CN115549746B - Multi-frequency combining and branching circuit and signal transmitting system - Google Patents

Abstract

The invention provides a multi-frequency combining and branching circuit and a signal transmitting system, wherein the circuit comprises: the first phase conversion circuit is used for respectively carrying out equal-division phase conversion on signals in different frequency bands to generate at least two corresponding signals; the combining circuit is used for respectively combining at least two signals with the same phase to generate an in-phase signal; the second phase conversion circuit is used for receiving at least two same-phase signals synthesized by the combining circuit, carrying out phase conversion on the at least two same-phase signals and synthesizing a combined signal; and the outgoing circuit is used for distributing power to the combined signal and outgoing signals with different powers. The invention carries out equally divided phase conversion, same phase conversion and synthesis on signals in different frequency bands, then carries out power distribution, and sends out signals in different powers, so as to realize the purposes of eliminating interference between different frequency bands, improving isolation between frequency bands and eliminating blocking outside the frequency bands.

Description

Multi-frequency combining and branching circuit and signal transmitting system

Technical Field

The present invention relates to the field of communication technology, and in particular to a multi-frequency combining and branching circuit and a signal transmitting system.

Background technique

The Pico Remote Radio Unit (PRRU) is a new type of miniaturized distributed network coverage mode. It places large-capacity macrocell base stations in an available central machine room, centrally processes the baseband part, and uses optical fiber to pull the RF module in the base station to the remote RF unit, which is placed at the site determined by the network planning. This mode has two forms, built-in antenna type and external antenna type. The so-called built-in antenna type has antennas of different frequency bands placed inside the PRRU, and regional coverage is achieved through the internal antenna, that is, the coverage of the area where the PRRU is located. The external antenna structure is to realize signal combining inside the PRRU and then connect the antenna externally. In this case, an additional external model needs to be designed. The PCBs of the two models cannot be shared, which often increases the cost of the product. Alternatively, the signal combining is realized through an external combiner, and then the antenna is connected externally. However, an additional combiner structure is required, and the combiner often used is a relatively large cavity combiner or other customized form.

The existing additional combiner uses a specific method to achieve FDD channel transmission and reception isolation. Currently, there is basically no solution focused on solving the problem of interference between different-frequency channels, and there is no relevant solution aimed at solving the problem of insufficient isolation between channels in different-frequency combining.

Summary of the invention

In view of the problems existing in the prior art, the present invention provides a multi-frequency combining and splitting circuit and a signal transmitting system.

In a first aspect, the present invention provides a multi-frequency combining and splitting circuit, comprising:

A first phase conversion circuit is used to perform phase conversion on signals of different frequency bands in equal parts to generate at least two corresponding signals, wherein the phase difference between each signal in the at least two signals is a preset difference value;

A combining circuit, used for combining at least two signals with the same phase to generate a same-phase signal;

A second phase conversion circuit is used to receive at least two in-phase signals synthesized by the combining circuit, perform phase conversion on the at least two in-phase signals, and synthesize a combined signal;

The outgoing circuit is used to distribute the power of the combined signal and send out signals of different powers.

In one embodiment, the first phase conversion circuit comprises at least two first broadband bridges, wherein:

Each first broadband bridge is used to perform equal phase conversion on the signal of the corresponding frequency band to generate at least two signals, and the phase difference between each signal in the at least two signals is a preset difference value.

In one embodiment, the combining circuit comprises at least two combiners, wherein:

Each combiner is used to receive at least two signals with the same phase, and combine the at least two signals with the same phase to generate an in-phase signal.

In one embodiment, the second phase conversion circuit is a second broadband bridge, which is used to receive the in-phase signals synthesized by all combiners, perform phase conversion on all the in-phase signals, and synthesize a combined signal.

In one embodiment, the external transmission circuit includes a power divider, wherein:

The power divider is used to distribute the power of the combined signal and send out the signals of different powers through antennas. The number of the antennas is the same as the number of power distribution.

In a second aspect, the present invention provides a signal transmission system, comprising:

Radio remote unit, used to output signals of different frequency bands;

The multi-frequency combining and branching circuit described in any one of the above claims 1-5 is used to perform equal phase conversion, same-phase conversion and synthesis on signals of different frequency bands, and then perform power distribution and externally transmit signals of different powers.

In one embodiment, the system further includes an antenna presence detection unit, and the antenna presence detection unit is used to detect whether the multi-frequency combining and branching circuit is connected to the antenna, and feed back the detection signal to the radio frequency remote unit.

In one embodiment, the system further comprises a standing wave detection unit, and the standing wave detection unit is used to feed back the signal fed back by the port of the antenna to the radio remote unit to calculate the standing wave ratio.

