Universal equalizer

• US 4,243,957 A
• Filed: 07/28/1978
• Issued: 01/06/1981
• Est. Priority Date: 09/20/1975
• Status: Expired due to Term

• Current Assignee: Tekade Felten & Guilleaume Fernmeldeanlagen GmbH
• Original Assignee: Tekade Felten & Guilleaume Fernmeldeanlagen GmbH
• Inventors: Schmidt, Hans-Joachim
• Primary Examiner(s): Gensler, Paul L.
• Application Number:
  US05/928,884
• Time in Patent Office: 893 Days
• Field of Search: 333/28 R
• US Class Current: 333/28.00R
• CPC Class Codes: H04B 3/141 using multiequalisers, e.g. bump, cosine, Bode

Abstract

An equalizer introduces into the attenuation versus frequency curve of a signal carrier transmission system compensatory bumps of adjustable magnitude and of adjustable frequency location. When the bumps are in their initial frequency locations, they exhibit the following features: (a) The middle frequencies of the bumps are each shiftable with respect to frequency by an amount equal to at least one half the frequency interval to the respective neighboring bump. (b) Adjoining bumps of equal magnitude have facing flanks which overlap and intersect at a point which is at least 0.6 of the way up the height of the bump. (c) The middle frequencies of the individual bumps are distributed within the frequency range to be equalized in at least approximate correspondence to the detail density distribution function d*. The function d* is a novel function defined herein.

Claims

1. An equalizer of the type operative for equalizing the attenuation-versus-frequency curve of a signal carrier transmission system within a predetermined frequency range by providing a compensatory attenuation-versus-frequency transfer function compensating for the unequalized attenuation-versus-frequency curve of the signal carrier transmission system,

the equalizer comprising

input circuit means;

output circuit means;

N compensating means connected between the input and output circuit means of the equalizer and operative for establishing a compensatory attenuation-versus-frequency transfer function comprised of N compensatory attenuation-versus-frequency-curve bumps,

each of the N compensating means comprising a respective reactor-resistor circuit stage operative for establishing a respective one of the N bumps of the compensatory transfer function of the equalizer,

each reactor-resistor circuit stage including amplitude-selecting means adjustable for changing the amplitude of the respective compensatory bump,

each reactor-resistor circuit stage furthermore including frequency-selecting means adjustable for shifting the frequency of the extreme-amplitude point of the respective compensatory bump between the minimum and maximum end frequencies of a respective one of N different frequency ranges,

each of the N different frequency ranges including a middle frequency midway between the minimum and maximum end frequencies of that frequency range,

the difference between the middle frequency and the end frequencies within each frequency range being in excess of one half the difference between the middle frequency of that frequency range and the middle frequency of the adjoining frequency range,

the flanks of each two adjoining compensatory bumps overlapping and intersecting at a point which is at least 0.6 of the amplitudes of the two adjoining bumps whenever the amplitudes of the two adjoining bumps are set to equal values,

the N middle frequencies being substantially equidistantly spaced when measured along a normalized frequency axis the constituent portions of which have been expanded and compressed in correspondence to the function d*, wherein ##EQU2## k is a simple proportionality constant and q is normalized frequency f/f_max.

2. The equalizer defined in claim 1, each reactor-resistor circuit stage being a resonant circuit stage.

3. The equalizer defined in claim 2, each resonant circuit stage comprising a resistor, an adjustable capacitor which constitutes the respective amplitude-selecting means, and an adjustable inductor which constitutes the respective frequency-selecting means.