Thanks Laura, the diagnostic tools look very useful.
I hadn’t appreciated that you can have a bitwidth of 128 with the snapshot
block. The maximum bitdepth of the snapshot block is 2^16=65k, so after
cramming 16x 8-bit samples together you can indeed get to 2^20 = 1M points.
- Danny
> On Jul 22, 2015, at 1:05 AM, Vertatschitsch, Laura E.
> wrote:
>
>
> Hi Danny,
>
>
> We have a project called the R2DBE (Roach2 digital backend) that we use for
> VLBI.
>
>
>
> In our github repository (https://github.com/sma-wideband/r2dbe
> ) you can see:
>
> [*] casper_files/r2dbe_top.slx
>
>
> This model file will show you the layout of our digital backend. You will
> see 2 parallel signal chains, each with a snapshot on the 8-bit data and the
> quantized 2-bit data, both triggered off the sync pulse. Click around to see
> how it's used.
>
>
> In terms of a script, you will also see:
>
> [*] software/r2dbe_monitor.py
>
>
> This script unpacks data from the snapshots (uses r2dbe_snaps.py, also in
> software directory), so that we can look at time-aligned data and view
> histograms and auto-correlations (or cross-correlations).
>
>
> Now obviously you don't have the same hardware set up so you can't see these
> in action, but you can perhaps see how things are used and pull what you need.
>
>
> I've attached a screen grab of the r2dbe_monitor.py script to help you
> visualize the outpu. Not the prettiest layout, but a helpful diagnostic for
> us in the field. Here we saw that there was a strong tone where we expected
> in IF0, and nothing connected to IF1, however a spur from the ADC5G quad core
> mis-alignment is visible at 1024 MHz.
>
>
> --Laura
>
>
>
> On Tue, Jul 21, 2015 at 12:42 PM, Vertatschitsch, Laura E.
> >wrote:
>> Danny,
>>
>>
>> We routinely fill snapshots with 250k ADC samples, then read them out with
>> the get_snapshot command.
>>
>>
>> If you are interested I can point you to the R2DBE github design (so you can
>> see how we use the snapshots) and I can get you some scripts I was using
>> quite recently in the lab to buffer up 10s to 100s of these snapshots and
>> compute statistics.
>>
>>
>> Or did you specifically want to use the QDR?
>>
>>
>>
>> --Laura
>>
>>
>> On Tue, Jul 21, 2015 at 11:30 AM, Danny Price >>wrote:
>>>
>>> Hi all
>>>
>>>
>>> Does anyone have an example ROACH2 design + readout script to buffer up a
>>> large amount of ADC samples (around 200,000 would be ideal) in BRAM/QDR,
>>> then read them out slowly via KATCP? If so, may I please get a copy?
>>>
>>>
>>> Thanks
>>> Danny
>>>
>>>
>>>
>>
>>
>>
>>
>>
>
>
>
