JPH10108038A - Fpu repeater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the FPU(field pickup) repeater small in size, to reduce power consumption and to attain high reliability. SOLUTION: The FPU repeater 30 directly converts a reception frequency Fin at an SHF band into a transmission frequency Fout. A BPF 35 having a prescribed frequency band characteristic is inserted after an LNA 37 in a reception section 31. A signal with the frequency Fin is mixed with a signal at a MIX 33 with a frequency between the Fout and the Fin from an OSC 34. A BPF 36 in a transmission section 32 has a prescribed band width in which a center frequency is the frequency Fout. A PA 38 amplifies an output power from the BPF 36 and transmits the amplified signal from a transmission antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field pickup (hereinafter abbreviated as "FPU") for transmitting information used as a material for a television broadcast program by using two frequencies allocated in an SHF band. Regarding repeaters.

[0002]

2. Description of the Related Art When transmitting information by radio waves, if the distance is long or there is an obstacle in the middle, it is necessary to receive the radio waves once, perform power amplification, and relay the signals. . JP-A-7-273703 and JP-A-7-2703
97783 discloses a prior art for performing relaying at the same frequency. However, generally, at the same frequency, there is a problem such as interference between a received signal and a transmitted signal, and a method of repeating reception and transmission at different frequencies is often used.

Conventionally, when producing a live broadcast program, a news program, or the like in television broadcasting, if a site where an object to be reported exists and a broadcasting station are separated,
An FPU repeater as shown in FIG. 8 is used. Such an FPU repeater has a receiving unit 1 and a transmitting unit 2, and the receiving unit 1 and the transmitting unit 2 are connected by an IF signal cable 3 and an AV signal cable 4. Receiver 1
Receives a radio signal in the SHF band via the receiving antenna 5. The received signal in the SHF band is converted into a signal in an intermediate frequency band of 130 MHz (hereinafter sometimes abbreviated as “IF”) in the receiving unit 1 and input to the transmitting unit 2 via the IF signal cable 3. You. Further, the signal may be demodulated to a baseband signal and transmitted via the AV signal cable 4. The transmitting unit 2 converts the IF signal into an SHF band signal, amplifies the power, and transmits the signal as a wireless signal from the transmitting antenna 6.

[0004] A high-frequency signal received by a receiving antenna 5 is input to a receiving unit 1 and a low-noise amplifier (hereinafter referred to as “L”).
NA) 10 and is amplified with low noise.
The output of the LNA 10 is such that the reception frequency Fin is the center frequency F
o, which is selected by a bandpass filter (hereinafter abbreviated as “BPF”) 11 and mixed with a local signal from a local oscillator (hereinafter abbreviated as “LOC”) 13 by a mixer (abbreviated as “MIX”) 12 And BPF1
4 extracts a first intermediate frequency signal of, for example, 1500 MHz. The output of the BPF 14 is MIX1
5, mixed with the local signal from the second LOC 16,
The signal is extracted by the BPF 17 as a second intermediate frequency signal of, for example, 130 MHz. The output of the BPF 17 is amplified by an intermediate frequency amplifier (hereinafter abbreviated as “IF”) 18. The output of the IF 18 is a detector (hereinafter “DE”).
T) 19, which is detected, demodulated, and a video signal or an audio signal is extracted as a baseband signal.

[0005] The second intermediate frequency output of the receiver 1 is provided to one of the changeover contacts of the changeover switch 20 of the transmitter 2 by the IF signal cable 3. The output from DET19 is
The signal is supplied to a modulator (hereinafter abbreviated as “MOD”) 21 in the transmission unit 2 via the AV signal cable 4. MOD2
In 1, a carrier having a second intermediate frequency of 130 MHz is modulated based on a baseband signal supplied via the AV signal cable 4. The output of the MOD 21 is provided to the other switching contact of the changeover switch 20. Selector switch 20
Connects one of the switching contacts or the other switching contact to the common contact, and inputs one of the two signals to the BPF 22. The output of the BPF 20 is MIX2
3 is mixed with the local signal from the LOC 24, converted to the first intermediate frequency of 1500 MHz,
Is input to MIX26. In MIX26, LOC
27 and the transmission frequency Fou
As a signal of t, the signal is supplied from the BPF 28 to a power amplifier (hereinafter abbreviated as “PA”) 29 and power-amplified.
It is transmitted as a radio signal from the transmitting antenna 6.

FIG. 9 shows a BPF used in the repeater shown in FIG.
The band characteristics of each of 11, 14, 17, 22, 25, and 28 are expressed by relative attenuation (ATT) with respect to the center frequency.
As shown. The two-dot chain line shows the characteristics of the BPFs 11 and 28 in the SHF band, and the one-dot chain line shows the first intermediate frequency of 1500.
The characteristics of the BPFs 14 and 25 at MHz are shown, and the solid lines show the band characteristics of the BPFs 17 and 22 at the second intermediate frequency 130 MHz. The BPF having a high frequency has a wide band, and a required 17 MHz frequency band is obtained in the BPF of the second intermediate frequency.

