JPH06105881B2 - Wireless repeater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) (Technical Field of the Invention) The present invention amplifies a reception signal of a radio frequency received by a reception antenna, and retransmits a transmission signal from the transmission antenna on the same radio channel as the reception signal. The present invention relates to a device configuration for slightly offsetting the frequency of a transmission / reception signal in order to measure the amount of coupling between transmission antennas in a wireless relay for transmission.

(2) (Prior Art and Problems Thereof) FIG. 1 shows a basic configuration of a wireless relay device in which a received signal and a transmitted signal have the same wireless channel in wireless communication. In FIG. 1, the wireless relay device includes a receiving antenna 1 (gain
G ₁ ), branch circuit 2, detector 3, control unit 4, frequency converter 5 (gain G ₅ ), signal generator 6, amplification unit 7 (channel filter 7a and amplification unit 7b (gain G ₇ )), frequency Converter 8 (gain G ₈ ), signal generator 9, and transmitting antenna 10 (gain
G ₁₀ ).

The basic operation of the wireless relay device is that after receiving the received signal 11 by the receiving antenna 1, converting it to an intermediate frequency by the frequency converter 5, selecting the channel to be relayed by the channel filter 7a, and amplifying it by the amplifier 7b, The frequency converter 8 converts the signal into a radio frequency again and transmits it as a transmission signal 12 from the transmission antenna 10. The signal 11 and the signal 12 are the same radio channel, and when the radio channel to be relayed is switched, the frequency f ₀ of the signal generator 6 and the frequency f ₀ + of the signal generator 9
By switching Δf, tuning is performed on the wireless channel to be relayed. Further, the repeater gain G is G = G ₁ · G ₅ · G ₇
・ G ₈ and G ₁₀ .

13 is a sneak signal of the transmission signal in the receiving antenna 1, and when the amount of propagation loss between the transmitting and receiving antennas is L ₁₃ ,
The level of the signal 13 is 1 / L ₁₃ times that of the signal 12. Therefore, G / L ₁₃ is the loop gain of the loop signal. Here, if the loop gain is larger than 1 (L ₁₃ <G), the system becomes unstable and oscillates, which adversely affects the communication system. Therefore, when a repeater is used, it is necessary to consider the mounting of the transmit / receive antenna and the gain of the amplifier so that the amount of propagation loss L ₁₃ between the transmit and receive antennas is sufficiently larger than the repeater gain G.

A conventional technique for measuring the amount of propagation loss between transmitting and receiving antennas for this purpose is as described in Japanese Patent Application No. 60-281219.
That is, the frequency of the received signal 11 is F ₀ and the frequency of the signal generator 6 is f ₀ . The reception signal 11 is converted into an intermediate frequency by the frequency converter 5, and is converted into a signal of the same radio channel as the reception signal by the amplified frequency converter 8 to become a transmission signal 12. Here, when the frequency of the received signal 11 is F ₀ and the frequency of the signal generator 9 is f ₀ + Δf, the transmitted signal is
The frequency of 12 becomes F ₀ + Δf, and the transmission signal 12 becomes the reception signal 11
The frequency is offset by Δf compared to. Δf is
Since it is a low frequency of about 100 Hz, which is a little lower than the radio frequency, it does not affect communication.

Loop signal of received signal 11 and transmitted signal to the receiver of the repeater
Although the signal 13 is input, since the frequencies of the signal 11 and the signal 13 are offset by Δf, a beat having a frequency of Δf is generated in the envelope of the composite wave of the reception signal 11 and the sneak signal 13.
The detector 3 detects this beat and measures the amount of wraparound of the transmission signal from its level. The control unit 4 determines whether or not there is a risk that the loop gain becomes larger than 1 based on the measured value of the wraparound amount obtained by the detector 3, and if there is a risk, lowers the gain of the amplification unit 7, etc. Control.

However, for example, F ₀ is a radio signal with a channel interval of 25 kHz in the 900 MHz band, and f ₀ is 810 MHz if the intermediate frequency is in the 90 MHz band.
Is. The frequency difference between the signal generator 6 and the signal generator 9 is Δf
= 100Hz and the error of Δf within 10%, the frequency stability required for the signal generators 6 and 9 is 100 × 0.1 /
(810 x 10 ⁶ ) = 1.2 x 10 ^-8 . Considering the temperature change of the wireless relay device used outdoors, it is difficult to obtain the above frequency stability with an individual temperature-compensated crystal oscillator, etc., and an expensive and large highly stable oscillator such as a cesium oscillator is required. I needed it.

