Ok. And, If I understand correctly, the main bottleneck in data readout is USB. I.e., theoretically maximum readout rate is 500 Hz. Is it true?

On the evaluation board, yes. This board is not optimized for high readout rate. If you do your own electronics, like GBit Ethernet, you could be much faster. 

 What is the readout rate via GBit Ethernet that you have achieved?

Where is the bottleneck in ethernet?

What is the proposed scheme by which the GBit Ethernet will be implemented, will the DRS4 Eval Board have to wait for the computer to respond before sending the data (wouldn't this make the readout much slower?), or will the DRS4 Eval Board keep sending the data to the computer?

With GBit Ethernet you get close to 100 MB/sec, which is the maximal line speed. The protocol to be implemented will achieve that rate. What one usually does is to send events in large blocks upon request from the PC. The trick is to do the request in a clever way, like using a high water mark on the receiving event buffer. So as long as the PC can digest the data quickly enough, the board just keeps sending, which means no overhead.

Dear Stefan,

I daisy-chained two boards (master sn#: 2514 - slave sn#: 2513) each with 2048 samples. However, when I use drsosc and put check mark in "configure multi-board daisy-chain" I see only 1024 samples. Namely, the first 1024 samples, the last part is missing. When I remove this check mark, I see all 2048 samples. Is there a simple software fix for this or is it a more involved firmware limitation? 

Other parameters: software version: 5.0.4, firmware version 21305, configured for 0.7 GSPS, display at 500 ns/div

Thank you,

Dmitry Hits.

The multi-board mode has never been tested with 2048 samples, so is very likely not to work. I don't know yet how much work this will be to fix, but I'm on a business trip the next three weeks and probably will only have time to look at it when I return.

Stefan

Hi Stefan

Any chance you have time to fix the software for multiboard configuration with 2048 samples each. I tried 5.0.5, but drsosc still shows only half of the waveform.

Dmitry

Hello! I'm using DRS4 evaluation board V5 with the drs command line interface,but the mannal only explained the meaning of the command--"info".And I can't get the hang of the use of other commands through "help",so is there anywhere can I learn more about other commands?Or I can only learn it through the datasheet of DRS4 chip.

Thanks!

The command line interface is more a debugging tool for experts, and you are not supposed to use it except to test the connection to the evaluation board. The programs for the user are the DRS Oscilloscope and the drs_exam.cpp example program to read out the board with your own program.

Stefan

OK!Thank you! One more question,when I use the Oscillocope ,I found that the actual speed is a constant value of 1.007G,how can change this speed.

Remove the check mark from the "Lock" box and enter a different value in the sampling speed box and hit return.

Thank you very much !! All my fault for I thought it too comlicated. Thank you sincerely!

 Hi

Question:

In v4 board, which channel has best calibration ?

Should it be possible to simulate v5 board and read calibration values for v4 board by other method .. for example using external calibration signal source connected to all channels? 

Is it  needed to detach all input signals from EVM board during calibration ?( I see there are switches on channel inputs.)

Some comments: averager.h, averager.cpp are missing in windows v.5 sources (it should be copied from linux sources)

PF2014 and thank You for development new EVM 5 and new time precision.

Martin

In v4 board, actually no channel has a good calibration. The timing calibration is done with channel #9, which is hard connected to a (poor) clock. So the best you can get there is ~30 ps. In principle one can calibrate the V4 board with an external source. The problem there is to find a good sine wave oscillator (we have several expensive ones and only one was good enough), and that the software does not support this. You would have to write your own calibration code (where of course you can "recycle" the one from the V5 software.

Thanks for pointing out the missing averager.*, I will add it.

/Stefan

Hi Stefan,

A quick question, what is the typical variation of the sampling capacitors in DRS4?  Will this variation be significant to affect your sampling result?

 Best,

Jinhong

The capacitors sample the input voltage, not the charge, so the actual size of the capacitors does not matter on first order (the variations might be in the order of 5%). A bigger effect is the variation of the analog switches in the front of the capacitors, which is about 15%. So the actual bandwidth each cell sees varies by maybe 20% (given by the R and the C), but this comes only into play when sampling steep edges.

Stefan

 Great to know this! Thanks~

Jinhong

 Hi Dr. Stefan,

So the sampling capacitors store the input voltage instead of the charge. What about the readout circuits? I saw there is a buffer followed each sampling capacitor. Do you buffer the charge (like a charge sensitive amplifier)  or the voltage? From Fig.12, 14 in datasheet, it seems most probably the readout is a charging or discharging of a capacitor. Could you please add some comments on this? 

Cheers,

Jinhong

The buffer buffers the voltage, not the charge. The curves in Fig. 12, 14 indicate that the voltage followers take some time until they settle. 

Stefan

Hi, Stefan,

I found that my collaborator bought 2 older version of evaluation board before.
They are the version 1.2 in plastics case with firmware 13191.

Can I upgrade the firmware from 13191 to 13279?
I'm wondering if the older version of evaluation board is working with firmware 13279.

Thanks,
Heejong