Reply by Lasse Langwadt Christensen●March 22, 20142014-03-22
Den torsdag den 13. marts 2014 15.51.15 UTC+1 skrev Frnak McKenney:
> I have two "atomic clocks": one is a La Crosse LCD unit, the other an
>
> "analog" wall clock whose hands are driven by a WWVB-sync 1xAA-powered
>
> mechanism. Following the recent "let's screw with everybody's clocks"
>
> cycle neither of my "atomic clocks" caught it, and I was reminded that
>
> I was Going To Fix This Problem last time. And the time before...
>
> <grin!>
>
>
>
> After some years I've discovered that, if I place my clocks near the
>
> west-most window and leave them for a few days, they will usually
>
> re-sync with the current WWVB time; if I don't do this it may be weeks
>
> or months before they pick up a strong enough signal to reset. This
>
> isn't a particularly onerous task, but it's only slightly less effort
>
> than pushing buttons in some arcane sequence to manually update a
>
> clock.
>
>
>
> Is there some simple way of strengthening the WWVB signal so my clocks
>
> will reset themselves automatically, preferably one that doesn't
>
> involve stringing wires to each device?
>
>
>
> The main axis of the house is a few degrees clockwise from a true E-W
>
> line. What I picture is an antenna near the westernmost window to
>
> pick up, amplify slightly (no kilowatt linears! <grin>) and and
>
> rebroadcast the WWVB signal directionally "down" (east) the house so
>
> that every device would get a stronger signal. Is there some
>
> commercial gadget that does this? Or would I need to roll my own?
>
>
>
> And, if I have to build it, what would be a good unidirectional LF
>
> antenna type? I have two neighbors to my SW and NW, and I really don't
>
> want to mess up their equipment. <grin!>
>
>
>
> I don't seem to be the only one with this problem, as these threads
>
> indicate:
>
>
>
> <http://comments.gmane.org/gmane.org.user-groups.linux.blu.hardware/589>
>
> <http://doityourselfchristmas.com/forums/showthread.php?11305-60-khz-Transmitter>
>
> <https://groups.google.com/forum/#!topic/rec.radio.broadcasting/x8WnIcRO__o>
>
>
>
> Suggestions welcome.
>
>
On Wed, 19 Mar 2014 09:51:18 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:
> On Wed, 19 Mar 2014 09:34:17 -0500, Frnak McKenney
><frnak@far.from.the.madding.crowd.com> wrote:
>
>>Before I read your reply I managed to get SpectrumLab installed (under
>>Wine) and hooked up one end of a 30' microphone cable to the D630's
>>Mic_In socket. In spite of whatever filters Dell has on its audio
>>input, last night SpectrumLab reported two (FFT-averaged) "peaks" at
>>59940Hz and 60060Hz varying from 10 to 20dB above everything else. (
>>Right now I can barely pick out the same peaks from the surrounding
>>"noise" (a.k.a. "Stuff I don't care about." )
>
> I think you'll find that laptop internal sound cards have a rather
> horrible SNR (signal to noise ratio). They pickup digital hash and
> junk from all over the laptop. It's mostly a problem with the higher
> gain microphone input, but the noise can also be found on the audio
> output.
You mean that a laptop manufacturer would put 192ksps/24-bit ADCs and
ADCs in his equipment and then _not_ use gold-plated cables as well?
Ouch. But thanks for the warning.
> ... To get rid of the junk, you should use an external USB
> connected sound card. I've been using cheap CM108 type USB sound
> dongles found on eBay for about $3 such as:
><http://www.ebay.com/itm/300715727779>
> but there are better devices available. However, those are all
> usually limited to about 20KHz maximum frequency. I think a mixer to
> downconvert to about 12Khz will be much easier.
Yup. My fingers are too fat and my eyesight too poor to really hack
surface-mount hardware very well.
