tom@wcc.oz (Tom Evans) (12/05/89)
In article <843@n3dmc.UU.NET>, johnl@n3dmc.UU.NET (John Limpert) writes: > In article <693@rsiatl.UUCP> jgd@rsiatl.UUCP (John G. De Armond) writes: > > Is anyone besides me concerned about the RFI/EMI vulnerabilities > of twisted pair? I see enough problems with non-existent or poor > shielding in current business/consumer electronics equipment. > Is your LAN going to collapse every time someone keys up their > radio? Is your LAN going to blanket the area with RF garbage? 1. Has anyone actually _MEASURED_ the RFI emissions from UTP - 10BaseT? 2. Isn't this the FCC's business? Shouldn't they have something to do with it, or is it "you installed it - your problem"? --------- Tom Evans tom@wcc.oz.au | Webster Computer Corp P/L | "The concept of my 1270 Ferntree Gully Rd | existence is an Scoresby VIC 3179 Australia | approximation" Australia | 61-3-764-1100 FAX ...764-1179 | D. Conway 2109 O'Toole Avenue, Suite J SAN JOSE CA 95131 - 1303 CALIFORNIA 1-408-954-8054 FAX 1-408-954-1832
pat@hprnd.HP.COM (Pat Thaler) (12/06/89)
> tom@wcc.oz (Tom Evans) asks: > > 1. Has anyone actually _MEASURED_ the RFI emissions from UTP - 10BaseT? > > 2. Isn't this the FCC's business? Shouldn't they have something to do > with it, or is it "you installed it - your problem"? > Yes, I have measured it (on real product). The emissions are about the same as 10BASE2 (ThinLAN) products that I have measured. They meet the requirements of FCC and VDE (VDE is roughly the German equivalent of FCC). In my experience, any problems come from common mode signals that are allowed to couple to the cable. The source is usually processor clock harmonics or the switching power supply rather than the data signal. If you allow noise to couple to it, the shield of the coax cable radiates as does the twisted pair. If a product violates the FCC limits, the manufacturer may be required to fix it. In some cases, the manufacturer may also be fined. VDE has even stricter enforcement which in some cases may include jail. If you are not using the product as the manufacturer intended (for instance, if you operate without the covers in place) you may be required to fix the problem. Many products were not subject to FCC limits until several years ago. (I think it was about 10 years ago.) Products in production at the time were "grandfathered." The noisy 1200 baud modem I mentioned in a previous posting was made before the FCC limits applied (and was not an HP product). If you are worried about emmissions, 10BASE-T is not likely to be a problem. Pat Thaler