[time-nuts] Spectracom 8170 time clocks simple suggestion

[Bob Camp]

Hi

If you take a look at the CMOS switches the direct conversion radio guys use, that's probably the easiest way to do the inversion. If they work well enough for a 30 MHz receiver, they probably will do just fine at 60 KHz. You probably would need a transformer in and a transformer out to keep things from getting to crazy noise wise. Simple couple of windings on a ferrite core should do just fine. Mini Circuits probably would be happy to sell you some as well. 

I suspect you still need some sort of smarts involved simply to decide when to flip and when not to flip the signal. There's not enough to it to tax a cheap micro. Until they publish the "final" description of the modulation, I see no reason to go crazy writing code.

Bob

On Jun 15, 2013, at 12:33 PM, paul swed <paulswedb at gmail.com> wrote:

> Bob no idea actually. But I do have the MSA 8160 rcvr on the bench and
> simply can add the ne602. Also John Lowe from NIST actually
> suggested/alluded to it over a year ago before he ducked out of time-nuts.
> Its one of those fairly obvious answers. Definately not high on my priority
> list.
> Its as simple as I can imagine and doesn't use a FPGA or a uProc.
> 
> As a discussion point on "simple" folks that work armchairs always have
> something to say. But they rarely contribute to actual results. Far to easy
> to debate simple.
> 
> I know that you do help and I appreciate that.
> Regards
> Paul.
> 
> 
> 
> On Sat, Jun 15, 2013 at 10:35 AM, Bob Camp <lists at rtty.us> wrote:
> 
>> Hi
>> 
>> I believe I suggested this approach back about 6 months ago. There was a
>> significant controversy about my use of the term "seems simple".
>> 
>> Bob
>> 
>> On Jun 15, 2013, at 9:51 AM, paul swed <paulswedb at gmail.com> wrote:
>> 
>>> As I have been working on the d-psk-r its always been clear to me that a
>>> simple non invasive approach to fix the 8170 class clocks existed. Since
>>> the d-psk-r has consumed far more time then I ever would have guessed, I
>>> would like to offer the approach up to the group. Maybe someone else has
>>> some time to do this and it is easy. However with easy there are trade
>> offs
>>> as always.
>>> 
>>> Here is teh approach
>>> Using a wwvb clock chip like the MSA 8160 still obtainable (And no doubt
>>> others say from an atomic clock)
>>> Take the am time code out.
>>> Feed that to a NE 602, SA602 or 612 series balanced modulator there all
>> the
>>> same as a AM modulator.
>>> The 60Khz comes from a tuning fork crystal using the SA602 built in
>>> oscillator.
>>> Attenuate the output to 100 uv or so. I don't think you really need any
>>> filtering.
>>> 
>>> There you go. No real magic.
>>> Possible downsides
>>> Drift as the tuning fork crystals are OK. If true use a better source
>>> I expect the tick to be slightly delayed by this method.
>>> Regards
>>> Paul
>>> WB8TSL
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