AmateurRadio.com

A posting yesterday in the Yahoo MW DXer's Group pointed to a new article at RadioWorld.com, re the new urgency within the broadcast field to address the growing noise floor.


The article "Noise Inquiry Spurs Recommendations" discusses the fallout from last year's FCC Technical Advisory Council's (TAC) Inquiry ET-16-191, seeking public comments on the rapid increase in "man-made RF noise issues".

As radio amateurs have known for decades already, there is a huge problem when it comes to spectrum noise levels. They were even complaining about this way back in 1932's Short Wave Craft ... "The reasons for this extraordinary amount of noise which we have to contend with at the present time are manifold." If only they knew how quiet it really was!

Now that noise is beginning to have severe affects on profit margins when it comes to AM, FM, TV and Wi-Fi connected devices, it seems that there may now be a larger appetite for some resolution.

"Other industries using RF wireless technologies report growing noise trouble as well. A recent IEEE Spectrum article was subtitled “Electronic Noise Is Drowning Out the Internet of Things.” Designers of IoT devices are not getting the range they expect due to unexpectedly high background noise, it reported."

Comments to the enquiry pointed out the usual offenders, all well-known to hams, such as noisy powerlines, switching power supplies, noisy motors etc and emphasized the fact that none of these offenders should cause interference if properly designed.

The TAC Working Group recommended some steps that it thought the FCC should take with the key one being an FCC Notice of Proposed Rulemaking to "resolve unanswered questions and take corrective action".

According to a recent meeting between The Association of Federal Communications Consulting Engineers and FCC officials, it was pointed out that:

• there had been no official RF noise studies done in over 40 years. 
• some manufacturers are deliberately cheating to skirt emission requirements.
• those in charge of enforcement (FCC) need to be more diligent. 

Much can be said for the same conditions here in Canada where our ISED has failed to properly safeguard spectrum noise pollution.
Other somewhat "telling" recommendations were also put forward and can be viewed in the Radioworld article here.

If you're one of the hundreds (thousands?) struggling with a new mystery noise source, perhaps you can identify the noise signature from one of these two sites:

http://www.arrl.org/sounds-of-rfi

http://www.rfiservices.com/sound.htm

It is reported that the new FCC Chairman seemed receptive to the concerns presented but so far there has been no official action. Hopefully he will soon tackle this with the same gusto shown for chasing down illegal broadcasters. With recent FCC cutbacks and proposed budget slashing from Washington, one wonders if this problem will be given the attention that it needs before it is truly too late to reverse.

A posting yesterday in the Yahoo MW DXer's Group pointed to a new article at RadioWorld.com, re the new urgency within the broadcast field to address the growing noise floor.


The article "Noise Inquiry Spurs Recommendations" discusses the fallout from last year's FCC Technical Advisory Council's (TAC) Inquiry ET-16-191, seeking public comments on the rapid increase in "man-made RF noise issues".

As radio amateurs have known for decades already, there is a huge problem when it comes to spectrum noise levels. They were even complaining about this way back in 1932's Short Wave Craft ... "The reasons for this extraordinary amount of noise which we have to contend with at the present time are manifold." If only they knew how quiet it really was!

Now that noise is beginning to have severe affects on profit margins when it comes to AM, FM, TV and Wi-Fi connected devices, it seems that there may now be a larger appetite for some resolution.

"Other industries using RF wireless technologies report growing noise trouble as well. A recent IEEE Spectrum article was subtitled “Electronic Noise Is Drowning Out the Internet of Things.” Designers of IoT devices are not getting the range they expect due to unexpectedly high background noise, it reported."

Comments to the enquiry pointed out the usual offenders, all well-known to hams, such as noisy powerlines, switching power supplies, noisy motors etc and emphasized the fact that none of these offenders should cause interference if properly designed.

The TAC Working Group recommended some steps that it thought the FCC should take with the key one being an FCC Notice of Proposed Rulemaking to "resolve unanswered questions and take corrective action".

According to a recent meeting between The Association of Federal Communications Consulting Engineers and FCC officials, it was pointed out that:

• there had been no official RF noise studies done in over 40 years. 
• some manufacturers are deliberately cheating to skirt emission requirements.
• those in charge of enforcement (FCC) need to be more diligent. 

Much can be said for the same conditions here in Canada where our ISED has failed to properly safeguard spectrum noise pollution.
Other somewhat "telling" recommendations were also put forward and can be viewed in the Radioworld article here.

