JPS61117918A - Sweeping type tuning receiver - Google Patents

Abstract

PURPOSE:To tune the title receiver to an input frequency corresponding always to a tuning frequency data by comparing a measured data of a mixing frequency between a reference signal and a local oscillation signal from a reference signal oscillator of a local oscillator with the tuning frequency data so as to correct the tuning frequency data. CONSTITUTION:An input signal FI is mixed with an output (frequency FL) of a voltage controlled oscillator 1 by the first mixer 3 to form an intermediate frequency signal (frequency FIF). The output FL of the voltage controlled oscillator 1 is corrected in a way that the FIF is equal to a center frequency Fc of a band pass filter 4 when the frequency of the input signal FI is equal to the frequency of a tuning frequency data, then the input frequency corresponding to the tuning frequency data is selected at the center of the band pass filter 4. Then a signal turned and selected in this way is outputted to a frequency measuring circuit 6 through a signal switch 8 and a mixer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sweep type tuning receiving device such as a radio receiver.

[Conventional technology]

FIG. 2 is a diagram showing a conventional sweep type tuning receiver of this type. In the figure, 1 is a voltage controlled oscillator whose oscillation frequency can be controlled by voltage, and 2 is external tuning frequency data a.
A frequency control circuit applies a voltage corresponding to the above voltage controlled oscillation I1) to control its oscillation output (local oscillation signal) frequency; 3 is an input signal (frequency Fl) and an oscillation output (frequency PL) of the voltage controlled oscillation ill; a first mixer for mixing the 4
is a bandpass filter for pass band limitation, 5 is filter 4
A second mixer 6 mixes the signal (frequency PIF) passed through the oscillator 1 with the oscillation output of the voltage controlled oscillator 1, and 6 is a frequency measuring circuit that measures the frequency of the output signal of the mixer 5.

The voltage controlled oscillator 1 is oscillated at an arbitrary frequency FL by the 0 frequency control circuit 2 whose operation will be explained next, and the mixer 3 mixes the input signal (frequency F■) and the oscillation output of the voltage controlled oscillation 1s1. The relationship between Fl, FL, and FIF, which becomes a frequency signal (frequency PIF), is PIF-FL-Fl・
-(1), where the center frequency Fc of the bandpass filter 4 is set to FC-FIF, the intermediate frequency signal passes through the bandpass filter 4 which develops the center frequency Fc and the passband width By, and then the mixer 5, the above voltage W*oscillation a
1 output (frequency FL) and the tuning signal (frequency F
o), where Fo is expressed by the following equation.

Fo=FL -PIF ・"@ Substituting equation 1) into this equation (2), Fo-FL-CF
L-Fl)-Fl = (3).

Therefore, by controlling voltage-controlled mail by giving interlayer frequency data that sequentially increases or decreases, the tuning frequency changes continuously, and the input frequency can be arbitrarily selected for tuning (pass band width BY). Frequency measurement circuit 6
can be output to. And this frequency measurement circuit 6
When the frequency measurement data b is outputted from the station, by comparing this with the tuning frequency data a, it is possible to know whether the two match, and whether or not it has been tuned to the desired station can be determined.

Here, if the range of the tuning frequency data is TDL~TDH, the tuning frequency will be FI(L)~FI as shown in Figure 3.
(H), and the tuning frequency Fl(L) ~ Fr
The tuning characteristic of (I() is shown in the fourth [).

[Problem that the invention seeks to solve]

Conventional sweep-type tuning receivers are configured as described above, so if the voltage-controlled oscillator's voltage-output frequency characteristic has poor linearity or there is a frequency drift, the frequency error is directly reflected in the tuning frequency. If this error becomes larger than the passband width of the bandpass filter, it becomes impossible to tune to the input frequency corresponding to the tuning frequency data.

The present invention has been made in order to eliminate the drawbacks of the conventional devices as described above, and aims to provide a sweep type tuning receiving device that can always tune to an input frequency corresponding to tuning frequency data.

[Means for solving problems]

The sweep type tuning receiving device according to the present invention connects the reference signal oscillator and the output of the reference oscillator to a second mixer instead of the output of the bandpass filter, and corrects the tuning frequency data based on the frequency measurement data obtained thereby. oscillation frequency correction means.

