Re: [time-nuts] WWVB Dephaser Question

[rcbuck]

Paul, by going to high power mode I meant at the 200, 500, or 800 msec
point of each second.

Ray

 Original Message 
Subject: Re: [time-nuts] WWVB Dephaser Question
From: Bob kb8tq 
Date: Fri, October 09, 2020 4:12 pm
To: Discussion of precise time and frequency measurement


Hi

I don’t believe that the WWVB transmitters change power day
to night. Both the north and south antenna’s are fed with the same
power, regardless of the time of day…..

Bob

> On Oct 9, 2020, at 5:59 PM, rcb...@atcelectronics.com wrote:
> 
> Paul,
> I was seeing a -10 dBm on the SA when they enter high power mode at
> night. At low power they are only a couple of dB above the nearby noise
> makers. But that is at the output of the last stage of my receiver. The
> WWVB signal was about 10-15 dB above the noise makers in my work shop. I
> don't know what the actual WWVB signal level is and have no way to
> measure it. I estimate the ferrite antenna to be approx 20k ohm which
> doesn't match the 50 ohm input of the SA. Maybe feed the rod antenna
> into a single stage op amp with a gain of 1 to feed the SA would work
> give me a rough idea?? I previously said I had 1 mV of daytime signal
> according to the WWVB maps. But that was wrong. In my mind I was
> thinking 1000 uV when the maps show the 100 uV coverage area. So receive
> level during the day should be around 0.1 mV. I have PCB's on order that
> hopefully will improve the receiver performance.
> 
> Bob,
> I'm still trying to figure out if a software or hardware solution is
> better. I've looked at the Costas loop and a PLL angle. But I run into
> the problem of the LO being on the same frequency as WWVB. Plus as Paul
> said the math is intimidating to me. Locking WWVB to a HF oscillator and
> dividing down to 10 kHz or so for the control voltage and I/Q
> demodulation may be an answer but involves more hardware.
> 
> For a software solution I don't know exactly how to approach the task. I
> don't have any DSP software experience so that option is out. I haven't
> made a decision on the CPU yet. I will just use whatever it takes for
> the job, probably a STM32 part of some sort. I have a couple of STM32
> development boards I can use when I get to that point.
> 
> Ray
> 
> 
>  Original Message 
> Subject: Re: [time-nuts] WWVB Dephaser Question
> From: Bob kb8tq 
> Date: Fri, October 09, 2020 12:23 pm
> To: Discussion of precise time and frequency measurement
> 
> 
> Hi
> 
> Since you need a MCU to decode the data, you might as well get
> things in there sooner rather than later. There are a number of MCU’s
> out there that have fast enough ADC’s to do the job. They do have
> limited
> dynamic range. You can go to one of the 24 bit converters and have 
> a ton of dynamic range. It’s all up to you.
> 
> Once it’s into the MCU, it’s just code :). Depending on how much cpu
> 
> horsepower you have (and how much code you want to write) you can
> go more or less crazy …. PHK has some interesting tidbits on his web 
> site. http://phk.freebsd.dk/AducLoran/AducLoran-0.0.pdf
> 
> 
> Bob
> 
> 
>> On Oct 9, 2020, at 1:38 PM, rcb...@atcelectronics.com wrote:
>> 
>> Paul, Bob,
>> 
>> I am not using any commercial receiver. I am building everything from
>> scratch. The RF front end starts with a ferrite rod antenna feeding a
>> differential first op amp followed by 5 stages of op amp filtering and
>> amplification. When the last stage is fed to my spectrum analyzer
>> (through attenuators) the WWVB signal is clearly visible. I'm now trying
>> to figure out how to detect the phase shift so I can get the time data
>> for my CPU to process and send to a display.
>> 
>> I already have a GPS based clock that I built so I thought the WWVB
>> phase clock would be an interesting project.
>> 
>> Ray
>> 
>>  Original Message 
>> Subject: Re: [time-nuts] WWVB Dephaser Question
>> From: Bob kb8tq 
>> Date: Fri, October 09, 2020 7:35 am
>> To: Discussion of precise time and frequency measurement
>> 
>> 
>> Hi
>> 
>> At least to me, anything dimensioned in the 100’s of feet is
>> “massive” compared to
>> the rod antennas normally seen in WWVB use ….
>> 
>> The other point being that if the antenna is some sort of large loop,
>> it’s going to be
>> a good long ways away from the receiver. You get both a larger signal
>> voltage and better
>> isolation …..
>> 
>> Bob
>> 
>>> On Oct 8, 2020, at 11:30 PM, John C. Westmoreland, P.E. 
>>>  wrote:
>>> 
>>> Hello All,
>>> 
>>> Are there any design details someplace regarding these massive antennas?
>>> 
>>> Thanks,
>>> John
>>> AJ6BC
>>> 
>>> 
>>> On Thu, Oct 8, 2020, 19:27 paul swed  wrote:
>>> 
 Hello to the group.
 Ray as Bob mentions you are taking a 10s of uv signal to a logic level of
 maybe 4V.
 If the loop is any place close to the divided down signal, it will
 oscillate. It would take incredible shielding to protect the receiver.
 Tha

