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. > <[email protected]> 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. > <[email protected] >>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 <[email protected] >>>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 >>> >>> >>> >> >> >> >> >> > > >
