Paolo, You may want to check if the FTP cable has a 100 Ohms characteristic impedance which would make it compatible with interfaces designed for UTP cable. STP cable is supposed to have a 150 Ohms impedance which is not compatible with standard 10baseT interfaces which are usually designed for UTP.
Eric =================================== Éric Meunier Hardware Architect E-mail: [email protected] <mailto:[email protected]> Kontron Communication Inc. (Teknor) 616, rue Curé-Boivin Boisbriand, Québec Canada, J7G 2A7 Tel: 1-450-437-4661 ext. 2419 Fax: 1-450-437-8053 Web: http://www.teknor.com <http://www.teknor.com> -----Original Message----- From: Paolo Roncone [SMTP:[email protected]] Sent: Thursday, September 06, 2001 4:18 AM To: Doug McKean Cc: EMC-PSTC Discussion Group Subject: Re: STP vs FTP Ethernet cables (2) Doug, I re-paste the first part of the definition in IEEE 802.3 (2000): <<1.4.249 shielded twisted-pair (STP)cable: An electrically conducting cable,comprising one or more ele- ments,each of which is individually shielded.There may be an overall shield,in which case the cable is referred to as shielded twisted-pair cable with an overall shield (from ISO/IEC 11801:1995)>> My understanding is that "elements" should refer to individual PAIRS (signal/return), rather than single wires. But - as I said in my previous e-mail - I'd like to check whether this is put into practice by some vendors. So far I didn't get any clue on this. The STP cables that I found so far (form a couple of vendors) have just an OVERALL shield around all wires, and these are identical to FTP (Foiled Twisted Pair) cables that are also on the market. I agree with you, something doesn't sound right... Paolo At 09:36 05/09/2001 -0700, Doug McKean wrote: Paolo Roncone wrote: > > The reason of my inquiry is that we bought samples of "STP" and "FTP" > cat.5 cables for 10bT ethernet applications from different vendors and to > our surprise we discovered that both "STP" and "FTP" types have an > overall (external) shield made of aluminum foil, but no shields on individual > wires or wire couples (as per 802.3 definition above). Maintaining a characteristic impedence of a twisted pair by shielding the individual wires of that twisted pair? Something doesn't sound right. - Doug McKean ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ <http://www.ewh.ieee.org/soc/emcs/pstc/> To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. ---------------------------------------------------------------------------- --- Paolo Roncone EMC Compliance Engineer - Cisco Photonics Italy via Philips 12 - Monza (MI) 20052 mailto:[email protected] <mailto:[email protected]> phone: +39 039209 1538 fax: +39 039209 2036 ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
