Applying filter on incoming signal at serial port

[Abuzar]

hello,

I want to apply filter response on a signal arriving at serial port.

I also want to simulate its response in labview first to as to check whether it will work or not.

Please inform me how can i achieve this(filtering the signal at com port)

Which type of filter should i use? 

I want to develop a filter of 50Hz

The baud rate is 115200.

Regards

[Norbert_B]

That question, honestly, makes no sense.

Serial is a digital communication protocol while filter are either applied to analog signals or digitized measurement values.

So i wonder if you get digitized data via the serial port and want to apply a digital filter on those measurement values. If that is the case, the baud rate of the serial port is of no interest.....

Norbert

EDIT: Applying an analog filter to the serial line with 50Hz will filter out the complete serial protocol, so you will not receive anything anymore......

[Abuzar]

Yes i mean the same, i am having an analog signal converted to digital at serial port.

The actual question is still unanswered!

[Norbert_B]

OK, so i understand what you want: design a filter for the digitized signal within your application software.

For this, you have to get the desired size of measurement values (signal you want to filter). The baudrate defines (in addition to the pure acquisition time of your serial device) how fast the package will be "full", but for the filter function, it does not matter.

For filtering signals in LV:

Depending on the developer version (Base, Full, Professional), you have access to a palette called "Signal Processing". It contains a sub-palette called "Filter".

If you have to design and evaluate filters, you might want to take a look into the Filter Design Toolkit.

hope this helps,

Norbert

[Abuzar]

May you pls tell.

What you mean by desired size of measurement values. 

Also another question in mind, how does the baud rate does not effect in filtering a signal. As for example if a signal is coming at 50 Hz, we cant transfer it completly at a lower baudrate so if it is not transmitted than how it could be filtered out.

Yes i have digital filter design tool kit installed i will try it and will inform

Thanks v.much for answering me.

[Abuzar]

I request to please reply on this post.

[crossrulz]

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@Abuzar wrote:

Also another question in mind, how does the baud rate does not effect in filtering a signal. As for example if a signal is coming at 50 Hz, we cant transfer it completly at a lower baudrate so if it is not transmitted than how it could be filtered out.

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The filter itself does not care where the data came from.  All it cares about is the data coming in and the rate as which it was sampled.

Yes, you need to transfer the data fast enough to get all of the data in, but the filter already assumes this.

[johnsold]

Abuzar,

What everyone who has responded is asking is this: What is the sampling rate of your signal?

Lynn

[Norbert_B]

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@Abuzar wrote:

[..]What you mean by desired size of measurement values.[..]

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A filter has effect on signals regarding the frequency. Frequency is like speed: Something you observe over time.

So you require more than a single data point that you can apply a filter. You have to have a couple of data points (samples) and you have to know what time between the samples elapsed. That time is called "sample rate".

So for a digital filter, you need a couple of samples and you need to know the sample rate. Both information has to be passed to the filter function. The result will be the filtered signal, containing the same number of samples as the original data set.

hope you now have a better understanding about what you are asking....

Norbert

[ejkaiser]

The type of filter to be used depends on the characteristics of the raw signal and what you want to do with the filtered signal. Some aspects are required bandwidth, response time and what kind of noise and interference is present.

You will need to provide more information about your intention to get some useful assistance.

In many cases one would like to remove the 50 Hz from a signal , but from your post it is not clear if you want to remove the 50 Hz from the input signal (e.g. by using a notch filter) or you want to evaluate the 50 Hz signal and remove anything else (using a bandpass filter, the inverse of a notch).

Cheers

Edgar