In one embodiment, the system further includes a lightning protection and discharge unit, and the lightning protection and discharge unit is used to discharge the risk signal fed back externally.

The multi-frequency combining and branching circuit and signal transmission system provided by the present invention perform equal phase conversion, same-phase conversion and synthesis on signals in different frequency bands, and then distribute the power and transmit the signals with different powers to eliminate the interference between different frequency bands, improve the isolation between frequency bands, and eliminate the blocking outside the frequency band.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic diagram of the structure of a multi-frequency combining and splitting circuit provided by the present invention;

FIG2 is a structural diagram of a specific example of a multi-frequency combining and splitting circuit provided by the present invention;

FIG3 is another schematic diagram of the structure of the multi-frequency combining and splitting circuit provided by the present invention;

FIG4 is a structural diagram of another specific example of the multi-frequency combining and splitting circuit provided by the present invention;

FIG5 is a schematic diagram of the structure of the signal transmission system provided by the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The multi-frequency combining and splitting circuit and signal transmitting system of the present invention will be described below in conjunction with FIG. 1 to FIG. 5 .

FIG1 shows a schematic diagram of the structure of a multi-frequency combining and dividing circuit of the present invention. Referring to FIG1 , the multi-frequency combining and dividing circuit includes a first phase conversion circuit 11, a combining circuit 12, a second phase conversion circuit 13 and an external transmission circuit 14, wherein:

The first phase conversion circuit 11 is used to perform phase conversion on signals of different frequency bands in equal parts to generate at least two corresponding signals, wherein the phase difference between each signal in the at least two signals is a preset difference value;

A combining circuit 12, used for combining at least two signals with the same phase to generate an in-phase signal;

The second phase conversion circuit 13 is used to receive at least two in-phase signals synthesized by the combining circuit, perform phase conversion on the at least two in-phase signals, and synthesize a combined signal;

The external transmission circuit 14 is used to distribute the power of the combined signal and transmit signals of different powers.

In the present invention, in order to adapt to the signal transmission between different frequency channels, the system is configured with a first phase conversion circuit, which can perform equal phase conversion on the received signals of different frequency bands separately to generate corresponding at least two signals. That is, after the phase conversion, the signal of each frequency band generates at least two signals. For example, after the phase conversion, the 900M signal generates two signals with the same amplitude and a phase difference of 90 degrees. One is a signal with a phase of 0 degrees, and the other is a signal with a phase of 90 degrees. After the phase conversion, the 1.8G signal generates two signals with the same amplitude and a phase difference of 90 degrees, one is a signal with a phase of 0 degrees, and the other is a signal with a phase of 90 degrees. It can be seen that the phase difference between each signal in at least two signals is a preset difference, and the preset difference is set according to the specific situation. In the present invention, when the phase conversion is performed, the signal of each frequency band is converted according to the preset difference to obtain at least two signals with the same phase.

In the present invention, the combining circuit is used to combine signals with the same phase to obtain a combined signal. Since the signal is a combination of multiple signals with the same phase, it can be called a co-phase signal.

For example, a 900M signal is phase-converted to generate a signal with a phase of 0 degrees, and a 1.8G signal is phase-converted to generate a signal with a phase of 0 degrees, and they are synthesized into one signal.

The 900M signal is phase-converted to generate a signal with a phase of 90 degrees, and the 1.8G signal is phase-converted to generate a signal with a phase of 90 degrees, and they are synthesized into one signal.

In the present invention, when the signal separated by the first phase conversion circuit is input into the combining circuit, it will leak into the channel where the signal of other frequency bands is input into the combining circuit through the first phase conversion circuit. Since the signal separated by the signal of other frequency bands is also input into the combining circuit on the channel, the leakage signal will be canceled out on the channel.

For example, after the phase conversion of the 900M signal, the generated signal with a phase of 0 degrees will generate a leakage signal on the channel where the 1.8G signal is input to the combining circuit. The leakage signal is also a signal with a phase of 0 degrees. However, after the phase conversion of the 1.8G signal, the generated signal with a phase of 0 degrees will be input to the combining circuit. Therefore, the leakage signal corresponds to the equally divided signal. Since the phase is 0 degrees, no phase conversion is required and it is regarded as phase cancellation.

For example, after the 900M signal is phase-converted, the generated signal with a phase of 90 degrees will generate a leakage signal on the channel where the 1.8G signal is input to the combiner circuit. The leakage signal is also a signal with a phase of 90 degrees. However, after the 1.8G signal is phase-converted, the generated signal with a phase of 90 degrees will be input to the combiner circuit. Therefore, the leakage signal corresponds to the equally divided signal. Since the phase is 90 degrees, the two signals will have opposite phases and cancel each other out.

