RE: RJ45 filtered connector
FYI, This is an interesting web site for connectors et al http://www.mouse.demon.nl/ckp/misc/conchart.htm http://www.mouse.demon.nl/ckp/misc/conchart.htm RH -Original Message- From: John Shinn [mailto:john.sh...@sanmina-sci.com] Sent: Thursday, December 20, 2001 6:10 PM To: 'Bill Owsley'; 'John Shinn'; 'Reginald Henry'; emc-p...@majordomo.ieee.org Subject: RE: RJ45 filtered connector Acutally, the term RJ is used by the FCC for designating connectors that are part of the registration (now approval) process. So why would you want to call a ethernet connector by a designation used by the telephone industry? I am not going to police the use of the term, but I wanted to put that information out to everyone. Regards, John Shinn -Original Message- From: Bill Owsley [mailto:ows...@cisco.com] Sent: Thursday, December 20, 2001 2:32 PM To: John Shinn; 'Reginald Henry'; emc-p...@majordomo.ieee.org Subject: RE: RJ45 filtered connector so if we called it an RJ-48C, would that be better ?? At 04:56 PM 12/20/2001 , John Shinn wrote: Although it may suprise some, and I may get flak, but an RJ45 connector is an specific configuration used exclusively for a programmable data connection. It has a specific wiring configuration. The RJ stands for Registered Jack. This is an FCC designation of that specific configuration. There is nothing against using an 8-pin modular plug/jack for 10Base-Tor 100Base-T, or even microphone inputs to my Ham radio, but do not call it a RJ45. Now, yes, there are several vendors that produce shielded and filtered 8-pin modular jacks. I remember using them and working with several vendors a few years ago, but I would suggest you look at the website or catalogs of the major connector suppliers. John Shinn, P.E. Manager, Lab. Operations. Sanmina-SCI -Original Message- From: owner-emc-p...@majordomo.ieee.org [ mailto:owner-emc-p...@majordomo.ieee.org]On mailto:owner-emc-p...@majordomo.ieee.org%5DOn Behalf Of Reginald Henry Sent: Thursday, December 20, 2001 10:51 AM To: emc-p...@majordomo.ieee.org Subject: RE:RJ45 filtered connector To All, Can anyone out there tell me where I would be able to purchase a fully shielded and filter RJ45 connector that is Bulkhead mountable. The RJ45 must be able to handle data rates from 10Base T to 100Base T I will be performing CE testing in the chamber so it must be bulkhead mountable ! Thanks and Happy Holidays to YOU ALL ! Reg --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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. --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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. Bill Owsley, ows...@cisco.com 919) 392-8341 Compliance Engineer Cisco Systems 7025 Kit Creek Road POB 14987 RTP. NC. 27709
Re: noise figure
NoiseFigure new
= sqrt ( ( NF1^2 - 1 ) + ( NF2^2 - 1 ) + ( NF3^2 - 1 ) + ... + 1 )
where all noise figures are ratios and referenced to a
single location.
A few points:
1 Definition:
Noise Figure is the ratio of increased noise in a system above the expected
level of Johnson noise. For our 50 ohm system that will give a voltage of
sqrt(4KTRBw) where K is Boltzmann's constant, T is temperature in absolute
Kelvin, R is the resistance of the system (for our case 25 ohms {50 ohms in
parallel with 50 ohms}), and Bw is the bandwidth of interest in Hertz. For
a Bw of 1 MHz that yields a noise floor of around 0.641uV, or -3.9dBuV
2 Relate noise figure to some place in your system.
For simplicity (and ease of using specs) relate to the front end Noise
figure specs relate to the front end of a system block. The noise is
amplified, or attenuated, along with the signal and therefore track
together. As you go from the output to the input of each system block, gain
subtracts from the NF and attenuation adds to the NF. Modify the Noise
Figure by each block you must go through to get to the input. For example,
through cable loss, add the few dB. For gain, subtract the gain.
3 Make up a list (Use Excell spread sheets) You will end up with
contributions from every block now referenced to the front end. then...
4 Remember that uncorrelated noise does not add, but adds as the square
root of the sum of squares. However! you must only take into consideration
the noise contribution from each additional noise source. You cannot keep
adding in the contribution from the 50 ohm source impedance. Therefore,
each Noise Figure ratio must be squared and then have 1 subtracted from it.
After combining all the contributions, you will add the 1 back. Simply take
the square root of that total sum and find the 20log value and you will have
your total system's new NoiseFigure.
For example, let's find the noise figure for a receiving system that
attaches to an antenna consisting of long cable, amp, cable, and spectrum
analyzer (SA).