[0007]

In a conventional FPU repeater for the SHF band in which reception and transmission frequencies are changed, the carrier frequency Fin of the reception signal is set to an intermediate frequency different from the carrier frequency Fout of the transmission signal. Is once converted into a signal. The transmission unit 2 converts the signal of the intermediate frequency into a signal of the transmission carrier frequency Fout, amplifies the power, and transmits it as a radio wave. In the receiving unit 1, the input carrier frequency Fin is temporarily set to 1500 to remove image interference.
The signal is converted to a first intermediate frequency of 130 MHz, and further converted to a second intermediate frequency of 130 MHz, which is a lower frequency, to obtain a required selectivity, and demodulated by DET19. In transmitting section 2, for example, second intermediate frequency 130M
Hz signal can be directly converted to the transmission carrier frequency Fout. However, in order to enhance the suppression of spurious waves, the signal is once converted to the first intermediate frequency 1500 MHz, and the two-stage conversion process in the receiving unit 1 is reversed. Repeat.
For this reason, the number of LOCs, MIXs, BPFs, etc. required for frequency conversion is increasing, and since this is an important functional component, the volume occupied in the repeater also increases, and the shape of the repeater increases. , The weight is also increasing.

[0008] The FPU repeater is required to be able to move promptly as needed in order to arbitrarily form a relay path connecting a site to be reported and a broadcasting station. In addition, the moving place may be a place where traffic and power conditions are not always good, for example, on a mountain. Considering such circumstances, the FPU repeater as shown in FIG. 8 has a complicated structure, consumes a large amount of power, is large and heavy, and therefore has room for improvement as an FPU repeater.

An object of the present invention is to provide an FPU repeater that is small and lightweight, has high reliability, and can reduce power consumption.

[0010]

SUMMARY OF THE INVENTION The present invention relates to an SHF band,
An FPU repeater that receives a radio signal having a pre-assigned first frequency as a carrier frequency, converts the carrier frequency to a pre-assigned second frequency, and transmits the radio signal as a radio signal. Receiving means for receiving and amplifying a radio signal in a frequency bandwidth; oscillating means for generating a signal having a difference frequency between the first frequency and the second frequency; a signal having a difference frequency from the oscillating means; Mixing means for mixing the signal of the first frequency, and transmission means for power-amplifying a signal of a predetermined frequency bandwidth centered on the second frequency among the outputs from the mixing means and transmitting the amplified signal as a radio signal. An FPU repeater characterized by including: According to the present invention, an FPU repeater that receives and transmits a radio signal having a first frequency and a second frequency respectively assigned as carrier frequencies in the SHF band, and does not perform conversion to an intermediate frequency, and transmits the first frequency And the second frequency directly. The receiving means and the transmitting means amplify the signal in a predetermined bandwidth with the first frequency and the second frequency as center frequencies, respectively. In the frequency conversion, a difference frequency between the first frequency and the second frequency is generated by the oscillating means, mixed with the output of the receiving means by the mixing means, and the signal of the second frequency is power-amplified by the transmitting means as a radio signal Send. Since conversion to the intermediate frequency is not performed, the number of mixers, local oscillators, band-pass filters, and the like used can be reduced, the configuration of the repeater can be simplified, and power can be saved. Furthermore, compared to a configuration using a lower intermediate frequency,
Since signal processing is performed at a high frequency in the SHF band, the number of frequency conversion stages is reduced, the circuit configuration is simplified, reliability is improved, and downsizing and cost reduction can be achieved.

Further, in the present invention, the receiving means and the transmitting means are provided with a band-pass filter having the first frequency and the second frequency as center frequencies and having the predetermined frequency bandwidth. According to the present invention, a bandpass filter is inserted in the receiving means and the transmitting means, and a frequency characteristic of selecting a predetermined frequency bandwidth with the first frequency and the second frequency as center frequencies is realized.
Since a band-pass filter having a predetermined frequency bandwidth is used around the carrier frequency received by the receiving unit, there is no need to remove image interference as in the case of conversion to an intermediate frequency. Further, since the center frequency is different from the second frequency transmitted from the transmitting unit, there is no possibility that interference occurs between the transmitting unit and the receiving unit as in the case where relaying is performed at the same frequency. Further, if the second frequency is sufficiently away from a predetermined frequency bandwidth centered on the first frequency, the output to be transmitted goes to the receiving unit to lower the receiving sensitivity or cause interference in reception. There is no danger.