Due to the above phase cancellation processing of the leakage signal, the requirement of high isolation can be achieved.

In the present invention, the system is configured with a second phase conversion circuit, which can receive at least two in-phase signals synthesized by the combining circuit, perform phase conversion on the at least two in-phase signals, and synthesize a combined signal.

The second phase conversion circuit includes multiple ports, each port corresponding to each equally divided phase. The synthesized in-phase signals are connected to the corresponding ports according to their respective phases. Then the second phase conversion circuit performs phase conversion and synthesis, synthesizing multiple signals into one signal, which is regarded as a combined signal.

In the present invention, the system is configured with an external transmission circuit, which distributes the power of the combined signal, divides it into signals of different powers, and transmits the signals of different powers externally through corresponding antennas.

The multi-frequency combining and splitting circuit provided by the present invention performs equal phase conversion, same-phase conversion and synthesis on signals in different frequency bands, and then distributes power and transmits signals of different powers to eliminate interference between different frequency bands, improve isolation between frequency bands, and eliminate blocking outside the frequency bands.

In the further description, the structures of the first phase conversion circuit, the combining circuit, the second phase conversion circuit and the external transmission circuit are mainly explained, as follows:

Referring to FIG. 1 , the first phase conversion circuit 11 includes at least two first broadband bridges, wherein:

Each first broadband bridge is used to perform equal phase conversion on the signal of the corresponding frequency band to generate at least two signals, and the phase difference between each signal in the at least two signals is a preset difference value.

The combining circuit 12 includes at least two combiners, wherein:

Each combiner is used to receive at least two signals with the same phase, and combine the at least two signals with the same phase to generate an in-phase signal.

The second phase conversion circuit 13 is a second broadband bridge, which is used to receive the in-phase signals synthesized by all combiners, perform phase conversion on all the in-phase signals, and synthesize a combined signal.

The outgoing circuit 14 includes a power divider, wherein:

The power divider is used to distribute the power of the combined signal and send out the signals of different powers through antennas. The number of the antennas is the same as the number of power distribution.

In this regard, it should be noted that one first broadband bridge receives only one signal, and the frequency bands of the signals received by the various first broadband bridges are different.

The first broadband bridge will perform phase conversion on the received signal in equal parts to generate a preset number (e.g., two) of signals. The phase difference between these signals is configured according to the preset difference. For example, after the phase conversion of a 900M signal, two signals with the same amplitude and a phase difference of 90 degrees are generated. One is a signal with a phase of 0 degrees, and the other is a signal with a phase of 90 degrees.

Each broadband bridge converts the received signal according to the preset phase difference and the number of equal divisions. Therefore, all the equally divided signals will have signals with the same phase. All the signals with the same phase are connected to the same combiner. Therefore, the number of the combiners is the same as the number of equal divisions.

Each combiner will synthesize the multiple signals with the same phase received to generate a signal with the same phase.

In the present invention, there are two or more combiners, and therefore, two or more in-phase signals are obtained. These in-phase signals are connected to the second broadband bridge, which includes ports with different phases and can receive different in-phase signals, and then perform phase conversion on all in-phase signals and synthesize a combined signal.

The combined signal is connected to the power divider, which distributes the power of the combined signal and sends the signals of different powers out through antennas. The number of antennas is the same as the number of power distribution.

The above structure is explained below with a specific example. Referring to FIG. 2 , the multi-frequency combining and splitting circuit is composed of four first broadband bridges, one second broadband bridge, two combiners, and one power divider.

The four first broadband bridges realize the functions of one-to-two division and phase conversion, and are used to convert the signal into two signals with the same amplitude and a phase difference of 90°.

The combiner is used to combine the separated signals.

A second broadband bridge is used for signal combining and phase conversion.

The power divider is used to achieve power distribution of combined signals.

Broadband antennas are used to achieve coverage of signal transmission.

Take 900M signal as an example.

