JPS6343421A - Radio equipment - Google Patents

Abstract

PURPOSE:To stabilize an automatic frequency control characteristic by using a received local oscillation signal so as to convert a transmission frequency component leaked to a receiving section via an antenna multicoupler circuit into an intermediated frequency signal and giving the signal to an automatic freqnency control signal to apply frequency identification. CONSTITUTION:A part of the transmission signal Pf of a carrier frequency (f) inputted to a multicoupler circuit 4 is leaked in the direction of a reception band pass filter 44 via a circulator 41. The leaked transmission frequency (f) is mixed with a received local oscillation frequency FLOC at the frequency converter 32 of the reception section 3, converted into a 2nd intermediate frequency fIF2, led to an automatic frequency control circuit 2 and inputted to a frequency identifier 21. The identifier 21 compares the input frequency with a reference frequency F0 to output an error voltage EC corresponding to the frequency deviation. The error voltage EC is fed back to the input side of an FM modulation oscillator to apply an automatic frequency control operation.

Description

Detailed Description of the Invention [1 Already Required] An FM modulation oscillator that oscillates a carrier wave and at the same time modulates the frequency with a modulation signal, identifies the carrier wave frequency f of its output using a reference frequency fo, and uses the error voltage to determine the frequency of the FM modulation oscillator.
Controlling the oscillation frequency f of the M modulation oscillator? A transmitting section with an AFC circuit that sets the specified transmission frequency FT at ffl L, and a reception frequency fR that has a certain relationship with the specified transmission frequency FT.
A wireless device comprising a heterodyne type receiving section that converts the signal into a fixed intermediate frequency and receives the signal, and a shared circuit in which the output signal of the transmitting section and the input signal of the receiving section share one antenna system via a circulator. A carrier wave with a frequency f, in which the output of the transmitter leaks to the input of the receiver inside the circulator of the shared circuit, is input to the receiver, and the frequency is converted to an intermediate frequency flF,2 by the local oscillation frequency FLOC of the receiver, and the intermediate frequency f By identifying the IF2 signal with an intermediate frequency frequency discriminator, the stability of the center frequency of the discrimination circuit, which is the reference frequency for AFC operation, is improved, and as a result, the frequency deviation of the frequency f of the carrier wave of the transmission output is reduced to an allowable deviation. Something that you want to hold stably inside.

[Industrial application field]

The present invention relates to a radio device consisting of a transmitting section T, a receiving section R, and a shared circuit section T/R in which one antenna system A is shared by transmitting signals and receiving signals. The carrier frequency f of the transmission output is set to the specified transmission frequency I'
Automatic frequency word that controls T? 'l11 circuit (AFC')
It is desired to improve the stability of the reference frequency fo, which is the standard for frequency identification of .

[Conventional technology]

FIG. 5 shows a conventional circuit configuration of a wireless device related to the present invention.

As shown in the figure, the transmitter T of the wireless device directly oscillates a carrier wave in the G11z band with a high frequency r, and at the same time transmits a carrier wave of several MHz.
F which is frequency modulated by the following low frequency modulation signal
? The I modulation oscillator 1 is the main body, and an automatic frequency control circuit (AFC) 2 is attached to this to control the carrier frequency f of the FM modulation signal output from the FM modulation oscillator so that it becomes the specified transmission frequency FT of the transmitter T. It is of composition. The receiver R uses a fixed intermediate frequency flF to receive the receiving frequency fR that has a fixed frequency relationship with the transmitting frequency FT.
It has a so-called heterodyne type circuit configuration that converts it into one signal and receives it. In addition, since the transmission signal of the transmitter T and the reception signal of the receiver R share the same antenna system, this vA=i is a shared circuit that determines the amount of transmission loss depending on the transmission direction for the transmission signal and the reception signal. a transmission signal having a transmission frequency f, which has T/R and is directed from the transmitter T to the antenna system;
and the receiving frequency [1? from the antenna system toward the receiver R? The structure is such that transmission loss for reception number 18 is small.

Since the main body of the transmitter T of the wireless device according to the present invention is an FM modulation oscillator that self-oscillates a carrier wave of a high frequency f in the GH2 band and is frequency-modulated at the same time, the carrier wave frequency f
In order to keep F within the allowable deviation with respect to the specified frequency FT,
It is desired that the reference frequency fo of the AFC circuit that controls the oscillation frequency f of the M modulation oscillator to the specified transmission frequency FT is stable against changes in the surrounding environment such as the ambient temperature.

