JP7171937B2 - radio transmission equipment - Google Patents

Description

The present invention relates to a two-piece wireless transmission device in which a control section and a high frequency section are separated.

In a two-piece type FPU (Field Pickup Unit: portable wireless transmission device) in which the control unit and the high frequency unit are separated, the control unit and the high frequency unit are connected by an intermediate frequency cable such as a coaxial cable. be done. Therefore, in the case of the MIMO (Multiple Input Multiple Output) system, signals are divided into even waves for transmission and reception, so it is necessary to connect an even number of coaxial cables between the control unit and the high frequency unit.

However, since the coaxial cable connected between the control unit and the high frequency unit may be wired over a long distance such as 400 m at maximum, it is not preferable to connect multiple cables. Therefore, a technology has been proposed to implement the MIMO system with a single coaxial cable (see Patent Document 1, for example).

The technique of Patent Document 1 has a low UHF frequency band (for example, 1.2 GHz band or 2.3 GHz band), a small number of modulation levels (for example, 64 QAM), and a number of modulation carriers of 2000 or less, Adoptable. That is, in the FPU standard ARIB-STD B57, which adopts the MIMO method in the 1.2 GHz band and 2.3 GHz band, the frequency deviation between systems is set to 50 Hz or less for stable transmission. It is described as a power value, and the technique of Patent Document 1 can satisfy this condition.

JP 2016-58999 A

However, in the conventional technology, frequency synchronization between the control unit and the high frequency unit cannot be achieved, and the difference in frequency deviation between the systems in the high frequency unit becomes large. There is a problem that the frequency deviation of is large, and it cannot be applied to the FPU in the microwave band. In ARIB-STD B71, the maximum number of modulation levels is 4096QAM and the number of modulation carriers is about 8000, and it is necessary for stable transmission to keep the frequency deviation between transmission output systems below 10Hz. The described prior art fails to meet this condition.

FIG. 2 shows a configuration example of the FPU 10 in which the conventional technology is applied to the microwave band.
The FPU 10, referring to FIG. A single intermediate frequency cable 40, such as a cable, is connected.

The control section 20 includes a digital modulation unit 211, a digital modulation unit 212, a local oscillator 220, a mixer 231, a mixer 232, a bandpass filter 241, a bandpass filter 242, and a synthesizer 250. .

A modulated wave of the first frequency f ₀ band (for example, f ₀ =30 MHz), which is a baseband signal generated by the digital modulation unit 211, is a reference signal of frequency f ₁ generated by the local oscillator 220 (for example, f ₁ = 100 MHz) by the mixer 231, filtered by the (f ₁ +f ₀ ) band band-pass filter 241, and frequency-converted upward from the frequency f ₁ (f ₁ +f ₀ ) band intermediate frequency signal ( Hereinafter, it is referred to as a 1-system primary IF signal, which is converted to, for example, 130 MHz.

A modulated wave in the second frequency f ₀ band (for example, f ₀ =30 MHz), which is a baseband signal generated by the digital modulation unit 212, is a reference signal of frequency f ₁ generated by the local oscillator 220 (for example, f ₁ =100 MHz) multiplied by a mixer 232, filtered by a bandpass filter 242 in the (f ₁ −f ₀ ) band, and frequency translated down from frequency f ₁ to the middle of the (f ₁ −f ₀ ) band. It is converted into a frequency signal (hereinafter referred to as a 2-system primary IF signal, for example, 70 MHz).

The 1-system primary IF signal and the 2-system primary IF signal in different frequency bands are combined as a combined IF signal by a combiner 250 and output to the high frequency section 30 via a single intermediate frequency cable 40 .

Here, assuming that the frequency deviation due to the accuracy of the local oscillator 220 is α, the 1-system primary IF signal is (f ₁ +α)+f ₀ =f ₁ +f ₀ +α, and the 2-system primary IF signal is (f ₁ +α )−f ₀ =f ₁ −f ₀ +α, and each signal has a deviation of α.