A. Signal main road:

After the 900M signal passes through the corresponding first broadband bridge, it is divided into two signals with the same amplitude and a phase difference of 90 degrees. One of the signals passes through combiner 1 and is combined with the other three signals that have also been divided and phase-changed. For example, the signal frequency band and power output by combiner 1 are 1/2*(900M+1.8G+2.3G+2.6G), and the phase is 0°. Similarly, the signal frequency band and power output by combiner 2 are 1/2*(900M+1.8G+2.3G+2.6G), and the phase is 90°. After the two signals are combined and phase-changed by the second broadband bridge, due to the characteristics of the bridge, the two signals are directly superimposed, and the input signal at the entrance of the power divider, that is, the output signal of the second broadband bridge, is 1*(900M+1.8G+2.3G+2.6G), with a phase of 90°. Then the power divider output is obtained, and the signal output by the broadband antenna is 0.5*(900M+1.8G+2.3G+2.6G), with a phase of 90°

B. Leakage signal pathway:

After the 900M signal passes through the corresponding broadband bridge, it is equally divided into two signals with the same amplitude and a phase difference of 90 degrees. One signal will leak to the other three channels (1.8G+2.3G+2.6G) at combiner 1 with a phase of 0°. The second signal will also leak to the other three channels (1.8G+2.3G+2.6G) at combiner 2 with a phase of 90°. These leakage signals are combined at the corresponding broadband bridges, where the 0° signal does not undergo a phase change, and the 90° signal undergoes a 90° phase change again, which will cause the two signals to have opposite phases and cancel each other out, so the high isolation requirement can be achieved.

The multi-frequency combining and splitting circuit provided by the present invention performs equal phase conversion, same-phase conversion and synthesis on signals in different frequency bands, and then distributes power and transmits signals of different powers to eliminate interference between different frequency bands, improve isolation between frequency bands, and eliminate blocking outside the frequency bands.

Referring to FIG. 3 , the present invention further provides a multi-frequency combining and branching circuit, comprising a first phase conversion circuit 31, a second phase conversion circuit 32 and an external transmission circuit 33, wherein:

The first phase conversion circuit 31 is used to perform phase conversion on signals of different frequency bands in equal parts to generate at least two corresponding signals; synthesize at least two signals with the same phase to generate an in-phase signal; the phase difference between each signal in the at least two signals is a preset difference;

The second phase conversion circuit 32 is used to perform phase conversion again on all equally phase-converted signals and synthesize a combined signal;

The external transmission circuit 33 is used to distribute the power of the combined signal and transmit signals with different powers.

The first phase conversion circuit comprises at least two filter bridges, wherein:

Each filter bridge is used to perform phase conversion on the signal of the corresponding frequency band in equal parts to generate at least two signals; the phase difference between each signal in the at least two signals is a preset difference value;

At least two filter bridges are used to jointly synthesize at least two signals with the same phase to generate an in-phase signal.

The second phase conversion circuit is a broadband bridge, which is used to receive the in-phase signals synthesized by all combiners, perform phase conversion on all the in-phase signals, and synthesize a combined signal.

The outgoing circuit includes a power divider, wherein:

The power divider is used to distribute the power of the combined signal and send it out through antennas. The number of antennas is the same as the number of power distribution.

In this regard, it should be noted that, referring to FIG4, four filter bridges are used to replace the four broadband bridges + two combiners in FIG2. This makes the circuit more concise and achieves the same function.

In the present invention, the signal combination can be directly connected by electrical connection, and the impedance mismatch characteristics of the filter outside the band are applied here. For example, the bandpass filter of the 900M signal is in an impedance mismatch state in the 1.8G/2.3G/2.6G frequency band, and most of the signal will be reflected and will not pass. Therefore, through direct electrical connection, as for the requirement of high isolation, the analog cancellation method can be used to improve it.

FIG5 shows a schematic diagram of the structure of a signal transmission system provided by the present invention. Referring to FIG5 , the system includes:

A radio remote unit PRRU 51 is used to output signals of different frequency bands;

The multi-frequency combining and splitting circuit 52 mentioned above is used to perform equal phase conversion, same-phase conversion and synthesis on signals of different frequency bands, and then perform power distribution and transmit signals of different powers.

Based on the above explanation of the multi-frequency combining and dividing circuit, the multi-frequency combining and dividing circuit will not be elaborated on in detail here.

Refer to Figure 5. The main signal path in the figure is the transmission direction of the RF signal for combining and splitting. The signal is sent out through the PRRU, and the RF connector on the multi-frequency combining and splitting circuit contacts the signal transmission point on the PRRU's PCB (printed circuit board) to lead out the signal, and then enter the combining and splitting circuit after filtering out the DC signal through the DC blocking capacitor. After the signal is combined and split, it enters the direct path of the circulator through the DC blocking capacitor to directly connect to the external RF connector or RF cable and then connect to the antenna.

The system also includes an antenna presence detection unit 53, which is used to detect whether the multi-frequency combination and branching circuit is connected to the antenna and feed back the detection signal to the radio remote unit.