Re: [time-nuts] WWVB Dephaser Question

[Chris Howard]

For my little WWVB project  I used the table saw to cut off the
upper 3 inches of a 5 gal bucket from Lowes (having removed the handle 
first).

Then I wrapped that with about 30 turns of enameled wire from
an old TV flyback transformer.  I then measured the inductance
and added the required capacitance to tune it to 60 kHz.

I am doing direct sampling with a teensyduino and sound card.
I have not tackled the phase decoding, which would be superior.


https://github.com/chris-elfpen/Teensy4WWVBsdr


On 10/9/20 7:04 PM, John C. Westmoreland, P.E. wrote:

Paul,

Thanks for that detailed explanation.  I've done something similar for MARS
but of course higher frequency and that was transmit also.

I've seen the site of something similar but I think that was a 3' diameter
design; and I've looked at some of the Symmetricom schematics I've
been able to find but have yet to find a schematic of one of
the Symmetricom receive antennas.  I was hoping to find the one they had
for outdoor pole mount.  It's mentioned in a lot of their documents and
even some pics but no schematic details or BOM for that I've been able to
find.

Thanks to Tim also for the response and have a good weekend!

73's,
John
AJ6BC

On Fri, Oct 9, 2020, 15:24 paul swed  wrote:


John I don't think so as not sure how many have built a large antenna.
Certainly any of the old wwvb receivers have details and thats pretty much
what most people copy.
Essentially a 3 foot copper loop with numbers of turns of wire connected
together. Like 25 pair telco cable connected end to end. A large capacitor
is then put across the loop to resonate it at 60 KHz. Then the preamp. Some
use a FET transistor followed by a line driver transistor. Power is sent
over the coax so a blocking cap and inductor.
Really big is 10' by 10' using shielded 36 wire ribbon cable. ( did not use
all 36 conductors it was to much L but 800 ft worth. The shield acts like
the copper pipe and it must be broken so that it does not look like a
shorted loop. Add the cap and preamp.
In this case I built a 2 transistor NPN 2n3904 preamp.
On the large antenna I use a 2 X 6 post 4ft in the ground with cement. A
mast above that to support the antenna and to allow it to be turned a bit
to null MSF.
Thats it no real magic. Its been operational for 7 years with an occasional
transistor replacement. Also coax, darn woodpeckers!
Regards
Paul
WB8TSL


On Fri, Oct 9, 2020 at 5:14 PM John C. Westmoreland, P.E. <
j...@westmorelandengineering.com> wrote:


Bob,

Thanks for the answer; but does anyone actually have a documented
specification posted for one of these 'massive' WWVB 60kHz antennas
someplace?

Thanks.

73's,
John
AJ6BC


On Fri, Oct 9, 2020, 08:35 Bob kb8tq  wrote:


Hi

At least to me, anything dimensioned in the 100’s of feet is “massive”
compared to
the rod antennas normally seen in WWVB use ….

The other point being that if the antenna is some sort of large loop,

it’s

going to be
a good long ways away from the receiver. You get both a larger signal
voltage and better
isolation …..

Bob


On Oct 8, 2020, at 11:30 PM, John C. Westmoreland, P.E. <

j...@westmorelandengineering.com> wrote:

Hello All,

Are there any design details someplace regarding these massive

antennas?

Thanks,
John
AJ6BC


On Thu, Oct 8, 2020, 19:27 paul swed  wrote:


Hello to the group.
Ray as Bob mentions you are taking a 10s of uv signal to a logic

level

of

maybe 4V.
If the loop is any place close to the divided down signal, it will
oscillate. It would take incredible shielding to protect the

receiver.

Thats why you often see a solution that doubles to 120 KHz and

modifies

the

detectors to work at that frequency. That means hacking the radio
internally. Not fun. The other really annoy effect is that the

doubling

slips phace due to noise and propagation. So if charting suddenly

you

get a

180 degree flip. Thats messy.
The doubling solution can work. Search for carter and there are

several

others.
But having tested and used all of the alternates and lots more on

the

east

coast decided they were too much trouble. You should see the box of

boards

I have chuckle.
For me I am very happy with the d-psk-r. Though in being above

board I

designed version 1 and Rodger and I did version 2. Its solid and no

mods to

any receiver. Everything has always been released to the time-nuts

group.

