Claims
- 1. A system for demodulating angle-modulated wave signals comprising:
- a first phase shifting circuit supplied with an angle-modulated signal;
- first amplitude limiting means for limiting the amplitude of an output signal of said first phase shifting circuit;
- a second phase shifting circuit supplied with the angle-modulated signal, said first and second phase shifting circuits producing outputs having a relative phase differece of 90.degree.;
- tracking band-pass filtering means responsive to the output signal of the second phase shifting circuit and having a pass band with a center frequency which is controlled by a control signal;
- second amplitude means for limiting the amplitude of the output signal of said tracking band-pass filtering means;
- phase comparing means responsive to the output signals of said first and second amplitude limiting means for producing an error signal in accordance with the phase difference between said output signals;
- means responsive to said error signal for controlling said tracking band-pass filtering means; and
- means responsive to said error signal for deriving a demodulated signal.
- 2. A system for demodulating angle-modulated signals comprising:
- tracking band-pass filtering means supplied with an angle-modulated input signal, said filter means having a pass band with a center frequency which is variably controlled responsive to a control signal;
- first amplitude limiting means for limiting the amplitude of the angle-modulated input signal;
- phase-shifting means for establishing a phase difference of 90.degree. between a signal passing through said tracking band-pass filtering means and a signal passing through said amplitude limiting means;
- phase comparing means responsive to the 90.degree. phase difference signals for producing an output error signal in accordance with said phase difference;
- amplitude expansion means in a signal transmission system including a first amplitude limiting means, means whereby said amplitude expansion means lowers the level of the angle-modulated signals supplied to the phase comparing means responsive to levels of the input angle-modulated signals which are below a predetermined level;
- means responsive to said output error signal for controlling said tracking band-pass filtering means; and
- means responsive to said output error signal for deriving a demodulating signal.
- 3. A system for demodulating angle-modulated signals comprising:
- tracking band-pass filtering means supplied with an angle-modulated input signal, said filter means having a pass band with a center frequency which is variably controlled responsive to a control signal;
- first amplitude limiting means for limiting the amplitude of the angle-modulated input signal;
- phase-shifting means for establishing a phase difference of 90.degree. between a signal passing through said tracking band-pass filtering means and a signal passing through said amplitude limiting means;
- phase comparing means responsive to the 90.degree. phase difference signals for producing an output error signal in accordance with said phase difference;
- means responsive to said output error signal for controlling said tracking band-pass filtering means;
- envelope detecting means for generating a control signal responsive to a detection of the envelope of the input angle-modulated signal;
- loop gain controlling means for controlling the level of the output signal of the phase comparing means responsive to the control signal of the envelope detecting means;
- means for supplying the output of said loop gain controlling means to the tracking band-pass filtering means as the control signal; and
- means responsive to said output error signal for deriving a demodulated signal, said demodulated signal driving means including operation circuit means responsive to the output signal of the phase comparing means and the output signal of the loop gain controlling means for producing an output signal having a constant level.
- 4. A system for demodulating angle-modulated signals comprising:
- tracking band-pass filtering means supplied with an angle-modulated input signal, said filter means having a pass band with a center frequency which is variably controlled responsive to a control signal;
- first amplitude limiting means for limiting the amplitude of the angle-modulated input signal;
- phase-shifting means for establishing a phase difference of 90.degree. between a signal passing through said tracking band-pass filtering means and a signal passing through said amplitude limiting means;
- first phase comparing means responsive to the 90.degree. phase difference signals for producing an output error signal in accordance with said phase difference;
- means responsive to said output error signal for controlling said tracking band-pass filtering means;
- second phase comparing means for comparing the phase of the input angle-modulated signal to be supplied to the tracking band-pass filtering means and the phase of the output signal of the tracking band-pass filtering means, thereby producing an output signal responsive to the difference of both phases; and
- means responsive to said output error signal for deriving a demodulated signal.
- 5. A system for demodulating angle-modulated signals comprising:
- tracking band-pass filtering means supplied with an angle-modulated input signal, said filter means having a pass band with a center frequency which is variably controlled responsive to a control signal;
- first amplitude limiting means for limiting the amplitude of the angle-modulated input signal;
- phase-shifting means for establishing a phase difference of 90.degree. between a signal passing through said tracking band-pass filtering means and a signal passing through said amplitude means;
- phase comparing means responsive to the 90.degree. phase difference signals for producing an output error signal in accordance with said phase difference;
- means responsive to said output error signal for controlling said tracking band-pass filtering means; and
- means responsive to said output error signal for deriving a demodulated signal, said demodulated signal deriving means including a double integral circuit for removing unnecessary carrier components and higher harmonics thereof from the output signal of the phase comparing means.
Priority Claims (7)
Number |
Date |
Country |
Kind |
50-98498 |
Aug 1975 |
JA |
|
50-98499 |
Aug 1975 |
JA |
|
50-142333 |
Dec 1975 |
JA |
|
50-142334 |
Dec 1975 |
JA |
|
51-58301 |
May 1976 |
JA |
|
51-58302 |
May 1976 |
JA |
|
51-58303 |
May 1976 |
JA |
|
BACKGROUND OF THE INVENTION
This application is a continuation-in-part application of a copending U.S. Patent application Ser. No. 712,707 filed Aug. 9, 1976.
US Referenced Citations (5)
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
712707 |
Aug 1976 |
|