Transport processor filter

• US 5,001,445 A
• Filed: 04/24/1989
• Issued: 03/19/1991
• Est. Priority Date: 11/05/1986
• Status: Expired due to Fees

• Current Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Horvath, Anton F., Hostetter, Gene H.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/342,718
• Time in Patent Office: 694 Days
• Field of Search: 333/134, 333/129, 333/132, 333/138, 333/166, 333/165, 333/167, 333/168, 455/610, 455/617, 350/313-316, 350/311, 364/724.01, 364/724.03, 364/724.06, 364/724.11, 364/726, 364/724.09
• US Class Current: 333/166
• CPC Class Codes: G02B 6/2861 using fibre optic delay lines and optical elements associated with them, e.g. for use in signal processing, e.g. filtering delay lines in general H03H, H01P9/00; optical computing devices G06E
• CPC Class Codes: H03H 17/02 Frequency selective networks digital computers for complex mathematical operations G06F17/10

Abstract

A new structure for electro-magnetic signal filters is described. The structure of the invention incorporates ideal time lag elements having delay values selected to match an arbitrarily selected set of frequencies matched to a desired frequency response and connected in a cascade array by second filter elements which null the frequency filtered by the preceding array, the output of which is summed to provide a composite output with the desired frequency response. The resultant filters are easily implemented in conventional hardware and the techniques may be applied to a broad range of the electro-magnetic spectrum by the choice of appropriate components.

Claims

1. A filter structure which comprises a first plurality of filter elements each consisting of an array of delay elements arranged in parallel, and summing means to receive the output of said delay elements to produce a composite filtered output thereof, each delay element having a delay parameter individually selected as a function of an arbitrarily ordered set of frequencies exactly matched to a desired frequency response;

a second plurality of filter elements each consisting of an array of delay elements arranged in parallel, and summing means to receive the output of said delay elements to produce a composite filtered output thereof, each said delay element having a delay parameter individually selected as a function of an arbitrarily ordered set of frequencies exactly matched to a desired frequency response, said second plurality of filter elements being connected with said first plurality of filter elements in cascade array, and each filter element in said second plurality of filter elements having means to attenuate the input frequency, each of said filter elements in said first plurality of filter elements having as an input signal said arbitrarily ordered set of input frequencies passed by preceding ones of said filter elements in said second plurality of filter elements;

and means to sum the output of said first plurality of filter elements to provide a composite output signal of desired amplitude and phase.

2. The filter structure of claim 1, wherein said delay elements further comprise delay elements having a time lag function of exponential form.

3. The filter structure of claim 1, wherein said filter structure comprises an electro-optical filter.

4. The filter structure of claim 3, wherein said delay elements comprise means to alter a portion of the input frequency of an optical signal.

5. The filter structure of claim 4, wherein said filter elements in said second plurality of filter elements comprise means to attenuate an optical signal at a desired frequency.

6. The filter structure of claim 3 which further comprises:

optical beam splitting means operative to provide a multiplicity of input beams for said delay elements.

7. A frequency filter for electro-magnetic signals which comprises;

a first plurality of filter elements arranged in parallel, and a second plurality of said filter elements connected with said first plurality of filter elements in cascade, each filter element of said second plurality of filter elements being connected between an input signal and one of said filter elements in said first plurality of filter elements, each of said filter elements in said second plurality of filter elements having a frequency null at the response frequency of said filter elements in said first plurality of filter elements and serving to essentially prevent the passage of signals of the frequency filtered by said first plurality of filter elements, each said filter element consisting of an array of delay elements arranged in parallel, each delay element having a delay individually selected as a function of an arbitrarily ordered set of frequencies exactly matched to a desired frequency response at a predetermined input frequency, each delay element having a time lag function of exponential form, an input signal being applied to each delay element of said array of delay elements; and

summing means connected to receive the output of said delay elements to produce a composite filtered output thereof.

8. A frequency filter for electro-magnetic signals which comprises:

a first plurality of filter elements arranged in parallel, and a second plurality of said filter elements connected with said first plurality of filter elements in cascade, each filter element of said second plurality of filter elements comprising a notch filter connected between an input signal and one of said filter elements in said first plurality of filter elements, each of said filter elements in said second plurality of filter elements having a frequency null at the response frequency of said filter elements in said first plurality of filter elements and serving to essentially prevent the passage of signals of the frequency filtered by said first plurality of filter elements, each said filter element consisting of an array of delay elements arranged in parallel, each delay element having a delay individually selected as a function of an arbitrarily ordered set of frequencies exactly matched to a desired frequency response at a predetermined input frequency, each delay element having a time lag function of exponential form, an input signal being applied to each delay element of said array of delay elements; and

summing means connected to receive the output of said delay elements to produce a composite filtered output thereof.

9. A frequency filter for electromagnetic signals which comprises:

a first plurality of filter elements arranged in parallel, with a first one of said filter elements being connected to receive a source input signal;

remaining ones of said first plurality of filter elements being connected to receive an input signal from a second plurality of filter elements connected in cascade with the remaining ones of said filter elements in said first plurality of filter elements, with a first one of said second plurality of filter elements being connected to receive said source input signal;

each of said filter elements in said first and second plurality of filter elements having a summed array of delay elements arranged in parallel, with each said delay element receiving an input signal and providing an output signal, and a means for summing the outputs of said delay elements to produce a composite filtered output, each of said delay elements having a delay parameter individually selected as a function of an arbitrarily ordered set of frequencies exactly matched to a desired frequency response; and

each of said second plurality of filter elements having a frequency null at the response frequency of preceding ones of said filter elements in said first plurality of filter elements to essentially prevent the passage of signals of the frequency filtered by said preceding ones of said filter elements in said first plurality of filter elements; and

means for receiving and summing the output from said first plurality of filter elements to produce a composite output of desired amplitude and phase.