[time-nuts] Remote GPS Oscillator Steering

Iain Young iain at g7iii.net
Thu Apr 18 07:23:27 EDT 2013


On 18/04/13 11:50, Hal Murray wrote:

>
>> 10MHz over unshielded CAT6 is not good practice, to say the least, and
>> simply not going to happen.
>
> What do you mean by "not good practice"?
>
> Gigabit Ethernet works over CAT5.  I think it's 125 megabaud, 5 level, 2 bits
> per baud.  Whatever, it's way over 10 MHz.

Oh I know it can handle it, I was trying to avoid a nice 10MHz signal
on an unshielded conductor smack on the Amateur Radio 30m band :) It's
more RF here than Time/Frequency, and if I can avoid clashes, so much
the better...

(I detest these ethernet over powerlines things, and it seemed
hypercritical to complain about them, then smack a nice signal right
on our 30m band. Maybe I worry too much about such things)

[SNIP]


>> I would rather fibre between the house and outhouse for EMC and grounding
>> reasons. My hope is that thee 10MHz Osc would then be steered from the
>> remote Z3801, although the lab Z3801 itself would complain bitterly about no
>> lock no doubt.
>
> I can't figure out what you are trying to do.  The lab Z3801 isn't setup to
> be steered by an external PPS or 10 MHz signal.
>
>
>> Does anyone have any comments on this madhat scheme ? Or have other
>> suggestions of how I might go about getting that 10MHz signal converted to
>> fibre, and back again to send into the "lab" equipment ?
>
> I think you want to send 10 MHz from your outhouse to your house/lab.  You
> may need a distribution amplifier if you want to send it to more than one
> device.

Indeed, Sorry I wasn't clear, I guess I was trying to avoid sending the
actual 10 MHz signal over that unshielded copper conductor, so was
thinking about sending the data needed to  steer the Oscillator instead

With it ending up as a -5V to +5V signal to the 10811 in the end, The
idea of sending the EFC came from reading 
http://www.realhamradio.com/joe-geller.htm and noting said EFC was 
available on a SMB connector.

> Fiber transmitters and receivers are reasonably common.  You can get modules
> targeted at Ethernet with both transmit and receive in the same package.
> There is a blizzard of variations depending on distance and bit rate and type
> of fiber.  The trick is that the receiver includes AGC so you get logic level
> signals out.

Noted, thanks, I'll keep hunting :)


All the Best

Iain



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