If you're one of the hundreds (thousands?) struggling with a new mystery noise source, perhaps you can identify the noise signature from one of these two sites:

http://www.arrl.org/sounds-of-rfi

http://www.rfiservices.com/sound.htm

It is reported that the new FCC Chairman seemed receptive to the concerns presented but so far there has been no official action. Hopefully he will soon tackle this with the same gusto shown for chasing down illegal broadcasters. With recent FCC cutbacks and proposed budget slashing from Washington, one wonders if this problem will be given the attention that it needs before it is truly too late to reverse.

How often have you struggled to pull a weak signal out of the noise? "Just give me one more db", you tell yourself.





A recent posting to the Topband reflector by Frank, W3LPL, sent me to the interesting webpage of Dave, AB7E. Dave had been pondering two antenna systems, one of which would provide a 2db improvement in forward gain but at a much higher cost ... he wondered if the extra expense would be worthwhile and could he even hear the difference that 2db would make? He created a series of CW files, incrementing the signal level in 1db steps to see for himself!

Now I've always been told that you need to increase signal strength by at least 3db before your ears can detect any difference ... but listen carefully and you may be in for a surprise, as AB7E discovered.

It's probably best to listen to this signal with headphones but, even on my I-Pad's tiny speaker, the demonstration is clear. The first recording starts at "zero db", which is sent twice while the next signal is "one db", sent twice. See if you can hear the difference between each 1 db increment as he steps up to "six db":

Try going the other way, from "six db" down to "zero db":

The following recording has two signals, one of which is one db louder then the other. Can you hear the difference?

Although I was able to hear one call slightly better than the other, it was difficult. How about two signals again, one of them being 2db louder this time ... this one is much easier:


Lastly, AB7E demonstrates the problem with sending too fast when conditions are very marginal. Here, several signals are sent at 20, 25, 30 and 35 WPM. Sending calls at high speed can often seem effective, even under poor conditions but this seems to demonstrate that slowing down just a bit would make it somewhat easier:


One of the more interesting comments posted regarding these recordings was from Bob, N6RW who cited his work in satellite communications:

"I spent part of my engineering career designing satellite command FSK
demodulators - including the deep space Pioneer Venus orbiter. To test
the performance of them, we would mix the test signal with white noise.
When you look at the FSK Bit-Error-Rate (BER) curve (bit errors versus
signal to noise ratio in a bandwidth equal to the bit rate), you can see
the BER improves by a factor of 10 to 1 for every dB in S/N ratio. In
other words, for every dB improvement, you get one tenth the errors."

Now Dave never did tell us if he bought the bigger antenna or not but I'm betting that he did ... it looks like "just one more db" may really be just enough after all.

I admit it. I have an extraordinarily kind next door neighbour!




Ever since erecting a new, much bigger LF antenna several years ago, she has allowed me to run its large, three-wire 100' tophat, directly over the top of her house to a tree on the far edge of her property. As well, she removed her only light dimmer, knowing that it was creating a LOT of nasty RF 'hash' throughout the LF / MF spectrum, seriously degrading my LF reception. To hear the RF noise-signature of a typical light dimmer, listen here, on the ARRL's helpful page of 'household' RFI recordings ... that's just how it sounded here as well!

She recently did a major renovation, which included a new multi-light dining-room fixture and expressed to me a desire to be able to dim it ... oh-oh, I was definitely not looking forward to this.

I did a little web-research and soon learned that some of the most RF-quiet dimmers were being produced by Lutron. One model in particular, claimed to pay special attention to RF noise-filtering and that was the "Centurion", whose smallest model is a 600 watt-capable unit, with a large finned heatsink front plate ... model #C-600P-WH.

I decided to order one from the only dealer I could find in Vancouver that seemed to carry this line of dimmers. The cost was just a little over $40 Canadian (sells for about $25 in the U.S.A.) ... cheap enough if it would do the job!


When the unit came in, I picked it up on my next ferry trip to the city and upon my return, installed it the following afternoon. Before doing the installation, I fired-up the receiving system, tuned to 300kHz, and with the baby monitor set up beside the speaker, took the portable monitor with me.

After installing the new dimmer, I turned on the baby monitor, held my breath ... and turned on the light fixture. Wow ... not a trace of hash could be heard! Adjusting the dimmer from high to low produced no difference in the noise level. I later did a more thorough bandscan and could find no evidence of RFI, on any frequency. The only RFI that I could detect was when placing my Sony ICF-2010 close to the actual dimmer. I was unable to detect any noise further than 6" away from the lights or the dimmer!

