I have some question according to GetWave function. In drs_exam.cpp simple GetWave(0,0,wave_array[]) etc...is used. Is there primary (cell) calibration, secondary calibration (Readout) and remove Spikes used, as in DRS Oscilloscope application?

 Yes, yes, no. To get spike removals, you need the function RemoveSpikes from Osci.cpp in the DRSOsc project.

I'd like to be able to know which channel (0,1,2,3 or external) was responsible for the trigger.  DRSBoard::GetTriggerSource() seems to always return 1.  Is there a way to get this information?  Using the DRS4 evaluation board and software version 5.0.3.

Thanks,

Cosmin

DRSBoard::GetTriggerSource() simply returns what has been enabled via DRSBoard::SetTriggerSource(). The actual source which causes the trigger is not stored in the hardware of the board, because I can be reconstructed easily from the waveforms. So just look which of the channels is above your trigger threshold. If none of the channels has a waveform obove the threshold, then the trigger must have been come from the external trigger.

Hi all

We're building a product which will use two different operating modes; firstly a long capcture using channel daisy chaining (2048 samples) and secondly a segmented capture (2 separate captures of 1024 samples each). 

For the long capture, I'm looking to capture 2048 samples for 4 channels.  Therefore I configure the Write Shift Register to 0b01010101 and the Write Config Register to 0b11111111.  During capture with DWRITE=1 the Write Shift Register will update.  Am I correct that once the capture is done and DWRITE=0, I can set A3..0 to 0b1101 and simply read the value of WSROUT to tell the difference?

For the segmented capture, I'm looking to capture 1024 samples for 4 channels on a first tirgger pulse, followed by 1024 samples for 4 channels on a second pulse.  Therefore I configure the Write Shift Register to 0b11111111 and the Write Config Register to 0b01010101 and set DWRITE=0 to capture.  After the first trigger I set DWRITE=0 and need to update the Write Config Register.  Do I need to write in a whole 8 bits to the Write Config Register (i.e. 0b10101010), or can I just shift in a single new bit (value 0b0)?

This is correct. Setting A0-A3 to 0b1101 multiplexes the Shift Write Register to SROUT, so you will either a "0" or a "1" depending on which of the two channels was written last.

Your segmented capture does unfortunately not work. Due to a bug in the silicon, the first (e.g. even) written channel gets half overwritten when you start sampling the second (odd) channel. I should remove that from the documentation.

Furthermore, reading the chip while writing on the "other side" introduces quite some additional noise. The recommended way to do simultaneous reading and writing is therefore to use two separate DRS4 chips and split the input signals to both chips, then read from one chip while writing to the other chip. This keeps the crosstalk at a minimum and both chips run at full performance.

Stefan

Hi Stefan

Just so I'm 100% clear; is there no reliable way to perform 2 segmented captures with a single DRS4 IC?

While not a showstopper, this is a bit disappointing.

Yes this is correct. Anyhow, even if it would be working, you would not be happy with it. After having designed ~10 boards with the DRS4 chip, I learned the hard way that any digital activity on the board during the sampling phase is strictly forbidden. You see crosstalk up to 100's of mV in some cases (with a preamplifier on the board, 10-20mV without preamp). So rule #1 is to keep the board as "quite" as possible when sampling the input. If you would readout the odd channels of the DRS4 during sampling of the even channels, you would probably get so much crosstalk that the samples are almost unusable. Even if you would do this with two DRS4 chips next to each other, you have to make sure to put proper grounding between the two chips, and operate them completely independent (like each one has it's onw contol lines going to the FPGA). Designing such boards is not so easy and takes lots of experience from the layouter.

Stefan

All right, thank you for the clarification.

hello i am an student and i want to do my final project with drs4 board and i really can´t find how to open waveform file and how can i save or opened many of them quickly.

if you can tell me how i will be very grateful.

thanks,

kind regards.

There is no built-in possibility to open waveform files, you have to write your own programs to do that. 

Hi Stefan,

    I read in the DRS datasheet that the bandwidth for the transparent mode OUT+ is only 200MHz which I think cannot be improved by any active input buffer; so if you want to operate the chip for really high frequency input, would it be better to feed on-board discriminators not from the output of DRS but from the input end?

    Thanks!

First, the 200 MHz is not correct. Table 1 clearly states ANALOG OUTPUTS - Bandwidth (-3dB): 50 MHz. This is also shown in plot 11 (revision 0.9). But that does not necessarily mean that you have to drive your discriminators from the input of the DRS4 chip. If you use this for triggering, a 1-2 ns timing jitter does not matter, since stopping the domino wave anyhow has a 3-4 cell jitter. If you send a very fast signal though a 50 MHz low pass filter, the timing anyhow doe not change, only the slope of your signal gets lower, so you are more sensitive to noise, which in turn causes the 1-2 ns timing jitter. But I personally would not worry about that too much. Putting any signal splitting components in the input path would reduce the input bandwidth, which would be much more of an issue.

Dear Stefan,

I have emailed drs4@psi.ch a couple of times regarding the pricing of the evaluation kits for academic use in India and have not received any reply and hence writing in this forum. Could you please help me in this?

Thanks and regards,
Deepak Samuel.

I am using the `drscl` app. My prior experience is practically zero, sorry if this is a very naive question. When I read using `read 0 1` (channel 0, with calibration) I get this:

```
Calibration not valid for board #2946
  10    3    7    4   10    8   14    5    5    9    3    4    9    8    9    4
   3    3   12    5    5   13    3    8    1    5    0    4    8    6    6    3
...etc...
```

Why does it says that the calibration is not valid? How am I supposed to go from integers to volts?

If I run the `info` command I get this:

```
==============================
Mezz. Board index:    0
DRS type:             DRS4
Board type:           9
Serial number:        2946
Firmware revision:    30000
Temperature:          43.4 C
Input range:          -0.5V...0.5V
Calibrated range:     -0.5V...0.5V
Calibrated frequency: 0.000 GHz
Status reg.:          0000009A
Control reg.:         00000000
  DMODE circular
Trigger bus:          00000000
Frequency:            1.007 GHz
```

The 'drscl' tool is more for experts, normal users are advised to use the DRSOsc oscilloscope.

The board has to be calibrated for a given sampling speed before calibrated data can be read out. Do that with the "calib" command, specifying 5 for the sampling rate, 0 for the range (which is the middle between -0.5 and +0.5) and 1 for 1024 mode. If you then do "start", "stop", "read 0 1" you get calibrated data in mV.

Stefan

I want to measure the signal from PMT . But it is a current signal, should i just put a series resistance, or use a amplifier to convert it to voltage signal before drs4?  

Can you give me some advice ? 

The evaluation board has a 50 Ohm termination resistor, which already converts your current into a voltage signal. If the resulting signal is too low (<20 mV) you can put in an amplifier or raise the HV of your PMT (inside the valid range given by its datasheet of course).

- Stefan 

Hello, everyone.
I'm a student in Japan.
Please forgive me if this is a very rudimentary question.

Am I right in thinking that inputting 1 to DMODE (Bit0) in the configuration register will connect the 1024th cell to the 1st cell?

Also, let's assume that after sampling 1024 cells on channel 0, 200 cells are sampled in the second week.
Does the readout of 1024 cells start from cell 0?
Or does it start from the 200th cell?

Yes, as desceribed in the manual .

I don't understand what you mean by "second week". 

Normally, you run the chip continously (DMODE=1) until you receive a trigger. Then, you typically read out the chip from the stop position by using a RSRLOAD pulse (as described unter "REGION-OF-INTEREST READOUT MODE".

Stefan