Send-on-Delta sampling

from Wikipedia, the free encyclopedia

Send-on-delta sampling (SOD sampling, from English send on delta , German as much as "send on change") is the principle of non- equidistant sampling , in which not all sampled values ​​are sent on, but only those that show sufficiently large differences to the signals previously sent.

Send-on-Delta principle

The send-on-delta principle is mostly applied to discrete signals that are already equidistantly (periodically) sampled. If a series of equidistant sample values s ( i ) is present, the value is sent only if the following condition is met:

where the value sent last and the threshold value ("Delta") is. If the condition is met, the value is sent.

application areas

SOD scanning is often used when interrogating distributed sensors in order to reduce the number of values ​​sent, for example in LON devices . This improves the utilization of the communication channel. With autonomous battery-powered sensors, SOD scanning also extends the life of the batteries.

When using SOD sampling in controllers such as B. in PID controllers , the resulting approximation errors should be taken into account in the control algorithm.

Individual evidence

  1. LONMARK® Functional Profile: Pressure Sensor (PDF; 33 kB). LONMARK Interoperability Association, 1997, version 1.0.
  2. J. Ploennigs, V. Vasyutynskyy, K. Kabitzsch: Comparative Study of Energy-Efficient Sampling Approaches for Wireless Control Networks. In: IEEE Transactions of Industrial Informatics. Vol. 6, No. 3, 2010, pp. 416-424, doi : 10.1109 / TII.2010.2051812 .
  3. Volodymyr Vasyutynskyy: Send-on-Delta-Sampling in PID- Controls . Jörg Vogt Verlag, 2009, ISBN 978-3-938860-28-1 .