On Saturday, August 26, 2017 at 12:54:12 PM UTC-7, Jeff Liebermann wrote:
> On 26 Aug 2017 18:36:58 GMT, Rob <nomail@example.com> wrote:

> >Swiching power supplies are much more efficient, both in operation
> >and in manufacturing.  They use a lot less resources to manufacture.
> >
> >That is what the world needs more than clean HF bands.  Live with it.

That's a false dichotomy, you know.   There's no shortage of good designs
that, in mass production, produce negligible RF with very minor
layout or component changes from the 'junk emitter' wallwarts
under discussion.   In medical designs, for instance, there are some
stiff ISO standards, and medical-grade power supplies are VERY
quiet.   Even at close range with a pickup coil, one Condor supply
gave me NO indications, couldn't even find what its switch frequency
was.   It was pumping out a couple of hundred watts at DC.

>... it takes some fairly
> narrow band radiated switching junk and splatters it all over a wider
> bandwidth.  The FCC allows this because some brilliant attorney
> decided that only the peak emission level was important, not the
> overall power belched by the interference source.  So, you're right...
> the world needs more than clean HF bands.  It needs a non-political
> FCC.

There was a time when all the inexpensive computer monitors (remember 
the Heath/Zenith H19?) in town were doing the same crystal-controlled power
handling, and one could find the RF in every street, every building, all over
Seattle.   You just couldn't pin it down to a single source.   The FCC cracked
down after a bunch of complaints came in.

What you need, is to complain to the FCC, and for the FCC to be sensitive to
the complaints, and proactive in sending out vans to find the source... which
means you WANT the FCC to be political, in that sense.   Or, you want
to get a retirement home in Green Bank, West Virginia.

Anything less than a federal agency won't have a van to do a survey with, and
the FCC has the jurisdiction (so to speak) that speaks to the issue.

 The FCC allows this because some brilliant attorney
> decided that only the peak emission level was important, not the
> overall power belched by the interference source.  So, you're right...
> the world needs more than clean HF bands.  It needs a non-political
> FCC.

+++1

Jeff Liebermann <jeffl@cruzio.com> wrote:
>>I am the one that realistically sees
>>that the use of frequency bands in the world has irreversibly changed.
>
> True.  Until now, ham radio in the US has been a "sacred cow".  It's
> unlikely to stay that way, but I don't mind enjoying it while it
> lasts.  The limiting factor is the average age of the licensed ham
> radio population. 
> <https://en.wikipedia.org/wiki/Amateur_radio_operator>
>   "In some countries, the average age is over 80 years old
>   with most amateur radio operators earning their license 
>   in their 40s or 50s."
> That's probably wrong, but close enough to make my point.  When all
> the aging hams drop dead from brain cancers caused by a lifetime of RF
> exposure, the bands should then be clear enough to auction off to the
> highest bidder to be used for whatever acronym is then in fashion.
> This may be the reason why the FCC are not particularly anxious to do
> battle over a sacred cow.  The merely have to wait.

Sure the radio amateurs are a dying breed.  But contrary to your
statement there is no scarcity of HF spectrum.  In the past years,
we got our allocation extended several times.  The original user
left, the space was unused, and re-allocated to ham radio.  So I
don't think the authorities are anxious to sell it to others, they
could have done that instead of giving it to radio amateurs and they
did'nt.

>>In the past the HF bands were used to do radio transmissions, now they
>>are emitted as unwanted byproduct by modern equipment, and they are
>>no longer used for radio.  At least not like before.
>
> You forgot to blame the internet.  A local group recently bought an FM
> broadcast license and went on the air.
> <https://www.kbcz.org>
> Based upon some rather dubious research, they have more online
> listeners than OTA (over the air).  It's also much the same with AM
> broadcast and OTA TV, where streaming and cable handle the bulk of the
> users.  New technology, such as HD Radio (Ibiquity) was suppose to
> save FM from a premature demise.  In the US, there are about 1,700 HD
> Radio stations out of 6,600 commercial FM and 4,000 educational
> stations.  In my never humble opinion, the reason for the low uptake
> is techno-political.  The station owners didn't want to take the
> gamble and switch to an all digital system.  So, they opted for a
> hybrid mess that does a miserable job of digital and a tolerable job
> of analog.  Anyway, if the FCC maintains it's generally poor batting
> average for new technology, we could very well see the premature
> demise of everything except cellular data.

