[time-nuts] WWVB Chronverter update progress
Mike Feher
mfeher at eozinc.com
Mon Aug 27 11:29:44 UTC 2018
Simple error. It is 1.667. 73 - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ 07731
848-245-9115
-----Original Message-----
From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf Of Bob kb8tq
Sent: Sunday, August 26, 2018 6:34 PM
To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
Subject: Re: [time-nuts] WWVB Chronverter update progress
Hi
Well …. 1Hz at 60KHz is …. errr … (off to Google Calc …) …. 16.67 ppm. That’s a pretty major lock range for a TCXO. It’s likely > 10X what an OCXO will do. What the bare crystal in a watch will do … who knows.
Bob
> On Aug 26, 2018, at 5:52 PM, paul swed < <mailto:paulswedb at gmail.com> paulswedb at gmail.com> wrote:
>
> Looks like the signal has to be with in 1 hz. I new it was tight.
> Need a bit more experimentation across the several receivers though
> they all use the same approach with a sharp Xtal filter.
>
>
> On Sat, Aug 25, 2018 at 8:24 PM, paul swed < <mailto:paulswedb at gmail.com> paulswedb at gmail.com> wrote:
>
>> My mistake the chronverter uses a pic 12f1840.
>>
>> On Sat, Aug 25, 2018 at 8:23 PM, paul swed < <mailto:paulswedb at gmail.com> paulswedb at gmail.com> wrote:
>>
>>> Have to look at what oscillators and crystals I have then a divide.
>>> Thats old style and most likely the junk box has everything.
>>> Have to look in my box of tricks as I built several chains for the
>>> de-psk-er experiments.
>>> Have to agree on the micro the chronverter uses a pIC 12F64 as I
>>> recall and it has quite a nice set of dividers in it. Just not an
>>> external crystal input so a better oscillator can be used. Getting lazy these days.
>>> I have some number of tcxos from a company called vectron. Several
>>> cards of each. Can't imagine how I came by those.
>>> :-) Believe the lowest freq was 12 MHz.
>>> Regards
>>> Paul.
>>>
>>>
>>> On Sat, Aug 25, 2018 at 8:07 PM, Bob kb8tq < <mailto:kb8tq at n1k.org> kb8tq at n1k.org> wrote:
>>>
>>>> Hi
>>>>
>>>> A pretty simple modest Q tuned circuit on the output of a gate will
>>>> turn the square wave into a sine. Not much to it since there are a
>>>> lot of power supply components out there that work fine at 60 KHz.
>>>> In order to get a stable 60KHz, a divider is the way to go. I’d
>>>> probably use one that’s built into an MCU as part of a timer or
>>>> something similar.
>>>>
>>>> Bob
>>>>
>>>>> On Aug 25, 2018, at 7:00 PM, paul swed < <mailto:paulswedb at gmail.com> paulswedb at gmail.com> wrote:
>>>>>
>>>>> Bob The generator sig is 60 Khz sinewave.but as a I build up a
>>>>> divider chain and such your idea makes great sense.
>>>>> Then filter to 60 KHz.
>>>>> But I see the issue with the Chronverter carrier its 120-150 Hz high.
>>>>> Bounces around a fair amount.
>>>>> There could be a secondary issue in that the carrier may not
>>>>> actually
>>>> be
>>>>> phase stable.
>>>>> It really doesn't matter as for the Truetimes and Spectracoms its
>>>> simply
>>>>> not good enough.
>>>>> I still need to try the cheapy clocks as that is what it was
>>>>> intended
>>>> for.
>>>>> Not throwing stones as so much of what it does saves me a bunch of
>>>> coding
>>>>> and doing exactly what Dave did.
>>>>> Regards
>>>>> Paul
>>>>> WB8TSL
>>>>>
>>>>> On Sat, Aug 25, 2018 at 5:31 PM, Bob kb8tq < <mailto:kb8tq at n1k.org> kb8tq at n1k.org> wrote:
>>>>>
>>>>>> Hi
>>>>>>
>>>>>> You can do the 14 db deep modulation with a tristate gate and a
>>>>>> pair
>>>> of
>>>>>> resistors.
