[South Florida DX Association] BPL Interference

[Bill Marx]

 Here is an interesting note sent to me by Bill NA2M of the NNJDXA
-Bill W2CQ



This may be a repeat of the message I sent this past weekend. 
Bill - NA2M 

----------------------------------------------------------------------------------------------------------------------------
From: Joel Gilly
 Sent: Thursday, July 31, 2003 11:41 AM
 Subject: BPL in Emmaus, PA and My Meeting with Ed Hare.

 Gentlemen,

 As I had mentioned previously, Ed Hare W1RFI and ARRL Lab Manager, was
 stopping over in the Lehigh Valley, PA on Wednesday as part of a three state
 sweep to monitor and collect data about BPL.  I had the pleasure of meeting
 and spending time with Mr. Hare on Wednesday morning and had the
 opportunity to witness the effects BPL has on the Amateur HF bands.

 On Tuesday night, my cell phone rang and when I answered, it was Mr. Hare.
 He was in the Valley, in Dorneyville, and wanted to touch base with me
 before our meeting the following morning.  I was in West Chester at the  time
 visiting my son, but Mr. Hare had mentioned that he had already swung
 through Emmaus that evening to make a preliminary assessment of the area.

 On Wednesday morning, I met Mr. Hare at the Comfort Suites in Dorneyville.
 After the introductions, during which he presented me a copy of the  "ARRL
 RFI Book", we discussed a rough agenda, then loaded into his well-used
 Subaru wagon replete with measuring equipment and a Buddi-pole portable
 compact dipole strapped to the roof rack, and headed off towards Emmaus.
 The area in Emmaus that is being used by PPL for the BPL test is in the area
 of Pine St. just behind Emmaus High School and the East Penn School District
 Administrative building.  We drove around to find a spot were we could setup
 to do some measurements.  Mr. Hare had selected a spot the previous evening
 that he thought might be a good area to listen to and measure BPL's radio
 signature.  We parked outside a residence and he began setting up his equipment.

 Mr. Hare is using a very simple set-up in order to make an estimate of the
 field strength of signals that he is interested in.  Strapped to the back
 seat of the Subaru was a wooden palette that contained a deep cycle battery,
 an inverter, a step RF attenuator, an ICOM PCR-1000 receiver, and his laptop
 computer running custom data acquisition and processing software that Mr. Hare 
 authored.  As mentioned before, he used a Buddi-Pole compact loaded
 dipole mounted in a tripod strapped to the roof rack as the antenna. The
 measurement process involves using the sound card in the laptop PC as an
 audio voltmeter.  It is first desirable to calibrate the system by first
 measuring the noise generated by the soundcard and the receiver without the
 antenna attached.  The antenna is attached, and the attenuator is adjusted
 until the desired signal is audible just above the noise floor.  The software is then 
 used to sample the audio an that is processed to determine the RMS value based 
 on the 9 kHz bandwidth that the FCC specifies for emissions from Part 15 devices 
 in the HF band.  A calculation is then performed against this value taking into account the 
 parameters of the receiver system (radio, feed line, and antenna) to determine the dbuV/M
 fields strength of the signal.  It is a simple and elegant system that Mr. Hare feels will 
 produce the consistent and high quality data that will be needed to address the Amateur Radio
 communities about BPL to the FCC.

 The real eye-opening part of the day was to listen to BPL in action on the
 HF bands.  Mr. Hare disconnected the PCR-1000 and replaced it with a
 Kenwood TS-440 and we listened to several amateur bands.  The type of BPL used
 in the Emmaus area (there are several "flavors" which Mr. Hare showed
 later) creates an impulse type noise on the bands.  It sounds very much like a
 Geiger counter.  The noise generated is very broad banded and can be
 heard continuously up-and-down the bands.  It seemed to be strongest on 21 MHz
 and faded below 5 MHz and a little above 24 MHz, but this may have been due
 to our receive antenna not being optimized for those frequencies.  BPL created
 a consistent S5 to S7 noise level on the bands.  We listened for a while
 to 14.060 Mhz to hear what it would sound like on a popular frequency.
 Some faint CW stations in the background could be heard, but the opinion was
 that they would be "un-copyable" under the circumstances.  We then got back
 in the car and began driving around the area listening to the radio and the
 noise.  As we got farther away from the test area, the noise faded
 dramatically.  A few blocks from our initial location, the noise level had
 dropped dramatically to S1 to S2, the typical "quiet band" conditions.