FIG. 2 shows an example of a conventional synthesizer method using the same signal oscillator as a reference. 2 shows the configuration of the signal generators 6 and 9 of FIG. 1, and the configuration and operation of the other parts of the relay device are the same as those of FIG. 14 is a reference signal oscillator, 15
Is a frequency divider. 16a and 16b are phase comparators, 17a and 17b are low-pass filters, 18a and 18b are voltage controlled oscillators, and 19a and 19b are variable frequency dividers, which constitute a synthesizer.
b shows two systems of the signal generators 6 and 9, respectively.
The reference signal oscillator 14 is an oscillator such as a temperature-compensated crystal oscillator, and the output of the reference signal oscillator 14 is divided by a divider 15 into a frequency that is a basic unit for frequency switching of the synthesizer. The variable frequency divider 19a (19b) divides the output of the voltage controlled oscillator 18 into the frequency of the basic unit,
The frequency divider 15a and the variable frequency divider 19a (1
The output frequency of 9b) is compared, the difference amount is passed through a low-pass filter 17a (17b) and then used as the control voltage of the voltage controlled oscillator 18a (18b) so that the synthesizer output frequency is controlled to be always correct. In this method, the frequency difference between the signal generator 6 and the signal generator 9 is always constant, and when a frequency drift occurs in the reference signal oscillator 14, the signal generator 6 and the signal generator 9 keep the frequency difference constant and drift. To do.
Therefore, the reference signal oscillator 14 does not need to be an extremely high stable oscillator.

However, as in the above example, F ₀ has a channel spacing in the 900 MHz band.
Assuming a radio signal of 25 kHz, an intermediate frequency of 90 MHz and a transmission and reception frequency offset of 100 Hz, the basic frequency setting unit of the synthesizer is 100 Hz. In this case, the cut-off frequency of the low-pass filter 17a (17b) is several tens of Hz, and the time constant of frequency control becomes long. It has a drawback that the pull-in time becomes long, about several seconds.

(3) Object of the Invention An object of the present invention is to provide a wireless relay device using a circuit for easily and stably offsetting a radio frequency transmission / reception signal by a predetermined small frequency.

(4) Configuration of the Invention (4-1) Differences between Features of the Invention and Prior Art The first invention of the present application is to use an infinite phase shifter in the transmission section and operate this at an offset frequency to offset the radio frequency of transmission and reception. The main feature is that

A second invention of the present application is a baseband relay that demodulates a relay signal, modulates the relay signal again, and sends the demodulated signal. The main feature is to offset the frequency.

According to a third aspect of the present invention, the local signal of the transmission / reception frequency converter is composed of two signal generators with the same oscillator as a reference, and the first signal generator is a synthesizer with the oscillator as a reference. The second signal generator comprises a first and a second synthesizer, the first synthesizer having its output as a reference and its output as a reference signal of the second synthesizer, which is generated by the first synthesizer. The reference signal is slightly offset in frequency from the signal used as a reference by the synthesizer of the first signal generator to generate local oscillation signals for transmission and reception which are slightly different in frequency from each other. The main feature is to offset.

In the conventional technology, the local signal generators for transmission and reception are used and the local signals for transmission and reception are slightly offset, so that there is a drawback that a highly stable oscillator is required and the apparatus is large and expensive. Further, the method of slightly offsetting the local oscillation signal of transmission and reception by the synthesizer method using the same reference oscillator has a drawback that the pull-in time becomes long when the frequency of the synthesizer is switched.

On the other hand, the present invention is different in that the radio signal frequency of transmission and reception can be slightly offset in a stable manner with a simple configuration, and the relay radio channel can be switched in a short time.

[Embodiment 1] FIG. 3 is a diagram showing a first embodiment of the present invention.
Reference numeral 10 is the same as that in FIG. 1, 20 is a phase modulator, and 21 is a modulation signal oscillator.