Over here, "official" AM radio has nearly died.  The medium wave
transmissions of the public radio stations have ceased, the frequencies
were auctioned and some "higher profile commercial" stations took them
and subsequently went away, some are still used by "radio nuts" and
religious groups without a viable commercial plan and they often sit
unused or used at only very low power.  Now you can apply for an AM
license as an individual for "community radio", a lot of them were taken
but as I predicted the majority never went on-air.
There is initial enthousiasm but after being faced with reality most
of them throw in the towel.

And FM will go the same way.  The official stations are transitioning
to DAB+ (as a dying gasp, of course online is the future), and will stop
transmitting on FM within a decade, the route will then probably be
the same: issueing licenses to ever smaller operations and finally
sitting unused or taken over by pirates.  Or maybe even ham radio.

>>For sure it would be good to design switching supplies with low emission,
>>but don't think that would solve the problem of "HF bands not being
>>as quiet as they used to be".  There are too many other sources of
>>emissions that are not so easy to handle.  E.g. ethernet over powerline.
>
> That would be BPL.  To the best of my limited knowledge, BPL is dead
> in the US.
> <https://en.wikipedia.org/wiki/List_of_broadband_over_power_line_deployments>

No, I don't mean the use of powerlines to transport internet to the home.
Here, it is used to distribute internet and other local network traffic
inside the home.
E.g. when a subscriber decides to switch from traditional cable TV
to IPtv, they get a fiber or VDSL router at their switchboard and they
don't want to run a UTP from there to their TV set.  So they get a
set of two wall warts with RJ45 connector that send the IPtv signal
via powerline, locally.
(of course they would be much better off with a MoCA set using their
existing coax, but these decisions are made by marketeers not technicians)

> However, all is not lost for BPL caused interference.  The HomePlug
> technology is basically just BPL for use inside a home or building.

That is what I mean.

>>One can argue that many of them are just "bad ideas" and "irresponsible
>>engineering" but it is just irrelevant in a world where nobody cares
>>about HF radio reception except some old-hat radio amateurs.
>
> There's still quite a bit of HF traffic on the marine bands.  Not as
> much as before but still plenty.  

Our coast station on HF bands was shut down at least a decade ago.

>>In the modern society they are irrelevant and only hampering innovation.
>
> Wasn't that the argument used by industrial chemical companies after
> they polluted a river?  Nobody ever drinks from the river, so it must
> be ok to pollute it.  Can't have a few dead fish get in the way of
> progress.

Never heard that here...

<krw@notreal.com> wrote in message 
news:22o6qch4445a56qq36sb38hto39prbeqtf@4ax.com...
> Again, the fundamental is *NOT* the problem with switching power
> supplies.  If it is, you're doing something *very* wrong.

Don't you just love generalizations?

I've got a pair of these wired up at the moment, as part of another project:
https://www.seventransistorlabs.com/Images/100WPowerSupplies.jpg
They just so happen to be running from a LISN, because I already know 
they're noisy as hell, but I CBA to fix them right now. ;-)

So, what the hey, let's turn on the speccy and entertain that thought, huh?
https://www.seventransistorlabs.com/Images/100W_Flyback_3MHz_Conducted.jpg
(No, I don't have log sweep, so this is in segments.)  Tons of crap at the 
fundamental and low harmonics.  Eww!

And yes, both are running pretty much spot on 200kHz.  Kind of a silly 
choice, 140kHz would be much better suited.  But there you have it, eh?  Oh, 
but what about the rest of conducted --
https://www.seventransistorlabs.com/Images/100W_Flyback_30MHz_Conducted.jpg
Mid-band peak, about 84dBuV -- but still less than the 92dBuV fundamental 
(note different ATTEN settings).

So, if one were to take your words literally, your argument is pretty well 
fucked.  If /NO/ supplies have issues at fundamental, then the above plot 
doesn't exist, right?

But this is just one example, right?  Maybe you don't literally mean "all", 
you're just calling out a stereotype, and you've worded it badly.  Over 
several posts..

And what about radiated?

Well, I don't have antennas set up, of course, and you are welcome to 
question the veracity of "300MHz conducted".  But, whatever, it definitely 
shows things.  Here it is:
https://www.seventransistorlabs.com/Images/100W_Flyback_300MHz_Conducted.jpg
(The peak at 125MHz is related to the "another project".  Actually, I'm not 
sure why it's so strong, it should be well within a metal box.  Another 
thing to fix, it seems.)

Even if the mains wiring is particularly unlucky (-20dB or more?) in the VHF 
band, and even if a lucky wiring accident made this radiate egregiously at 
some frequency, it seems unlikely that those <= 60dBuV peaks could match the 
fundamental, in a proper radiated test.  (Also, there's less and less above 
300MHz, and nearby activity at 360 and 540MHz makes that range even more 
questionable.  This isn't a shielded room, it's just a bench.  Needless to 
say, a proper 30MHz to 1GHz sweep ain't gonna be useful.)