> The only problem is that if it works, the WWVB spectrum display is
> going to be rather dull. With only 5Hz bandwidth and very slow
> modulation, you're not going to see much in the way of sidebands. The
> only thrill will be to watch the amplitude variations. Maybe watching
> the other time signals might be more interesting:
><http://genesisradio.com.au/VK2DX/time_signals.html>
Yup. I'd need a tunable LO for that (see below).
>>I've got some other things I need to get done before I spend much more
>>time on this.
>
> Gee thanks. I was hoping that you would work on the problem, so I
> could steal the results.
If I get something working I'll send you a copy of the schematic. ( Hey!
Who cued Sonny and Cher on "The Twelfth of Never"??? )
>>That will give me time to decide whether I'd rather
>>solder up a downconverter or write code to have some microcontroller
>>do the sampling at >120ksps for me. Decisions, decisions. <grin!>
>
> Another possibility is to reverse engineer a sound card, and modify
> the audio circuitry to pass up to 88KHz. Personally, I hate
> programming and recommended the mixer scheme, since it has a good
> chance of working (and because it's my suggestions).
And a very good one! <grin>
I put an order in to Mouser last night for the parts to build a variant
of Lyle Koehler's downconverter:
A LowFER Receiver Using a "Software" IF
http://www.qsl.net/k0lr/SW-RX/sw-rx.htm
It uses an SA602 mixer chip, which is handy for me. My understanding of
"mixing" -- of the "why" signals sometimes add and sometimes multiply --
is limited to throwing around words like "nonlinear" and "sum and
difference" without necessarily being able to create one of my own.
( If I ever have my "Electron Choreographer" cards printed up -- and if
I'm honest about it -- I might get away with claiming I had reached
"Senior Apprentice" level. )
I'll be using a 4.000MHz crystal divided by 64 so my LO will run at
62500Hz, giving me several hours of debugging followed by -- hopefully --
2500Hz into the laptop. Once everything works. <grin!>
I have a couple of MSP430 LauchPads lying around, so later I can think
about replacing the crystal/xx4060 LO with something generated under
software control (think "programmable DDS"). This would let me add an
LCD, buttons for adjusting the LO frequency, etc. to make a tunable VLF
superhet.
But that's for later.
Have a good weekend.
Frank
--
There is something deeply fulfilling, even thrilling, in doing almost
anything difficult extremely well. There is a joy and pride that come
from pushing yourself to another level, or across a new frontier.
A life devoted only to the present -- to feeling good in the now -- is
unlikely to deliver real fulfillment. The present moment by itself is
too small, too hollow. We all need a future, someting beyond and
greater than our own present gratification, at which to aim or to which
we feel we've contributed.
-- Amy Chua, Jed Rubenfeld / The Triple Package
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney aatt mindspring ddoott com
Reply by Jeff Liebermann●March 19, 20142014-03-19
On Wed, 19 Mar 2014 09:34:17 -0500, Frnak McKenney
<frnak@far.from.the.madding.crowd.com> wrote:
>Before I read your reply I managed to get SpectrumLab installed (under
>Wine) and hooked up one end of a 30' microphone cable to the D630's
>Mic_In socket. In spite of whatever filters Dell has on its audio
>input, last night SpectrumLab reported two (FFT-averaged) "peaks" at
>59940Hz and 60060Hz varying from 10 to 20dB above everything else. (
>Right now I can barely pick out the same peaks from the surrounding
>"noise" (a.k.a. "Stuff I don't care about." )
I think you'll find that laptop internal sound cards have a rather
horrible SNR (signal to noise ratio). They pickup digital hash and
junk from all over the laptop. It's mostly a problem with the higher
gain microphone input, but the noise can also be found on the audio
output. To get rid of the junk, you should use an external USB
connected sound card. I've been using cheap CM108 type USB sound
dongles found on eBay for about $3 such as:
<http://www.ebay.com/itm/300715727779>
but there are better devices available. However, those are all
usually limited to about 20KHz maximum frequency. I think a mixer to
downconvert to about 12Khz will be much easier.
