75 and 50 us emphasis filter

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dinone

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Hello to all

I am testing a FM radio device and I need to know the table of the 75 and 50 us pre and de emphasis filter of the USA and Australian standard: can someone give me these information or give the adrress where I can load them?

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These are single pole (R C) filters whose RC time constant is the value you listed. At the transmitter it is high pass, at the receiver it is low pass.
 

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    dinone

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HI Flatulent

I need to have the attenuation in the various frequency (from 10 Hz to 15 kHz): can you help me?

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Use this formula for a single RC filter. This gives you the attenuation at the frequency you want.

T(f) = 1/sqrt(1 + (2*pi*f*tau)^2)

tau is the RC time constant is the value you listed, f is the frequency.

Bastos
 

I was incomplete on my description of the filters. The receive filter is a low pass and its response is described in the post above.

The transmitter filter is the inverse of the receive filter. It is flat response for a while and the the amilitude rises. The product of these two frequency responses is flat.

The purpose is to counteract the high audio frequency noise of the FM process.
 

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