The main body of the transmitter T of the wireless device includes the original modulation oscillator 1 described above.
and a directional coupler 1a that branches a part of the output of the Fl'l modulation oscillator to an automatic frequency control circuit AFC2.

The automatic frequency control circuit AFC2 inputs the branch output Pf from the directional coupler 1a, and uses a frequency discriminator 23 to discriminate the frequency of the carrier wave of the frequency f by a discrimination circuit of a reference frequency fo, and an error voltage Ec of the output thereof. amplify and FM
It consists of a DC amplifier 23a that returns to the modulation input terminal of the modulation oscillator 1.

To further describe the automatic frequency control circuit AFC2, in the frequency discriminator 23, the reference frequency fo for identifying the carrier frequency r of the human power Pf is set to the specified transmission frequency FT of the transmitter.

As mentioned above, the specified transmission frequency FT is a high frequency in the Gtlz band, so the reference frequency fo of the frequency discriminator 23 is also a high frequency in the same GHz band. The circuit length is mechanically shortened in proportion to the wavelength.

The receiving section R3 includes a frequency converter 32 that converts the signal at the receiving frequency fR into a signal δ of a constant intermediate frequency NFI (generally 70 MHz), and oscillates a local carrier wave at the frequency fLOG to be supplied to the frequency converter 32. a local oscillator 31 that converts the signal, and an intermediate frequency filter I that selects the converted signal of the indicated intermediate frequency r IFI at the output stage of the frequency converter 32.
Consists of 33 FIs.

The shared circuit T/R4 includes a transmission bandpass filter TBF 42 that passes a transmission signal of a specified transmission frequency FT, and a reception frequency fl? A reception bandpass RBF 43 that does not pass the reception signal of
Circulator 4 that gives directionality to the transmitted and received signals
Consists of 1.

The circulator 41 transmits the transmission signal of the transmission frequency f in the direction to the antenna system with a low loss of 11, and transmits the reception signal of the reception frequency fR from the antenna system to the receiving section R with a loss of 1. , transmission in the opposite direction, and transmission of the transmission signal of the transmission frequency f to the input direction of the reception band filter RBF 43 have large transmission losses.

Next, to briefly describe the overall operation, the FM modulation oscillator 1 of the transmitter T directly oscillates a high carrier frequency f in the G11z band, and at the same time performs frequency modulation (FM) with a low frequency modulation signal input from the outside. However, the stability of the carrier frequency f of the output FM modulation signal Pf is relatively low because FV variation All is applied due to self-oscillation.

A part of the output P of the FM modulation oscillator 1 is connected to the directional coupler 1a.
The signal is input to the frequency discriminator 23 of the automatic frequency control circuit meter C2 and the discriminator circuit (RF, /old SCI?
) is identified by frequency.

The operation of this identification circuit (RF/DTSCR) is such that when the frequency f of the input signal deviates from the central reference frequency fo, as shown in the frequency deviation vs. error voltage characteristic diagram in Figure 3, the magnitude of the frequency deviation changes. It is proportional and outputs an error voltage Ec according to its polarity.

The error voltage Ec outputted from the frequency discriminator 23 is amplified by the DC amplifier 23a and added to the modulation frequency of the FM modulation oscillator 1.

The error voltage Ec applied to the modulation input terminal operates a frequency variable element such as a varactor inside the F1 modulation oscillator 1, and performs loop control so that the frequency r of the oscillation carrier wave becomes the specified transmission frequency FT.

Specified transmission frequency F by automatic frequency control circuit AFC2
The transmission of the frequency f controlled to be T (, ilj output Pf is input to the shared circuit T/R4, passes through the transmission bandpass filter TBF 42, and is transmitted to the circulator 41
is input.

The circulator 41 transmits the input transmission output Pf in the direction of the arrow with low loss, and most of it is routed to the antenna system.

Since the transmission output Pf of this frequency f is generally a large power (several watts), a part of it leaks out to the input direction of the reception bandpass filter RBF 43 inside the circulator 41, but its level is low and the bandpass It is cut by the filter 43 and does not reach the receiving section R.

Further, the circulator 41 transmits the reception signal of the reception frequency fR from the antenna system A to the reception bandpass filter RBF 4
Transmit with low loss in the direction of 3, receive band filter RBF
43 passes the received signal of this frequency [R with low loss and inputs it to the receiving section R3.

