Bandwidth of Analog Inputs
Posted: Fri Nov 29, 2013 3:36 am
As I know very little about what it takes software-wise to run an engine, I am curious as to what impact the bandwidth of the analog inputs has on performance.
I assume that the bandwidth of a particular signal should be limited to as low as possible, without impacting performance, in order to filter out "noise".
For temperature inputs, in which values change relatively slowly, a low-pass filter of 1 - 100Hz would seem to be reasonable / sufficient.
But for potentially rapidly changing inputs such as TPS, MAP, Battery Voltage,..., how does one determine what bandwidth is needed?
I started to wonder about this because I ran across a Freescale app note in which they recommended a 5kHz low-pass filter for the MAP input and I saw that the Jaguar design uses a ~723Hz filter for internal MAP applications (and a ~1540Hz filter for external MAP applications).
Thanks,
TonyS
I assume that the bandwidth of a particular signal should be limited to as low as possible, without impacting performance, in order to filter out "noise".
For temperature inputs, in which values change relatively slowly, a low-pass filter of 1 - 100Hz would seem to be reasonable / sufficient.
But for potentially rapidly changing inputs such as TPS, MAP, Battery Voltage,..., how does one determine what bandwidth is needed?
I started to wonder about this because I ran across a Freescale app note in which they recommended a 5kHz low-pass filter for the MAP input and I saw that the Jaguar design uses a ~723Hz filter for internal MAP applications (and a ~1540Hz filter for external MAP applications).
Thanks,
TonyS