>>>>>> Ground the input and feed the “modulation” signal to the tristate
>>>> control.
>>>>>>
>>>>>> Bob
>>>>>>
>>>>>>> On Aug 25, 2018, at 4:35 PM, paul swed < <mailto:paulswedb at gmail.com> paulswedb at gmail.com> wrote:
>>>>>>>
>>>>>>> From the earlier threads OOK modulation does not work for high
>>>>>>> end
>>>> clocks
>>>>>>> like spectracoms and truetimes. Have not tried it on the cheapy
>>>> clocks
>>>>>> yet.
>>>>>>>
>>>>>>> I added an external modulator. A dg419 analog switch and then
>>>>>>> with a
>>>> few
>>>>>>> resistors added DC offset and anttenuation so that the carrier
>>>>>>> drops
>>>> by
>>>>>> -14
>>>>>>> db per the wwvb spec. The logic control is driven from the
>>>> chronverter
>>>>>> and
>>>>>>> it totally works. Spectracom Netclock 2 locked up in the normal time.
>>>>>>> There are far better modern single supply analog gates that will
>>>> work.
>>>>>> Just
>>>>>>> did not have any.
>>>>>>>
>>>>>>> The 60 KHz carrier is supplied by a fluke 6060 generator. This
>>>> eliminates
>>>>>>> any chance of being off frequency and is not the long term answer.
>>>>>>>
>>>>>>> The chronverter actually uses a dallas semiconductor clock chip
>>>>>>> thats reasonably accurate.(dangerous to say on time-nuts) So
>>>>>>> that even if
>>>> you
>>>>>> do
>>>>>>> not add the GPS receiver it will run quite some time correctly
>>>>>>> after setting the time.
>>>>>>>
>>>>>>> Chronverter draws 6 ma from a 5 V supply. I always like low power.
>>>>>>>
>>>>>>> All in all a very nice answer to what do we do if WWVB goes away.
>>>>>>> As mentioned it handles timezones and DST and you can change DST
>>>>>>> if
>>>> those
>>>>>>> silly politicians screw with it again.
>>>>>>>
>>>>>>> Speculation
>>>>>>> The chronverter actually puts out carriers for the popular LF
>>>> stations
>>>>>>> along with the time codes for them.
>>>>>>>
>>>>>>> Though the modulator allows quality clocks to lock I speculate
>>>>>>> the frequency from the chronverter is not tight enough. All of
>>>>>>> these
>>>> clocks
>>>>>>> have very sharp crystal filters in them. 10 Hz. Plan to measure
>>>>>>> the
>>>>>> output
>>>>>>> of the chronverter see what the 60 KHz is actually at. Though
>>>> listening
>>>>>> on
>>>>>>> a HP3586 receiver it appears pretty close to frequency maybe its
>>>> just not
>>>>>>> good enough. Or the fact is OOK modulation does not work because
>>>>>>> it
>>>> gaps
>>>>>>> the PLL in these clocks.
>>>>>>>
>>>>>>> Next steps
>>>>>>>
>>>>>>> - Determine and lay to rest the OOK/need for external modulator.
>>>>>>> - Power amplifier and loopstick transmitting antenna staying at
>>>>>>> or
>>>>>> below
>>>>>>> 30uv at 30 meters.
>>>>>>> - Integrate a neo6 GPS receiver in. (Seriously easy)
>>>>>>> -
>>>>>>> - Box it up.
>>>>>>>
>>>>>>> Have my eye on one of the Truetime DC468 units and the classy
>>>> panelplex
>>>>>>> display.
>>>>>>>
>>>>>>> Hope this helps those of you concerned with what to do should
>>>>>>> WWVB go
>>>>>> away.
>>>>>>> Regards
>>>>>>> Paul
>>>>>>> WB8TSL
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