The only problem is that if it works, the WWVB spectrum display is
going to be rather dull. With only 5Hz bandwidth and very slow
modulation, you're not going to see much in the way of sidebands. The
only thrill will be to watch the amplitude variations. Maybe watching
the other time signals might be more interesting:
<http://genesisradio.com.au/VK2DX/time_signals.html>
>I've got some other things I need to get done before I spend much more
>time on this.
Gee thanks. I was hoping that you would work on the problem, so I
could steal the results.
>That will give me time to decide whether I'd rather
>solder up a downconverter or write code to have some microcontroller
>do the sampling at >120ksps for me. Decisions, decisions. <grin!>
Another possibility is to reverse engineer a sound card, and modify
the audio circuitry to pass up to 88KHz. Personally, I hate
programming and recommended the mixer scheme, since it has a good
chance of working (and because it's my suggestions).
--
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
Reply by Frnak McKenney●March 19, 20142014-03-19
On Tue, 18 Mar 2014 15:08:41 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:
> On Tue, 18 Mar 2014 11:51:15 -0500, Frnak McKenney
><frnak@far.from.the.madding.crowd.com> wrote:
>
>>> Nice. I have a GC-1000 Most Accurate Clock that I'm slowly
>>> rebuilding. The original builder was seriously lacking in mechanical
>>> ability and made a nice mess.
>>
>>Ouch! again. Did you get a manual with it? ( Hm. I'd better make
>>sure I can locate _mine_ before I make any offers. <grin!> )
>
> Thanks, but I have both the printed and scanned manuals. What I lack
> is time and incentive.
Understood.
[...]
>>Thanks. I've been looking at USB audio interfaces that would (a) work
>>with Ubuntu Linux and (b) sample at greater than 2x60kHz, and while
>>there are a lot of inexpensive ones out there, it's really hard to
>>tell what their spec's are.
>
> There are quite a few that offer 192KHz sampling rate. The problem is
> that the audio sections usually roll off at about 20KHz. I've found
> cards that will allegedly go to 90KHz, but they're expe$ive. For
> example:
><http://www.asus.com/Sound_Cards_and_DigitaltoAnalog_Converters/Xonar_Essence_STX/#specifications>
> I have yet to find a USB version that does above 20KHz, but suspect
> that once can be found which might be modified. (Yet another
> project).
Nice specs, but, as you say, a bit pricey.
>>Punchline? I finally got around to
>>checking the specifications on my laptop's built-in audio... and found
>>that Dell dropped an STAC9205 into this D630... and that chip says it
>>can deliver 24-bit samples at 192kHz.
>
> No, that's NOT the spec. The 192KHz is the sampling rate not the
> frequency response. If you want to go up to the Shannon limit, you
> theoretically can get about 80Khz for the upper frequency.
Yes. Sampling rate. To directly sample a 60kHz signal the way I was
describing ( and be able to reconstruct it <grin!> ) one needs
to sample faster than 120kHz. (Nyquist)
> ... You'll
> need to butcher the audio amplifier section of the sound card to do
> that.
Yup. That's the part I overlooked in my excitement. The ADCs I've
used before were on microcontrollers, and I didn't stop to think about
what kind of filtering -- with all the best intentions -- a laptop
manufacturer might put ahead of an ADC "intended" for audio input,
even one capable of 192ksps.
Oops. My bad. <grin!>
Before I read your reply I managed to get SpectrumLab installed (under
Wine) and hooked up one end of a 30' microphone cable to the D630's
Mic_In socket. In spite of whatever filters Dell has on its audio
input, last night SpectrumLab reported two (FFT-averaged) "peaks" at
59940Hz and 60060Hz varying from 10 to 20dB above everything else. (
Right now I can barely pick out the same peaks from the surrounding
"noise" (a.k.a. "Stuff I don't care about." )
> ... My guess(tm) is that's easier to add a mixer and downconvert
> the 60KHz RF to a lower frequency that's more easily digested by a
> sound card. That's the way DRM broadcasting is done from the 455KHz
> IF frequency of a receiver.