The receiving unit R3 mixes the frequency [R of the input received signal with the specified frequency FLOC of the local carrier wave of the local oscillator 31 in the frequency converter 32 to obtain the frequency fR and the frequency FL.
A signal of a first intermediate frequency fTF 1 having a constant frequency different from OC is generated.

The (i) of the first intermediate frequency fIF1 generated by the frequency converter 32 is outputted to the outside via the intermediate frequency filter IFI 33 at its output stage.

The specified frequency fiFLOc of the local carrier wave of the local oscillator 31 is connected to the specified transmission frequency F of the transmitter T via the reception frequency fR.
There is a certain frequency relationship with T, but in conventional wireless equipment,
The frequency F L OG of this local carrier is independent of the frequency term '4111 of the transmission frequency of the third part T.

[Problem that the invention seeks to solve]

In the conventional wireless device, as described above, the accuracy (absolute deviation from the specified transmission frequency FT) of the transmission output frequency r of the transmitting unit r is determined by the frequency discriminator 23 of the automatic frequency control circuit meter 02.
It depends on the stability of the reference frequency fo of the identification circuit (RF/DISCR).

As already mentioned, the reference frequency fo of the identification circuit (RF/DISCR) of the frequency discriminator 23 is set to the high frequency FT value of the GHz band, so the entire three-person circuit is proportional to the wavelength. Although it can be made smaller, the mechanical dimensions of the circuit length that determines the frequency discrimination characteristics are short, and the stability is poor as it easily changes due to changes in the operating environment such as the ambient temperature and vibration of the device. There is a problem in that it is difficult to maintain the accuracy of the carrier frequency r of the output FM modulation signal Pf within a tolerance.

[Means for solving problems]

This problem can be solved by configuring the reference frequency fo of the frequency discriminator of the automatic frequency control circuit AFC2 to a relatively low intermediate frequency of several hundred Ml+2 band, instead of setting it to a low frequency of GHz band. To solve the problem by maintaining stability against the surrounding environment while still allowing room for downsizing.

Therefore, the shared circuit T/R, which was not used in the past,
4 and the characteristics of the receiving section R3 are utilized. That is, as already explained, the characteristics of the shared circuit T/R4 are as follows:
Although a part of the α transmission frequency multiplied signal Pf is at a low level, the reception bandpass filter RBF is applied as shown by the dotted line.
As shown in the principle block diagram of FIG. 1, a reception bandpass filter RBF 44 which can also pass the leaked transmission carrier wave of frequency f is constructed by utilizing the leakage in the direction of human power of the bandpass filter I. ? The leaky transmission carrier wave of frequency f is guided through the BF 44 to the receiving section R3.

Further, as the characteristics of the receiving section R-3, the specified frequency F1 of the local carrier wave of the local oscillator 31. When the specified transmission frequency FT of the transmitting section is determined, OC is uniquely determined via the receiving frequency fR, and the local carrier wave of the specified frequency FLOC is determined at that frequency for any frequency input signal of the receiving section R. It utilizes converting the signals into signals with frequencies of a certain width separated by a certain frequency.

That is, the reception bandpass filter l? of the shared circuit T/R?
The frequency f of the leaked transmission carrier output from the BF 44 is converted to the local oscillator 31 in the frequency converter 32 of the receiving section R.
Convert the frequency using the frequency FLOC to obtain the frequency ¥lr
and the frequency FLOC to extract a signal of the second intermediate frequency f[F2.

The signal of the second intermediate frequency fIF2 thus obtained is input to the frequency discriminator 21 of the automatic frequency control circuit AFC2 to identify the frequency.

As a matter of course, the reference frequency fo that serves as the reference for the frequency identification circuit of the frequency discriminator 210 is selected as the specified difference frequency FIF 2 which is the difference between the specified transmission frequency FT of the transmitting section and the specified frequency r'LOc of the local carrier wave of the receiving section. be done.

C Effect] The overall operation of the wireless device of the present invention configured based on the above concept will be explained using the principle block diagram shown in FIG.

F - FM of carrier frequency f obtained by modulated oscillator 1
The modulated signal Pf is output as the S output of the transmitter T and is input to the shared circuit T/R4.