Passive devices have 0 dB noise figure (they do not add any noise)
Antenna is passive, but converts volts per meter into volts in a 50 ohm
system. Since it does not add any noise, there is no difference between
minimizing the NF at the antenna port or at the field that it measures.
So let's find out the NF of our system at 200MHz
long cable 3dB attenuation
amp24dB 6 dB NF
cable -
SA 32dB
Note: You could have a perfect receiver that contributes no noise located
after the long cable and you would still have a 3 dB NF That's why
amplifiers are placed near the signal source.
Check your particular SA. It can have a Noise Figure from 26dB to 36dB
depending on its design. That means for a 1 MHz bandwidth you can only see
down to around -80dBm.
So let's move the amplifier out to the antenna and change the order of the
list:
cable -
amp gain 24dB with NF = 6 dB
long cable atten 3dB
SA with NF = 32dB
The list would show 6 dB NF at the input and (32-24+3=11) 11dB from the SA.
That is a ratio of 2 and a ratio of 3.55.
New Noise Figure is sqrt( (2^2-1) + (3.55^2-1) + 1 ) = 4 or 12dB
See how the SA still dominates?
To rewrite the equation:
NoiseFigure new
= sqrt ( ( NF1^2 - 1 ) + ( NF2^2 - 1 ) + ( NF3^2 - 1 ) + ... +
1 )
where all noise figures are ratios and referenced to a
single location.
- Robert -
Robert A. Macy, PEm...@california.com
408 286 3985 fx 408 297 9121
AJM International Electronics Consultants
619 North First St, San Jose, CA 95112
-Original Message-
From: KC CHAN [PDD] kcc...@hkpc.org
To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Friday, December 21, 2001 5:46 PM
Subject: noise figure
Hi all
It may not be purely EMC question, actually it is RF related, but I am sure
the experts here can answer my questions.
We all know that we need to have a pre-amp. that is as lower noise figure
as possible, but how low it is enough or how it is related to the noise
floor viewed by a receiver or spectrum analyzer.
Thank you
KC Chan
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RE: RJ45 filtered connector
John, The pertinent specification, ANSI/IEEE 802.3 (a.k.a. ISO/IEC8802.3), describes the Ethernet physical layer plug/jack as an RJ-45. ArcNet twisted pair was RJ-11. If you purchase jacks that include internal filters, be sure the filters are designed for Ethernet/F-E (10BaseT 100BaseTX). Some ferrite filters are designed to suppress digital noise in voice telephone lines. These ferrites can cause 'back pressure' on the digital signal, resulting in cable-length sensitivity; i.e. the impedance curve no longer meets 802.3. You can live with cable-length sensitivity on emissions (to 'isolate' the EUT), but expect diminished RF immunity with certain cable lengths when filters are inserted in the T-P line. Ethernet components are rigorously tested for 802.3 compliance (waveforms, jitter, SQE, bit-error rate) and for compatibility with components from other manufacturers. These compatibility-suite tests are performed without any additional T-P line filters. Any altered interface is your responsibility; results may or may not represent real world installations. David -Original Message- From: John Shinn [mailto:john.sh...@sanmina-sci.com] Sent: Thursday, December 20, 2001 6:10 PM To: 'Bill Owsley'; 'John Shinn'; 'Reginald Henry'; emc-p...@majordomo.ieee.org Subject: RE: RJ45 filtered connector Acutally, the term RJ is used by the FCC for designating connectors that are part of the registration (now approval) process. So why would you want to call a ethernet connector by a designation used by the telephone industry? I am not going to police the use of the term, but I wanted to put that information out to everyone. Regards, John Shinn -Original Message- From: Bill Owsley [mailto:ows...@cisco.com] Sent: Thursday, December 20, 2001 2:32 PM To: John Shinn; 'Reginald Henry'; emc-p...@majordomo.ieee.org Subject: RE: RJ45 filtered connector so if we called it an RJ-48C, would that be better ?? At 04:56 PM 12/20/2001 , John Shinn wrote: Although it may suprise some, and I may get flak, but an RJ45 connector is an specific configuration used exclusively for a programmable data connection. It has a specific wiring configuration. The RJ stands for Registered Jack. This is an FCC designation of that specific configuration. There is nothing against using an 8-pin modular plug/jack for 10Base-Tor 100Base-T, or even microphone inputs to my Ham radio, but do not call it a RJ45. Now, yes, there are several vendors that produce shielded and filtered 8-pin modular jacks. I remember using them and working with several vendors a few years ago, but I would suggest you look at the website or catalogs of the major connector suppliers. John Shinn, P.E. Manager, Lab. Operations. Sanmina-SCI -Original Message- From: owner-emc-p...