><http://www.radiomuseum.hu/radiomuseum/rajzok/drmvevo.pdf>
> With a working bandwidth of only about 5Hz, this should be easy
> (famous last words).
I've got some other things I need to get done before I spend much more
time on this. That will give me time to decide whether I'd rather
solder up a downconverter or write code to have some microcontroller
do the sampling at >120ksps for me. Decisions, decisions. <grin!>
On the good side, it looks like we've finally gotten past the 2014
Groundhog's Curse. The sleet/freezing rain we got Monday and Tuesday
will be replaced by sunny, high-60s weather by the weekend.
Frank
--
...the fact that some geniuses were laughed at does not imply that
all who are laughed at are geniuses. They laughed at Columbus, they
laughed at Fulton, they laughed at the Wright Brothers. But they
also laughed at Bozo the Clown. -- Carl Sagan
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney aatt mindspring ddoott com
Reply by Jeff Liebermann●March 18, 20142014-03-18
On Tue, 18 Mar 2014 10:24:22 -0700, Don Lancaster <don@tinaja.com>
wrote:
>WWVB recently added a whole new modulation method that should stunningly
>improve their reception reliability.
Yep.
>Unfortunately, the new chips are half a year overdue and appear to be
>stuck in the pipe.
On Tue, 18 Mar 2014 11:51:15 -0500, Frnak McKenney
<frnak@far.from.the.madding.crowd.com> wrote:
>> Nice. I have a GC-1000 Most Accurate Clock that I'm slowly
>> rebuilding. The original builder was seriously lacking in mechanical
>> ability and made a nice mess.
>
>Ouch! again. Did you get a manual with it? ( Hm. I'd better make
>sure I can locate _mine_ before I make any offers. <grin!> )
Thanks, but I have both the printed and scanned manuals. What I lack
is time and incentive.
Yech. That's ugly. With real Nixie tubes, you can read all the
digits instead of just the one up front. However, if you're using
real Nixie tubes with a 60KHz receiver, you're going to have RFI
problems from the usual switching high voltage power supply. I've
seen it done, but it required lots of shielding and ferrite filters.
>Thanks. I've been looking at USB audio interfaces that would (a) work
>with Ubuntu Linux and (b) sample at greater than 2x60kHz, and while
>there are a lot of inexpensive ones out there, it's really hard to
>tell what their spec's are.
There are quite a few that offer 192KHz sampling rate. The problem is
that the audio sections usually roll off at about 20KHz. I've found
cards that will allegedly go to 90KHz, but they're expe$ive. For
example:
<http://www.asus.com/Sound_Cards_and_DigitaltoAnalog_Converters/Xonar_Essence_STX/#specifications>
I have yet to find a USB version that does above 20KHz, but suspect
that once can be found which might be modified. (Yet another
project).
>Punchline? I finally got around to
>checking the specifications on my laptop's built-in audio... and found
>that Dell dropped an STAC9205 into this D630... and that chip says it
>can deliver 24-bit samples at 192kHz.
No, that's NOT the spec. The 192KHz is the sampling rate not the
frequency response. If you want to go up to the Shannon limit, you
theoretically can get about 80Khz for the upper frequency. You'll
need to butcher the audio amplifier section of the sound card to do
that. My guess(tm) is that's easier to add a mixer and downconvert
the 60KHz RF to a lower frequency that's more easily digested by a
sound card. That's the way DRM broadcasting is done from the 455KHz
IF frequency of a receiver.
<http://www.radiomuseum.hu/radiomuseum/rajzok/drmvevo.pdf>
With a working bandwidth of only about 5Hz, this should be easy
(famous last words).
Good luck.
--
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
Reply by Don Lancaster●March 18, 20142014-03-18
On 3/18/2014 9:51 AM, Frnak McKenney wrote:
> On Sat, 15 Mar 2014 14:11:29 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:
>> On Sat, 15 Mar 2014 15:05:27 -0500, Frnak McKenney
>> <frnak@far.from.the.madding.crowd.com> wrote:
>>
>>> Good thought. Unfortunately, I've had WWV/WWVB reception problems as
>>> long as I've lived here.