And so, yeah, this is just a shitty test, on some shitty supplies, that 
aren't even cleaned up for emissions -- but then... shouldn't they be all 
kinds of horrible, if that's the case?

You're welcome to claim that /I've/ done something "very wrong" here.  Well. 
You've /seen/ the power supplies -- I'd be glad to share the schematic and 
layout privately if you think you can spot what's "very wrong" with them.


But no.  The thing is, I have seen it be the case, in many, real, 
regulatory, tests: the PSUs don't kill radiated, the MCUs do.

Of course, I can't share these plots, you'll have to take me at my word on 
this matter.

Most of those projects were powered by good, brand name, off the shelf 
(e.g., Meanwell) PSUs, by the way.  It seems they have the same general 
downward slant to their spectra, without things being "very wrong"!

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com

On Sat, 26 Aug 2017 19:52:31 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Sat, 26 Aug 2017 22:12:37 -0400, krw@notreal.com wrote:
>
>>On Sat, 26 Aug 2017 18:30:08 -0700, Jeff Liebermann <jeffl@cruzio.com>
>>wrote:
>
>>>Look at a spread spectrum clock on a spectrum analyzer:
>>><https://en.wikipedia.org/wiki/Spread_spectrum>
>>
>>Oh, good grief!
>
>That's all I could find while eating dinner.  This article explains it
>in more detail and with nicer looking spectrum analyzer screen shots.
><https://interferencetechnology.com/spread-spectrum-clock-generation-theory-and-debate/>
>
>>YEs, and a receiver is sensitive to the area under its sensitivity
>>curve, too.  The idea is to spread the interference signal further out
>>than the interferred.
>
>Right and spreading the signal over a wider bandwidth allows it to
>interfere with more narrowband receivers operating on adjacent
>channels.  Instead of trashing one receiver, the SS noise causes
>problems with all of them.  Of course, the noise power bandwidth will
>be less, so the interference would be less, which is why the FCC
>accepted the idea.  Whether this is a good tradeoff is subject to
>considerable debate.
>
>>It's not uncommon for the interference to be the 100th harmonic, or
>>even higher.  I've seen combs into the FM band and above.  
>
>Sure, but like I previously muttered, a common ferrite bead on the
>in/out wires can stop 100 MHz trash quite easily.  Trying to do the
>same at 100 KHz would require a much larger ferrite bead.  If you're
>seeing a comb line at 100 MHz (assuming the harmonics weren't created
>in the spectrum analyzer front end from overload), then someone didn't
>do a very good job of designing the switcher.

If the problem is conducted, a ferrite may work, though at 100MHz,
radiated emissions ten to dominate.  The are certainly more
problematic.  Again, the fundamental is _rarely_ the problem.

>>Who cares about "of the day"?
>
>I was commenting about the lack of modern solutions, techniques, and
>devices that were not available in about 1977 when we were working on
>a political solution.

Screw ill thought out "political solutions".  They certainly aren't.
>
>>Even so, you're talking about 13MHz,
>>which would have been silly in 1977.
>
>Yep.  See my comments elsewhere about the selection of frequencies and
>the lack of harmonically related possibilities among the ISM
>frequencies.  Basically, we were trying to have allocated marine LW
>beacon band frequencies and their harmonics after the LW beacon band
>transmitters were shut off.  The allocation of RF spectrum is normally
>not done for the convenience of power supply manufacturers and we
>didn't have even a preliminary list of usable frequencies.  13.56 MHz
>would probably have been a harmonic of some lower frequency.

Again, the fundamental is *NOT* the problem with switching power
supplies.  If it is, you're doing something *very* wrong.

On 27 Aug 2017 08:35:13 GMT, Rob <nomail@example.com> wrote:

>I'm not "the one who knows best",

I'm the one who knows all, knows what's best, and is always right,
even when I'm wrong.

>I am the one that realistically sees
>that the use of frequency bands in the world has irreversibly changed.

True.  Until now, ham radio in the US has been a "sacred cow".  It's
unlikely to stay that way, but I don't mind enjoying it while it
lasts.  The limiting factor is the average age of the licensed ham
radio population. 
<https://en.wikipedia.org/wiki/Amateur_radio_operator>
  "In some countries, the average age is over 80 years old
  with most amateur radio operators earning their license 
  in their 40s or 50s."
That's probably wrong, but close enough to make my point.  When all
the aging hams drop dead from brain cancers caused by a lifetime of RF
exposure, the bands should then be clear enough to auction off to the
highest bidder to be used for whatever acronym is then in fashion.
This may be the reason why the FCC are not particularly anxious to do
battle over a sacred cow.  The merely have to wait.

