[time-nuts] Fwd: Re: local WWVB ?

[Alex Pummer]

-------- Forwarded Message --------
Subject: 	Re: [time-nuts] Re: local WWVB ?
Date: 	Sat, 11 Dec 2021 09:57:49 -0800
From: 	Alex Pummer <alex at pcscons.com>
To: 	Attila Kinali <attila at kinali.ch>



Hi Attila,
actually there are some repeaters, which do not generate their own 
carrier, but just receive and amplifying re-radiate the wwvb signal with 
different polarization, and since the amplified and radiated signal is 
phase coherent with the original it is not a "newly generated" one. Also 
if you -- like in many application using that underneath the earth 
surface -- you could re-radiate the magnetic component only with a loop, 
and since the length
of the loop will be most likely much shorter, than a 1/4 wave length the 
current along the loop will be constant. To be able to couple to the 
loop you need to set the receiver's ferrite antenna vertically. That 
magnetic radiation of the loop will not interfere with the original -- 
horizontally polarized -- wwvb and outside of the loop the strength of 
the field will drop very fast, at 1/3 of the loop's radial outside of 
the loop the field strength  is  at list 50dB down.
Thus, the same loop could work with a  Raspberry  Pi transmitter without 
causing any interference or get noticed from anybody outside of the loop
Greetings
Alex

On 12/11/2021 5:43 AM, Attila Kinali wrote:
> On Fri, 10 Dec 2021 15:54:55 -0500
> "Lawrence Brandt" <lawrence.brandt at gmail.com> wrote:
>
>> Has anyone designed and/or sold a "WWVB repeater" device? I can picture a
>> Raspberry Pi which had software to get NTP data or GPS-referenced 
>> time, and
>> a small 60 kHz transmitter, which would send the proper WWVB timecode 
>> data
>> to the several "atomic clocks" I have around the house.
> Today, with all the non-licensed wireless stuff we have as
> gadgets, it doesn't seem to be as obvious as it once was, but:
> Transmitting on a frequency you don't have the explicit license
> for is forbidden. And there are some quite hefty fines for that.
> Especially transmitting on a widely used frequency of an
> infrastructure service like WWVB might not be looked kindly upon.
>
> If you want to lock WWVB clocks that are placed somewhere, where
> the reception is not good enough. Then you should inject the signal
> directly into the clock. This way you avoid transmitting.
>
> Alternatively, replace the electronics with some 802.15.4 system
> (e.g., 6LowPan) and distribute time in this network. There are
> plenty of developer boards available for this kind of stuff,
> just check adafruit and sparkfun.
>
> Attila Kinali


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