When there is no antenna connected to the outside, that is, the antenna is not in place, the outside is in an open circuit state. When there is an antenna connected to the outside, that is, the antenna is in place, the outside is in a grounded state. In these two states, different level signals will be fed back to the PRRU, and then the antenna can be judged by logic level. The inductance/resistance in the path is mainly used to block the RF signal. The TVS tube is in a straight-through state at this time and does not affect the level signal transmission.

The system further comprises a standing wave detection unit 54, which is used to feed back the signal fed back from the port of the antenna to the radio remote unit to calculate the standing wave ratio.

The signal reflected from the antenna port is mainly fed back to the PRRU for judgment, and the standing wave ratio is calculated by judging the amplitude of the main signal and the reflected signal. Due to the directivity of the circulator, the reflected signal will not pass through the main signal path and will not affect it.

The system further comprises a lightning protection and discharge unit 55, wherein the lightning protection and discharge unit is used to discharge the risk signal fed back from the outside.

When there are external dangerous signals such as lightning strikes and surges, the dangerous signals are discharged through the ground through the discharge unit, that is, the path of inductor-TVS tube-ground, and the risk of sparking or damaging the PRRU is also avoided. It should be noted that the capacitor behind the shunt circuit needs to be a capacitor with a relatively high withstand voltage.

The signal transmission system provided by the present invention can adapt the multi-frequency combining and branching circuit to the PRRU structure, and is independently embedded inside the base station, without affecting the original structure and realizing structural simplification and integration in combination with actual needs. There is no need to use RF cables to connect external combiners to cause structural redundancy, so that the multi-frequency combining and branching circuit can be placed inside the PRRU structure. From the outside, there is no difference from the built-in model, and the PRRU can be conveniently calibrated at the same workstation. It can be applied to large open spaces (for example: stadiums, stations, airports) to reduce coverage overlap areas and thus reduce interference/increase capacity, and can be applied to elevator shafts to increase antenna gain and thus increase coverage distance, while also reducing costs.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A multi-frequency combining and splitting circuit, comprising:

The first phase conversion circuit is used for respectively carrying out equal-division phase conversion on signals in different frequency bands to generate at least two corresponding signals, and the phase difference between the signals in the at least two signals is a preset difference value; when the phase of the signals of each frequency band is converted, conversion processing is carried out according to the preset difference value, so that at least two signals with the same phase are obtained;

The combining circuit is used for respectively combining at least two signals with the same phase to generate an in-phase signal;

The second phase conversion circuit is used for receiving at least two same-phase signals synthesized by the combining circuit, carrying out phase conversion on the at least two same-phase signals and synthesizing a combined signal;

And the outgoing circuit is used for distributing power to the combined signal and outgoing signals with different powers.

2. The multi-frequency combining and splitting circuit of claim 1, wherein the first phase conversion circuit comprises at least two first broadband bridges, wherein:

Each first broadband bridge is used for carrying out halving phase conversion on signals of corresponding frequency bands to generate at least two signals, and the phase difference between the signals in the at least two signals is a preset difference value.

3. The multi-frequency combining and splitting circuit of claim 2, wherein the combining circuit comprises at least two combiners, wherein:

each combiner is used for receiving at least two signals with the same phase, and synthesizing the at least two signals with the same phase to generate one same-phase signal.

4. The multi-frequency combining and splitting circuit of claim 3, wherein the second phase conversion circuit is a second broadband bridge for receiving the in-phase signals synthesized by all the combiners, performing phase conversion on all the in-phase signals, and synthesizing a combined signal.

5. The multi-frequency combining and splitting circuit of claim 4, wherein the external power generation circuit comprises a power divider, wherein:

and the power divider is used for distributing power to the combined signal and transmitting signals with different powers through antennas, wherein the number of the antennas is the same as the number of the distributed power.

6. A signal transmission system, comprising:

the remote radio unit is used for outputting signals of different frequency bands;

the multi-frequency combining and splitting circuit according to any one of claims 1-5 is used for equally dividing, phase-converting and synthesizing signals in different frequency bands, then distributing power, and transmitting signals in different powers.

7. The signal transmitting system of claim 6, further comprising an antenna in-place detecting unit for detecting whether the multi-frequency combining and splitting circuit is connected to the antenna and feeding back the detected signal to the remote radio unit.

8. The signal transmission system of claim 7, further comprising a standing wave detection unit for feeding back a signal fed back by a port of the antenna to the remote radio unit to calculate the standing wave ratio.

9. The signal transmission system of claim 8, further comprising a lightning protection bleed unit for bleeding off an externally fed risk signal.

10. The signal transmission system of claim 9, wherein the lightning protection bleed unit comprises a TVS tube, the TVS tube being grounded.