>>
>> Find a spectrum analyzer and look at what you're actually receiving
>> from the antenna. I spent a day troubleshooting a WWVB receiver
>> before I discovered that I had an oscillating RF amplifier in the
>> remote antenna section.
>
> Ouch!
>
>>> I finally build a 1m dia tuned loop so my
>>> Heath Most Accurate Clock could reliably receive WWV 10MHz.
>>
>> Nice. I have a GC-1000 Most Accurate Clock that I'm slowly
>> rebuilding. The original builder was seriously lacking in mechanical
>> ability and made a nice mess.
>
> Ouch! again. Did you get a manual with it? ( Hm. I'd better make
> sure I can locate _mine_ before I make any offers. <grin!> )
>
>>> Good thought. As in, "make sure you're solving the right problem".
>>
>> Yep. In general, if you have at least 10dB SNR, you should be able to
>> demodulate WWVB. If you look at the plots at:
>> <http://www.febo.com/time-freq/wwvb/sig-strength/wwvb-spectracom.html>
>> The >10dB SNR is typically about 20 hrs per day. Avoid working around
>> sunset and you'll probably be ok.
>>
>> Most people spend their time trying to maximize the antenna gain. Bad
>> idea as that increases both the signal and the noise equally. What's
>> needed is a way to improve the SNR by reducing the noise pickup.
>> That's the real problem.
>
>
>>> My analog clock has a WWVB-sync'ed movement like this one:
>>> http://www.amazon.com/Atomic-Clock-Movement-Shaft-Length/dp/B007KA54RW/
>>>
>>> and there isn't room inside it for much of an antenna. One might
>>> guess that the LaCrosse WS-8418 has a slightly larger antenna, but it
>>> would be a guess; I haven't had an excuse to take it apart (yet).
>>
>> Well, it's probably larger than the tiny loopstick used in the wrist
>> watches. Here's a possible dissection of a similar clock movement:
>> <http://www.amug.org/~jthomas/wwvbmod.html>
>> Looks like a reasonable size ferrite rod and coil winding. No
>> shielding, which is typical.
>
> Thanks. Now I can find a replacement movement if I need one.
>
> Oh, and if any of our readers are interested in making their own
> 3"-tall nixie-ish displays from EL wire:
>
> http://hackaday.com/2014/02/24/el-wire-nixie-tube-is-in-your-reach/
>
>>>> <http://www.c-max-time.com/tech/antenna.php>
>>>
>>> Thank you for the pointer. I've filed it for future reference. ( Do
>>> the Aerial Connection diagrams a-d look mislabeled to you? )
>>
>> You have good eyes. They should be labeled:
>> a) single ended b) single ended something strange
>> c) balanced center d) balanced center
>> tap coil tap resistors
>
> Okay. Thanks for the reassurance -- I thought I was going crazy.
> ( Okay, crazier. <grin> )
>
>>> Agreed. I don't forsee ever needing instant mid-day updates, though.
>>
>> To save battery power, most such clocks play dead during the day and
>> only wake up when a strong signal might be expected. Typical for the
>> chip is only a few updates per night with a 1 to 24 hr delay after
>> each successful update. If battery operated, they do NOT listen
>> continuously. This is all settable in the chip at the whim of the
>> designer. See the flow chart at:
>> <http://www.c-max-time.com/tech/software6005.php>
>
> Another page I hadn't noticed the last time I visited c-max. Thanks
>
>>>> Build a 60 KHz sniffer and see if they really are a problem. My bet
>>>> is that if you have interference problems, it's local.
>>>
>>> Good suggestion, but I think I was trying to say that I didn't want
>>> any signal amplifier I built to cause problems for my neighbors.