In the present invention, the band-pass filter is
It is characterized in that it is detachable and interchangeable for receiving means and for transmitting means. According to the present invention, the receiving frequency and the transmitting frequency are exchanged without changing the oscillation frequency of the oscillating means by exchanging the band-pass filter which is detachable and exchangeable for the receiving means and the transmitting means. be able to. As a result, if the first frequency and the second frequency are allocated, the transmission and reception frequencies are alternately switched by using a plurality of stages of FPU repeaters, so that the FPU relay can be performed even in a multistage relay over a long distance. It can be easily performed by using a common machine.

[0013]

FIG. 1 shows a schematic electrical configuration of an FPU repeater 30 according to an embodiment of the present invention. The repeater 30 includes a receiving unit 31 and a transmitting unit 32, a MIX 33 for performing frequency conversion between the receiving unit 31 and the transmitting unit 32, and an oscillator (hereinafter, abbreviated as “OSC”) that oscillates a signal having a frequency of a difference between the receiving frequency and the transmitting frequency. ) 34. Receiver 3
1 and the frequency characteristics of the transmission unit 32 are BPFs 35 and 36
Respectively. The BPF 35 is a high-performance linear phase filter having a predetermined frequency bandwidth of, for example, 17 MHz with the reception frequency Fin as the first frequency as the center frequency Fo. A BPF 36 having a predetermined frequency bandwidth at the transmission frequency Fout whose center frequency is the second frequency is also inserted into the transmission unit 32. BPF
36 also has the same characteristics as the BPF 35 except that the center frequency is different.

In the receiving section 31, on the input side of the BPF 35,
An LNA 37 is provided. The LNA 37 is, for example, a field effect transistor (F) made of gallium arsenide (GaAs).
ET) or the like, and is configured using an element capable of amplifying with high frequency and low noise in the SHF band. In the present embodiment, the BPF
The BPF 35 is arranged on the output side of the LNA 37 to compensate for the passage loss of the LNA 37. When the electric field strength of the received signal is large, the BPF 35 can be arranged on the input side of the LNA 37. Further, it can be arranged on both the input side and the output side of the LNA 37.

The transmitting section 32 power-amplifies the signal of the second frequency selected by the BPF 36 with the PA 38.
Part of the output of the PA 38 is controlled by automatic gain control (hereinafter referred to as “AG”).
C "). Most of the output of the PA 38 is extracted as high-frequency power to be transmitted at the transmission frequency Fout. The AGC circuit 39 adjusts the gain of the LNA 37 via the AGC line 40 according to the output of the PA 38.

FIG. 2 shows an operation state when the relay is performed by the FPU repeater 30 of FIG. The repeater 30 is supplied with operating power from a power supply 44. The receiving antenna 45 for receiving the signal and the transmitting antenna 46 for transmitting the signal are arranged at separate positions in order to avoid interference.
0 is directly connected to the transmitting antenna 46. Between the repeater 30 and the receiving antenna 45, a coaxial cable 47 and an LNA
48 is interposed. The LNA 48 is directly connected to the receiving antenna 45 and amplifies a small signal received by the receiving antenna 45 with as low a loss as possible. A direct current (DC) current for operating the LNA 48 is supplied from the repeater 30 via the coaxial cable 47. SH, which is the output of LNA 48
The F-band high-frequency signal is input to the repeater 30 via the coaxial cable 47. The output side of repeater 30 is directly connected to transmitting antenna 46 to minimize power loss. The connection between the repeater 30 and the receiving antenna 45 and the transmitting antenna 46 can be made via only the coaxial antenna. Further, the distance from the receiving antenna 45 can be further increased, and a plurality of LNAs can be inserted.

Regarding power consumption, most of P
Consumed at A38. The power required for the remaining circuits is about 2W. If the power of the PA 38 can be suppressed, it can be operated with very little power. If the output power of PA38 can be reduced by line design,
A significant reduction in power consumption can be expected.
Can be reduced in size and weight, or a solar cell or the like can be used.

FIG. 3 shows an example of the band pass characteristics of the BPFs 35 and 36 shown in FIG. Although the BPFs 35 and 36 have different center frequencies Fo, they have the same frequency band characteristics. The frequency bandwidth is 17 MHz, and flat characteristics are obtained in this band, and good characteristics in which the degree of attenuation sharply increases outside this band.

FIG. 4 shows an example of a level diagram of each part of the FPU repeater 30 of FIG. In LNA37, A
Gain control via GC line 40 results in a gain of 42
It can be adjusted in the range of ~ 52 dB and 10 dB. The input -40 dBm when the gain is 42 dB is a standard input level. If the gain is increased by 10 dB, -50 dBm
Corresponding to the input level. Next, BPF3
5 has a pass loss of 2 dB, and MIX33 has a pass loss of 8 dB.
And the BPF 36 has a passing loss of 2 dB. The PA 38 has a power gain of 40 dB, and finally obtains an output of +30 dBm.

