Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Simple first order lpf?

Status
Not open for further replies.

seyyah

Advanced Member level 2
Joined
Oct 7, 2001
Messages
644
Helped
8
Reputation
16
Reaction score
7
Trophy points
1,298
Activity points
6,216
I'm not famliar with digital filters. I want to implement a simple one to learn. Here is an example:
https://lorien.ncl.ac.uk/ming/filter/fillpass.htm

In that, there is a coefficient α, which is obvious, an output, a previous value of the output and an input. I wonder, if i want to apply this how would i decide somethings like;

1-What's the first value of the previous output value?
2-How to decide sampling time or α coefficient in the example?
 

vadkudr

Advanced Member level 4
Joined
Jul 12, 2005
Messages
109
Helped
15
Reputation
30
Reaction score
4
Trophy points
1,298
Activity points
2,236
>>1-What's the first value of the previous output value?
Of course zero. Imagine you begin process from silence. and after for ex 5 sec of silence you obtain real signal. Zero begin state is commonly used init state


>>2-How to decide sampling time or α coefficient in the example?
You can regard impulse response of this filter (reaction to 1,0,0,0,0,.... sequence)
it will be
1,alpha, alpha^2, alpha^3, and so on
Considering sampling period, you can estimate how long time period covers your filter
 

haydaa

Member level 3
Joined
Feb 21, 2006
Messages
58
Helped
4
Reputation
8
Reaction score
3
Trophy points
1,288
Location
turkey
Activity points
1,766
you can see at matlab demos more clerly and easyly.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top