EP0204570A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Digital mixing apparatus
Assignee: The General Electric Company PLC
•
Filing: 1986-06-05
•
Granted: —
•
Expires: 2006-06-05
Abstract
Abstract In a radar receiver signals at IF are converted to digital form at 22 and the real and imaginary components are separated at 24 and 25 before passing to respective digital low-pass filters 28 and 29. These filters operate by adding samples within blocks of a given number of samples. In order to reduce the response of these filters at the sum frequency the first and last member of each blocks of samples taken by the filter is weighted so as to reduce its value relative to the centre values of the batch which are left unchanged relative to each other.
Inventors
- 👤 Michael Cullen Jackson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 18:12
CPC Classifications
H; H03; H03D; H03D7/00; H03D7/16; H03D7/165; H03B; H03B28/00
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
94 words
Digital mixing apparatus comprising means for providing digital signals representing sum and difference frequencies resulting from mixing a variable input signal with a predetermined signal, and a digital filter for removing the sum frequency, the digital filter comprising means for taking numbers representing successive samples of the mixer output in blocks and Weighting at least the first and last number of each block to reduce their values relative to the others and/or vice versa, whilst leaving the majority of the numbers within each block, between the first and last, unchanged relative to each other.
Claim 2
Dependent Claim
48 words
Apparatus according to Claim 1 in which the means for providing digital signals is adapted to provide such signals on two channels representing respective real and imaginary components of complex numbers, and in which a digital filter, as defined in Claim 1, is provided for each such channel.
Claim 3
Dependent Claim
24 words
Apparatus according to Claim 1 or 2 in which the weighting has the effect of halving the end two samples relative to the others.
Claim 4
Dependent Claim
31 words
Apparatus according to Claim 1 or 2 in which the weighting has the effect of giving the end two samples weights of approximately and giving the adjacent samples weights of approximately
Claim 5
Dependent Claim
47 words
Apparatus according to Claim 1 or 2 in which the weighting has the effect cf giving the end two samples weights of approximately one eighth, the adjacent samples weights of approximately one half, and those samples which are third from the ends weights of approximately seven eighths.
Claim 6
Dependent Claim
106 words
Digital mixing apparatus comprising means for providing digital signals representing sum and difference frequencies resulting from mixing a variable input signal with a predetermined signal, and a digital filter for removing the sum frequency, the digital filter comprising means for taking numbers representing successive samples of the mixer output in blocks, and weighting at least the first and last number of each block relative to the others or vice versa in such a way that successive changes in the weights are given by the coefficients of X in the binomial expansion of where I is an integer from O to M and M is another integer.
Claim 7
Dependent Claim
89 words
Apparatus for producing from a digital input signal at a particular sampling frequency, two further signals representing the real and imaginary components of .it, the apparatus comprising means for generating two sequences of weights each at the sampling frequency representing sine waves in phase quadrature and means for applying the weights of each sequence to successive input signal numbers to produce the real and imaginary components characterised in that some of the weights lying on or closest to the zero crossing points of the sine waves are made zero.
Claim 8
Dependent Claim
19 words
Apparatus substantially as described with reference to Figures 2, 3, 4, 5, 6 and 7 of the accompanying drawings.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.