1 Multi-Rate Digital Signal Processing Y. C. Jenq, Ph.D. Department of Electrical & Computer Engineering Portland State University Portland, Oregon
2 Decimation System (Down Sampling) M x d [n]x[n] M=3
3 x d [n] = x[nM],where M is an integer X d (z) = n x d [n]z -n =(1/M) m=0,(M-1) X(z (1/M) e -jm2 /M ) X d ( e j ) =(1/M) m=0,(M-1) X(e j( -m2 /M ) Decimation System (Down Sampling)
4 0 0 22 M=3 0 X(e j )X(e j ) X(e j( ) X(e j( ) X d (e j ) =(1/M) m=0,(M-1) X(e j( -m2 /M ) 44 22
5 Sampling Rate Reduction System M y d [n] x[n] Low-pass filter with cutoff at /M y[n]
6 Interpolation System (Up Sampling) L x u [n]x[n] L=3
7 Interpolation System (Up Sampling) x u [n] = x[n/L],n = 0, ±L, ±2L, … 0,otherwise X u (z) = n x u [n]z -n = X(z L ) X u ( e j ) = X(e j L )
8 Interpolation System (Up Sampling) 0 2 L=3 X(e j L )X(e j ) X u ( e j ) = X(e j L )
9 L Sampling Rate Increase System y[n] x[n] Low-pass filter with cutoff at /L x u [n]
10 Decimation and Interpolation x[n] M M y[n] M=3
11 Decimation and Interpolation x[n] M M LetW M = e -j2 /M Y(z)= (1/M) m=0,(M-1) X(ze -jm2 /M ) = (1/M) m=0,(M-1) X(zW M m ) Y(e j )= (1/M) m=0,(M-1) X(e j( -m2 /M) ) y[n]
12 Decimation and Interpolation Y(e j )= (1/M) m=0,(M-1) X(e j( -jm2 /M) ) M=3 0 X(e j ) X(e j( ) X(e j( ) 2
13 Fractional Sampling Rate Change L y[n] x[n] Low-pass filter with cutoff at min( /L, /M) M
14 Block Interconnection Identities M C M C M M M Multiply by a Constant
15 Block Interconnection Identities M M M
16 LC LC L L L Block Interconnection Identities
17 Block Interconnection Identities L L L
18 Multi-Rate Identities M H(z M ) M H(z) LH(z L ) L H(z)
19 Multi-rate Switch Models n = 0, 3, 6,… n = -1, 2, 5,… n = -2, 1, 4,… x[n]
20 Multi-rate Switch Models x[n] x[3n] x[3n-1] x[3n-2] Serial to Parallel Converter x[n]
21 Multi-rate Switch Models n = 2, 5, 8,… n = 1, 4, 7,… n = 0, 3, 6,… x 1 [n] x 2 [n] x 3 [n]
22 Multi-rate Switch Models x 1 [n] x 2 [n] x 3 [n] x[3n+2] x[3n+1] x[3n] Parallel to Serial Converter x[n]
23 Poly-phase Structure of Decimation Filter 3 x[n] D 0 (z 3 ) D 2 (z 3 ) D 1 (z 3 ) H(z) = D 0 (z 3 )+ z -1 D 1 (z 3 )+z -2 D 2 (z 3 ) y[n] y[3n] H(z) 3 x[n] y[3n] y[n]
Poly-phase Structure of Decimation Filter x[n] D 0 (z 3 ) D 2 (z 3 ) D 1 (z 3 ) 3 y[3n] H(z) = D 0 (z 3 )+ z -1 D 1 (z 3 )+z -2 D 2 (z 3 )
x[n] D 0 (z) D 2 (z) D 1 (z) 3 y[3n] Poly-phase Structure of Decimation Filter H(z) = D 0 (z 3 )+ z -1 D 1 (z 3 )+z -2 D 2 (z 3 )
26 x[3n] x[3n-1] x[3n-2] Serial to Parallel Converter x[n] Poly-phase Structure of Decimation Filter D 0 (z) D 2 (z) D 1 (z) y[3n] H(z) = D 0 (z 3 )+ z -1 D 1 (z 3 )+z -2 D 2 (z 3 )
27 Poly-phase Structure of Interpolation Filter 3 x[n] H(z) = z -2 I 0 (z 3 )+ z -1 I 1 (z 3 )+I 2 (z 3 ) y[n] I 0 (z 3 ) I 2 (z 3 ) I 1 (z 3 ) H(z) 3 x[n] y[n]
28 Poly-phase Structure of Interpolation Filter 3 x[n] H(z) = z -2 I 0 (z 3 )+ z -1 I 1 (z 3 )+I 2 (z 3 ) y[n] I 0 (z 3 ) I 2 (z 3 ) I 1 (z 3 ) 3 3
29 Poly-phase Structure of Interpolation Filter 3 x[n] H(z) = z -2 I 0 (z 3 )+ z -1 I 1 (z 3 )+I 2 (z 3 ) I 0 (z) I 2 (z) I 1 (z) 3 3 y[n]
30 Poly-phase Structure of Interpolation Filter x[n] H(z) = z -2 I 0 (z 3 )+ z -1 I 1 (z 3 )+I 2 (z 3 ) I 0 (z) I 2 (z) I 1 (z) y[3n+2] y[3n+1] y[3n] Parallel to Serial Converter y[n]
31 Poly-phase Structure of Fractional Sampling Rate Filter 3 x[n] F 0 (z 3 ) F 2 (z 3 ) F 1 (z 3 ) 4 y[n] H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 ) (M=4, L=3)
32 Poly-phase Structure of Fractional Sampling Rate Filter (M=4, L=3) 3 x[n] F 0 (z) F 2 (z) F 1 (z) 4 y[n] 3 3 H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 )
33 Poly-phase Structure of Fractional Sampling Rate Filter (M=4, L=3) 3 x[n] F 0 (z) F 2 (z) F 1 (z) 4 y[n] 3 3 H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 )
34 Poly-phase Structure of Fractional Sampling Rate Filter (M=4, L=3) 3 x[n] F 0 (z) F 2 (z) F 1 (z) y[n] 3 3 H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 ) 4 4 4
35 Poly-phase Structure of Fractional Sampling Rate Filter (M=4, L=3) 3 x[n] F 0 (z) F 2 (z) F 1 (z) y[n] 3 3 H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 ) 4 4 4
36 Poly-phase Structure of Fractional Sampling Rate Filter (M=4, L=3) 3 x[n] F 0 (z) F 2 (z) F 1 (z) y[n] 3 3 H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 ) 4 4 4
37 Poly-phase Structure of Fractional Sampling Rate Filter (M=4, L=3) x[n]F 0 (z) F 2 (z) F 1 (z) y[n] H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 ) Parallel to Serial Converter
38 Poly-phase Structure of Fractional Sampling Rate Filter (M=4, L=3) x[n]F 0 (z) F 2 (z) F 1 (z) y[n] H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 ) F k (z) = F k0 (z 4 )+ z -1 F k1 (z 4 )+z -2 F k2 (z 4 )+z -3 F k3 (z 4 ) Parallel to Serial Converter
39 Poly-phase Structure of Fractional Sampling Rate Filter (M=4, L=3) x[n] F 2 (z) F 1 (z) y[n] H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 ) F k (z) = F k0 (z 4 )+ z -1 F k1 (z 4 )+z -2 F k2 (z 4 )+z -3 F k3 (z 4 ) 4 4 Parallel to Serial Converter Serial to Parallel Converter F k0 F k1 F k2 F k3
40 Poly-phase Structure of Fractional Sampling Rate Filter (M=4, L=3) x[n] F 2 (z) F 1 (z) y[n] H(z) = z -2 F 0 (z 3 )+ z -1 F 1 (z 3 )+F 2 (z 3 ) F k (z) = F k0 (z 4 )+ z -1 F k1 (z 4 )+z -2 F k2 (z 4 )+z -3 F k3 (z 4 ) 4 4 Parallel to Serial Converter Serial to Parallel Converter F k0 F k1 F k2 F k3
41 Efficient Design for Very Narrow-band Filters G(z M ) x[n] y[n]H(z) x[n]y[n]F(z)
42 Efficient Design for Very Narrow-band Filters G(z M ) H(z) F(z) 0 G(z) 0 0 0 p s pp s ss pp ss Desired passband Images pp
43 Efficient Design for Very Narrow-band Filters G(z M ) x[n]y[n]F(z) M G(z ) x[n]y[n]F(z) M G(z ) x[n] y[n] F 0 (z ) M z -1 M F 1 (z ) +
44 Efficient Design for Very Narrow-band Filters G(z ) x[n] y[n] F 0 (z ) F 1 (z ) + Serial to Parallel Converter F M-1 (z )
45 Multi-stage Decimation System H(z ) x[n]y[n] M G(z ) x[n] y[n] F(z) M 1 G(z M 1 ) x[n]y[n]F(z) M 1 M 2 M 2
46 Multi-stage Decimation System x[n] y[n] F 0 (z ) F 1 (z ) + Serial to Parallel Converter F M 1 -1 (z ) G 0 (z ) G 1 (z ) + Serial to Parallel Converter G M 2 -1 (z )
47 Multi-stage Interpolation System H(z ) x[n]y[n] L G(z ) x[n] y[n] F(z) L 1 G(z L 1 ) x[n]y[n]F(z) L 1 L 2 L 2
48 Multi-stage Interpolation System x[n] y[n] F 0 (z ) F 1 (z ) F L 1 -1 (z ) G 0 (z ) G 1 (z ) Parallel to Serial Converter G L 2 -1 (z ) Parallel to Serial Converter