I got the following "leaked" by someone in Europe (name witheld at his request) regarding Part 15 devices, PLC
and the gradual trashing of the HF bands feared by radio users.
Look at what is the BIG differnce between what we have gotten in Europe (and what still is much too much) and what you would get if PLC is being introduced and becoming widespread in the US under Part 15 coverage. We will keep our fingers crossed that US amateurs would not have to move to the uninhabited plains of New Mexico to enjoy HF bands... The Llano Estacado is no place your xyl would like to follow you... Keep an eye on what your local power supplier is doing besides providing you with 60 Hz engergy - or what they might be planning to invest into! From: Sent: Saturday, April 06, 2002 4:36 PM To: Subject: PLC in The Netherlands Dear all, I just posted the following message as a reply on questions by (name deleted per request) why PLC would not be allowed under the current ruling. It is believed that, because CISPR-22 / EN55022 do not specify radiated limits below 30 MHz, PLC would be allowed without limits to its radiated field! As this misunderstanding seems to be fairly common, I thought a reply was necessary. Also, it seemed a good idea to point out the big difference between NB30 and FCC Part 15 (20 dB or more depending on the propagation model used). Then think of how big the differences are between FCC Part 15 and the BBC proposal (the only proposal which would really protect HF reception): some 50 dB! ----- Original Message ----- From: To: Sent: Saturday, April 06, 2002 11:00 PM Subject: PLC in The Netherlands Posted By (name witheld per request) In response to questions asked by (name deleted) and to clear up the difference between FCC Part 15 and the German NB30 standard: CENELEC EN 50052 currently is the only European standard allowing a form of Home Plug. Because its frequency band is limited to 148.5 kHz (the lower edge of the LW broadcast band in Europe) data rates are limited to some 128 kb/s. Some firms are on the market with this type of devices. Its market success is fairly limited. This may change once the ETSI/CENELEC Joint Working Group on EMC of conducted transmission networks finalizes its work on a European standard which will cover the EMC requirements for many different conducted networks such as PLC (both access/local loop and in-house), xDSL, cable TV etc. So far, only Germany has a national "Usage provision NB30" which allows PLC in the HF range under strict conditions: PLC operates on a Non-Interference Base, cannot claim protection against intended emissions from radio stations and must protect a number of safety- -of-life-frequencies (emergency/aeronautical freqs etc). The max allowable fieldstrength measured at 3 m from the cable, in the 1 - 30 MHz band, peak mode detection in 9 kHz bandwidth is defined as (in dB above 1 microvolt per meter): 40 - 8.8 LOG10(f in MHz). For in-house HF reception or for rooftop antenna installations this is still too much, but NB30 is already a hard-fought compromise between the interests of HF users and the PLC community. Hams would have to place antennas away from houses to get rid of the PLC noise. If you calculate the fieldstrength according to NB30 on 14 MHz at 30 m distance (assuming a worst case line-of-sight type roll-off of fieldstrength with distance), you get a fieldstrength of 3.1 microvolts per metre, which is 20 dB lower than you would get if the system would radiate up to the FCC Part 15 limit. Note, that PLC spectra tend to be continuous (both in time and frequency) while many other Part 15 systems radiate only on one or a few frequencies or have a limited duty cycle. As a radio amateur I am glad not to live in a US urban environment once PLC is becoming popular! The CENELEC EN55022 standard deals with EMC requirements for IT equipment (single pieces of equipment, not networks). For frequencies below 30 MHz conducted limits are given (RF voltage measured on the mains terminals with respect to earth, when terminated with a line simulating network). Above 30 MHz, radiated limits (in dB microvolts per meter) are given. This does not mean that there would be no limits to radiation below 30 MHz! It is only the agreed measurement method, nothing else. The allowable RF voltage on the mains connections has been determined with the radiating properties of mains wiring in mind. If you put an RF voltage according to EN55022 (= CISPR-22) on the mains, the resulting fieldstrength would be comparable with the NB30 radiation limit at 3 m from the source. In the absence of network standards, all digital products on the market have to comply with EN55022 at least. So far, none of the PLC trial networks has fully complied with the NB30 limit in the HF range. Measurements in Germany, Norway, Finland and The Netherlands show between 10 and 30 dB excess fieldstrength over NB30. In Norway and Finland the experiments have been forced to stop by the Regulatory Authorities and I expect this to happen in The Netherlands as well. There is evidence that the output levels of many PLC modems are far above the CISPR-22 (EN55022) conducted limit and that PLC modem manufacturers are unable to meet range expectations at the lower output levels which are required to meet the NB30 standard. Non- compliance to CISPR-22 makes this sort of equipment illegal in many countries until the new network standard is in place. 73, (name witheld by request) Rotterdam, The Netherlands _________________________________________________________________ Send and receive Hotmail on your mobile device: http://mobile.msn.com
