# DSP

Discussion in 'Homework Help' started by praveen450, Aug 1, 2011.

1. ### praveen450 Thread Starter New Member

Aug 1, 2011
1
0
x(t) is multiplied by exp(-j2*pi*fo*n) followed by LPF and decimator (16)

The incoming signal is assumed to be obtained from a
continuous-time signal xc(t) using a sample rate of Fx = 48 ksps. The value of f0 is selected as 12.5/48, so that the
system analyzes a desired signal band centered at 12:5 kHz. For the purposes of this quiz, assume that the incoming
signal band is 11:5 kHz < F < 13:5 kHz.
Because the bandwidth of the signal at the output of the lowpass filter is greatly reduced, the sample rate is to
be reduced by the decimator as shown in the figure. For this quiz, you are to determine the required lowpass filter
specification such that:
Signals within the signal band are passed with gain 0 dB 0.2 dB.
Signals which would alias into the signal band when the sample rate is reduced are attenuated by at least
70 dB.

Can anyone suggest an approach to this problem?.

2. ### guitarguy12387 Active Member

Apr 10, 2008
359
12
Are you supposed to use an FIR or an IIR filter? I suppose FDAtool is out of the question for a quiz... haha!

Also, you will need to know your transition band of the filter. No such thing as a brickwall filter

3. ### guitarguy12387 Active Member

Apr 10, 2008
359
12
Or do we assume that no signal exists between 13.5k and 24k?