FIG. 5 shows the input / output characteristics of the FPU repeater 30. The output Pout increases linearly until the input Pin reaches −40 dBm. When the input Pin exceeds -40 dBm, the output Pout becomes substantially constant by AGC.

FIGS. 6 and 7 show BPFs 35 and 36, respectively.
Appearance shapes when configured as a polarized type and a coaxial type are shown respectively. FIGS. 6 and 7A are front views, and FIGS. 6 and 7B are right side views. The polar BPFs 35 and 36 shown in FIG. 6 receive an input from one end of the main body 50 in the axial direction via a coaxial connector 51, and output an output via a coaxial connector 52 of the same standard. Removed from the other end. In the coaxial type shown in FIG.
The coaxial connectors 51 and 52 for input and output are attached to the upper and lower sides of one end in the axial direction. Therefore,
Disconnect the connection to the coaxial connectors 51 and 52, and
It is easy to swap 5, 36 and swap the input and output frequencies.

When transmitting video and audio for television broadcasting using microwaves such as the SHF band or higher frequency radio waves, SNG such as SNG using satellite communication in addition to the FPU described above is used. A method is also used. SN
In G, transmission is basically possible as long as the same communication satellite can be seen, but the number of communicable lines is limited, and a high usage fee is required to keep the communication available. Even if you only use it when you need it,
Reservation is required, and the price of the radio becomes expensive. FPU
When a repeater is used, it is used only on the ground because it is used on the ground, and the transmission distance is limited. For transmission over long distances or in places where it is difficult to see, it must be relayed many times. However, if the FPU repeater of the present embodiment is used, the FPU repeater can be manufactured small and lightweight at low cost, so that even if the number of repeats increases, it can be quickly prepared as needed.

[0023]

As described above, according to the present invention, an FPU repeater that performs transmission and reception using the first and second frequencies pre-assigned in the SHF band can be provided directly between the first and second frequencies. This can be realized by conversion, so that the size and weight of the device, high reliability, and low power consumption can be achieved. As a result, the FPU repeater can be easily moved to a location where traffic and power conditions are not good, and information transmission using radio waves can be quickly performed over a long distance.

According to the present invention, the desired frequency band characteristics centered on the first and second frequencies of the SHF band are obtained by the band-pass filter in the receiving unit and the transmitting unit, respectively. Wave suppression can be easily performed.

Further, according to the present invention, since the band-pass filters inserted into the transmitting section and the receiving section are detachable and interchangeable, the first frequency and the second frequency can be used for receiving and transmitting and transmitting. And reception can be easily switched. As a result, a plurality of stages of FPU repeaters can be used while switching frequencies alternately, and a plurality of stages of relay can be easily performed over a long distance by a common repeater.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic electrical configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic operation example of the FPU repeater 30 of FIG.

FIG. 3 is a band characteristic diagram of the BPFs 35 and 36 in FIG.

FIG. 4 is a level diagram of the FPU repeater 30 of FIG.

FIG. 5 is an input / output characteristic diagram of the FPU repeater 30 of FIG. 1;

FIG. 6 is a front view and a right side view when the BPFs 35 and 36 in FIG. 1 are configured as polarized.

7 is a front view and a right side view when the BPFs 35 and 36 of FIG. 1 are configured as coaxial.

FIG. 8 is a block diagram showing a schematic electrical configuration of a conventional FPU repeater.

9 is a band characteristic diagram of each BPF in FIG.

[Explanation of symbols]

 Reference Signs List 30 repeater 31 receiving unit 32 transmitting unit 33 MIX 34 OSC 35, 36 BPF 37 LNA 38 PA 39 AGC 45 receiving antenna 46 transmitting antenna

Claims (3)

[Claims] 1. An FPU repeater for receiving a radio signal having a first frequency assigned in advance in a SHF band as a carrier frequency, converting the carrier frequency to a second frequency assigned in advance, and transmitting the converted signal as a radio signal. Receiving means for receiving and amplifying a radio signal in a predetermined frequency bandwidth centered on one intermediate frequency; oscillating means for generating a signal having a difference frequency between the first frequency and the second frequency; The difference frequency signal and the first signal from the receiving means.
Mixing means for mixing a signal of a frequency, and transmission means for power-amplifying a signal of a predetermined frequency bandwidth centered on the second frequency among outputs from the mixing means, and transmitting the amplified signal as a radio signal. Features FPU repeater. 2. The FPU according to claim 1, wherein the reception unit and the transmission unit each include a band-pass filter having a first frequency and a second frequency as center frequencies and having the predetermined frequency bandwidth. Repeater. 3. The FPU repeater according to claim 2, wherein the band-pass filter is detachable and interchangeable for a receiving unit and a transmitting unit.