[time-nuts] Setting Osc Frequencies

Robert Atkinson robert.atkinson at genetix.com
Mon Mar 5 04:25:18 EST 2007


Hi Bruce,
It's a while since I looked at the HP circuit and patent, but if I
recall correctly a lot of the performance relied on the input circuit.
This used a line receiver with feedback. When I looked there did not
seem to be an equivalent receiver chip available. I'm aware of the sine
-square conversion thread that ran a while ago, but guess this needs as
much attention as the phase comparator.

Robert.

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Dr Bruce Griffiths
Sent: 04 March 2007 07:27
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Setting Osc Frequencies

Hal Murray wrote:
>> I can design a suitable circuit but may need someone else to do the
>> layout as my PCB layout software is rather ancient. 
>>     
>
> I'll be willing to turn the crank on the board layout as long as a few
people 
> are willing to double check whatever I do.  (and nobody is in a hurry)
>
> I've been happy with PCB Express.
>   http://pcbexpress.com/
> $125 for 10 boards up to 9 sq inches, two layers, no solder mask or
silk 
> screen.
> $265 with solder mask and silk screen.
>
>
>   
Hal

What file format can you accept for schematics?
I can produce Protel for Windows schematic files or Protel for DOS 
schematic files.

One thing to remember about the circuit is that it will exhibit 
nonlinearity at the each end of the range.
This is due to the minimum pulse width the logic (XOR gate) will produce

(about 3ns or so for 74LCX and similar logic, 1.5ns for the original HP 
version, 400 psec for modern ECL).

Other than using the fastest logic possible the simplest way to 
circumvent this limitation is to use 2 such circuits (with the one of 
the clocks inverted in the second circuit.) and sort out which output to

use in software when analysing the data.

The best way to implement this is to just build the extra output into 
the circuit, as it only requires a few extra flipflops and another 
inexpensive opamp.

Bruce

_______________________________________________
time-nuts mailing list
time-nuts at febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts


--------------------------------------------------------




Genetix Limited - Queensway, New Milton, Hampshire, BH25 5NN  Registered in England No. 2660050   www.genetix.com 
Any opinions expressed in this email are those of the individual and not necessarily Genetix Ltd (Genetix) or any company associated with it. This email and any files transmitted with it are confidential and solely for the use of the intended recipient. If you are not the intended recipient or the person responsible for delivering to the intended recipient, be advised that you have received this email in error and that any use is strictly prohibited. If you have received this email in error please notify Genetix by telephone on +44 (0)1425 624600.
The unauthorised use, disclosure, copying or alteration of this message is strictly forbidden. This mail and any attachments have been scanned for viruses prior to leaving Genetix network. Genetix will not be liable for direct, special, indirect or consequential damages as a result of any virus being passed on, or arising from alteration of the contents of this message by a third party.
--------------------------------------------------------



More information about the time-nuts mailing list