The evaluation board normally has 1024 bins per channel. We offer an option with 2048 bins using channel cascading, to capture longer waveform windows. The binary data format is however defined as having 1024 bins. Therefore, for the 2048 bin boards, the software averages over two adjacent cells and saves effectively 1024 bins. The noise of each bin improves this way by sqrt(2). The time however is not very well defined, since you average the voltage of two bins. Therefore, I simple also average over the time of the two bins. Maybe this is not the best way, so feel free to change this.

Stefan

Hi,

I am trying to understand some details about the timing calibration.

We wrote our own code but we more or less use the ideas of the Oscilloscope class.

In the binary file writing of in the function Osci.cpp::SaveWaveforms() (line 924ff)

the following code is executed:

if (m_waveDepth == 2048) {
    t = (tcal[j]+tcal[j+1])/2;
    j++;
} else
    t = tcal[j];

I do not understand the averaging of the to adjacent calibration constants. Could you explain this? Do one have two measurements?

Cheers

Felix

The coilcraft part number is: JA4220-ALB. Iordered two of them and they were sent as free samples. You might want to buy some slightly bigger ones. I found them so small it was very hard to solder the coax cable to the connectors. Since I got them, I managed to damage one as they are quite fragile! In the confirmation email I got there was some contact info which may be useful for you: "For help, contact Victoria Berner at 847-516-5551  vberner@coilcraft.com "  BTW every time I use this forum I'm told that my password is not valid. Each time I reset it according to the "Lost pasword preceedure. Then I can log on again. Its quite annoying.

Hi Chris,

 I am looking at Sensl SiPMs as well,  can you send the part number from Coilcraft?

Thanks!

Abaz

I needed a fast pulse inverter in order to feed signals from the recent SensL SiPMs into a conventional CFD which only accepted negative signals. I got a very small ferite torridal transformer from Coilcraft and wired up to invert signals then inserted into in 50 ohm coax cable and it works fine. These things cost only a few cents each!

Thanks, that looks just fine.

Here is one (SI 100): https://www.picoquant.com/products/category/accessories/adapters-splitters-cables-various-accessories-for-photon-counting-setups

Ok, thanks!  do you know an easy in-line inverter like mini-circuit or digikey?    Can also redesign the detector I gues to produce positive signals, just it might be easier if there was a simple inverter if you are aware of? thanks Abaz

No. You have to use an inverter for one of your signals.

Stefan

I would like to be able to trigger in this fashon:  channel 0 > 0.1 and. channel 1< -0.1,  because I have a positive and a negative signal.  Can DRS4 (5) Eval board do this kind of trigger?

Thanks!

Abaz

Yes this is correct. But it is a sample-and-hold circuit. So the sampling cell follows the input for 3.2 ns, then samples and holds the current value at the end of the period.

Dear Stefan Ritt,

I am using a DRS4 v5 to do timing measurements of Positron lifetime. I use the DRS Oscilloscope with triggering on 2 channels when I have a coincidence. Attached is a picture with all the setting that I use. When I use the DRS4 for a long measurements of 5 million events for a couple of hours, the DRS Oscilloscope stops showing any signal .After the first restart of the program I get a strange signal which is at the bottom of the scope range of voltage picture below(in the picture I changed the vertical positions of the channels for better viewing). Only after a couple of DRS Oscilloscope restarts and USB reconnections do I get the results again.

I currently am using another DRS4 v5 and the same situation occurs again although with lower frequency.

What can I do to solve this problem?

thank you very much,

Daniel

Hello Stefan,

I just stumbled again over a phrase in the DRS4 datasheet I never really understood, but didn't find the time to ask.

On page 8 it says: "An internal circuit ensures that the write signal is always 16 cells wide."

So when I look at a single channel, do I understand correctly, that at any given time during sampling, always 16 cells are open, i.e. 16 cells are connected to the analog inputs? So when the domino frequency is e.g. 5GHz then each cell sees the analog input not for 200ps but for 3.2ns correct?

Hi,

I would like to use the DRS4 board with LabView for fast readout.
Do you know anyone who has written a VI for that?

Thanks,
Christian

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

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 baseline shift comes from some instable power supply inside the evaluation board which cannot be controlled to the mV level. In a real measurement, you usually get an additional baseline shift due to some environmental electromagnetic interferences, such as a 50 Hz signal. People fix this shifting baseline by always aquiring a small portion (10-20 samples) of the baseline before any signal from a particle detector. The signal is then corrected event-by-event by subtracting the baseline from each waveform. By doing that, you fix not only the 50 Hz noise, but also the shifting baseline you mention.

Stefan

Hello! My name is Dmitry. I am from SiPM Lab is NRNU MEPhI (Russia, Moscow). We bought DRS4 evaluation board V5 with firmware 21305. We use 5.0.4 build 21911 2015-11-23 software version (and before that we used 5.0.3 build 21508, 2014-10-15) with Windows 7 32bit.

We observe some strange behaviour. When we save waveforms (in xml or binary data) we see that some of them have the baseline shifted of about -5 mV.

The first picture (pic1) is 1000 waveforms which were glued in one. It is clearly see that baseline quite often has the shift.

The same effect can be seen without saving (writting): rarely when we use normal or auto trigger mode (pic3), and always in single trigger mode (pic2).

The images are attached.

Do you have any idea how it can be fixed?

Thanks, Dmitry.

You can use qtpals, there is posibility to save histograms (energy, time diference), only set trigger on channel which you use. https://sourceforge.net/projects/qtpals/files/?source=navbar

There is no histogram save functoinality in ther DRSOscilloscope program - on purpose. The board and the software are meant to evaluate the board, not to replace a full DAQ system. If we want to save histograms, you maybe also want to set the range, make cuts, do fits etc. So it would take lots of resources to add all that. Therefore we recommend to use the stand-alone C program drs_exam.cpp to read the board, the you can either do whatever you want in the C program, including saving of histograms. Alternatively, you can use ROOT to analyze binary stored DRS data and do whatever histogram manipulation you want there.

Stefan