JPH01165227A - Frequency tracking oscillator - Google Patents

Abstract

PURPOSE:To always follow up a high frequency input signal with high accuracy by outputting a discrimination signal setting the high frequency input signal as a reference signal, and feeding it back to a wide band area oscillator as a correction signal. CONSTITUTION:The title oscillator is the one in which a frequency discrimination circuit 14 having a discrimination characteristic setting always the high frequency input signal extending over a wide band area as the center of the discrimination characteristic is provided, and the output of a wide band area tuning oscillator 8 is fed back to the discrimination circuit 14, then, a discrimination signal proportional to a frequency difference with the input signal can be obtained, and it is fed back to the oscillator 8 as a frequency correction signal. In other words, since action so as to always set the center of the discrimination characteristic at the frequency of the high frequency input signal is performed and also, a discrimination range is set in proportion to the inverse of the delay time of a delay line 20, it is possible to always obtain a stable discrimination characteristic extending over the wide band area, and to correct and control the frequency of the oscillator 6 with constant sensitivity. In such a way, a frequency tracking oscillator always fitting in the frequency of the high frequency input signal with high accuracy and possible to follow up can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a frequency tracking oscillator that follows the carrier frequency of a high-frequency input signal while precisely matching it.

[Conventional technology]

Conventionally, this type of circuit has been shown in FIG.

In the figure, (1) is a high-frequency signal input terminal such as a continuous wave or pulse modulated wave, (2) is a two-power distribution circuit, α1J is a two-power distribution circuit (2), a wideband tunable bandpass filter (3a), and ( 3N, saturation line detection 1l (4a) and (
4b).

A wideband tunable frequency discriminator circuit (6) consisting of a video adder circuit (5) is controlled by a high frequency signal input timing detection circuit (to), and the discrimination output signal level (2) of the frequency discriminator circuit (b) is controlled by a high frequency signal input timing detection circuit (to). A frequency correction control circuit for amplification or storage, (7) is an addition of the output signal of the frequency correction circuit (6) and a coarse tuning control signal that is tuned to the center frequency of the frequency discrimination range by the frequency tuning control circuit (9). The circuit (8) is a broadband home oscillator and an acbVi high frequency signal output terminal.

Next, the operation will be explained.

High frequency signal input terminal (1) The high frequency signal to which K is applied is.

Frequency discrimination is performed by a broadband tuned frequency discrimination circuit surface having high frequency discrimination characteristics shown in FIG.

Frequency discrimination circuit α1) it% Y engineering G (Yittliu
A set of band-pass filters (3a) that utilizes a 3-channel (Gar-net) element.

(3b) etc., 1g! A is tuned to center frequency f1, and the other is tuned to center frequency f1. and the difference (f,
-fb) is kept almost constant over a wide band, and the outputs of each filter are connected to saturation line detectors (4a) and (4b) with different polarities (positive and negative polarities), and their outputs are By performing video addition of the signals, it is possible to obtain a discrimination output whose amplitude changes between positive and negative in proportion to the carrier frequency of the high-frequency signal input.

Therefore, this discrimination output signal is used to generate a wideband tuned oscillator (8
) corrects the coarse tuning control signal Jl! [Problem to be solved by the invention] Conventional tracking oscillators are configured in one or more ways.
In order to accurately match and follow the input signal frequency, Vi
, first the center frequency f of the frequency discrimination circuit over a wide band
0 and the oscillation frequency based only on the coarse tuning control signal must be matched. In addition, the frequency discrimination characteristics are obtained by detuning the characteristics of two tunable bandpass filters and using their amplitude characteristics, so that the frequency discrimination sensitivity and discrimination range over a wide band are all bandpass filter characteristics. The discrimination characteristics are not constant and fluctuate. For this reason, the discrimination sensitivity at the center frequency fc and fcVc of the discrimination characteristic fluctuates,
It has drawbacks such as the inability to perform accurate frequency correction control for high-frequency input signals.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and by obtaining a stable frequency discrimination range and discrimination sensitivity over a wide band without adjustment, it can always match the high frequency input signal frequency with high accuracy. , the purpose is to obtain a frequency tracking angular oscillator that can track the frequency.

[Means for solving problems]

The frequency tracking oscillator circuit according to the present invention employs a frequency discrimination circuit having a discrimination characteristic in which a high frequency input signal is always the center of the discrimination characteristic over a wide band, and feeds back the output of a broadband tuned angular oscillator to this discrimination circuit, A discrimination signal proportional to the frequency difference with the input signal is obtained and fed back to the oscillator as a frequency correction signal.

[Effect]

In this invention, the frequency discrimination circuit operates so that the center of the discrimination characteristic is always at the high-frequency input signal frequency, and the discrimination range is proportional to the reciprocal of the delay time of the delay line, so that stable discrimination is always achieved over a wide band. This function is used to correct and control the oscillator frequency with a certain sensitivity.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. In Fig. 1, [1] is a high frequency signal input terminal;
(2) is a tracking amount bandpass filter that accurately follows the oscillation frequency from the broadband tuned total oscillator after being roughly tuned by the coarse tuning signal from the frequency tuning control circuit (9);
Vi power 2-divider circuit, α41I-1t wideband frequency discrimination circuit and 2-power distribution circuit (2), wideband mixer with O/90 hybrid circuit αη as input (x5a)
.