The high frequency section 30 includes a distributor 310, a bandpass filter 321, a bandpass filter 322, a local oscillator 331, a local oscillator 332, a mixer 341, a mixer 342, a bandpass filter 351, and a bandpass filter 352. , a variable local oscillator 333 , a mixer 361 , a mixer 362 , a bandpass filter 371 , a bandpass filter 372 , an amplifier 381 , and an amplifier 382 . The local oscillator 331, the local oscillator 332, and the variable local oscillator 333 constitute a synthesizer 330 together with a crystal oscillator 334 serving as a reference.

A combined IF signal from the control unit 20 is distributed by a distributor 310 to a (f ₁ +f ₀ ) bandpass filter 321 and a (f ₁ −f ₀ ) bandpass filter 322 .

Only the 1-system primary IF signal of the (f ₁ +f ₀ ) band is extracted from the combined IF signal input to the (f ₁ +f ₀ ) band-pass filter 321 . Then, the 1-system 1st-order IF signal is multiplied by a reference signal of frequency f ₂ (for example, f ₂ =1370 MHz) generated by a local oscillator 331 by a mixer 341 to obtain a bandpass signal of (f ₂ +f ₁ +f ₀ ) band. Filtered by filter 242 . As a result, the 1-system primary IF signal is an intermediate frequency signal in the (f ₂ +f ₁ +f ₀ ) band frequency-converted upward from the frequency f ₂ (hereinafter referred to as a 1-system secondary IF signal. For example, f ₂ +f ₁ +f ₀ =1500 MHz).

Only the two-system primary IF signal in the (f ₁ -f ₀ ) band is extracted from the synthesized IF signal input to the (f ₁ -f ₀ ) band-pass filter 321 . Then, the 2-system 1st-order IF signal is multiplied by a reference signal (for example, f ₃ =1430 MHz) of frequency f ₃ generated by the local oscillator 332 by the mixer 342, and the (f ₃ +f ₁ −f ₀ ) band Filtered by pass filter 242 . Here, the frequency f3 multiplied by the 2-system primary IF signal is set to a value obtained by adding _twice the frequency _f0 of the baseband signal to the frequency f2 multiplied by the ₁ -system primary IF signal, (f ₂ +f ₁ +f ₀ )=(f ₃ +f ₁ -f ₀ ). As a result, the _{2 -} system _{primary IF} signal is an intermediate frequency signal (hereinafter referred to as This is referred to as a two-system secondary IF signal, for example f ₃ +f ₁ −f ₀ =1500 MHz).

The 1st-system secondary IF signal and the 2nd-system secondary IF signal are multiplied by a reference signal of frequency f4 ₍ for example, f4 = ₅₅₃₈ MHz) generated by a variable local oscillator 333 and a mixer 361 and a mixer 362, respectively, Filtered by a bandpass filter 371 and a bandpass filter 372 in the (f ₄ +f ₂ +f ₁ +f ₀ ) band. As a result, the 1-system secondary IF signal and the 2-system secondary IF signal are high-frequency signals in the (f ₄ +f ₂ +f ₁ +f ₀ ) band that are frequency-converted upward from the frequency f ₄ (hereinafter referred to as 1-system RF signal). These are referred to as RF signals of system 2. For example, they are converted to f ₄ +f ₂ +f ₁ +f ₀ =7038 MHz=approximately 7 GHz. The 1-system RF signal and the 2-system RF signal are amplified by the amplifiers 381 and 382, respectively, output from the microwave output terminals Z1 and Z2 to an antenna (not shown), and transmitted by radio.

Here, if the frequency deviation due to the precision of the local oscillator 331 is β, the frequency deviation due to the precision of the local oscillator 331 is θ, and the frequency deviation due to the precision of the local oscillator 331 is η, the first system secondary IF signal is (f ₂ +β)+(f ₁ +f ₀ +α)=f ₂ +f ₁ +f ₀ +α+β, and the two-system secondary IF signal is (f ₃ +θ)+(f ₁ −f ₀ +α)=f ₃ +f ₁ −f ₀ +α+θ , the 1-system RF signal is (f ₄ + η) + (f ₂ + f ₁ + f ₀ + α + β) = f ₄ + f ₂ + f ₁ + f ₀ + α + β + η, and the 2-system RF signal is (f ₄ + η) + (f ₃ + f ₁ −f ₀ +α+θ)=f ₄ +f ₃ +f ₁ −f ₀ +α+θ+η.