The received signal 11 received by the receiving antenna 1 is converted to an intermediate frequency by the frequency converter 5, amplified by the amplifier 7 and converted again to a radio frequency by the frequency converter 8, and then the phase modulator 20.
Is phase-modulated by. The phase modulator 20 is an infinite phase shifter. With such a configuration, the RF frequency to the infinite phase shifter 20 is offset by the modulation signal frequency Δf and output. Therefore, if the frequency of the reception signal 11 is F ₀ and the output frequency of the modulation signal oscillator 21 is Δf = 100 Hz, the transmission signal frequency is F ₀ + Δf. As described above, according to the present invention, the radio signal frequency of transmission and reception can be slightly offset with a simple structure and stably. It should be noted that it is the same as the conventional technique that the detector 3 detects the beat of the envelope due to the sneak signal and the control unit 4 controls the gain of the amplification unit 7 according to the detected amount.

Furthermore, since the local signal generator 6 of the frequency converters 5 and 8 is common, the radio frequency of the signal at the output of the frequency converter 8 is equal to the received signal 11. Therefore, it is obvious that the first embodiment of the present invention can be applied to the wireless relay system in which the frequency conversion is not performed in the amplification section.

The phase modulator 20 is an infinite phase shifter and is often used in wireless communication, but since it is an important component of the present invention, a configuration example is shown in FIG. 22 is a 90 ° hybrid that splits the input signal into two signals at the same level but different in phase by 90 °. Each of 23a and 23b is a 180 ° hybrid and the input signal is at the same level and the phase is 1
Branch into two signals that differ by 80 °. 24a, 24b, 24c and 24d are variable attenuators each of which changes its attenuation amount by a control signal. The inputs of the variable attenuators 24a to 24d are at the same level, but the phases are advanced by the hybrids 22 and 23a, 23b in the preceding stage,
24a is 0 °, 24b is 180 °, and 24c is based on the input signal of
Signals with advanced phases of 270 ° are input to 90 ° and 24d. 25 is a 4-input combiner which combines the inputs in phase.
26a, 26b, 26c, and 26d are phase shifters, each of which is a modulation signal oscillator 21
The low frequency output of 26a is 0 °, 26b is 180 °, 26c is 90 °,
26d advances the phase by 270 ° each. Phaser 26a, 26b, 26c,
The outputs of 26d are the control signals of the variable attenuators 24a, 24b, 24c, 24d, and 26a is 24a, 26b is 24b, 26c is 24c, and 26d is 24d.
It is a control signal for d. The vector in the 4-input combiner 25 of this circuit configuration is shown in FIG. The output vectors of 24a and 24b are on the axis of 0 ° -180 °, and their combined vectors are simple oscillations on the axis of 0 ° -180 ° in opposite phases. Similarly, the output vectors of 24c and 24d are on the 90 ° -270 ° axis, and their combined vectors are simple oscillations on the 90 ° -270 ° axis in opposite phases, but the output combined vectors of 24a and 24b. And are 90 degrees out of phase. Therefore, the phase modulator 20 becomes an infinite phase shifter, and the combined vector in the 4-input combiner 25 is 1 on the circumference for each cycle of the output signal of the modulation signal oscillator 21.
It rotates and its phase shift amount is equal to the phase shift amount of the modulation signal oscillator 21.

With this configuration, when the frequency of the reception signal 11 is F ₀ and the output frequency of the modulation signal oscillator 21 is Δf = 100 Hz, the transmission signal frequency is F ₀ + Δf. As described above, according to the present invention, it is possible to directly frequency shift a radio frequency transmission signal.

[Embodiment 2] FIG. 6 is a view showing a second embodiment of the present invention.
Up to 10 are the same as above, 27 is a demodulator, 28 is a baseband amplifier, 29 is a modulator, 30 is a local oscillator for modulation including a VCO, and 31 is a phase comparator.

The signal received by the receiving antenna 1 is converted by the frequency converter 5 into an intermediate frequency of f _IF = 455 kHz, for example. Next, the demodulator 27 demodulates the signal into a baseband, and the baseband amplifier 28
After being amplified by, the modulator 29 again modulates the output of the local oscillator for modulation 30 to return it to the intermediate frequency, and the amplifier 7
Is amplified by the frequency converter 8 and returned to the radio frequency again by the frequency converter 8 and is transmitted from the transmission antenna 10 as a transmission signal.

