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w2co
join:2003-07-16
Longmont, CO | reply to JohnnyKnowal
Re: Obligatory FAQ Link Post :-) If you are a ham operator, then you must be only on VHF and UHF bands because on HF from 1-30Mhz it gets totally wiped out with s9 +10-15db over noise floor near the BPL systems. I for one have seen the results at 14Mhz and up, and they render those bands totally useless. So if you never operate HF in the area of a BPL system (within 10-30 blocks), Try turning on a shortwave receiver and tuning into radio netherlands or the bbc at around 9.5Mhz band. You will not be able to hear anything but noise S9+10-15db over. We have a relatively quiet noise floor out here in the front range of the rockies, and I am documenting that quiet noise floor with NIST traceable equipment. This will enable a reference to measure by in case BPL ever gets deployed out here, in which to make formal complaints. If and when it gets deployed here, if the noise floor raises even 1db (part 15 limits today within 30 ft.), I will make formal complaints. But it will be way over that range because in Manassas, VA., the ARRL has shown with just an ordinary HF rig (tuned to 14Mhz band)and mobile antenna that has mega losses that the noise level increases as much as 30db over normal levels. I for one operate in the HF bands and also operate in VHF, UHF, and microwave bands as well for the AO-40 satellite which has it's downlink at 2.4Ghz and uplink at 70cm/1.2Ghz simultaneously. So I will be monitoring and documenting all those bands normal noise levels also. Be careful what you say here as there are many knowledgeable people reading this stuff. Rf Engineer's idea of deploying broadband signals way up the spectrum is a valid idea, especially with the bandwidths of spectrum that will be needed under high user loads. It would not interfere with a tenth of the services it will at the HF bands (1-80Mhz).
That's just a bad idea and opens the door to a whole plethora of interference issues. The power lines are not designed to carry HF signals and much less microwave signals very far, as they will radiate. The power lines make great longwire antennas at around 5Mhz, but thats not to say they won't radiate at any other frequencies. They will. And as for underground power lines, they will still radiate although attenuated by aprox. 3db. That's nothing when you're dealing with 30+db of broadband noise, and when they come up into buildings walls and ceilings, walla another radiator at full strength. Your everyday items like baby monitors, cordless phones, garage door openers etc., will have randomly unpredictable problems also. I seriously doubt you operate HF, if you are a ham, you are probably one of those (no code lids) who stay on 2m and 70cm. If not, speak up I want to hear more about your noise levels on HF. | |
| I operate on several bands and have no problem, in fact I have had more problems with a motorcycle going past or someone using a drill than I have had with the PLC. If you know anything they you know that every electronic device that exists emits so to say that it is only BPL is very naive. In fact with a radio things as common as ADSL or ethernet cause interference, so what do we do get rid of them all. If you have results then I would love to see them and like to know how they were taken. So how about some of those documkents that you have been preparing.
The idea of using 5Ghz is not a good option and putting 5Ghz down the line how far will you get 2cm, come on get real. I thought you knew something. The attenuation would be enormous
My motto is live and let live, we cannot stand in the way of something that is such a breakthrough, because we want to use our radios we are going to deprieve thousands of people of information that can be downloaded, and that can improve the education of our children, this is very selfish and egoistic. To bring communications to thousands in remote places is not a bad thing it is good for society as a whole.
As far as the emergency services are concerned here in the UK those frequencies have been protected and there is no problems.
I a an enthusiastic radio user and I accept that we have to welcome this technology as something good. | |
w2co
join:2003-07-16
Longmont, CO | Yes I agree that it would be good if it does not cause interference to existing radio services through unintended radiation from the power line grid. I don't know about there, but over here the power lines are in sad shape and have been neglected over the years by the power companies. This is true for most of the country, some places worse than others though. The poor line conditions will cause non-linear components to be radiated as well through poor insulators, leaky connections/splices etc. The power companies here have a hard time responding to legitimate interference complaints now, which would be very easy to remedy, if they respond at all. What's to say they will take care of additional complaints after BPL is deployed? I don't think the give a damn - never will. All they want is money money money. Why deploy an archaic technology when there is broadband in most places already (cable modem, DSL, satellite, etc etc.)? Heck most internet users still are happy with just a "dial up" connection from their homes, and they use T1 lines at work to do any downloading.
But I also understand how people would want a cheap broadband solution too, so they can do online gaming and downloading that porn stuff that they can't do at work.
If they want to complete that "last mile" then just finish laying the fiber optic cable that was started 10 or more years ago. It should've been done by now but the networking companies got greedy and kept the termination ends in their server locations and then just farmed out connections to it. The data I am compiling is incomplete as of yet because BPL is not being tested in my location yet, so far I only have the normal "quiet" s-3 type noise floor here on most bands from 80meters up to 1.2GHz. This I can use against any new readings after deployment here. If you had looked at the videos at ARRL webpage taken in Manassas, Va. you would see why we are all upset. It shows s-9 +15db of hash noise across the entire 20 meter band. That happens to be my favorite band, and I do weak signal DXing there, have for years. It also is right smack in the middle of the BPL spectrum when under light user loads. QRP operation would be all but usable. Oh well they are removing CW requirements now, so what's stopping them from destroying any weak signal HF work? Nothing. It's who's got the money.
To hell with physics and any common sense. Physics will not change for any money hungry companies, an open wire will radiate when an RF signal is introduced to one end, regardless of frequency. Many studies on this BPL technology have already been done in other countries and have shown excessive interference to HF/VHF bands and either banned all together or put on the shelf until something is invented that will improve it. Those who ignor history are doomed to repeat it. Nothing has been done to show the effects to BPL when HF transmissions occur nearby. That is a whole other subject but will the companies responsible do any studies on this direction before deployment? I seriously doubt it, they have hardly shown the interference potentials to date why should they when the dollar sign is in their eyes. | |
w2co
join:2003-07-16
Longmont, CO | Interference to PLC systems Interference to PLC systems from Amateur Radio Operation
Interference is a two-way street, and PLC systems are at significant risk from amateur HF operation. In the US, amateurs are limited to 1500 watts PEP RF output, but there is no limit to the antenna gain. As a practical matter, few amateur antennas exceed 13 dBi on HF. This means, however, that the EIRP from amateur stations can exceed 20,000 watts. These stations can have antennas that are as close as about 10 meters or so the the electrical distribution systems.
Here is an estimate of the interference potential of a more modest HF station on 7.15 MHz:
Those unshielded overhead power lines are not great antennas, but they can and will pick up our signals. Here is a quick calculation:
Transmit power: +26 dBW (400 watts)
Transmit frequency: 7.15 MHz
Distance between antenna and power line: 20 meters
Path loss: -15.6 dB
Transmit antenna gain (with ground reflection): 6 dBi
Power-line antenna gain: -10 dBi (estimate)
Power picked up on power line:
+26 dBW
-15.6 dB
+6 dBi
-10 dBi
-------
+6.4 dBW (4.4 watts)
The total power of their signal inside the line is going to be about 10 milliwatts, and when we transmit, PLC wiring may pick up 4 watts of our power right inside the frequencies PLC is using. It is unlikely that PLC systems will continue to function in the presence of these signal levels. And this example is of a completely legal operation of an amateur radio station on 40 meters. Now on 20, 15, and 10 meters it will be possible to have much higher eirp because of the directional antennas in use there, many of which are on an even level with the power lines and many of which are using horizontal polarization. This will ad a few more db to the "gain" of the system into the power lines. | |
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