User manual

Programmer’s Guide Page 18 of 64
3.4. Configuring Averagers
3.4.1. Basic configuration
The averagers have 2 operational modes, digitizer and averager, controlled with the function:
AcqrsD1_configMode(instrID, mode, 0, 0);
The value mode can be set to 0 (digitizer) or 2 (averager).
The averager mode uses a number of additional configuration parameters, which describe the requested averaging
conditions.
Use the following short code fragment to configure an average of 1000 waveforms of 20’000 data points, with a
dithering range of ± 15 ADC LSB’s and a start delay of 128 samples for an AP100:
// Configure
long channelNbr = 0, nbrSamples = 20000, nbrWaveForms = 1000;
long ditherRange = 15, trigResync = 1;
long startDelay = 128, stopDelay = 0;
AcqrsD1_configAvgConfig(instrID, channelNbr,
"NbrSamples", &nbrSamples);
AcqrsD1_configAvgConfig(instrID, channelNbr,
"NbrWaveforms", &nbrWaveForms);
AcqrsD1_configAvgConfig(instrID, channelNbr,
"DitherRange", &ditherRange);
AcqrsD1_configAvgConfig(instrID, channelNbr,
"TrigResync", &trigResync);
AcqrsD1_configAvgConfig(instrID, channelNbr,
"StartDelay", &startDelay);
AcqrsD1_configAvgConfig(instrID, channelNbr,
"StopDelay", &stopDelay);
Comments:
• The value channelNbr is usually 0. However, for multi-channel Signal Analyzer platforms (AP240/AP235,
U1084A) it can take on the value of the desired channel for some of the parameters.
• When in averager mode, the following digitizer parameters are ignored:
 delayTime of the function AcqrsD1_configHorizontal is replaced by “StartDelay” and “StopDelay”
 nbrSamples and nbrSegments of the function AcqrsD1_configMemory are replaced by “NbrSamples”
and “NbrSegments”
• For the AP family of averagers, the values nbrSamples, startDelay and stopDelay must be integer multiples
of the ‘averaging block size’, which is always 16 in the AP100 or AP240/AP235 Dual-channel mode, and
32 in the AP200 or AP240/AP235 Single-channel mode. If the supplied value is not an integer multiple of
the ‘averaging block size’, it is truncated to the next lower integer multiple. Thus, nbrSamples = 250 will be
truncated to 240 (15 * 16) on an AP100, and to 224 (7 * 32) on an AP200. You can query the actual value
with the function AcqrsD1_getAvgConfig.
• For the U1084A Averager, the values startDelay and stopDelay must be integer multiples of the ‘averaging
block size’, which is 16 in Dual-channel mode, and 32 in Single-channel mode. The value nbrSamples must
be a multiple of 256 in Dual-channel mode or 512 in Single-channel mode. You can query the actual value
with the function AcqrsD1_getAvgConfig
• The value startDelay controls the time between the trigger and the first data sample that is to be added to the
averager sum.
• The stopDelay permits the addition of an extra delay to the dead time between the averaging of subsequent
waveforms. Its minimum value is zero.
• The ditherRange value may be between 0 (no dithering) and 15 (max dithering). Please refer to the next
section for further explanations.