[time-nuts] Inexpensive Alternative to a 5120A

Michael Wouters michaeljwouters at gmail.com
Mon Oct 10 02:55:31 EDT 2016


The Red Pitaya is a lower cost (but lower performance) alternative to
the USRP boxes.

I've implemented a RF phase meter using the RP and get about 1 ps time
resolution at an averaging time of 1 s.
The RP analog input side seems to be a bit noisy so loses a few bits.
There was some discussion about this on timenuts some time back.

Someone has implemented an SDR on the RP
http://redpitaya.com/red-pitaya-and-software-defined-radio/
 - this may be useable in the same way as described in the NIST paper.
It's on my list to try it out some day.

The summary is that if you only want to pay $400, rather than $40 000,
you have to do some/a lot of work.

Cheers
Michael

On Mon, Oct 10, 2016 at 10:16 AM, Bob Camp <kb8tq at n1k.org> wrote:
> Hi
>
>
>> On Oct 9, 2016, at 6:18 PM, Chris Albertson <albertson.chris at gmail.com> wrote:
>>
>> Likely the lowest cost way to get into that is with a TV tuner USB
>> dongle. They cost about $20.   People are able to get about 2.4 mega
>> samples per second.
>
> Except that you need about 30 mega samples ...
>
>
>> Not a lot of dynamic range but you can control
>> that.    Use a mixer to move the signal  of interest into the range
>> the tuner can handle.   Tuniers typically tune from about 20Mhz to
>> 1Ghz or 2Ghz approximate.
>
> You also need a very specific dual ADC architecture as described in the paper. Their
> hardware was > $1K and probably the only suitable system at that low a price.
>
> No free lunch :)
>
> Bob
>
>>
>>
>> On Sun, Oct 9, 2016 at 12:05 AM, Paul Boven <p.boven at xs4all.nl> wrote:
>>> Hi Randal,
>>>
>>> On 2016-10-07 18:52:57, Cube Central wrote:
>>>>
>>>> Is there an alternative that someone could point me to that would cost
>>>> only a couple hundred rather than (what I expect) is a couple thousand?  How
>>>> would I go about gathering the data needed for these nifty ADEV graphs I see
>>>> floating about in here?
>>>
>>>
>>> People have reported (also on this list) that some SDR (software defined
>>> radio) hardware is quite capable of emulating a 5120/5125, and even going
>>> beyond it in performance.
>>>
>>> "Oscillator metrology with software defined radio, Sherman, J.A., J├Ârdens,
>>> R." - arXiv:1605.03505 [physics.ins-det]
>>> https://arxiv.org/abs/1605.03505
>>>
>>> Regards, Paul Boven.
>>>
>>>
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>>
>>
>>
>> --
>>
>> Chris Albertson
>> Redondo Beach, California
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>
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