(15b), the output signals (I, Q,
), one of them is connected to a delay line wire with a delay time of 2 and combined with a mixer at (to), and a frequency discrimination signal (V is output through the wire's low-pass filter. (6) is the timing of high-frequency signal input. Controlled by detection circuit α3 rL
, the discrimination output signal level (v
), a frequency correction control circuit that amplifies or stores - (7);
) is an addition circuit for adding the output signal of the frequency correction control circuit (6) and a coarse tuning control signal that is tuned to the center frequency of the frequency discrimination range by the frequency tuning control circuit (9); The total frequency generator is a three-power distribution circuit, with one wire being fed back to the frequency discriminator circuit α4, one wire being fed back to the tracking type band pass filter (incorporated), and the remaining one being sent to the high frequency signal output terminal αO. It is output to.

Next, the operation will be explained.

Obtaining the coarse tuning control signal output from the frequency tuning control circuit (9), the adder circuit (7) adds the frequency to the high frequency signal input (
The broadband oscillator (8) is controlled to be tuned to f8), and the oscillation frequency is set to (fo) to (f, ). Also, at the same time, a tracking bandpass filter? C. The center frequency of the bandpass filter is set by the coarse tuning control signal output of the frequency tuning control circuit (9) and the output of the wideband oscillator (8) distributed by the three-power distribution circuit (a). It is tuned to the output frequency - Is it a tracking type bandpass filter? The sword has an AFO circuit inside, which is controlled by both of the above signals and is coarsely tuned to always operate to control the center frequency of the filter to the high frequency signal input frequency (in this case, the frequency of the wideband oscillator (FO)). Since there is no error, there is an advantage that the bandwidth of the bandpass filter can be reduced to the required bandwidth.

The high frequency signal applied to the high frequency signal input terminal (1) is
If the frequency Cf exists within the band of the tracking type bandpass filter (c), it passes through the filter (c) and is frequency discriminated by the wideband frequency discrimination circuit α4.

The high frequency signal (Si
nω, t) is distributed by the power 2 distribution circuit (2), inputted to the wideband mixer (x5a), (x5b), and 0/9o
It is mixed with the output of the hybrid circuit αη. Here, input to Mi*t-(15a), (15N./9o The output of the hybrid circuit aη is obtained by changing the phase of the output (sinω.t) of the broadband oscillator (8) by 0.90.

Therefore, the output signal of the mixer is low-pass filtered (1
6a), (161)), the difference component signal (1
) and (ri are given by the following equations.

Engineering = Sinω, t X Sinω. 1 = Kz*Co
s (ω8-ω.'It (however, K is a constant)
---fl) Q= Sin ω, t X Oos GJ
ot” Q・Sin (ω8−ω.)t C However,
KQk'i constanta) -1-[2)rl), [2)
are difference signals with a phase difference of 90°, and the following 1c
[After passing the signal side through the delay line (1) having a delay time (Z), it is mixed with the above-mentioned engineered signal again in the second mixer (to), and then passed through the frequency discrimination circuit α4 through the low-pass filter α
Discrimination signal output (v)V linear equation: Given OV =
KzmCOe(ω, -ωo)tXQ'5in(ω, -ω
. )(t-Z)=K-8in(ω6-ω.)・z
(However, KVi constant)---(33 That is, the output of the wideband frequency discrimination circuit α→ is the frequency difference (ω.-ω.) between the high-frequency signal input and the output signal of the wideband total vibrator (8).
A frequency discrimination signal (V) proportional to VC can be obtained as a DC component. As shown in Fig. 2, the discrimination range of this discrimination signal can be a constant value proportional to the reciprocal of the delay time (inclination) of the delay line.Next, in the frequency correction control circuit (6), the timing Using the timing of the high frequency signal input output from the detection circuit (to), the above discrimination signal is output during the time when there is no high frequency signal input (for example, the time between pulses in the case of pulse input). It is held constant and used as a frequency correction signal (DC output).

The frequency correction signal is generated by the frequency control signal addition circuit (7)
, the frequency tuning control circuit (9) that outputs first
is added to the coarse tuning signal from O to the high-frequency input signal to control the correction so that the oscillation frequency (fo) of the wideband oscillator (8) matches the input signal frequency (f, ) (i.e. %f0 = f, ). The matched output of the wideband oscillator (8) is distributed by the three-power distribution circuit ■, and then sent to the frequency discrimination circuit a4 and the tracking type bandpass filter system υ.
The signal is fed back to the oscillator and output from the high frequency signal output terminal αO as the output of the tracking foil oscillator.

Therefore, a high frequency output that accurately follows the carrier frequency of the input high frequency signal can always be obtained at the high frequency signal output terminal.