As they say have fun.
Regards
Paul.
WB8TSL

On Thu, Oct 8, 2020 at 5:39 PM  wrote:


Bob,

I am using a ferrite rod antenna for the receiver. No outside

antenna.

Ray

 Original Message 
Subject: Re: [time-nuts] WWVB Dephaser Question
From: Bob kb8tq 
Date: Thu, October 08, 2020 12:40 pm
To: Discussion of precise time and frequency measurement


Hi

A lot depends on your antenna setup. You can also swamp out the

incoming

WWVB signal…….

Bob


On Oct 8, 2020, at 2:07 PM,  <

rcb...@atcelectronics.com> wrote:

I have read several different articles where the WWVB phase shift

is

eliminated by doubling t

Re: [time-nuts] WWVB Dephaser Question

[Ole Stender Nielsen via time-nuts]

A general comment on the use of Schmitt-trigger and counters on a 
conditioned analog signal:
You will likely run into issues with missing counts or additional counts 
when the receiver experiences fadings or glitches (lightning, etc.)

If this happens, the 60 kHz signal will jump in phase.

Ole


Den 08-10-2020 kl. 20:07 skrev rcb...@atcelectronics.com:

I have read several different articles where the WWVB phase shift is
eliminated by doubling the signal to 120 kHz. Several members of the
list have built these units.

Assume I build a circuit to double the incoming signal and use a schmitt
trigger to get a 120 kHz square wave.  If I then divide that signal back
down to 60 kHz will that signal be strong enough to swamp out the WWVB
signal? I'm guessing it will be since it is at the 5 volt level and
somewhere in the +25 dBm or greater range.

Ray,
AB7HE

___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] WWVB Dephaser Question

[Bob kb8tq]

Hi

The standard 3’ loop was not anything really exotic. There are a lot of ham / 
SWL
articles out there showing very similar designs. 

One of many hits from Google:

https://www.rfcafe.com/references/electronics-world/vlf-loop-antenna-january-1963-electronics-world.htm
 



Bob

> On Oct 9, 2020, at 8:04 PM, John C. Westmoreland, P.E. 
>  wrote:
> 
> Paul,
> 
> Thanks for that detailed explanation.  I've done something similar for MARS
> but of course higher frequency and that was transmit also.
> 
> I've seen the site of something similar but I think that was a 3' diameter
> design; and I've looked at some of the Symmetricom schematics I've
> been able to find but have yet to find a schematic of one of
> the Symmetricom receive antennas.  I was hoping to find the one they had
> for outdoor pole mount.  It's mentioned in a lot of their documents and
> even some pics but no schematic details or BOM for that I've been able to
> find.
> 
> Thanks to Tim also for the response and have a good weekend!
> 
> 73's,
> John
> AJ6BC
> 
> On Fri, Oct 9, 2020, 15:24 paul swed  wrote:
> 
>> John I don't think so as not sure how many have built a large antenna.
>> Certainly any of the old wwvb receivers have details and thats pretty much
>> what most people copy.
>> Essentially a 3 foot copper loop with numbers of turns of wire connected
>> together. Like 25 pair telco cable connected end to end. A large capacitor
>> is then put across the loop to resonate it at 60 KHz. Then the preamp. Some
>> use a FET transistor followed by a line driver transistor. Power is sent
>> over the coax so a blocking cap and inductor.
>> Really big is 10' by 10' using shielded 36 wire ribbon cable. ( did not use
>> all 36 conductors it was to much L but 800 ft worth. The shield acts like
>> the copper pipe and it must be broken so that it does not look like a
>> shorted loop. Add the cap and preamp.
>> In this case I built a 2 transistor NPN 2n3904 preamp.
>> On the large antenna I use a 2 X 6 post 4ft in the ground with cement. A
>> mast above that to support the antenna and to allow it to be turned a bit
>> to null MSF.
>> Thats it no real magic. Its been operational for 7 years with an occasional
>> transistor replacement. Also coax, darn woodpeckers!
>> Regards
>> Paul
>> WB8TSL
>> 
>> 
>> On Fri, Oct 9, 2020 at 5:14 PM John C. Westmoreland, P.E. <
>> j...@westmorelandengineering.com> wrote:
>> 
>>> Bob,
>>> 
>>> Thanks for the answer; but does anyone actually have a documented
>>> specification posted for one of these 'massive' WWVB 60kHz antennas
>>> someplace?
>>> 
>>> Thanks.
>>> 
>>> 73's,
>>> John
>>> AJ6BC
>>> 
>>> 
>>> On Fri, Oct 9, 2020, 08:35 Bob kb8tq  wrote:
>>> 
 Hi
 
 At least to me, anything dimensioned in the 100’s of feet is “massive”
 compared to
 the rod antennas normally seen in WWVB use ….
 
