David, The issue of longitudal balance is not a simple one.
Firstly, If your balance is low than the EMC characteristic of the system will suffer. The line will radiate because of common mode components present. Second issue is how much crosstalk from one line to another can you tolerate. the low longitudal balance line will "pick up" noise from outside and the conversions ratio is related to the londitudal balance of the line. third- lack of balance will manifest itself when you will try to pass IEC 61000-4-4. I hope that will help you to make a decision based on the system requirement. Jan At 06:32 PM 4/28/99 +0200, you wrote: >Dear Treggers, > >I wonder if any of you happens to know of a source for recommendations for >minimum >longitudinal balance values as a function of range. SLIC manufacturers, such >as AMD and Harris, sort their chips according to balance, and charge >accordingly (chips with poorer balance cost less). Different line ranges >call for different balance values. >Clearly, for a very short line running several feet within a room, the >lowest value can be used. However, when an application calls for a maximum >range of, say, 200 meters or 1 kilometer, how should one decide on the >appropriate minimum balance figure? As far as I can see, EIA/TIA-464B has >nothing to say on this matter, and specifies balance requirements only for >interconnections with the PSTN (which are also governed by FCC regulatory >balance requirements). > >The answer to this question seems to depend on the results of measurements >made in a range of locations, and therefore, ought to be available from >somewhere. > >Best regards, > >David Drori > >Novarex Enterprises Ltd., >POB 2833, >Luz Building, >5 Kiryat Hamada Street, >Har Hotsvim, >Jerusalem 91028, >Israel. >Tel: +972 2 586 4546 >Fax: +972 2 586 5890 >Mobile: +972 50 678686 >E-mail: [email protected] > Janusz Purwin Xedia Corp 119 Russell St. Littleton Ma 01460 Tel 978-952-6000 ext 166 Fax 978-952-6090 email; [email protected]