>In the past the HF bands were used to do radio transmissions, now they
>are emitted as unwanted byproduct by modern equipment, and they are
>no longer used for radio.  At least not like before.

You forgot to blame the internet.  A local group recently bought an FM
broadcast license and went on the air.
<https://www.kbcz.org>
Based upon some rather dubious research, they have more online
listeners than OTA (over the air).  It's also much the same with AM
broadcast and OTA TV, where streaming and cable handle the bulk of the
users.  New technology, such as HD Radio (Ibiquity) was suppose to
save FM from a premature demise.  In the US, there are about 1,700 HD
Radio stations out of 6,600 commercial FM and 4,000 educational
stations.  In my never humble opinion, the reason for the low uptake
is techno-political.  The station owners didn't want to take the
gamble and switch to an all digital system.  So, they opted for a
hybrid mess that does a miserable job of digital and a tolerable job
of analog.  Anyway, if the FCC maintains it's generally poor batting
average for new technology, we could very well see the premature
demise of everything except cellular data.

>For sure it would be good to design switching supplies with low emission,
>but don't think that would solve the problem of "HF bands not being
>as quiet as they used to be".  There are too many other sources of
>emissions that are not so easy to handle.  E.g. ethernet over powerline.

That would be BPL.  To the best of my limited knowledge, BPL is dead
in the US.
<https://en.wikipedia.org/wiki/List_of_broadband_over_power_line_deployments>
Note the large number of "concluded deployments" which is the
politically correct term for bankrupt or shut down.  The web site that
the FCC was ordered to provide listing existing deployments has been
down for at least 2 years.
<http://www.bpldatabase.org>
IBM continues to produce lurid press releases announcing the raising
of this dead technology, just to see if anyone is still interested.

However, all is not lost for BPL caused interference.  The HomePlug
technology is basically just BPL for use inside a home or building.
<http://www.homeplug.org>
Merely go to your nearest electronics vendor, purchase a pair of
these, and you too can trash the airwaves.  Here's your chance to
accuse me of being a hypocrite as I sometimes use these in place of
CAT5 when expedient.

>One can argue that many of them are just "bad ideas" and "irresponsible
>engineering" but it is just irrelevant in a world where nobody cares
>about HF radio reception except some old-hat radio amateurs.

There's still quite a bit of HF traffic on the marine bands.  Not as
much as before but still plenty.  
<http://www.latitude38.com/features/SSB.html>

>In the modern society they are irrelevant and only hampering innovation.

Wasn't that the argument used by industrial chemical companies after
they polluted a river?  Nobody ever drinks from the river, so it must
be ok to pollute it.  Can't have a few dead fish get in the way of
progress.

-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

On Sunday, August 27, 2017 at 4:35:31 AM UTC-4, Rob wrote:
> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
> > On 08/26/2017 02:36 PM, Rob wrote:
> >> Jeff Liebermann <jeffl@cruzio.com> wrote:
> >>> I do some computah work for the author.  I recently unloaded about 50
> >>> lbs of linear wall warts on his doorstep.  Over the years, he has
> >>> systematically replaced as many switchers with linear power supplies
> >>> as possible.
> >> 
> >> Swiching power supplies are much more efficient, both in operation
> >> and in manufacturing.  They use a lot less resources to manufacture.
> >> 
> >> That is what the world needs more than clean HF bands.  Live with it.
> >> 
> >
> > Gee, it's great that there are people like you, People Who Know Best. 
> > Otherwise we the great unwashed would have no one to tell us how to 
> > think, and then where would we be?
> >
> > There's nothing that prevents one from making quiet switching supplies. 
> > They just cost more.
> 
> I'm not "the one who knows best", I am the one that realistically sees
> that the use of frequency bands in the world has irreversibly changed.
> 
> In the past the HF bands were used to do radio transmissions, now they
> are emitted as unwanted byproduct by modern equipment, and they are
> no longer used for radio.  At least not like before.
> 
> For sure it would be good to design switching supplies with low emission,
> but don't think that would solve the problem of "HF bands not being
> as quiet as they used to be".

But it does fix the problem of noise from switchers.

>  There are too many other sources of
> emissions that are not so easy to handle.  E.g. ethernet over powerline.

Other noise sources should be cleaned up too.  But that doesn't mean we
should ignore the "easy to handle" (in your words).
 
> One can argue that many of them are just "bad ideas" and "irresponsible
> engineering" but it is just irrelevant in a world where nobody cares
> about HF radio reception except some old-hat radio amateurs.
> In the modern society they are irrelevant and only hampering innovation.