Then, since (f ₂ +f ₁ +f ₀ )=(f ₃ +f ₁ −f ₀ ), the difference between the 1-system secondary IF signal and the 2-system secondary IF signal, the 1-system RF signal and the 2-system RF Any difference from the signal is β−θ.

Furthermore, when (f ₂ +f ₁ +f ₀ )=(f ₃ +f ₁ -f ₀ )=1500 MHz, f ₂ =1370 MHz, and f ₃ =1430 MHz, respectively, and the maximum accuracy of the crystal oscillator 334 is assumed to be 1 ppm, The deviation between the first system and the second system has the maximum value of β-θ at (1430 MHz-1370 MHz)×1 ppm=60 Hz. For this reason, in the FPU of the microwave band, which requires 10 Hz or less, there arises a serious problem (variation between systems) and a problem that stable transmission cannot be performed.

As a countermeasure, it is conceivable to use a local oscillator with a high frequency accuracy of 0.1 ppm, but it is difficult to implement in the FPU in terms of cost and size.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a radio transmission apparatus capable of eliminating the frequency deviation between systems in the transmission output.

The radio transmission apparatus of the present invention includes a control unit that performs frequency conversion between a baseband signal having the same frequency between systems and an intermediate frequency signal that differs from system to system, and a control unit that performs frequency conversion between the intermediate frequency signal that differs from system to system and the intermediate frequency signal that differs from system to system. a high-frequency unit that performs frequency conversion between high- frequency signals of the same frequency, and a single synthesized intermediate-frequency signal obtained by synthesizing the intermediate-frequency signals for each system between the control unit and the high-frequency unit. wherein a first reference signal is used for frequency conversion in the control unit, and synchronization with the first reference signal is used in frequency conversion between the high frequency units The third reference signal is generated based on the first reference signal and the second reference signal.
Further, in the wireless transmission device of the present invention, the control unit frequency-converts the baseband signal of the first system upward from the frequency of the first reference signal to generate the intermediate frequency signal of the first system. , the frequency of the baseband signal of the second system is converted downward from the frequency of the first reference signal to generate the intermediate frequency signal of the second system, and the high-frequency section converts the intermediate frequency signal of the first system is frequency-converted upward from the frequency of the second reference signal, and the intermediate-frequency signal of the second system is frequency-converted downward from the frequency of the third reference signal, and the frequency of the third reference signal is A value obtained by adding the frequency of the second reference signal and twice the frequency of the first reference signal is set by multiplying the second reference signal by a multiplied signal obtained by doubling the frequency of the first reference signal. You can
Further, in the wireless transmission device of the present invention, the first reference signal may be transmitted from the control section to the high frequency section in a state of being synthesized with the synthesized intermediate frequency signal.

According to the present invention, even if the transmission between the control unit and the high frequency unit is performed via a single intermediate frequency cable, the frequency deviation between systems in the transmission output can be eliminated. can be applied to a MIMO-type FPU that uses a microwave band.

1 is a block diagram showing the configuration of an embodiment of a radio transmission device according to the present invention; FIG. 1 is a block diagram showing the configuration of a conventional radio transmission device; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The present embodiment is a MIMO type FPU 10a in which the frequency of wireless transmission is in the microwave band. Referring to FIG. A single intermediate frequency cable 40 such as a coaxial cable is connected to the high frequency section 30a.

The control section 20a includes a digital modulation unit 211, a digital modulation unit 212, a local oscillator 220a, a mixer 231, a mixer 232, a bandpass filter 241, a bandpass filter 242, and a synthesizer 250a. .

The modulated wave of the first frequency f ₀ band (for example, f ₀ =30 MHz), which is the baseband signal generated by the digital modulation unit 211, is the reference signal of the frequency f ₁ generated by the local oscillator 220a (for example, f ₁ = 100 MHz) by the mixer 231, filtered by the (f ₁ +f ₀ ) band band-pass filter 241, and frequency-converted upward from the frequency f ₁ (f ₁ +f ₀ ) band intermediate frequency signal ( Hereinafter, it is referred to as a 1-system primary IF signal, which is converted to, for example, 130 MHz.

