[time-nuts] WWVB Chronverter update progress

Mike Feher mfeher at eozinc.com
Mon Aug 27 07:29:44 EDT 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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>> 

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