>>
>> Unless it decides to oscillate and become a transmitter, I wouldn't
>> expect any problems. However, hanging a large loop antenna on the
>> fence line might produce some paranoia on the part of the neighbors. I
>> suggest threading some vines through it as natural camouflage.
>
> Vines... vines... how about that adorable plant named Audrey II from
> "Little Shop of Horrors"?
>
>>> Well, if I build a 60Hz "sniffer" I should be able to find one if I
>>> have it.
>>
>> Ummm... that's 60 KHz, not Hz. ...
>
> A-hum. I knew that... it's my spelling checker's fault! <grin!>
>
>> ... It's difficult to tell what you're
>> looking at with a scope. A portable spectrum analyzer would be
>> better, if you can find something that works at 60 Khz. A high end
>> 192 KHz sound cards should work. Probably already been done.... yep:
>> <http://www.geocities.jp/bitalemon3000/english.html>
>> <https://www.youtube.com/user/pobox22cpo>
>> <http://www.qsl.net/dl4yhf/spectra1.html>
>> More on VLF reception using Spectrum Lab software:
>> <http://abelian.org/vlfrx/>
>> Note the graphs with the noise plot. 60 KHz looks ugly and note the
>> comments on buzz from the 12 KV lines.
>
> Thanks. I've been looking at USB audio interfaces that would (a) work
> with Ubuntu Linux and (b) sample at greater than 2x60kHz, and while
> there are a lot of inexpensive ones out there, it's really hard to
> tell what their spec's are. Punchline? I finally got around to
> checking the specifications on my laptop's built-in audio... and found
> that Dell dropped an STAC9205 into this D630... and that chip says it
> can deliver 24-bit samples at 192kHz. ( Now I have to verify that the
> Linux drivers can reliably deliver this. That should not be taken as
> a jab at Linux, merely an exposure of my own inexperience. <grin!> )
>
> Sounds like a good time for lunch.
>
> Thanks again. It'll probably be a few weeks before I have any
> progress, but I'll post something back when I have results.
>
>
> Frank
>
On Sat, 15 Mar 2014 14:11:29 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:
> On Sat, 15 Mar 2014 15:05:27 -0500, Frnak McKenney
><frnak@far.from.the.madding.crowd.com> wrote:
>
>>Good thought. Unfortunately, I've had WWV/WWVB reception problems as
>>long as I've lived here.
>
> Find a spectrum analyzer and look at what you're actually receiving
> from the antenna. I spent a day troubleshooting a WWVB receiver
> before I discovered that I had an oscillating RF amplifier in the
> remote antenna section.
Ouch!
>>I finally build a 1m dia tuned loop so my
>>Heath Most Accurate Clock could reliably receive WWV 10MHz.
>
> Nice. I have a GC-1000 Most Accurate Clock that I'm slowly
> rebuilding. The original builder was seriously lacking in mechanical
> ability and made a nice mess.
Ouch! again. Did you get a manual with it? ( Hm. I'd better make
sure I can locate _mine_ before I make any offers. <grin!> )
>>Good thought. As in, "make sure you're solving the right problem".
>
> Yep. In general, if you have at least 10dB SNR, you should be able to
> demodulate WWVB. If you look at the plots at:
><http://www.febo.com/time-freq/wwvb/sig-strength/wwvb-spectracom.html>
> The >10dB SNR is typically about 20 hrs per day. Avoid working around
> sunset and you'll probably be ok.
>
> Most people spend their time trying to maximize the antenna gain. Bad
> idea as that increases both the signal and the noise equally. What's
> needed is a way to improve the SNR by reducing the noise pickup.
> That's the real problem.
>>My analog clock has a WWVB-sync'ed movement like this one:
>> http://www.amazon.com/Atomic-Clock-Movement-Shaft-Length/dp/B007KA54RW/
>>
>>and there isn't room inside it for much of an antenna. One might
>>guess that the LaCrosse WS-8418 has a slightly larger antenna, but it
>>would be a guess; I haven't had an excuse to take it apart (yet).
