[time-nuts] SE880 GPSDO

Ilia Platone info at iliaplatone.com
Tue Apr 26 23:30:49 UTC 2016


I will use a dedicated FPGA design, and the data will be stored into an 
SDXC card (UHS), or an IDE drive (maybe not), in RAW mode (no filesystem).

Each timestamp will be stored into a word of 48bits, the clock will be 
400MHz, so the quantization will be 2.5ns, but the maximum error/clock 
offset should be 1/10 of this, so 500ps , as said by Bruce.

Regards,

Ilia.

Il 27/04/2016 00:29, Attila Kinali ha scritto:
> On Tue, 26 Apr 2016 22:24:08 +0200
> Ilia Platone <info at iliaplatone.com> wrote:
>
>> I must print each photon event captured by an APD at the focus of more
>> telescopes, these events must be timestamped with an accuracy of 2.5ns,
> As i wrote before, 1ns should be doable with standard timing GPS receiver
> and calibration at those short baselines. Going below that will be a
> challenge though.
>
>> and the expected rate is lower than 10MHz.
> 10MHz is quite a high rate of events that need to be timestamped.
> How do you intend to measure events at such a high rate? And how
> do you intend to store so much data? Each measurement will need
> at least 40bit resolution, at 10MHz that's 50MByte/s. Even if you
> say that the average rate is only a fraction of that and you use
> lots of buffers, that's still a high data rate for a measurement
> instrument.
>
> 			Attila Kinali

-- 
Ilia Platone
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Cattolica (RN), Italy
Cell +39 349 1075999




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