Radio receiver for forming a baseband signal of time-varying frequencies

• US 5,428,836 A
• Filed: 10/14/1993
• Issued: 06/27/1995
• Est. Priority Date: 01/21/1992
• Status: Expired due to Term

• Current Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Sanecki, Theodore T., Moller, Paul J., Johnson, Robert M. Jr.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Pham, Chi H.
• Application Number:
  US08/137,377
• Time in Patent Office: 621 Days
• Field of Search: 455/207, 455/209, 455/260, 455/264, 455/265, 455/259, 455/295, 455/296, 455/315-319
• US Class Current: 455/315
• CPC Class Codes: H03B 23/00 Generation of oscillations periodically swept over a predetermined frequency range angle-modulating circuits in general H03C3/00
• CPC Class Codes: H03D 2200/0047 Offset of DC voltage or frequency
• CPC Class Codes: H03D 7/163 the local oscillations of at least two of the frequency changers being derived from a single oscillator
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H03D 7/166 using two or more quadrature frequency translation stages
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22

Abstract

A radio receiver, and associated method therefor, for generating a baseband signal having signal component portions of time-varying frequencies. The oscillating signal generated by at least one of the local oscillators of down-mixing circuitry of the receiver is modulated by a low-frequency signal thereby to cause the resultant, baseband signal to be comprised of signal component portions of time-varying frequencies. Because the signal component portions of the baseband signal are of time-varying frequencies, attenuation of such signal component portions and resultant distortion of the received signal, as a result of undesirable notches in the frequency response of a radio receiver is avoided.

Claims

1. A radio receiver for receiving a modulated, radio frequency signal having signal component portions of radio frequencies, said radio receiver comprising:

means for down-converting in frequency an electrical signal representative of the modulated, radio frequency signal received by the radio receiver, said means for down-converting having at least one down-mixing circuit including a reference oscillator for generating a reference oscillation signal and at least one local oscillator coupled to receive a signal representative of the reference oscillation signal, the at least one local oscillator for generating at least one mixing signal for down-mixing the electrical signal representative of the modulated, radio frequency signal such that the at least one down-mixing circuit forms thereby a first baseband signal having signal components of baseband frequencies;

means for altering the baseband frequencies of the signal components of the first baseband signal formed by said means for down-converting, said means for altering comprising a phase modulator coupled to receive the mixing signal generated by the at least one local oscillator and also to receive a modulating signal, wherein the phase modulator is operative to phase modulate the mixing signal which, in turn, is utilized to down-mix the electrical signal representative of the modulated, radio frequency signal and, in turn, convert thereby the first baseband signal into a time-varying baseband signal of time-varying frequencies; and

means for converting the baseband signal of time varying frequencies into a demodulated signal representative of the modulated, radio frequency signal received by the radio receiver.

2. In A radio receiver, a method for forming a baseband signal of time-varying frequencies responsive to reception of a modulated, radio frequency signal, said method comprising the steps of:

down-converting in frequency an electrical signal representative of the modulated, radio frequency signal received by the radio receiver by down-mixing the electrical signal with at least one mixing signal generated by at least one down-mixing circuit which is maintained in a frequency relationship with a reference oscillation signal generated by a reference oscillator to form thereby a first baseband signal having signal components of baseband frequencies; and

altering the baseband frequencies of the signal components of the first baseband signal formed during said step of down-converting by phase modulating the at least one mixing signal to form thereby a time-varying baseband signal of time varying frequencies.

3. A radio receiver for receiving a modulated, radio frequency signal having signal component portions of radio frequencies, said radio receiver comprising:

means for down-converting in frequency an electrical signal representative of the modulated, radio frequency signal received by the radio receiver, said means for down-converting having at least one down-mixing circuit including a reference oscillator for generating a reference oscillation signal and at least one local oscillator coupled to receive a signal representative of the reference oscillation signal, the at least one local oscillator for generating a mixing signal for down-mixing the electrical signal representative of the modulated, radio frequency signal such that the at least one down-mixing circuit forms thereby a first baseband signal having signal components of baseband frequencies;

means for altering the baseband frequencies of the signal components of the first baseband signal formed by said means for down-converting, said means for altering modulating the mixing signal by a phase modulator for phase modulating the reference oscillation signal generated by the reference oscillator and, in turn, to convert thereby the first baseband signal into a time-varying baseband signal of time-varying frequencies; and

means for converting the time-varying baseband signal of time varying frequencies into a demodulated signal representative of the modulated, radio frequency signal received by the radio receiver.

4. A radio receiver for receiving a modulated, radio frequency signal having signal component portions of radio frequencies, said radio receiver comprising:

means for down-converting in frequency an electrical signal representative of the modulated, radio frequency signal received by the radio receiver, said means for down-converting comprising;

a first down-mixing circuit and a second down-mixing circuit having a first mixing signal and a second mixing signal, said first down-mixing circuit operative to mix the electrical signal representative of the modulated, radio frequency signal with the first mixing signal to form a first down-mixed signal, and said second down-mixing circuit operative to mix the first down-mixed signal with second mixing signal to form a baseband signal thereby;

a reference oscillator for generating a reference oscillation signal and a first and a second local oscillator coupled to receive a signal representative of the reference oscillation signal, the first local oscillator generating the first mixing signal and the second local oscillator generating the second mixing signal for down-mixing the electrical signal representative of the modulated, radio frequency signal;

means for altering the baseband frequencies of the signal components of the first baseband signal formed by said means for down-converting by phase modulating the reference oscillation signal generated by the reference oscillator, said means for altering, modulating the first and second mixing signals generated by the first and second local oscillators which modulate the reference oscillation signal generated by the reference oscillator and, in turn, to convert thereby the baseband signal into a time-varying baseband signal of time-varying frequencies; and

means for converting the time-varying baseband signal of time varying frequencies into a demodulated signal representative of the modulated, radio frequency signal received by the radio receiver.