DRS4 Forum
  DRS4 Discussion Forum  Not logged in ELOG logo
 Back  |  Find  |  Login  |  Help 
Entry  Sat May 23 11:03:20 2015, Felix Bachmair, Issue with Trigger rates below ~100Hz drs_v5_newStefan_10Hz.pngdrs_v5_newStefan_4Hz.pngdrs_v5_500_160Hz.pngdrs_5-0-0_4hz.png
    Reply  Thu Jul 2 08:53:17 2015, Felix Bachmair, Issue with Trigger rates below ~100Hz 
Message ID: 435     Entry time: Thu Jul 2 08:53:17 2015     In reply to: 423
Author: Felix Bachmair 
Subject: Issue with Trigger rates below ~100Hz 

Hi,

We did a further investigation of this problem:

We figured out that this issue seems to be related to the kernel.

We tested it now on two machines with Ubuntu 14.04.2 LTS (kernel 3.16.0-41), one with RHEL 6.6 (kernel 2.6.32) , one with Fedora 20 (kernel 3.18.7) and one with Mac OSX. We see this issue  with the Ubuntu and the fedroa  machines.Both have a kernel above 3.0 while RHEL has a kernel of 2.6

 

We can repoduce the problem on all input channels as a trigger. 

I will try to find out what could be the cause of it.

Cheers

Felix

 

Felix Bachmair wrote:

Hi

We are working with the DRS 4 V5 version and we investigated an issue with the trigger at rates below ~120 Hz.

As long as we have a trigger rate of more than 125 Hz. everything seems to work fine and we are recording more or less all events.

As soon as we go lower in input trigger rate to 100Hz, we see a drop in trigger rates to approx 15 - 20 Hz.

When we use the new firmware we can see that the busy signal is  0 for much longer times than usual up to .5 seconds.

 

We made a plot of input trigger rate vs trigger rate of drs: https://plot.ly/~simon.corrodi/316

 

In the  oscilloscope plots one can see the the trigger in in yellow and the trig out from drs board in blue.

 

Do you have any idea what could be the reason?

 

We also

 

ELOG V3.1.5-3fb85fa6