>
> Well, it's probably larger than the tiny loopstick used in the wrist
> watches. Here's a possible dissection of a similar clock movement:
><http://www.amug.org/~jthomas/wwvbmod.html>
> Looks like a reasonable size ferrite rod and coil winding. No
> shielding, which is typical.
>>><http://www.c-max-time.com/tech/antenna.php>
>>
>>Thank you for the pointer. I've filed it for future reference. ( Do
>>the Aerial Connection diagrams a-d look mislabeled to you? )
>
> You have good eyes. They should be labeled:
> a) single ended b) single ended something strange
> c) balanced center d) balanced center
> tap coil tap resistors
Okay. Thanks for the reassurance -- I thought I was going crazy.
( Okay, crazier. <grin> )
>>Agreed. I don't forsee ever needing instant mid-day updates, though.
>
> To save battery power, most such clocks play dead during the day and
> only wake up when a strong signal might be expected. Typical for the
> chip is only a few updates per night with a 1 to 24 hr delay after
> each successful update. If battery operated, they do NOT listen
> continuously. This is all settable in the chip at the whim of the
> designer. See the flow chart at:
><http://www.c-max-time.com/tech/software6005.php>
Another page I hadn't noticed the last time I visited c-max. Thanks
>>> Build a 60 KHz sniffer and see if they really are a problem. My bet
>>> is that if you have interference problems, it's local.
>>
>>Good suggestion, but I think I was trying to say that I didn't want
>>any signal amplifier I built to cause problems for my neighbors.
>
> Unless it decides to oscillate and become a transmitter, I wouldn't
> expect any problems. However, hanging a large loop antenna on the
> fence line might produce some paranoia on the part of the neighbors. I
> suggest threading some vines through it as natural camouflage.
Vines... vines... how about that adorable plant named Audrey II from
"Little Shop of Horrors"?
>>Well, if I build a 60Hz "sniffer" I should be able to find one if I
>>have it.
>
> Ummm... that's 60 KHz, not Hz. ...
A-hum. I knew that... it's my spelling checker's fault! <grin!>
Thanks. I've been looking at USB audio interfaces that would (a) work
with Ubuntu Linux and (b) sample at greater than 2x60kHz, and while
there are a lot of inexpensive ones out there, it's really hard to
tell what their spec's are. Punchline? I finally got around to
checking the specifications on my laptop's built-in audio... and found
that Dell dropped an STAC9205 into this D630... and that chip says it
can deliver 24-bit samples at 192kHz. ( Now I have to verify that the
Linux drivers can reliably deliver this. That should not be taken as
a jab at Linux, merely an exposure of my own inexperience. <grin!> )
Sounds like a good time for lunch.
Thanks again. It'll probably be a few weeks before I have any
progress, but I'll post something back when I have results.
Frank
--
How much easier it is to do things yourself than to teach other
people to do them! ...throughout my foolish life, there has been
that inner something or other that compelled me to teach people
how to do things, no matter how eccentric or unorthodox -- a sense
of some great event ahead that would need every talent I could
develop in all who came under my influence. That strange urge was
behind every decision of policy in our medical work, in our
nurses' training; behind acceptance of duties for which I was
poorly trained: an urge to learn first, how to do the thing
myself, and then to find someone whom I could teach to do it for
me. -- Gordon S. Seagrave / Burma Surgeon
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney aatt mindspring ddoott com
Reply by Joe Gwinn●March 16, 20142014-03-16
In article <5324F143.5010807@electrooptical.net>, Phil Hobbs
<hobbs@electrooptical.net> wrote:
> On 3/15/2014 5:17 PM, Martin Brown wrote:
> > On 15/03/2014 02:59, Jasen Betts wrote:
> >> On 2014-03-14, Frnak McKenney <frnak@far.from.the.madding.crowd.com>
> >> wrote:
> >>
> >>>> I used a multi-turn 8" loop antenna encased in 1/2" copper pipe
> >>>> (with a fiber joint to avoid a shorted turn.