Most of the transmission signal Pf of carrier frequency f input to the shared circuit T/R4 is transmitted in the direction of the antenna system Δ in the circulator 41, but a portion of the transmission signal Pf is transmitted through the receiving bandpass filter RBF as shown by the dotted line. It leaks in the direction of 44.

The transmission characteristics of the reception bandpass filter RBF 44 are as follows:
As shown in the frequency characteristic diagram in the figure, it has a frequency characteristic that allows not only the reception signal of the reception frequency rR to pass, but also the leakage transmission carrier wave of the frequency ``. R
The signal passes through the BF 44 and is input to the receiving section R3.

The leaked transmission carrier wave Pf inputted to the reception unit R3 is mixed with the local carrier wave of the frequency FLOC oscillated by the local oscillator 31 in the frequency converter 32 of the reception unit R3, and the frequency r of the transmission carrier wave and the local carrier wave are mixed at the output stage. frequency FL
A signal at a second intermediate frequency f II'2 of the difference in OC is generated.

This second intermediate frequency PIF2 signal is the received signal r
The first intermediate frequency fIF obtained by similarly converting r+
1 signal from the frequency converter 32 of the receiving section R.

The signal of the second intermediate frequency frF2 outputted from the receiving section R is separated from the signal of the first intermediate frequency fIFI by JZ, and guided to the automatic frequency control circuit AFC2 to be passed through the frequency discriminator 21.
is input.

The second intermediate frequency f I input to the frequency discriminator 21
The frequency of the F2 signal is identified by the reference frequency fo, which is the center frequency of the identification circuit (IP/DISCR), and as shown in the characteristic diagram of the frequency discriminator in Fig. 3, an error voltage Ec corresponding to the frequency deviation is generated. Output.

Identification port 178 (IP/DISCR) of frequency discriminator 21
The reference frequency To is the specified transmission frequency L number F of the transmitter T.
Since the specified difference frequency PIF 2 of the difference between T and the specified frequency FLOC of the local carrier wave of the receiving section R is selected, the frequency discriminator 21 uses the frequency f IF2 of the input signal as a standard difference frequency FLOC. By identifying, the deviation Δf of the transmission frequency f can be identified.

The output error voltage Ec is applied to the FM modulation oscillator 1 of the transmitter T in the same manner as the automatic frequency control circuit AFC2 of the conventional example.
The oscillation frequency r is automatically controlled to be the specified frequency FT.

The above is an outline of the operation of the wireless device of the present invention whose principle block diagram is shown in FIG. 1. The identification circuit (IP/D
Intermediate frequency PIF which becomes the reference frequency fo of ISCIl)
2 is as explained below (if the transmitting frequency FT and receiving frequency fll are in the 20 GIIz to 30 GIIz band, the intermediate frequency value will be several hundred MII2 bands, so the mechanical dimensions of the circuit elements that determine this reference frequency fO) It is affordable and easy to make, has better stability against environmental changes such as changes in ambient temperature and vibration, and solves the problems of conventional wireless devices. Since the resistance is high, the identification circuit can be made smaller.

The specified difference frequency FTF 2, which is the reference frequency fo of the frequency discriminator 21 mentioned above, is the transmission frequency FT and the reception frequency fR.
To specifically explain that the intermediate frequency is lower than that of
In the case of the Gllz microwave frequency band, the transmission frequency F
The frequency interval f Sep between T and the receiving frequency fR is several hundred 1
The frequency is set to a constant frequency of 11z.

Also, the reception frequency rR and the local carrier frequency F[.

The first intermediate frequency f IFI of the OCO difference is generally 70
Since the frequency of MH2 is selected, the specified difference frequency FIF2 of the difference between the transmission frequency FT and the local carrier frequency FLOC is fS(!P +70MHz, which is also several hundred Mll
This is the intermediate frequency of the z band.

〔Example〕

FIG. 2 is a block diagram showing the configuration of a wireless device according to an embodiment of the present invention. Most of the circuit is the same as the circuit shown in the principle block diagram of Fig. 1, but the one difference is that for practical considerations, a second intermediate frequency is provided before the frequency discriminator 21 of the automatic frequency control circuit AFC2. [Intermediate frequency filter that separates the signal of IF2 and the signal of the first intermediate frequency f rFl (
IF2) 22 is provided, and the signal of the first intermediate frequency f IFI and the second
This is because a common amplifier 34 is provided which amplifies both the intermediate frequency fIF2 signals. In addition, significant differences regarding the transmission frequency stability of the wireless device of the present invention include:
The local oscillator 3I of the receiving section R is composed of a crystal oscillator 31a with good frequency stability and a high-order frequency multiplier 31b using a Stenbury force Halli diode, etc., and the frequency fLOc of the local oscillation carrier wave with good frequency stability is adjusted. This is easily obtained by multiplying the frequency all at once.