The second system frequency f ₀ modulated wave (eg, f ₀ =30 MHz), which is the baseband signal generated by the digital modulation unit 212, is a reference signal of frequency f ₁ generated by the local oscillator 220a (eg, f ₁ =100 MHz) multiplied by a mixer 232, filtered by a bandpass filter 242 in the (f ₁ −f ₀ ) band, and frequency translated down from frequency f ₁ to the middle of the (f ₁ −f ₀ ) band. It is converted into a frequency signal (hereinafter referred to as a 2-system primary IF signal, for example, 70 MHz).

The 1-system 1st-order IF signal and the 2nd-system 1st-order IF signal in different frequency bands are synthesized as a synthesized IF signal by a synthesizer 250 together with _a reference signal of frequency f1 generated by the local oscillator 220a, and a single intermediate frequency is obtained. It is output to the high frequency section 30a via the cable 40. FIG.

Here, if the frequency deviation due to the accuracy of the local oscillator 220a is α, the 1-system primary IF signal is (f ₁ +α)+f ₀ =f ₁ +f ₀ +α, and the 2-system primary IF signal is (f ₁ +α )−f ₀ =f ₁ −f ₀ +α, and each signal has a deviation of α.

The high frequency section 30 includes a distributor 310a, a bandpass filter 321, a bandpass filter 322, a bandpass filter 323, a local oscillator 331a, a local oscillator 332a, a mixer 341, a mixer 342, and a bandpass filter 351. , a bandpass filter 352 , a variable local oscillator 333 , a mixer 361 , a mixer 362 , a bandpass filter 371 , a bandpass filter 372 , an amplifier 381 , and an amplifier 382 . The local oscillator 331a, the local oscillator 332a, and the variable local oscillator 333 constitute a synthesizer 330a together with a crystal oscillator 334 serving as a reference.

The combined IF signal from the control unit 20a is passed through a bandpass filter 321 of (f ₁ +f ₀ ) band, a bandpass filter 322 of (f ₁ −f ₀ ) band, and a bandpass filter 322 of (f ₁ −f 0 ) band by the splitter 310a. and the pass filter 323 .

From the synthesized IF signal input to the (f ₁ ) band bandpass filter 323, only the reference signal of frequency f ₁ generated by the local oscillator 220a is extracted and input to the local oscillators 331a and 332a. . This synchronizes the local oscillator 220a of the controller 20a with the local oscillators 331a and 332a.

Only the 1-system primary IF signal of the (f ₁ +f ₀ ) band is extracted from the combined IF signal input to the (f ₁ +f ₀ ) band-pass filter 321 . Then, the 1-system 1st-order IF signal is multiplied by a reference signal of frequency f ₂ (for example, f ₂ =1370 MHz) generated by the local oscillator 331a by the mixer 341, and is converted into a bandpass signal of (f ₂ +f ₁ +f ₀ ) band. Filtered by filter 242 . As a result, the 1-system primary IF signal is an intermediate frequency signal in the (f ₂ +f ₁ +f ₀ ) band frequency-converted upward from the frequency f ₂ (hereinafter referred to as a 1-system secondary IF signal. For example, f ₂ +f ₁ +f ₀ =1500 MHz).

Only the two-system primary IF signal in the (f ₁ -f ₀ ) band is extracted from the synthesized IF signal input to the (f ₁ -f ₀ ) band-pass filter 321 . Then, the 2-system primary IF signal is multiplied by a reference signal of frequency f ₃ (eg, f ₃ =1430 MHz) generated by the local oscillator 332a by the mixer 342, resulting in (f ₃ −(f ₁ −f ₀ )) Filtered by band pass filter 242 .

The local oscillator 332a multiplies the reference signal of frequency f2 generated by the local oscillator 332a by _a multiplied signal obtained by _doubling the frequency f1 of the reference signal generated by the local oscillator 220a to obtain the frequency _f3 = Generate a reference signal of f ₂ +2f ₁ . For example, the local oscillator 332a is a multiplier circuit that _doubles the frequency f1 generated by the local oscillator 220a to _a frequency 2f1, _a reference signal of frequency f2 generated by the local oscillator 332a, and _a multiplier circuit of frequency 2f1. and a (f ₂ +2f ₁ ) band-pass filter for filtering the output signal from the mixer.