So it seems that this model can be highly recommended, for your own home or if you have a next door neighbour 'light-dimmer problem'.

Utilitech Pro Soft White LED Bulb

A recent posting by Phil, KO6BB, to Yahoo Group's ndblist, described his recent search for some LED lamps to replace the CFL's in his shack / radio workbench area. If you have been wondering how much RFI that LED lamps might be producing, you may find Phil's findings of some value.






"Recap  

I had a 60W equivalent CFL in the floor lamp directly over my operating position. I'd tried a 100W equiv one but it was extremely noisy! Also a couple CFLs in the ceiling lamp.

This is a floor lamp with a crookneck at the top and a triangular metal
shade reminiscent of the old style desk lamps, bulb is horiz to the
floor. I've used it for years and like it because it places the light
directly over the operating position work area (keyboard, radios etc).
The actual bulb was about 4.5 inches from the front of the Softrock SDR
receiver (in a plastic case), with the base of the lamp (where the
electronics are) about 7.5 inches (somebody asked about the distances).

This coupled a LOT of RFI directly into the SDR, visible on the
waterfall. For best results when recording and having the light on I'd
slip a 60W incandescent lamp in place of the CFL. The lamp is also
about 16 inches above the operating table, and when listening to ANY
portable radio on the table, if it was in the AM or Longwave band and
using the built in loopstick antenna, got a LOT of RFI from the lamp
(unless the lamp was off ;-)

So today I went down to Lowes (we have a Costco, but I don't have a
card) and looked at their LED lamp offerings. As I expected they had a
large variety of them, from a low cost 3 pack for ~$9.00 for 60W units
to about $18.00 or so each (Sylvania). From what I read here I wanted
to avoid the REALLY cheap ones as some reported them to be 'noisy'.
Also, I wanted to put a 75W equivalent unit in the one over the
operating position, and a pair of 100W equivalent units in the ceiling
lamp. All three had CFLs, and if I walked around the radio room with a
portable radio and the ceiling lamp on I could hear it's 'hash' anywhere
in the room. . .

The ones I settled on were a brand I'd never heard of, "UtiliTech Pro"
soft white, 75W for the bench and 2 100W ones for the ceiling. They
were what I'd call "mid-priced", $8.98 for the 75W and $9.98 for the
100W ones.

Specs:

75 W one draws 12W and gives 1100 Lumens.
100W one draws 16.5W and gives 1600 Lumens (the pair in the ceiling
should then be 3200 Lumens if I calculated right).

How low is the RFI to my Radios?

75W one over the bench:
NO trace from the lamp electronics visible in the SDR waterfall at
all. With a portable radio on the bench-top, NO audible RFI. Put a
portable radio up to the "bulb" part (light area) and with no station
tuned in can't hear ANY RFI. Move the portable to the base area of the
lamps there is SOME RFI, but I won't be putting the radio that close to
the lamp, move it a couple inches away and the noise disappears.

100W ones in the ceiling lamp, NO audible RFI in the portable when
walking around the room, RFI just barely perceptible right next to the
light wall switch that turns the lamp on, again, audible IF I put the
radio right up to the base of the lamps, not a likely real-world scenario!

Upshot? 

Based on the sample of three that I bought and the almost
non-existent RFI from them I'd consider the UtiliTech Pro lamps to be a
good product and suitable for use in the radio room. I consider them
good value for the ~$30.00 I spent for three."

I don't see these being sold here in Canada but I may be mistaken. If you have tested anything similar (other brands / models), please let me know and I will add it to Phil's helpful information.

KO6BB's website can be found here, along with some of his homebrew equipment.

courtesy: arrl.org

I see that the ARRL has filed three more formal complaints to the FCC concerning the bone-crushing HF emissions being produced by off-the-shelf grow light ballasts. The complaint also includes detailed lab data collected on all three devices and it is not pretty. One wonders why it is necessary at all that the ARRL be the industry watchdog instead of the FCC ... why aren't they being more diligent in filtering out these products before they hit the market? If importers and dealers are simply bypassing regulations for the sake of a quick-buck, then heavy fines must be imposed until someone 'gets the message'.

Some of the test products were ordered and purchased through Amazon and through Sears ... the ARRL's thorough report makes it obvious that rules are being ignored and amateurs are paying the price.

“The level of conducted emissions from [these devices] is so high that, as a practical matter, one RF ballast operated in a residential environment would create preclusive interference to Amateur radio HF communications throughout entire neighborhoods,” ARRL General Counsel Chris Imlay, W3KD, wrote in each complaint. The devices exceeded conducted emission limits under all test conditions, “sometimes by extreme margins, throughout most of the HF range ...”