 The other point being that if the antenna is some sort of large loop,
>>> it’s
 going to be
 a good long ways away from the receiver. You get both a larger signal
 voltage and better
 isolation …..
 
 Bob
 
> On Oct 8, 2020, at 11:30 PM, John C. Westmoreland, P.E. <
 j...@westmorelandengineering.com> wrote:
> 
> Hello All,
> 
> Are there any design details someplace regarding these massive
>>> antennas?
> 
> Thanks,
> John
> AJ6BC
> 
> 
> On Thu, Oct 8, 2020, 19:27 paul swed  wrote:
> 
>> Hello to the group.
>> Ray as Bob mentions you are taking a 10s of uv signal to a logic
>> level
 of
>> maybe 4V.
>> If the loop is any place close to the divided down signal, it will
>> oscillate. It would take incredible shielding to protect the
>> receiver.
>> Thats why you often see a solution that doubles to 120 KHz and
>>> modifies
 the
>> detectors to work at that frequency. That means hacking the radio
>> internally. Not fun. The other really annoy effect is that the
>>> doubling
>> slips phace due to noise and propagation. So if charting suddenly
>> you
 get a
>> 180 degree flip. Thats messy.
>> The doubling solution can work. Search for carter and there are
>>> several
>> others.
>> But having tested and used all of the alternates and lots more on
>> the
 east
>> coast decided they were too much trouble. You should see the box of
 boards
>> I have chuckle.
>> For me I am very happy with the d-psk-r. Though in being above
>> board I
>> designed version 1 and Rodger and I did version 2. Its solid and no
 mods to
>> any receiver. Everything has always been released to the time-nuts
 group.
>> As they say have fun.
>> Regards
>> Paul.
>> WB8TSL
>> 
>> On Thu, Oct 8, 2020 at 5:39 PM  wrote:
>> 
>>> Bob,
>>> 
>>> I am using a ferrite rod antenna for the receiver. No outside
>>> antenna.

Re: [time-nuts] WWVB Dephaser Question

[paul swed]

The additional article John sent us is a pretty good read. Having soldered
all the little wires together with heat shrink, I can see the advantage of
the epoxy approach.

A consideration for the discussion. So far its been about the various tried
and true methods for a RF frontend. But the real challenge that is in front
of us is the software that uses that frontend. How about a very easy to
build a phase flipper so that those that are software inclined do not need
to deal with the frontend to get going. The dpskr has a phase flipper in it.
But it can be even simpler than that.

A 60 KHz logic signal ( divide 6 Mhz down or anything else thats easy)
Feeds an inverter to generate the 180 degree phase. A gate to select 0 or
180 degrees. All of the gates/inverters can actually be a single quad
nand gate. A D flip flop with the clock from the 0 degree 60 KHz logic
level. Your data into the D input. The D flip flop synchronizes the data to
the clock. On the output you can filter the signal or not and cut the level
down or not.
Its a BPSK source.
Granted in a pure gate approach the actual bpsk flip will not be the 2 X 60
KHz for 1/2 cycle. But in real receivers the 120 KHz never comes through
the various stages and filters. So no real harm. This also doesn't supply
the AM signals 14-17 db modulation. But its good enough to allow software
to be developed and its simple.
Good luck
Paul
WB8TSL

On Sat, Oct 10, 2020 at 2:05 PM John Magliacane via time-nuts <
time-nuts@lists.febo.com> wrote:

> For WWVB reception, I use a single turn of 40-conductor ribbon cable,
> configured as a 40-turn loop, brought to resonance with a parallel
> capacitance, that differentially drives an instrumentation amplifier. No
> electrostatic shielding is needed to eliminate e-field pickup with this
> approach.
>
> The antenna hangs in my attic with thumbtacks and does a commendable job,
> day or night, 1622 miles east of WWVB.  See attached JPEG image.
>
> The March 2017 issue of "Circuit Cellar" magazine described an "improved"
> version of my antenna/preamp combination (which I haven't looked into).
> See attached PDF document.
>
> During my early experimentation, I realized that the preamp would need to
> have a high dynamic range in order to perform well in the high-noise
> environment that is LF.   And if the preamp is going to feed a receiver
> through any reasonable length of coax, it will need to be able to drive a
> high capacitance load as well.
>
>
> 73.000 de John, KD2BD
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.