[Effect]

In this invention, the oscillation frequency correction means compares and corrects the frequency measurement data of the mixing output of the reference signal oscillator output and the local oscillator output with the tuning frequency data, so that the oscillation frequency of the local oscillator matches the tuning frequency data. The value will be corrected accordingly.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a swept type tuning receiver according to an embodiment of the present invention, in which 1 is a voltage controlled oscillator, 2 is a frequency control mm path, 3 is a first mixer, 4 is a band pass filter,
5 is a second mixer, 6 is a frequency measurement circuit, 7 is a stable reference signal oscillator with an oscillation frequency Fos (=F (=, i.e., the center frequency of the bandpass filter 4)), 8 is a signal switch, and 9 is a tuning frequency This is a frequency error detection circuit that detects a frequency error between data a and frequency measurement data b. Reference numeral 10 is a frequency tuning local oscillator that oscillates a local oscillator signal according to the tuning frequency data a, and this It is composed of a controlled oscillator 1 and a frequency control circuit 2. Also, 20 is an oscillation frequency correction means, which is composed of a signal switch 82 and a frequency error detection circuit 9, and the output of the reference signal oscillator 7 is passed through a band-pass filter. 4 output instead of the second mixer 5, and the reference signal oscillator 7 output and the local oscillator 1
The tuning frequency data is corrected by comparing the measurement data b of the mixing frequency with 0 output and the tuning frequency data a.

Next, the operation will be explained. First, the frequency control circuit 2 applies a vi control voltage corresponding to the set frequency data to the voltage controlled oscillation I1), thereby setting the desired frequency (FL).
oscillates the voltage controlled oscillation s1.

Next, the frequency error detection circuit 9 switches the signal switching 1) 8 to the reference signal oscillator 7. By doing this, the output signal of the voltage controlled oscillation s1 (frequency FL
) and the output signal (frequency Fos) of the reference signal oscillation 1!7 are mixed and sent to the frequency measurement circuit 6 as F OI . Here, Fo”.

The relationship between Fos and PL is expressed by the following equation.

F o' = FL −Fos ・・
・(4 Also, since Fos = Fc (center frequency of bandpass filter 4), F o' = FL −F c −=
(5) becomes.

Next, the frequency measuring circuit 6 measures the frequency of this Fo'. This frequency measurement data b and frequency control 1 circuit 2
The frequency error detection circuit 9 compares the tuned frequency data a and the two frequency data a.

Detect the difference in b.

Next, the frequency error data C detected in this way is input to the frequency control circuit 2, where it is added to and subtracted from the tuned frequency data a, and thereby a control voltage with frequency error correction is given to the voltage controlled oscillation s1. . This frequency correction operation is based on country frequency data a and frequency measurement data b.
After completion of the correction operation such as 0 or more, which is performed until C becomes equal or error data C falls within an arbitrary range,
The frequency-error detection circuit 9 switches the signal switching s8 to the band-pass filter 4 side.

After signal switching 1) 8 is switched in this way, the input signal (F
I) is mixed with the voltage controlled oscillation s1 output (frequency FL) by the mixer 3, and becomes an intermediate frequency signal (frequency PIF). The PIF is sometimes corrected so as to be equal to the center frequency Fc of the bandpass filter 4, and therefore, the input frequency corresponding to the tuning frequency data can be tuned and selected at the center of the bandpass filter 4.

Then, the signal selected for tuning in this way is sent to the signal switch 8.
Through the mixer 5, the frequency measuring circuit 6 is
is output to.

〔Effect of the invention〕

As described above, according to the sweep/pull type reception device according to the present invention, the measurement data of the mixing frequency of the reference signal from the reference signal oscillator of the local oscillator and the local oscillation signal is compared with the tuning frequency data. Since the tuning frequency data is corrected, the voltage-output frequency characteristics and frequency drift of the local oscillator can be corrected, and there is an effect that the input frequency can always be tuned to the input frequency corresponding to the tuning frequency data.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a sweep type tuning receiving device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional sweeping type tuning receiving device, and FIG. 3 is tuning frequency data of the device shown in FIG. 2. A diagram showing the relationship between and the tuning frequency and number, Figure 4 is the second
FIG. 3 is a diagram showing the tuning characteristics of the device shown in the figure. DESCRIPTION OF SYMBOLS 10... Local oscillator for frequency tuning, 1... Voltage controlled oscillator, 2... Frequency control circuit, 3... First mixer, 4... Band pass filter, 7... Reference signal oscillator , 5... second mixer, 6... frequency measurement circuit,
20... Oscillation frequency correction means, 8... Signal switcher,
9...Frequency error detection circuit.

Claims (1)

[Claims] (1) A frequency tuning local oscillator that oscillates a local oscillator signal according to external tuning frequency data, a first mixer that mixes the input signal and the local oscillator signal, and a band that filters the mixer output. A sweep type tuning receiving device comprising a pass filter, a second mixer that mixes the filter output and the local oscillator signal and outputs a tuning signal, and a frequency measurement circuit that measures frequency data of the mixer output, A reference signal oscillator that oscillates a reference frequency signal, and the oscillator output is connected to the second mixer instead of the filter output, and the mixing frequency of the reference signal oscillator output and the local oscillator output is to be synchronized with the measurement data of the mixing frequency. 1. A sweep type tuning receiving device comprising: oscillation frequency correction means for correcting the tuning frequency data by comparison with frequency data.