PHASE DERIVATIVE MODULATION METHOD AND APPARATUS

• US 3,818,378 A
• Filed: 02/10/1972
• Issued: 06/18/1974
• Est. Priority Date: 02/10/1972
• Status: Expired due to Term

• Current Assignee: Chester C. Phillips
• Original Assignee: Chester C. Phillips
• Inventors: Phillips, Chester C.
• Primary Examiner(s): Hubler, Malcolm F.
• Assistant Examiner(s): Birmiel, H. A.
• Application Number:
  US05/225,357
• Time in Patent Office: 859 Days
• Field of Search: 332/11,21,22,23A,23R 325/40,47
• US Class Current: 332/100
• CPC Class Codes: H03C 3/38 by converting amplitude modulation to angle modulation

Abstract

A carrier frequency input is simultaneously applied to a pair of quadrature modulating paths or channels, each containing a pair of cascaded modulator or mixer circuits. In these two modulating paths, the quadrature components of the carrier input are multiplied or mixed with phase quadrature components of a modulating signal whose period is equal to twice the bit length of the input phase code data. The resultant or modulated signals are then additionally mixed with the input phase code data; the phase code input to one modulator path being shifted relative to the phase code input to the other path by one-half of the code bit length. The outputs from the two modulating paths are then recombined to produce an output signal containing no discontinuities in the time waveform.

Claims

1. A method for modulating a carrier signal of frequency omega c with an input code data signal having a preselected code bit length T, said method comprising the steps of:

generating quadrature components of said carrier signal, generating from said input code data signal a first pair of modulating signals which are displaced relative to one another by a time interval of T/2, generating from a signal whose frequency omega m is selected such that it equals 2 pi ( 1/2 T) a second pair of modulation signal components which are in phase quadrature relative to one another, modulating in a pair of modulation paths each of said carrier signal components with a different component of said second modulation signal pair to produce first and second modulated signals, subsequently modulating each of said first and second modulated signals with a different one of said first pair of modulating signals to produce third and fourth modulated signals, and combining said third and fourth modulated signals.

2. The method specified in claim 1 wherein the step of generating said quadrature components of said carrier signal is accomplished by applying said carrier signal as input to a quadrature hybrid network effective to produce a pair of output signals of frequency omega c but 90* apart in phase and then applying one output signal from said quadrature hybrid network to one of said modulation paths and the other output signal from said hybrid network to the other of said modulation paths.

3. The method specified in claim 1 wherein said second modulation signal pair is generated by applying said signal of frequency omega m to one modulation path directly and to the other modulation path through a delay network which produces an output delayed from its input by a time equal to T/2.

4. The method specified in claim 1 wherein said first modulation signal pair is generated by applying said code data input signal to one modulation path directly and to the other modulation path through a delay network which produces an output delayed from its input by a time equal to T/2.

5. The method specified in claim 3 wherein said first modulation signal pair is generated by applying said code data input signal to one modulation path directly and to the other modulation path through a delay network which produces an output delayed from its input by a time equal to T/2.

6. The method specified in claim 1 wherein the step of generating said quadrature components of said carrier signal is accomplished by applying said carrier signal as input to a quadrature hybrid network effective to produce a pair of output signals of frequency omega c but 90* apart in phase and then applying one output signal from said quadrature hybrid network to one of said modulation paths and the other output signal from said hybrid network to the other of said modulation paths, wherein said second modulation signal pair is generated by applying said signal of frequency omega m to one modulation path directly and to the other modulation path through a delay network which produces an output delayed from its input by a time equal to T/2, and wherein said first modulation signal pair is generated by applying said code data input signal to one modulation path directly and to the other modulation path through a delay network which produces an output delayed from its input by a time equal to T/2.

7. The modulAtion method specified in claim 1 wherein the successive steps of initially modulating each carrier signal component with a different component of said second modulation signal pair and subsequently modulating the resultant first and second modulated signals with a different one of said first pair of modulating signals are each accomplished in a suppressed carrier double side-band balanced mixer.