Here, the demodulator 27 is a demodulator of a synchronous detection waveform, applies the demodulation output of the baseband to the amplifier 28, reproduces the carrier wave of the frequency f _IF , and supplies it to the phase comparator 31. The output of the modulating local oscillator 30 and the reproduced carrier wave are input to the phase comparator 31, and the modulating local oscillator 30 is controlled by the output of the phase comparator 31 so that the frequency difference becomes equal to Δf. Therefore, the carrier frequency of the output of the modulator 29 becomes f _IF + Δf, and the radio frequency of transmission and reception can be slightly shifted. Further, since the signal generator 6 serving as the local oscillator of the frequency converters 5 and 8 is common, the difference between the signal frequencies of transmission and reception does not change due to the drift of the signal generator 6. When the demodulator is used for other than synchronous detection such as frequency detection and differential detection, it is necessary to separately provide a carrier recovery means.

[Embodiment 3] FIG. 7 is a diagram for explaining a third embodiment of the present invention, showing the configurations of the signal generator 6 and the signal generator 9 in FIG. 1, and other parts of the relay device. Figure 1 shows the configuration and operation of
Is equal to A signal oscillator 32 is a temperature-compensated crystal oscillator or the like. 33 is a divider, 34 is a phase comparator, 35 is a low pass filter, 36 is a voltage controlled oscillator, 37 is a divider, 38 is a divider, 39 is a phase comparator, 40 is a low pass filter, 41 is a voltage Controlled oscillator, 42 is a frequency divider, 43 is a frequency divider, 44 is a phase comparator, 45 is a low pass filter, 46 is a voltage controlled oscillator, 47
Is a frequency divider.

The signal generator 6 in FIG. 1 is a synthesizer composed of 34, 35, 36, 37, and the signal generator 9 is a first synthesizer composed of 39, 40, 41, 42, 43 and 44, 45, It consists of a second synthesizer consisting of 46 and 47.

The signal oscillator 32 is a reference for two systems of signal generators. For example, a 10 MHz temperature-compensated crystal oscillator is used for frequency division by the frequency divider 33.
Obtain a 5kHz signal. This signal serves as a reference signal for the synthesizer that constitutes the signal generator 6, and has a frequency equal to the radio channel interval. Output f ₀ of voltage controlled oscillator 36 is 800 MHz
It is a band signal and is a local signal of the frequency converter 5. The form of the synthesizer that constitutes the signal generator 6 is used in a 900 MHz band car telephone system or the like, and the time required to switch channels is several tens of milliseconds.

The output of the signal oscillator 32 is frequency-divided by the frequency divider 38 to obtain a signal of 100 Hz. This signal serves as a reference signal for the first synthesizer which is a component of the signal generator 9. Voltage controlled oscillator
The output of 41 is a signal of 10 ⁹ +100 Hz, and by dividing by the frequency divider 43, a signal of 25 × 10 ³ + (1/400) Hz is obtained, and this signal is used as the reference signal of the second synthesizer. . The structure of the second synthesizer is the same as that of the signal generator 6. Therefore, the output of the signal generator 9 is the signal generator 6
About 100Hz frequency is shifted compared to the output of.

In this configuration, since the reference signal of the first synthesizer forming the signal generator 9 is as low as 100 Hz, the pull-in time until the first synthesizer stabilizes takes several seconds. However, the first synthesizer is set only when the power of the wireless repeater is turned on, and the output frequency of the first synthesizer is not switched thereafter. When switching the wireless channel to be relayed, the synthesizer forming the signal generator 6 and the second synthesizer forming the signal generator 9 are changed over, and the pull-in time is several tens of milliseconds.

(5) (Effects of the Invention) As described above, according to the present invention, the transmission / reception frequency of the wireless relay device can be easily and stably shifted by a small frequency.

[Brief description of drawings]

