[time-nuts] WWVB Dephaser Question

[Chris Howard]

That's a fair assessment.  I'm really not very far into SDR programming,
would like to learn more.

I was working with someone who gave me a way forward toward
using the same hardware to do the BPSK demodulation, but I want
to get his OK before I spread his stuff into this group or other places.
And I have not yet done anything with it yet myself.


Chris


On 10/13/20 9:06 AM, paul swed wrote:
> The teensy is on order and downloaded the arduino plugin.
> In looking at the code I should mention it does not appear to be a I&Q
> sampling. Just a single stream I AM sampler. Though at 60 Khz. Its
> essentially a diode with AGC and a slicer to determine a 1 or 0. No matter
> a good start in the world of SDR. (At least I do not see an I&Q approach)
> Regards
> Paul
>
> On Tue, Oct 13, 2020 at 2:47 AM John C. Westmoreland, P.E. <
> john at westmorelandengineering.com> wrote:
>
>> Paul,
>>
>> Sure - even on my OpenHPSDR system using my vertical antenna - I am almost
>> able to decode WWVB (reliably) using the clock
>> program from:
>>
>> http://f6cte.free.fr/index_anglais.htm
>>
>> with no changes whatsoever.  If I 'fix' the antenna - I'm sure it'll work
>> more reliably.
>>
>> Teensy is Arduino compatible - pretty sure you can use the tools/libs
>> fairly easily from Arduino - I don't have a Teensy (yet) but I will
>> probably
>> get a kit like what's outlined in Chris's post and also here for the people
>> that may not be in the US:
>>
>> https://github.com/DD4WH/Teensy-DCF77 (referenced by Chris in his post).
>>
>> that describes the antenna circuit in more detail.
>>
>> 73's,
>> John
>> AJ6BC
>>
>>
>>
>>
>>
>>
>>
>> On Mon, Oct 12, 2020 at 8:20 PM paul swed <paulswedb at gmail.com> wrote:
>>
>>> John
>>> I would simply use any number of receivers and grab 60 KHz out of one or
>>> could use the IF at 10 KHz or 1 KHz. But more fun to use 60 KHz. The cost
>>> on the teensy components is very reasonable.
>>> Regards
>>> Paul
>>>
>>> On Mon, Oct 12, 2020 at 7:44 PM John C. Westmoreland, P.E. <
>>> john at westmorelandengineering.com> wrote:
>>>
>>>> Hello Time Nuts,
>>>>
>>>> Chris - maybe you can share that if that's something you can share
>> right
>>>> now.
>>>>
>>>> Jim and Paul,
>>>>
>>>> Like Chris pointed out - on that audio board in the design he's worked
>>> on -
>>>> the Line In has L and R channels - the input resistance is higher than
>>> for
>>>> the mic input -
>>>> but I suppose it's possible to try a BPSK implementation using that as
>> a
>>>> starting point.  There's no separate gain stage for the Line In inputs
>>> like
>>>> for the mic - but
>>>> it could work - a small preamp that works with the input impedance of
>> the
>>>> Line In circuitry may be necessary to get a good input signal - but
>> that
>>>> shouldn't be too hard
>>>> to add.  Also - do the internals of that chip - the
>>>>
>>>> https://www.pjrc.com/teensy/SGTL5000.pdf
>>>>
>>>> really allow the L/R Line In channels to be treated independently?  If
>>> so,
>>>> it should be good to go at least for experimentation.
>>>>
>>>> 73's,
>>>> John
>>>> AJ6BC
>>>>
>>>>
>>>>
>>>>
>>>> On Mon, Oct 12, 2020 at 12:07 PM Chris Howard <chris at elfpen.com>
>> wrote:
>>>>> I received a good pointer about doing the BPSK implementation
>>>>> but have just not gotten it done.
>>>>>
>>>>> Chris Howard
>>>>>
>>>>>
>>>>>
>>>>> On 10/12/20 11:02 AM, jimlux wrote:
>>>>>> On 10/12/20 7:40 AM, paul swed wrote:
>>>>>>> John really appreciate the pointer. Though it doesn't help wwvb
>> BPSK
>>>>>>> its a
>>>>>>> really good intro to SDR and DSP super simple. A good way to get
>>> your
>>>>>>> feet
>>>>>>> wet. Hmmm is there a parts order soon? :-)
>>>>>>> Regards
>>>>>>> Paul
>>>>>>> WB8TSL
>>>>>>
>>>>>> And the teensy has plenty of space and speed to implement a PLL for
>>>>>> doing BPSK demodulation.
>>>>>>
>>>>>>
>>>>>>> On Mon, Oct 12, 2020 at 10:33 AM Bob kb8tq <kb8tq at n1k.org> wrote:
>>>>>>>
>>>>>>>> Hi
>>>>>>>>
>>>>>>>> The “ideal” antenna solenoid would be a bit longer ( say 2 X to
>> 5X
>>> ).
>>>>>>>> The turns should be spaced apart by a few percent of the length.
>>>>>>>> ( so turns over 30 or so … not so much …).
>>>>>>>>
>>>>>>>> How much better is “ideal” compared to “just get it done?”. At
>>> least
>>>>>>>> from the stories that are told, it is significant. Since all
>> these
>>>>>>>> antennas
>>>>>>>> are very small (so non-ideal) it’s a bit of a snail race.
>>>>>>>>
>>>>>>>> Bob
>>>>>>>>
>>>>>>>>> On Oct 12, 2020, at 3:42 AM, John C. Westmoreland, P.E. <
>>>>>>>> john at westmorelandengineering.com> wrote:
>>>>>>>>> Paul,
>>>>>>>>>
>>>>>>>>> Doesn't the post by Chris Howard above appear to be a good/great
>>>>>>>>> starting
>>>>>>>>> point?
>>>>>>>>> Seems like that approach could be extended.
>>>>>>>>>
>>>>>>>>> https://github.com/chris-elfpen/Teensy4WWVBsdr
>>>>>>>>>
>>>>>>>>> 73's,
>>>>>>>>> John
>>>>>>>>> AJ6BC
>>>>>>>>>
>>>>>>>>>
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