In the above embodiment, the delay line (A) is inserted on the Q signal side, but it is also possible to obtain a discrimination output signal in the same way even if it is inserted on the output signal side.

Further, in the above embodiment, a certain arbitrary high frequency signal human power (f
, ), the frequency of the broadband all-wave generator (8) is corrected within the range of its frequency discrimination characteristics to obtain a tracking all-wave generator that matches the frequency. This will be explained below.

FIG. 3 is the same as in FIG. 1 except that a frequency correction range detection circuit is added, and other basic operations are the same as in FIG. 1.

The output amplitude range of the frequency correction range detection circuit +23Vi and the correction signal of the frequency correction control circuit (6) (i.e., the discrimination signal (DC component) shown in Fig. 4) is centered around the output amplitude at 10 o'clock (i.e., Ov). , the positive side output is the slice level (VTH), and the negative side output is the slice level (vT
L), and the output range of the discrimination signal is always (vTL
) to (vTH), a part of the frequency correction signal is added to or subtracted from the coarse tuning signal initially set by the frequency tuning control circuit (9). Therefore, the frequency correction signal in the state where the frequency correction control is completed is (vTL) ~ (
It will operate within the range of V, H).

As a result, even if the high-frequency input signal fluctuates continuously beyond the frequency discrimination range, the initially set coarse tuning signal is corrected, and a tracking aftershock that always accurately tracks over a wide band is obtained. be able to.

In addition, in the above embodiments, the case of a frequency tracking oscillator was described, but by changing part of the m configuration,
It can also be used as a frequency measurement circuit. In Figure 5, a frequency measurement circuit and its frequency measurement information 8 output terminal (C) are added to Figure 1, and conversely an addition circuit (7) is added.
) is removed, and other basic operations are the same as in FIG. 1.

The frequency discrimination range (instantaneous frequency Measurement range)
The carrier wave frequency of the high frequency input signal is discriminated, and the frequency measuring circuit (c) calculates the measured frequency based on the discrimination characteristic and outputs it to the output terminal. frequency n
Since v is, the measurement result is a relative frequency measurement result with the oscillation frequency as a reference. However, if a synthesized oscillator with high frequency stability is used instead of the wideband oscillator (8)0, high frequency input can be achieved. Absolute frequency measurements of signals can be made with high precision.

〔Effect of the invention〕

As described above, according to the present invention, the one-frequency discrimination circuit is configured to output a discrimination signal using a high-frequency input signal as a reference signal, and the output is fed back to the wideband oscillator as a correction signal, so that the constant VC This has the effect of being able to follow high-frequency input signals with high precision.

In addition, the frequency discrimination characteristic can be made without adjustment, and the discrimination range can be arbitrarily set constant over a wide band in proportion to the reciprocal of the delay time of the delay line, so the discrimination sensitivity is also constant. There is.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a wideband frequency tracking oscillator according to an embodiment of the present invention. FIG. 2 is a diagram showing the discrimination characteristics of the frequency discrimination circuit of the present invention. FIG. 3 is a block diagram of a wideband frequency tracking oscillator according to another embodiment of the present invention. Fig. 4 is a diagram showing the discrimination range of frequency discrimination characteristics of another embodiment, Fig. 5 is a configuration diagram when this invention is applied to a frequency measurement circuit, and Fig. 6 is a conventional wideband frequency tracking oscillator. FIG. 7 is a diagram showing the discrimination characteristics of a conventional frequency discrimination circuit. (1) is a high frequency signal input terminal, CI) is a tracking band pass filter, (2) is a power 2 distribution circuit, (15
a). (15b) is a broadband mixer, (16a), (16
b) ij O-pass filter, α71t'jO/90
Hybrid circuit % (a) is a delay line with delay time (Z), (to) (″l′ second mixer?-, Q is a low-pass filter, (6) is a frequency tuning control circuit, (7)
V'i adder circuit, (8) Vi wideband home oscillator, (Company) is power 3 distribution circuit, a3 is timing detection circuit, (9) is frequency tuning control circuit, αO high frequency signal output terminal, 04
is a wideband frequency discrimination circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A frequency tracking oscillator that tracks the carrier frequency of a high-frequency signal input has a tracking type band-pass filter at the high-frequency signal input end that tracks the frequency centered on the output frequency of the oscillator, and the tracking type band-pass filter The output of the oscillator is fed back to a frequency discrimination circuit having a frequency discrimination output based on the carrier frequency of the high frequency input signal passed through the oscillator, and the output frequency of the oscillator is controlled by the discrimination output of the frequency discrimination circuit. Features a frequency tracking oscillator. (2) A first mixer (I/Q detection circuit) that detects the frequency difference between the two signals distributed and input to the frequency discrimination circuit with a 90° phase difference, and a delay line on one of the I/Q signals. 2. The frequency tracking oscillator according to claim 1, wherein the frequency tracking oscillator is configured to combine the other signal with the second mixer.