The crystal oscillator 31a has a frequency stability of about 5×10 at an ambient temperature of -10C to +40C, and also functions as the base of the identification circuit (IF DISCR) of the frequency discriminator 21.
! ? When the frequency f IF2 is several hundred MHz, its stability is 1 x 10'' in the above ambient temperature range, so the fluctuation of the local carrier frequency fLOG and the fluctuation of the reference frequency FIF 2 of the frequency discriminator 21 Even if the difference is added under the worst conditions, the general transmission frequency r of the transmitting section is maintained within a deviation of 5×10-' from the specified transmission frequency FT, and there is no problem.

In addition, since the frequency discriminator 21 is made in an open frequency band of several hundred meters (2), it is easier to integrate the circuit (IC) than in the GI+2 band, making it easier to downsize the device and adapt to high reliability. .

〔Effect of the invention〕

As explained above, according to the present invention, the transmission frequency of the output signal of the three parts can be easily manufactured and resistant to changes in the surrounding environment. Automatic frequency control circuit (A) for stable intermediate frequency band
FC) has a stabilizing effect, and also has the effect of downsizing the device and reducing cost I/O.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram showing the configuration of a wireless device according to the present invention, FIG. 2 is a block diagram showing the configuration of a wireless device according to an embodiment of the present invention, and FIG. 3 is a diagram showing the frequency discriminator of the wireless device according to the present invention. FIG. 4 is a characteristic diagram illustrating the operation of the non-VAA device of the present invention, and FIG. 4 is a frequency characteristic diagram of the receiving bandpass filter of the shared circuit, illustrating the operation of the non-VA device of the present invention. FIG. 5 is a block diagram illustrating the configuration of a conventional wireless device. be. 1st. 2 and 5, 1 is an anti-modulation oscillator, 1a is a directional coupler, 2 is an automatic frequency control circuit (AFC), 21 is a frequency discriminator (1F/old SCI?), and 22 is an intermediate frequency filter ( IF2), 23 is a frequency discriminator (R
23a is a DC amplifier, 3 is a receiver, 31 is a local oscillator, 32 is a frequency converter, 33 is an intermediate frequency filter (IFI), 34 is a common amplifier, 4 is a shared circuit (T/R), 41 is a circulator, 42 is a transmission bandpass filter, and 43 and 44 are reception bandpass filters. ＋＼に=nee′

Claims (1)

[Claims] An FM modulation oscillator (1) that oscillates a carrier wave of frequency f and is frequency-modulated by a modulation signal at the same time, and a carrier wave frequency f of the output Pf of the FM modulation oscillator (1) is set to a reference frequency f.
an automatic frequency control circuit (2) that identifies the frequency by o, feeds back the error voltage Ec to the FM modulation oscillator (1), and automatically controls the carrier frequency f to a specified transmission frequency FT;
a local oscillator (31) that generates a local carrier wave of a frequency FLOC that converts a received signal of a receiving frequency fR that has a certain relationship with the specified transmission frequency FT into a signal of a certain intermediate frequency. By providing low-loss transmission characteristics to the transmitting signal of the carrier frequency f from the transmitting section (T) and the receiving signal of the frequency fR directed to the receiving section (R), System (A)
In a wireless device consisting of a shared circuit (T/R) that shares a signal, the shared circuit (T/R) has a leakage signal that outputs a transmission signal of a carrier frequency f from the transmitter (T) to the receiver (R). Means (44) is provided, and the leakage transmission carrier wave of frequency f obtained by the leakage means (44) is frequency-converted by the local carrier frequency FLOC of the local oscillator (31) of the receiving section (R) to obtain the frequency f.
and the second intermediate frequency (f IF2
) is output, and the signal of the second intermediate frequency (f IF2) is frequency-identified using the difference frequency (FIF2) between the specified transmission frequency FT and the local carrier frequency FLOC as a reference frequency fo for frequency identification. A wireless device characterized by: