Device for processing an echographic signal

• US 5,000,183 A
• Filed: 09/15/1989
• Issued: 03/19/1991
• Est. Priority Date: 09/30/1988
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Bonnefous, Odile
• Primary Examiner(s): JAWORSKI, FRANCIS J
• Application Number:
  US07/407,516
• Time in Patent Office: 550 Days
• Field of Search: 128/660.01, 128/661.01, 73/602, 73/626, 73/625
• US Class Current: 600/437
• CPC Class Codes: G01S 7/5206 Two-dimensional coordinated display of distance and direction; B-scan display

Abstract

A device for processing an echographic signal S_o (t), includes:

a sampling device which supplies N discrete values C_ok of S_o (t) where k is 1, 2, . . . , N,

p decomposition units (200j, j=1, 2, . . . , p), each comprising:

a low frequency transmission channel including a low pass filter (201j) for correlation of the input signal S_j-1 (t) with a sealing filter h(t), and a decimator (202j) which retain selective values with respect to k of the correlation, the N/2^j values C_jk, for k=1, 1+2^j, 1+2×2^j, . . . , representing s_j (t), the low-frequency component of S_o (t) of the order j,

a high-frequency reducing channel which successively comprises a high-frequency filter (203j) for correlation of the input signal S_j-1 (t) with a wavelet filter g(t), and a decimator (204j) which retains selective values with respect to k of the correlation, the N/2^j values W_jk for k=1, 1+2^j, 1+2×2^j, 1+3×2^j, . . . , stored in a memory and representing D_j (t) the high-frequency component of S_o (t) of the order j,

p cascade connected reconstruction units (400j), each comprising:

a high-frequency enhancement channel which comprises a cirucit (401j) for comparing C'"'"'_jk /W_jk with a predetermined threshold, A_j, C'"'"'_jk representing the values of S'"'"'_j (t), which outputs the N/2^j values of W_jk if C'"'"'_jk /W_jk <A_j for all k, or N/2^j zeros in the opposite case, a circuit (402j) for doubling the sampling, and a high-frequency convolution circuit (403j) for convolution of the signal supplied by the circuit (402j) for doubling sampling with the wavelet filter g(t),

an actual reconstruction channel comprising a sample doubling cirucit, a low-frequency convolution circuit (405j), an adder (406j) which supplies the reconstructed signal S'"'"'_j-1 (t) of the order j-1 by forming the sum of the output signals of high-frequency and low-frequency convolution circuits (403j, 405j).

Claims

1. An ultrasonic echographic apparatus for processing an echographic signal S_o (t), comprising:

a sampling means for supplying N discrete values C_ok of the echographic signal S_o (t) where k is 1, 2, . . . , N,

p cascade connected decomposition means each decomposition means comprising;

a low frequency transmission channel which successively comprises a low pass filter which realizes the correlation of the input-signal S_j-1 (t) with a scaling filter h(t), and a decimeter which retains only one out of two values with respect to k of the result of said correlation, so in total the N/2^j values C_jk for k=1, 1+2^j, 1+2×

2^j, 1+3×

2^j, . . . , representing s_j (t) which is the low-frequency component of s_o (t) of the order j,

a high frequency reducing channel which successively comprises a high frequency filter which realizes the correlation of the input signal S_j-1 (t) with a wavelet filter g(t), and a decimeter which retains only one of two values with respect to k of the result of said correlation, so in total the N/2^j values W_jk for k=1, 1+2^j, 1+2×

2^j, 1+3×

2^j. . . , and

memory means for storing said values and representing D_j (t) which is the high-frequency component of S_o (t) of the order j, said low-frequency and high-frequency filters being quadrature mirror filters,

p cascade connected reconstruction means, each reconstruction means comprising;

a high frequency enhancement channel which successively comprises a means for comprising |C'"'"'_jk /W_jk | with a predetermined threshold A_j, C'"'"'_jk representing the values of S'"'"'_j (t), which is the reconstructed signal of the order j, which comparison means outputs the N/2_j values of W_jk if |C'"'"'_jk /W_jk | <

A_j for all k, or N/2_j zeros in the opposite case, a first means for doubling the sampling which inserts a zero between two consecutive values of the signal supplied by the comparison means, and a high frequency convolution means which realizes the convolution of the signal supplied by the means for doubling sampling with the wavelet filter g(t), and

an actual reconstruction channel which successively comprises a second means for doubling the sampling which inserts a zero between two consecutive values of C'"'"'_jk, a low frequency convolution means which realizes the convolution of the signal supplied by the second means for doubling, for doubling the sampling with the scaling filter h(t), and an adder means which supplies the reconstructed signal S'"'"'_j-1 (t) of the order j-1 by forming the sum of the output signals of the high frequency and low frequency convolution means thereby providing enhanced processing of the echographic signal.