help

H

henchman

New Member

• Nov 26, 2008

• #1

help needed, in the design of a bandpass filter that has a lower cutoff frequency of 300Hz and upper cutoff frequency of 3400Hz

 

audioguru

Well-Known Member

Most Helpful Member

• Nov 26, 2008

• #2

Your bandpass filter is a lowpass filter in series with a highpass filter.
It will make audio sound awful like a telephone.

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Nov 27, 2008

• #3

audioguru said:

Your bandpass filter is a lowpass filter in series with a highpass filter.
It will make audio sound awful like a telephone.

Click to expand...

One would imagine that's the point - to bandpass speech frequencies (as our SSB friend should be doing, but isn't).

 

H

henchman

New Member

• Nov 27, 2008

• #4

am actually designing a transmitter that makes use of Psk modulation technique. can anyone suggest a suitable IC component for a pre-amplifier and a bandpass filter( 300Hz-3400Hz), giving me a reason why, it is being suggested. thanks

 

audioguru

Well-Known Member

Most Helpful Member

• Nov 27, 2008

• #5

I would use a TL074 quad low noise opamp.
It is low noise and has 4 opamps. One opamp for the mic preamp, the second opamp for the lowpass filter and a third opamp for the highpass filter. The fourth opamp can be used for something else.

 

Mikebits

Well-Known Member

• Nov 27, 2008

• #6

Since it is PSK use a PCM codec.
https://www.electro-tech-online.com/custompdfs/2008/11/tcm29c13a.pdf