> >>>
> >>> Square/rectangular, yes? Or is there some easy way to bend Cu pipe
> >>> into a nice, pretty circle? <grin!>
> >>
> >> anneal it first. (get it red-hot with a propane torch)
> >> then when it cools it'll be soft and can be formed by hand.
> >
> > ISTR You have to drop it in a bucket of water whilst red hot to make
> > copper stay soft (and avoid the jet of steam and boiling water).
> >
>
> Quenching usually makes metals hard and brittle.
For ferrous metals, yes.
The size of the quenching effect varies with specific alloy. For
instance, steel containing 1% carbon gets very hard, while steel
containing 0.18% carbon is not much affected by quenching.
For non-ferrous metals, no, it anneals them.
Copper alloys have variations in quenching effect, but I don't offhand
know which is which. Likewise, silver - I first heard the quench- to-
anneal story when taking jewelry making class in the 1970s. We would
combine quenching with firescale (oxide) and flux removal by quenching
in a dilute mineral acid after hard soldering.
> You can also just get Type K copper tubing.
Yes, but that's cheating. You should be drawing your own tubing from
billet.
Joe Gwinn
Reply by ●March 16, 20142014-03-16
On Sat, 15 Mar 2014 12:47:39 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
>On Sat, 15 Mar 2014 12:05:27 -0700, Jeff Liebermann <jeffl@cruzio.com>
>wrote:
>
>>I don't think battery operation will help much. At the low power
>>requirements for a WWVB front end, a simple analog power supply should
>>be adequate. If you're worried about conducted emissions from the
>>power lines, then there are various power line filters and ferrite
>>beads that should help.
The problem these days is that a house is surrounded by electric
"smog" due to all active electronics such as VFDs.
If you are used some small untuned whip antenna close to the house as
in many pictures in that article and links, you are going to have a
1-10 pF connection from the in-house wiring to that whip and hence
have a strong connection interference from the mains to the whip.
Typically a simple active is just not much more a high input
resistance FET drain follower that probes the voltage in the whip and
drives the 50 ohm coax with significant current gain.
Since the short antenna is highly reactive (some pF capacitance from
the "ether" to the whip) there is going to be a capacitive voltage
divider to ground, either through the FET gate-source capacitance or a
huge attenuation due to the coaxial cable capacitance, if such short
antenna is connected directly to a coax to avoid indoor noise pickup.
Since some of the link were broken, I don't know if this whip was
actually tuned, i.e. used some kind of loading coil to make the
antenna look like a resistive source to the amplifier ?
In my experiments I have used a few meters of wire suspended into some
trees in the garden, connected to a LC tank top through a 10 pF
capacitor. The inductance consisted of several coils in series and
selected by the band and the voltage at the lowest coil (relatively
low impedance), went through a darlington voltage follower to a short
50 ohm coax. The capacitance was tunable with mechanical multi section
capacitor. The short coax was required to avoid spurious radiation
from the receiver synthesizer to the antenna :-). The whole setup was
operated from a 12 V car battery.
With this setup, the 16 kHz Rugby UK station (nearly 2000 km away)
could heard with good SNR even during summer days. Of course this
setup with mechanical variable capacitors made sense only during warm
summer days :-).
Running an mains extension cord across the garden without connecting
the charger, increased the noise level.
>
>A bit more on power line emissions and WWVB:
><http://www.prc68.com/I/LF-Ant.shtml>
>The whip antenna is tunable and run from an AC power supply. However,
>the conducted junk from the power line made 60 KHz reception rather
>problematic, until the author added additional RF filtering and
>bypassing.
>
>Some performance reports with a Spectracom 8206 antenna, which is a
>shielded ferrite rod type:
><http://www.febo.com/time-freq/wwvb/sig-strength/wwvb-spectracom.html>
>Note that at some times of the day, the SNR is near zero making AM
>demodulation impossible.
Small magnetic loop antennas have some advantage compared to small
electric (capacitive) antennas in the near field due to the
cube/square relationship.