[time-nuts] Frequency counter recommendation

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Dec 17 10:36:00 UTC 2010


One possible relatively simple module could use an ACAM TDC-GP2 to 
compare the relative stability of a pair of low noise oscillators.
Performance comparable to a 5370A/B at a fraction of the power, weight 
should be achievable in this application.

One of the oscillators would be divided down to at least 1KHz and used 
to drive the start input whilst the undivided oscillator output drives 
the 1st stop channel and the other oscillator drives the 2nd stop channel.
The divider output jitter need not be state of the art as its only used 
to arm the device.
However its clock to output delay should be somewhat less than 1 period 
of the input frequency.

The ACAM TDC-GP2 uses an SPI interface.
In principle one can process all 4 hits in each of the 2 stop channels 
to reduce the noise.
The usable oscillator frequency range is around 200KHz to 50MHz.

Bruce


David C. Partridge wrote:
> If your spend is in that sort of region it doesn't cost a great deal more to get a batch of boards professionally pasted, picked, placed and reflowed.
>
> Regards,
> David Partridge
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Camp
> Sent: 16 December 2010 19:20
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] Frequency counter recommendation
>
> Hi
>
> Yes indeed, been there done that. Not very hard at all.
>
> All you need is the six layer pc board (can be bought), the FPGA (Digikey has them), a few of these and a couple of those. Spend less than $100 and you are in business if the PC board volume is high enough.
>
> In this case the next step in the business is to solder the 256 ball 1 mm spacing BGA package down on the pc board. Not so easy without the right tools...
>
> Bob
>
>
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