partly because of this, I prefer to use a 600 ohm termination for the designs > that I get approved under NTR 3. The test report does not look as impressive > (only about 2 dB margin at 4000 Hz), but it gets the job done. As we have > discussed, I do not believe that this poses any tangible threat to actual, > real-world performance. > > Joe Randolph >