@majordomo.ieee.org [ mailto:owner-emc-p...@majordomo.ieee.org]On mailto:owner-emc-p...@majordomo.ieee.org%5DOn Behalf Of Reginald Henry Sent: Thursday, December 20, 2001 10:51 AM To: emc-p...@majordomo.ieee.org Subject: RE:RJ45 filtered connector To All, Can anyone out there tell me where I would be able to purchase a fully shielded and filter RJ45 connector that is Bulkhead mountable. The RJ45 must be able to handle data rates from 10Base T to 100Base T I will be performing CE testing in the chamber so it must be bulkhead mountable ! Thanks and Happy Holidays to YOU ALL ! Reg --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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. --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online
RE: RJ45 filtered connector
Ron, Thank you for your assistance in getting me closer to completing my task at hand ! I really like the different alternative solutions that you have provided for me. I also tend to agree with you, in terms of the speeds ( Category 3 aka ... Cat 3 for 10 Base T, Category 5 aka Cat 5 for 100Base T)I will be working with, does not lend itself well to traverse thru mixed connectors ( terminations , DB connectors, etc ). My understanding in the little education that I have gotten since I first started investigating these connectors,is that the degree in which the wires are twisted ( number of twist per xxx distance )will make all the difference in the world if the information (data) gets thru or not. Once again thanks a million. PS. I loved your comment about the flames... very appropriate ! LOL Reg -Original Message- From: Ron Pickard [mailto:rpick...@hypercom.com] Sent: Thursday, December 20, 2001 5:40 PM To: emc-p...@ieee.org Cc: rhe...@vicon-cctv.com Subject: RE: RJ45 filtered connector Hi Reg, Trying to find a bulkhead RJ45 (shielded filtered) connector for an EMC chamber may prove to be an impossible task as, IMHO, this type of connector might be fairly fragile and hard to install for such use. To that end, I will offer some suggestions: 1. Talk to chamber manufacturers. I am quite sure that they would know about such a connector if one exists. 2. A bulkhead mounted DB25 connector might work. These can come filtered, however, the filtering involved should not impact the communication speeds you will be working with. To connect to standard ethernet cables, use 2x(DB25-RJ45) adapters (1 inside 1 outside). The whole thing would be connected as Outside Cable - Adapter - Bulkhead DB Connector - Adapter - Inside Cable. These adapters are quite common and shouldn't need to be filtered as the DB connectors would do that and if extra filtering is needed, a simple clip-on ferrite might be all that's needed (the ferrite might even be put inside the adapter backshell). And, the DB25 connector might be used for other interfaces during testing, as well. 3. You shouldn't need any connector if your EMC chamber has a ventilation opening. Just fit a cable thru the opening and put enough ferrite around the cable (inside and outside) to suppress any common mode interference. These suggestions are intended to get all those neurons firing to think of some connector alternatives to the one you're seeking. I hope this helps. Comments anyone? Bring on the flames. :-) Best regards, Ron Pickard rpick...@hypercom.com JK15@exchange.SanDiego CA.NCR.comTo: rhe...@vicon-cctv.com, emc-p...@majordomo.ieee.org Sent by: cc: owner-emc-pstc@majordomo.iSubject: RE: RJ45 filtered connector eee.org 12/20/01 12:34 PM Please respond to JK15 Reg, Look at Regal Electronics at http://www.regalusa.com. They have board mounted RJ-45 that have gasketing appropriate for a panel. Jim Jim Knighten, Ph.D. Teradata, a Division of NCRhttp://www.ncr.com 17095 Via Del Campo San Diego, CA 92127 USA Tel: 858-485-2537 Fax: 858-485-3788 jim.knigh...@ncr.com -Original Message- From: Reginald Henry [mailto:rhe...@vicon-cctv.com] Sent: Thursday, December 20, 2001 10:51 AM To:emc-p...@majordomo.ieee.org Subject:RE:RJ45 filtered connector To All, Can anyone out there tell me where I would be able to purchase a fully shielded and filter RJ45 connector that is Bulkhead mountable. The RJ45 must be able to handle data rates from 10Base T to 100Base T I will be performing CE testing in the chamber so it must be bulkhead mountable ! Thanks and Happy Holidays to YOU ALL ! Reg --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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. --- 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
Portable Fire Extinguishers
Hello Group, Does anyone know the CE Directives and standards for portable fire extinguishers? This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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.
