Combining oscillator with a phase-indexed control circuit for a

Details Combining oscillator with a phase-indexed control circuit for a Combining oscillator with a phase-indexed control circuit for a

1998-06-17

2000-07-18

Trost, William G.

Telecommunications

Receiver or analog modulated signal frequency converter

Local control of receiver operation

455 76, 4551501, 375376, H04B 106

Patent

active

060919434

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

In conventional radio receivers an oscillator circuit with a phase-locked control loop (PLL) which also includes an analog loop filter is used as a mixer oscillator. If a listener requires a change in the reception frequency of a radio receiver then, among other steps, the capacitors in the analog loop filter of the PLL must be recharged. The required recharging time causes the retuning of the radio receiver to seem slow, particularly during the switch-on of alternative frequencies during testing.
A mixer oscillator circuit with reduced a test time is described in German Application No. 145.102207.


ADVANTAGES OF THE INVENTION

A mixer oscillator circuit according to this invention, which differs from the background of the invention as reflected by the features cited in the characterizing, ensures an even more reduce switch-over time to a new frequency circuits. European Patent No. 0 406 469 describes a digital control circuit for a tuning system with a device for a generation of a tuner-tuning voltage. In this control circuit, the output signal of a phase discriminator is inputted to a digital integrator that is designed as a loop filter of a phase control loop, in which the inputted value to the integrator constitutes the tuning voltage after a digital/analog conversion. The integrator can be set to a value corresponding to the desired tuner-tuning voltage level for rapid switching of the tuner-tuning voltage.
In the case of greater frequency jumps, the present invention supports a brief switchover time. The present invention also provides phase discriminator with low-resolution digital output variables. In addition, the present invention provides varying means for compensating for the nonlinearity of the oscillator characteristic curve.
The present invention may further use the direct voltage component in a multiplex signal for reception tuning.


BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a block diagram of a radio receiver with a mixer oscillator which is controlled by a phase-locked control loop which includes a digital loop filter,
FIG. 2 shows a block diagram of a radio receiver with two switchable digital loop filters in the control loop of the mixer oscillator,
FIG. 3 shows a block diagram of a control loop with an additional circuit for the iterative approximation of the actual frequency to the desired frequency,
FIG. 4 shows the block diagram of a control loop with an additional circuit for the polynomial calculation of the inverse Voltage Controlled Oscillator characteristic curve,
FIG. 5 shows a block diagram of a control loop in which a direct-voltage component in a multiplex signal is evaluated.


DESCRIPTION OF THE EMBODIMENT

FIG. 1 shows to the essential contact elements of a radio receiver, the components of a mixer oscillator with a phase-locked control loop.
A frequency range, within which the carrier frequency of the desired program can be found, is received via antenna 1. This carrier frequency is filtered out of the reception spectrum with the aid of a mixer stage 2 and converted into the intermediate frequency position. An intermediate frequency stage 3 whose output is connected to an FM demodulator 4 from which a multiplex signal modulating the carrier frequency can be tapped, is connected to mixer stage 2.
As is known the multiplex signal has a direct voltage component until the radio receiver is fully tuned to the carrier frequency. This direct voltage component, however, is so low that it cannot be evaluated in analog tuning circuits due to the required component tolerance levels involved.
In a low frequency stage 5 the sound signal is recovered from the multiplex signal and made audible via a loudspeaker 6. In addition, the multiplex signal contains, in the course of the reception of radio-data-signal transmitters, radio-data-signals which are modulated to a 57-kHz auxiliary carrier and evaluated within a radio-data-signal decoder 25.
The radio receiver is tuned via mixer a oscillator to the carrier frequency of the desired program. The mixer

REFERENCES:
patent: 4211975 (1980-07-01), Kuroda
patent: 4270206 (1981-05-01), Hughes
patent: 4628270 (1986-12-01), Roberts
patent: 4856085 (1989-08-01), Horvat
patent: 5384551 (1995-01-01), Kennedy et al.
patent: 5781044 (1998-07-01), Riley et al.
patent: 5949281 (1999-09-01), Sharpe

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