I have a digital filter that is designed for 1kHz sampling frequency.

Everything else remaining the same, I want that filter to work for 4 kHz

sampling frequency.

What do I need to do?

I am not a filter guy and my background is power system. That is why I am

asking you here this basic question.

Kailash

# Changing sampling frequency

Started by ●January 14, 2010

Reply by ●January 14, 20102010-01-14

Hi,

I just have *a* and *b* coefficients. It would really help if you suggest a

reference.

Regards

Kailash

On Thu, Jan 14, 2010 at 20:37, Mreza rahimi wrote:

> hi

> you should just change ws and wp.

> ws and wp are related to sampling frequency.

> you can find the relation between these in MATLAB help.

> Regards

>

> On 1/14/10, kn srivastava wrote:

>>

>> I have a digital filter that is designed for 1kHz sampling frequency.

>> Everything else remaining the same, I want that filter to work for 4 kHz

>> sampling frequency.

>>

>> What do I need to do?

>>

>> I am not a filter guy and my background is power system. That is why I am

>> asking you here this basic question.

>>

>> Kailash

>

I just have *a* and *b* coefficients. It would really help if you suggest a

reference.

Regards

Kailash

On Thu, Jan 14, 2010 at 20:37, Mreza rahimi wrote:

> hi

> you should just change ws and wp.

> ws and wp are related to sampling frequency.

> you can find the relation between these in MATLAB help.

> Regards

>

> On 1/14/10, kn srivastava wrote:

>>

>> I have a digital filter that is designed for 1kHz sampling frequency.

>> Everything else remaining the same, I want that filter to work for 4 kHz

>> sampling frequency.

>>

>> What do I need to do?

>>

>> I am not a filter guy and my background is power system. That is why I am

>> asking you here this basic question.

>>

>> Kailash

>

Reply by ●January 19, 20102010-01-19

On Fri, Jan 15, 2010 at 03:07, yousef qoqazeh wrote:

> try this:

> N = 4; %Constant

> x = x(1:N:end,:);%x is your signal

> sample_rate = sample_rate* N;

>

> or you can use upsample command in matlab

I tried upsample command in Matlab but the upsampled filter is not good. I

will have to redesign the filter. The specifications are as follows:

It should be a digital filter (IIR) with sampling frequency of 4000 Hz and

doing the following:

1) Doesn't pass dc i.e. 0 Hz,

2) Also doesn't pass 50, 100 and 150 Hz

How can I do it?

Kailash

> try this:

> N = 4; %Constant

> x = x(1:N:end,:);%x is your signal

> sample_rate = sample_rate* N;

>

> or you can use upsample command in matlab

I tried upsample command in Matlab but the upsampled filter is not good. I

will have to redesign the filter. The specifications are as follows:

It should be a digital filter (IIR) with sampling frequency of 4000 Hz and

doing the following:

1) Doesn't pass dc i.e. 0 Hz,

2) Also doesn't pass 50, 100 and 150 Hz

How can I do it?

Kailash

Reply by ●January 29, 20102010-01-29

How about:

[b,a] = butter(10,0.5,'high')

and then

freqz(b,a,1000,4000)

what is the passband of your filter?

you want to reject dc and some lower freqs, but where is the signal content?

yours,

Raj

--- In m..., kn srivastava wrote:

>

> On Fri, Jan 15, 2010 at 03:07, yousef qoqazeh wrote:

>

> > try this:

> > N = 4; %Constant

> > x = x(1:N:end,:);%x is your signal

> > sample_rate = sample_rate* N;

> >

> > or you can use upsample command in matlab

> I tried upsample command in Matlab but the upsampled filter is not good. I

> will have to redesign the filter. The specifications are as follows:

>

> It should be a digital filter (IIR) with sampling frequency of 4000 Hz and

> doing the following:

>

> 1) Doesn't pass dc i.e. 0 Hz,

> 2) Also doesn't pass 50, 100 and 150 Hz

>

> How can I do it?

>

> Kailash

>

[b,a] = butter(10,0.5,'high')

and then

freqz(b,a,1000,4000)

what is the passband of your filter?

you want to reject dc and some lower freqs, but where is the signal content?

yours,

Raj

--- In m..., kn srivastava wrote:

>

> On Fri, Jan 15, 2010 at 03:07, yousef qoqazeh wrote:

>

> > try this:

> > N = 4; %Constant

> > x = x(1:N:end,:);%x is your signal

> > sample_rate = sample_rate* N;

> >

> > or you can use upsample command in matlab

> I tried upsample command in Matlab but the upsampled filter is not good. I

> will have to redesign the filter. The specifications are as follows:

>

> It should be a digital filter (IIR) with sampling frequency of 4000 Hz and

> doing the following:

>

> 1) Doesn't pass dc i.e. 0 Hz,

> 2) Also doesn't pass 50, 100 and 150 Hz

>

> How can I do it?

>

> Kailash

>