Sensor Definition file questions.

[nigelspeedy]

As a little flight test instrumentation project I am planning on using three 1Kohm string pots to measure stick and rudder displacements. I am just working through the sensor definition file and have a couple of questions.

1. In the 'shift' & 'age' definitions there is reference to 16Hz, is this the sample rate of the EMS?
2. Are all parameters sampled at the same rate?
3. For the example of shift the wiki says to use x=5 for a 1 second filter to 90%. Just to be sure of my maths, 2^5=32, 32/16=2sec? Is x=4 the correct number for a 1 second filter or have I got this wrong?
4. Is the filter a simple moving average or is it weighted?
5. Age: If I want the filter to expire and snap to the input value after 2 seconds do I use age = 2 or age =32?

Thanks for any help you can provide

 

[dynonsupport]

1) The EMS samples faster than 16Hz, but the data is filtered in the EMS and then sent up to the screen at 16Hz. So all filters run on 16Hz data.

2) Yes, all parameters are at 16Hz. The EMS doesn't know what is hooked to each pin so it can't be smart about anything.

3) It does appear the wiki is wrong on the filter time in two ways. The response of the filter is 66% of the step in the time given, so "4" = 2^4 = 16, means you will get 66% in 1 second, and 90% in two seconds. Alternately, you can say that a shift of "5" takes 2 seconds to get to 66%, not 90%.

4) The filter is a digital filter, where 1/2^shift of the value difference is added to the value each time. So basically, weighted.

5) You would use age 32 to make it snap after 2 seconds.

 

[nigelspeedy]

Dynon,

Thanks for the quick reply, just what I needed.