Therefore, (f ₃ −(f ₁ −f ₀ ))=((f ₂ +2f ₁ )−(f ₁ −f ₀ ))=(f ₂ +f ₁ +f ₀ )=. As a result, the 2-system 1st-order IF signal is in the (f ₃ −(f ₁ −f ₀ )) band frequency-converted downward from the frequency f ₃ , that is, the intermediate frequency in the same frequency band as the 1st-system secondary IF signal. It is converted into a signal (hereinafter referred to as a two-system secondary IF signal, for example, f ₃ +f ₁ -f ₀ =1500 MHz).

The 1st-system secondary IF signal and the 2nd-system secondary IF signal are multiplied by a reference signal of frequency f4 ₍ for example, f4 = ₅₅₃₈ MHz) generated by a variable local oscillator 333 and a mixer 361 and a mixer 362, respectively, Filtered by a bandpass filter 371 and a bandpass filter 372 in the (f ₄ +f ₂ +f ₁ +f ₀ ) band. As a result, the 1-system secondary IF signal and the 2-system secondary IF signal are high-frequency signals in the (f ₄ +f ₂ +f ₁ +f ₀ ) band that are frequency-converted upward from the frequency f ₄ (hereinafter referred to as 1-system RF signal). These are referred to as RF signals of system 2. For example, they are converted to f ₄ +f ₂ +f ₁ +f ₀ =7038 MHz=approximately 7 GHz. The 1-system RF signal and the 2-system RF signal are amplified by the amplifiers 381 and 382, respectively, output from the microwave output terminals Z1 and Z2 to an antenna (not shown), and transmitted by radio.

Here, if the frequency deviation due to the precision of the local oscillator 331a is β, the frequency deviation of the local oscillator 332a is β+2α (α is the frequency deviation due to the precision of the local oscillator 220a). Therefore, the 1st-system secondary IF signal is (f ₂ +β)+(f ₁ +f ₀ +α)=f ₂ +f ₁ +f ₀ +α+β, and the 2nd-system secondary IF signal is (f ₃ +β+2α)−(f ₁ − f ₀ +α)=f ₃ −(f ₁ −f ₀ )+α+β, and (f ₂ +f ₁ +f ₀ )=(f ₃ −(f ₁ −f ₀ )). The difference from the 2-system secondary IF signal becomes zero. Synchronization with the local oscillators 220a, 331a, and 332a makes it possible to eliminate frequency deviation between systems.

Assuming that the frequency deviation due to the accuracy of the local oscillator 331 is η, the 1-system RF signal is (f ₄ +η)+(f ₂ +f ₁ +f ₀ +α+β)=f ₄ +f ₂ +f ₁ +f ₀ +α+β+η, 2-system The RF signal is (f ₄ + η) + (f ₃ + f ₁ - f ₀ + α + β) = f ₄ + f ₃ - (f ₁ - f ₀ ) + α + β + η. becomes zero. That is, when the frequency is converted to a microwave band or the like, the same variable local oscillator 333 is distributed, and the frequency is converted by mixers 361 and 362 functioning as microwave band frequency converters. By selecting the same frequency conversion in , it is possible to perform frequency conversion to the microwave band without deviation between systems.

In the above-described embodiments, a transmission device is used as an example of a radio transmission device, but the operation can be applied to a reception device by performing operations opposite to those described above.

As described above, in the present embodiment, the control unit 20a performs frequency conversion between the baseband signal having the same frequency between the systems and the intermediate frequency signal different for each system, and the intermediate frequency signal different for each system and the intermediate frequency signal between the systems between the control unit 20a and the high frequency unit 30a. A wireless transmission device that transmits via one intermediate frequency cable 40, and uses a _first reference signal (a reference signal of frequency f1 generated by a local oscillator 220a) for frequency conversion in the control unit 20a, A _second reference signal (a reference signal of frequency f2 generated by a local oscillator 331a) and a third reference signal (a frequency f ₃ reference signals), and the third reference signal is generated based on the first reference signal and the second reference signal.
With this configuration, even if transmission between the control unit 20a and the high frequency unit 30a is performed via a single intermediate frequency cable 40, the frequency deviation between systems in the transmission output can be eliminated. It can be applied to the FPU 10a of the MIMO system using the microwave band as the frequency.