 We then drove to an area that had BPL, but had it's electrical service
 delivered through underground feeds.  In this case, we pulled up outside
 a residence that was owned by an engineer Mr. Hare had contacted about BPL
 and who had an Amateur Radio operator living near him.  In this case, the
 noise generated was somewhat reduced, but still around the S5 level outside
 the residence.  It was clear from this example, that if you were a ham
 living next door to this person, your operating conditions would be greatly
 compromised.

 Later, we drove around again to attempt to find a "hot spot".  In the areas
 that had BPL, it was interesting to note the changing profile of the noise
 as we roved around the area.  Every time we passed a utility pole, the noise
 level peaked dramatically.  We arrived at one area that exhibited a
 significant increase over neighboring areas.  This area happened to be a
 pole that contained a BPL injection point.  The noise present at this
 location was unprecedented.  On the Kenwood, I noted a consistent S9 to
 S9+10 noise level.  I tuned up to around 14.200 and found a 5 call area
 station in QSO with CY9A.  The five was copyable, but CY9A was much
 weaker, and the noise would have rendered a QSO with the station unmanageable.
 Mr. Hare then disconnected the TS-440 and made some field strength
 measurements. His measurements revealed field strengths well in excess of FCC limits.

 We then packed up and stopped for lunch.  During lunch, we discussed the
 ARRL ARIA project and BPL.  Mr. Hare explained that while the aim of the
 ARIA project is much broader than BPL, it will be instrumental in gathering
 evidence to support the ARRL's position on BPL.  He also touched on some
 ancillary issue regarding BPL.  On of the interesting points regarded the
 limits on conducted signals versus radiated signals from BPL.  He explained
 that some BPL systems are looking to use very high power levels and that
 these levels could exceed the design limits of other devices plugged into
 electrical outlets.  Another point was that the FCC mandated field strength
 levels were specified under certain conditions.  The vagaries of the various
 BPL schemes and implementations can provide "wiggle room" for BPL
 implementers pass the FCC requirements while still creating systems that
 will adversely affect amateur communications.  As Mr. Hare pointed out,
 an overhead electrical line is just a large radiator of an arbitrary size.
 The radiation pattern developed by such a line could take the main lobe
 outside of the test measurement area, but still present a significant problem
 for amateur radio signals.  Therefore, an integral part of the project is to
 gain "real world" experience about the affects of BPL on amateur
 communications.  Still another question is how BPL will affect other users
 of the HF radio spectrum.  Right now, the Amateur Radio community is the
 only organized response to BPL.  Mr. Hare hopes that when the data he and
 others are gathering is made public, other organizations will come on-board
 and voice their concerns about BPL.

 After lunch, we went out to the parking lot of the hotel and talked some
 more.  Mr. Hare showed me a video tape he had made of his visit to Briar
 Cliff Manor, NY (near White Plains), another BPL test site.  In that
 video, he is shown driving around with the TS-440 tuned to the 20m amateur
 frequencies.  As he drives around the area, he tunes around the band.
 It can be heard clearly that on frequency after frequency, block after
 block, the band is filled with extremely loud "birdies".  It almost made the
 Emmaus experience seem bearable.  The frightening thing about what I saw was
 that the situation will only get worse.  The interference that I heard in
 Emmaus is directly related to the amount of internet activity.  As more and
 more users come on-line, the crackling of the "Geiger counter" will get more
 and more persistent.  We saw BPL in the day at low usage levels.  I can only
 imagine what it might be like at peak usage hours.

 All-in-all, it was on of the most enlightening experiences I have ever had.
 I am extremely thankful to M. Hare for inviting me along.  I hope that
 in the near future, I can organize my material for the purposes of making a
 presentation to the DLARC and possibly the LARC.

 If you have any comments or questions, please do not hesitate to contact
 me.
 
Thank you for your time.

 Regards,
 Joel M. Gilly
 AKrion, LLC.
 (610) 530-3213



____________________________________________________________