FIG. 1 is a block diagram showing a prior art configuration of a wireless relay device in which received signals and transmitted signals have the same wireless channel, FIG. 2 is a block diagram showing an example of a synthesizer system according to the prior art, and FIG. 3 is a first embodiment of the present invention. A block diagram showing an example, FIG. 4 is a block diagram showing a configuration example of an infinite phase shifter used in the present invention, FIG. 5 is a vector diagram for explaining the operation of the infinite phase shifter, and FIG. 6 is a second embodiment of the present invention. FIG. 7 is a block diagram showing an example, and FIG. 7 is a block diagram showing a configuration example of a signal generator used in the third embodiment of the present invention. 1 ... Receiving antenna, 2 ... Branch circuit, 3 ... Detector,
4 ... control unit, 5 ... frequency converter, 6 ... signal generator, 7 ... amplification unit, 7a ... channel filter, 7b ... amplification unit, 8 ... frequency converter, 9 ... signal generation Bowl, 10 ……
Transmitting antenna, 11 ... Received signal, 12 ... Transmitted signal, 13 ...
... sneak signal, 14 ... reference signal oscillator, 15 ... frequency divider, 16a, 16b ... phase comparator, 17a, 17b ... low-pass filter, 18a, 18b ... voltage controlled oscillator, 19a, 19b ... variable Frequency divider, 20 ... Phase modulator, 21 ... Modulation signal oscillator, 22 ...
… 90 ° hybrid, 23a, 23b …… 180 ° hybrid,
24a, 24b, 24c, 24d ... Variable attenuator, 25 ... 4-input combiner, 26a, 26b, 26c, 26d ... Phase shifter, 27 ... Demodulator, 28 ...
… Baseband amplifier, 29… Modulator, 30… Modulation local oscillator, 31… Phase comparator, 32… Signal oscillator, 33…
… Divider, 34 …… Phase comparator, 35 …… Low-pass filter, 36 …… Voltage controlled oscillator, 37 …… Divider, 38 …… Divider, 39 …… Phase comparator, 40 …… Low-pass filter, 41
...... Voltage control type oscillator, 42 ...... divider, 43 …… divider,
44 …… Phase comparator, 45 …… Low-pass filter, 46 …… Voltage-controlled oscillator, 47 …… Frequency divider.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Sadayuki Nishiki 1, 2356 Take, Yokosuka City, Kanagawa Pref., Nippon Telegraph and Telephone Corporation, Second Communication Network Research Laboratory (72) Inventor Hisao Takahashi 1-1, Uchisaiwaicho, Chiyoda-ku, Tokyo No. 6 Nihon Telegraph and Telephone Corporation Examiner Shun Umezawa

Claims (3)

[Claims] 1. A radio frequency reception signal is received by a reception antenna, amplified by an amplifier, and then, when the transmission signal is retransmitted from the transmission antenna in the same radio channel as the reception signal, the frequency of the transmission signal is adjusted. A radio having a function of slightly offsetting from the frequency of the received signal and measuring the amount of radio waves wrapping between the transmitting antenna and the receiving antenna by detecting the amount of the signal component of the offset frequency included in the received signal. In the relay apparatus, an infinite phase shifter is used to phase-modulate the transmission signal with a modulation signal having a constant frequency, and the frequency of the transmission signal is offset from the reception signal. 2. A radio frequency reception signal is received by a reception antenna, amplified by an amplifier, and then, when the transmission signal is retransmitted from the transmission antenna in the same radio channel as the reception signal, the frequency of the transmission signal is adjusted. A radio having a function of slightly offsetting from the frequency of the received signal and measuring the amount of radio waves wrapping between the transmitting antenna and the receiving antenna by detecting the amount of the signal component of the offset frequency included in the received signal. In the relay device, the received signal is converted into an intermediate frequency signal using a local signal, demodulated and the carrier is regenerated, and a second carrier whose frequency is slightly offset using the carrier as a reference signal is used as the demodulated signal. By modulating the frequency of the intermediate frequency signal to a radio frequency using the local signal to generate the transmission signal. , Radio relay apparatus characterized by the frequency of the transmitted signal is configured to offset from the received signal. 3. A radio frequency reception signal is received by a reception antenna, amplified by an amplifier, and then, when the transmission signal is retransmitted from the transmission antenna on the same radio channel as the reception signal, the frequency of the transmission signal is adjusted. A radio having a function of slightly offsetting from the frequency of the received signal and measuring the amount of radio waves wrapping between the transmitting antenna and the receiving antenna by detecting the amount of the signal component of the offset frequency included in the received signal. In the repeater, two system signal generators with the same oscillator as a reference are provided, the first signal generator is configured by a synthesizer with the oscillator as a reference, and the second signal generator is A second synthesizer, the first synthesizer using the oscillator as a reference, and the output of the second synthesizer as a reference signal for the second synthesizer; The reference signal generated by the synthesizer is slightly offset in frequency from the signal used as the reference by the synthesizer of the first signal generator, so that the signal generators of the two systems have first and slightly different frequencies. , A second two local signals are generated, the first local signal is used as a receiving side local oscillation signal to convert the received signal to an intermediate frequency, and the second local signal is used as a transmitting side local oscillation signal to be an intermediate frequency signal. Is converted into the frequency of the transmission signal to offset the frequency of the transmission signal from the reception signal.