In a similar vein as its recent complaint about marketing of certain RF lighting devices by The Home Depot, the ARRL pointed out that there were no FCC labels on two of the devices mentioned nor any FCC compliance information “anywhere in the documentation, or in or on the box, or on the device itself,” in violation of FCC Part 18 rules.

The League asked the FCC to require removal of all such illegal “grow light” devices from retail sale and marketing and the recall of those devices already sold or available for retail sale, and it said the device importers should be subject to a forfeiture proceeding.

With the proliferation of both legal and illegal 'hydroponic' operations, this kind of QRN is probably just the tip of the iceberg. It's good to see the ARRL slowly pounding away at the rule-breakers on behalf of American amateurs.

I see these same devices being sold on E-Bay, where presumably, they could be purchased worldwide and installed anywhere. As well, several of the U.S. online dealers state "We ship to Canada" ... just great.

Hopefully Industry Canada and RAC are gearing-up for the fight.

The recent posting by BCB / NDB DXer, Steve Ratzlaff (AA7U in OR), describing the poor performance of his initial LNV, prompted another round of valuable discourse on the Yahoo NDBlist Group. Steve indicated that his new 40' LNV was virtually deaf compared to his loop and active whip. ... until he rewound the transformers.

"I've fixed the very low sensitivity of my 40 foot LNV. The transformer
needed more turns for my particular setup--that made all the difference
in the world. I'm also using coax cable, not twin lead--that apparently
makes a big difference in the proper transformer turns ratio too. But
the LNV with preamp is now about the same sensitivity as the active whip.

My transformer primary uses 110 turns, to give good reactance at
the low end of the NDB band. I started with 21 turns on the secondary,
tuned to my local beacon LGD on 296 and looked at the signal level,
removing two turns each time until I got to 8 turns. A broad peak was
with 16 turns which is what I used for the final secondary turns. That's
a turns ratio of 110/16 = 6.875.

Total coax run from the mast to the middle of the home is about
135 feet where it enters the home.

I did some ground rod checks for signal level too. I have 3 ground rods
installed at the LNV--6 foot, 4 foot and a short 2 foot. I started out
with all three connected and took a reference signal reading, then just
the 6 foot; then just the 4 foot and then just the 2 foot. Signal level
dropped several tenths of a decibel for the 2 foot rod and was the same
for the 4 and 6 foot rods by themselves and for all 3 rods connected. So
my particular setup likes something a little longer than 2 feet for the
ground rod. I'll leave all three rods connected for now since they're
already in place.

The LNV being in a different location is now quieter on some lower end
signals where the active whip is noisy due to the whip being closer to
AC power--a nice thing. The low end 195-205 kHz especially are often
unusable due to noise; the LNV is much quieter for those, apparently due
to it being 100 feet farther from the AC power at the home.
So, the bottom line is my LNV is now working like it should, I believe.
I'll continue to use it and do more comparison checks since I can switch
my antennas instantly."


From Roelof, PAØRDT:

" ... I believe the  term low noise vertical is a bit misleading. These verticals are only suffering less from local noise compared to loop antennas when
located close to the house.
The reason is that the vertical is receiving the electric field and
the electric field of local noise sources located in the house fall
off very quickly outside the house, especially at LF and MW.
A loop antenna does receive the magnetic field of local noise
sources and this field does not fall off close to the house.
I can demonstrate this effect here any time with my modified ALA1530
and mini-whip antenna.
"Matching" this type of vertical to the 50 ohm input of a receiver
is interesting. Connecting it directly to the receiver input, will
load the antenna too much and the voltage across the antenna
terminals will collapse.
This problem can be solved by using a high input buffer amplifier as
used in active whips or by a voltage step down transformer.
Due to imperfections in the step down transformer, e.g.
inter-winding capacitance and insufficient inductance of the
receiver tap / secondary winding, signal output will be way down
compared to an active whip of the same length, using a high input
impedance buffer amplifier.
You can use a tuned vertical to overcome this, however doing so the
broad band nature of the antenna is lost.
Living close to strong broadcast stations, which prevent the use of
active antennas, this particular type of E-probe is an excellent
alternative."

And from Anthony Casorso in CO:

"Motivated by your posts, I build a new transformer using an FT140J with 100 turns on the antenna side and a 10 tap secondary with a rotary switch to select the tap. The taps were from 8 turns to 26 turns in 2 turn increments.

courtesy: www.dxengineering.com/