HF has unique propagation properties.  It's a shame to throw those away.

Solution: we need VHF wallwarts, preferably in the two-meter region.  That
way only a small group of old-hat radio amateurs would be affected. ;-)

Cheers,
James Arthur

Jeff Liebermann <jeffl@cruzio.com> wrote:
>>But that is as it should be!  With the limited number of channels
>>available, it should be considered criminal to try to setup an outdoor
>>long range link without using high gain antennas with small sidelobes.
>
> Criminal?  Are you planning to prosecute someone for failing to use
> good engineering practices?  I wouldn't mind seeing that because it
> would put most of my competitors in jail.

THis is not "failing to use good engineering practices", this is simply
"antisocial behaviour".  Others should have their fair share of the
channel usage as well.

> Actually, the FCC "encourages" users of point to point links to use
> big high gain antennas.  Part 15.247 describes how the gain of a
> directional antenna can be increased by 3dB for every 1dB drop in
> transmit power.  That grinds out to a 24 dBm transmitter and a 24 dBi
> antenna, which produces 48 dBm EIRP or 62 watts EIRP.

That is quite a lot, we cannot have more than 1 Watt EIRP for unlicensed
usage.

> Note that the interference problem with high gain antennas and point
> to point links is along the line of sight of the antenna, not to the
> sides or back.  Along the line of sight, the gain of the antenna is
> highest.  It's very likely that some other wi-fi transmitter is
> located along this line of sight, usually behind the intended other
> end of the wireless link.

It of course still depends on the beamwidth of your antenna.
The lower the gain, the larger the beamwidth and the more likely there
is some other user in that beam.

> I have a 400ft link between my house and
> one of the neighbors.  When I first set it up, I failed to notice that
> a local mountain top radio site was directly in line with my antenna.
> The mountain top is about 8 miles away and is full of interference
> sources.  Nothing would work until I reduced my antenna gain and moved
> the link.
>
> Incidentally, for point to point wireless bridges, I like to use
> Ubiquiti PowerBeam PBE-M5-400 radios at about $100/end.
> <https://dl.ubnt.com/datasheets/powerbeam/PowerBeam_DS.pdf>
> There are 3 different sizes of antennas and some options to deal with
> the side lobes.  As long as I pick my channels carefully, I don't have
> much trouble with interference from other users of the 5GHz band.  The
> built in spectrum analyzer software is a big help.

You use those for 400ft links?  That should give very good results
at very low power.  We build 30-40km HAMNET links using these, with
1 Watt EIRP only.  We prefer to use the better -ISO variant.
(less sidelobes, mechanically more sturdy)

Jeff Liebermann <jeffl@cruzio.com> wrote:
>>Usually a receiving system has "some idea of the correct time" and can
>>determine with reasonable certainty if a received datagram is correct.
>>Receiving multiple datagrams of course can improve that certainty, but
>>they do not have to be consecutive for that.
>
> There is no storage in the C-Max chipset.  There are receivers with
> storage capabilities, but those use the storage for error correction
> and accuracy improvement by accumulating previous frames.

Here the typical DCF77 clock is a crystal-referenced digital clock
with synchronization to the DCF77 signal.  The battery-operated clocks
synhronize once per hour or twice a day.  At the time they receive the
datagram they know what to expect.

> For example, how hard would it be to throw together a diversity
> reception system using two DCF77 receivers that are geographically
> separated?  With data arriving at the screaming rate of 1 bit/second,
> there's plenty of time to perform computation on the probability that
> the bit is a one or a zero.  The disk drive manufacturers do that
> because the data from the head looks more like garbage than data. Lots
> of other error correction tricks can be used, all of which require
> storage of previous data and adequate computation time.

All the receivers I am still using are old and are simple AM receivers
with an AGC that kicks in on local interference and requires several
seconds to recover.  When I would want to build a receiver today, I
would just tune a ferrite antenna to 77.5 kHz, and connect it to a
suitable sound card (with 192 kHz sampling rate), and do it all in
SDR technology.  Easy to do both AM and BPSK.

> Incidentally, a problem with using WWVB as a reference is that it
> doesn't really make a good stabilized clock oscillator.  There were
> WWVB disciplined oscillators available:
> <http://www.ebay.com/itm/Spectracom-8164-NBS-Receiver-Disciplined-Oscillator-/172838067755>
> but they were replaced by GPSDO's long ago.

DCF77 and WWVB are only really suitable "network quality" time.
The jitter on the demodulated AM signal is about 200us here.
For purposes that require time in the microsecond accuracy range,
like our simulcast NBFM repeater, GPS is a must.