As described above, in the present embodiment, the control unit 20a frequency-converts the first-system baseband signal from the frequency f1 of the first reference signal upward to obtain the first-system intermediate frequency signal (first-system primary IF signal). ) is generated, and the frequency of the baseband signal of the second system is converted downward from the frequency of the first reference signal to generate the intermediate frequency signal of the second system (secondary primary IF signal), and the high frequency part is , the first-system primary IF signal is frequency-converted upward from the frequency of the second reference signal to generate a first-system secondary IF signal, and the second-system primary IF signal is frequency-converted downward from the frequency of the third reference signal. The frequency f3 of the third reference signal is obtained by multiplying the second reference signal by a multiplied signal obtained by doubling the frequency f1 of the first reference signal. It is set to a value obtained by adding the frequency f2 of the signal and twice the frequency f1 of the second reference signal.
With this configuration, the difference between the 1st-system secondary IF signal and the 2nd-system secondary IF signal becomes zero, and the synchronization with the local oscillators 220a, 331a and 332a eliminates the frequency deviation between the systems. becomes possible.

As described above, in the present embodiment, the first reference signal is transmitted from the control section 20a to the high frequency section 30a in a state of being synthesized with the synthesized intermediate frequency signal.
With this configuration, the first reference signal can be transmitted from the control section 20a to the high frequency section 30a without extra wiring.

The present invention has been described above based on the embodiments. It should be understood by those skilled in the art that this embodiment is merely an example, and that various modifications can be made to the combination of each component, and that such modifications are within the scope of the present invention.

Embodiments of the present invention can be used for FPUs and broadcast relay transmission devices. Further, it can be used for a two-piece type relay transmission device composed of a control section and a high frequency section. Further, the present invention can be used for broadcast relay transmission equipment in which a control unit and a high frequency unit are connected by a coaxial cable or the like, MIMO system FPU, broadcast transmission equipment, and the like. This application claims the benefit of priority based on Japanese Patent Application No. 2019-175225 filed on September 26, 2019, the entire disclosure of which is incorporated herein by reference.

10, 10a FPUs 20, 20a Control Units 30, 30a High Frequency Unit 40 Intermediate Frequency Cables 211, 212 Digital Modulation Units 220, 220a Local Oscillators 231, 232 Mixers 241, 242 Bandpass Filters 250, 250a Synthesizers 310, 310a Distributor 321, 322, 323 bandpass filters 330, 330a synthesizers 331, 331a, 332, 332a local oscillators 333, variable local oscillators 334 crystal oscillators 341, 342 mixers 351, 352 bandpass filters 361, 362 mixers 371, 372 bandpass filters 381, 382 amplifier

Claims (3)

A control unit that performs frequency conversion between a baseband signal with the same frequency between systems and an intermediate frequency signal that differs from system to system, and between the intermediate frequency signal that varies from system to system and a high frequency signal with the same frequency between systems between the control unit and the high-frequency unit via a single intermediate-frequency cable as a synthesized intermediate-frequency signal obtained by synthesizing the intermediate-frequency signals for each system. A wireless transmission device that transmits
Using a first reference signal for frequency conversion in the control unit and using a second reference signal and a third reference signal synchronized with the first reference signal for frequency conversion in the high frequency unit,
The radio transmission apparatus, wherein the third reference signal is generated based on the first reference signal and the second reference signal. The control unit converts the frequency of the baseband signal of the first system upward from the frequency of the first reference signal to generate the intermediate frequency signal of the first system, and converts the baseband signal of the second system. generating the intermediate frequency signal of the second system by frequency-converting the frequency of the first reference signal downward;
The high-frequency unit frequency-converts the intermediate frequency signal of the first system upward from the frequency of the second reference signal, and frequency-converts the intermediate frequency signal of the second system downward from the frequency of the third reference signal. convert,
The frequency of the third reference signal is obtained by multiplying the frequency of the second reference signal by a multiplied signal obtained by doubling the frequency of the first reference signal. 2. The radio transmission apparatus according to claim 1, wherein the value is set to a value obtained by adding twice the . 3. The radio transmission apparatus according to claim 1, wherein the first reference signal is transmitted from the control section to the high frequency section after being combined with the combined intermediate frequency signal.

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