CN112822131A - Adjacent channel suppression circuit and adjacent channel suppression method - Google Patents
Adjacent channel suppression circuit and adjacent channel suppression method Download PDFInfo
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Abstract
The invention provides an adjacent channel suppression circuit and an adjacent channel suppression method, which comprise the following steps: the device comprises a first frequency conversion module, a filtering module and a second frequency conversion module; the first frequency conversion module is used for converting the original signal received by the antenna into a first filtering signal in a down-conversion mode according to the bandwidth of the target channel; the filtering module is connected with the first frequency conversion module and used for carrying out band-pass filtering on the first filtering signal to obtain a second filtering signal; the second frequency conversion module is connected with the filtering module and is used for up-converting the second filtering signal into an output signal; wherein the frequency range of the original signal is the same as the frequency range of the output signal. The adjacent channel suppression circuit and the adjacent channel suppression method provided by the invention can effectively filter signals in the adjacent channel or the secondary adjacent channel, can improve the adjacent channel suppression ratio of the target channel, can improve the adjacent channel interference of the target channel, and can improve the data throughput of the target channel.
Description
Technical Field
The present invention relates to the field of wireless communication technologies, and in particular, to an adjacent channel suppression circuit and an adjacent channel suppression method.
Background
The 5G Wi-Fi is Wi-Fi which runs in a 5Ghz frequency band and adopts an 802.11ac protocol, and the 5G Wi-Fi has higher wireless transmission speed compared with 2.4G Wi-Fi. Theoretically, the working frequency band of 5G Wi-Fi can be distributed in the range of 4910 MHz-5835 MHz, and the working frequency band comprises a plurality of channels.
A Channel (Channel) is also called a Channel, a frequency band, and is a data signal transmission Channel in which a radio signal is used as a transmission carrier. Various wireless network devices may use different channels within the wireless signal coverage. An Adjacent Channel (Adjacent Channel) refers to a Channel whose frequency is immediately Adjacent to the target Channel. Adjacent Channel Interference (ACI) refers to Interference caused by signals in Adjacent channels. The adjacent channel interference will seriously affect the data throughput of the wireless local area network. The adverse effect of Adjacent Channel interference on the data throughput of the wireless local area network can be improved through Adjacent Channel Rejection (ACR), and the higher the Adjacent Channel Rejection ratio, the smaller the interference of the Adjacent Channel on the target Channel is.
In the prior art, a band-pass filter is adopted to filter 5G Wi-Fi signals, the band-pass range of the band-pass filter is between 5GHz and 6GHz, interference signals of adjacent channels existing in channels in the band-pass range are difficult to filter, and therefore the adjacent channels are low in inhibition.
Disclosure of Invention
The invention provides an adjacent channel suppression circuit and an adjacent channel suppression method, which are used for solving the defect of low adjacent channel suppression ratio of a 5G Wi-Fi signal in the prior art and realizing the improvement of the adjacent channel suppression ratio of the 5G Wi-Fi signal.
The present invention provides an adjacent channel suppression circuit, including: the device comprises a first frequency conversion module, a filtering module and a second frequency conversion module;
the first frequency conversion module is used for converting the original signal received by the antenna into a first filtering signal in a down-conversion mode according to the bandwidth of the target channel;
the filtering module is connected with the first frequency conversion module and is used for carrying out band-pass filtering on the first filtering signal to obtain a second filtering signal;
the second frequency conversion module is connected with the filtering module and is used for up-converting the second filtering signal into an output signal;
wherein the frequency range of the original signal is the same as the frequency range of the output signal.
According to an adjacent channel suppression circuit provided by the present invention, the filtering module includes: a plurality of filtering sub-modules;
each filtering submodule corresponds to different bandwidths respectively;
and the filtering submodule is used for carrying out band-pass filtering according to the bandwidth corresponding to the filtering submodule.
According to an adjacent channel suppression circuit provided by the present invention, further comprising: a local oscillator signal generating module;
the local oscillator signal generating module is respectively connected with the first frequency conversion module and the second frequency conversion module, and is configured to generate a local oscillator signal according to the bandwidth of the target channel, the center frequency of the target channel, and the center frequency of the filtering module, and respectively send the local oscillator signal to the first frequency conversion module and the second frequency conversion module.
According to an adjacent channel suppression circuit provided by the present invention, further comprising: a first switching module;
the first switching module is respectively connected with the first frequency conversion module and each filtering submodule, and is configured to switch the first filtering signal into the corresponding filtering submodule with a bandwidth that is the same as the bandwidth of the target channel.
According to an adjacent channel suppression circuit provided by the present invention, further comprising: a second switching module;
the second switching module is respectively connected with each filtering submodule and the second frequency conversion module, and is configured to transmit the second filtering signal output by any one of the filtering submodules to the second frequency conversion module.
According to an adjacent channel suppression circuit provided by the present invention, further comprising: the device comprises a first low-noise amplification module, a first radio frequency filtering module, a second radio frequency filtering module and a second low-noise amplification module;
the first low-noise amplification module is respectively connected with the antenna and the first radio frequency filtering module;
the first radio frequency filtering module is connected with the first frequency conversion module;
the second radio frequency filtering module is respectively connected with the second frequency conversion module and the second low noise amplification module.
The invention provides an adjacent channel suppression method, which comprises the following steps:
down-converting an original signal received through an antenna into a first filtered signal according to the bandwidth of a target channel;
performing band-pass filtering on the first filtering signal to obtain a second filtering signal;
up-converting the second filtered signal into an output signal;
wherein the frequency range of the original signal is the same as the frequency range of the output signal.
According to the adjacent channel suppression method provided by the present invention, the band-pass filtering is performed on the first filtered signal to obtain a second filtered signal, and the method specifically includes:
and performing band-pass filtering on the first filtering signal through a corresponding band-pass filter with the same bandwidth as that of the target channel to obtain the second filtering signal.
According to the adjacent channel suppression method provided by the present invention, before down-converting an original signal received through an antenna into a first filtered signal according to a bandwidth of a target channel, the method further includes:
acquiring a local oscillator signal according to the bandwidth of the target channel, the central frequency of the target channel and the central frequency of the band-pass filter;
correspondingly, the down-converting an original signal received through an antenna into a first filtered signal according to the bandwidth of the target channel specifically includes:
and mixing the original signal with the local oscillation signal to obtain the first filtering signal.
According to the adjacent channel suppression method provided by the present invention, the upconverting the second filtered signal into an output signal specifically includes:
and mixing the second filtering signal with the local oscillation signal to obtain the output signal.
According to the adjacent channel suppression circuit and the adjacent channel suppression method provided by the invention, the first frequency conversion module is used for converting the high-frequency original signal into the intermediate-frequency first filtering signal in a down-conversion mode, so that the filtering module with smaller bandwidth is used for filtering the first filtering signal to obtain the second filtering signal, the second frequency conversion module is used for converting the second filtering signal into the output signal with the same frequency range as that of the original signal in an up-conversion mode, signals in an adjacent channel or a secondary adjacent channel can be effectively filtered, the adjacent channel suppression ratio of a target channel can be improved, the adjacent channel interference of the target channel can be improved, and the data throughput of the target channel can be improved.
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In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an adjacent channel suppression circuit provided in the present invention;
fig. 2 is a second schematic structural diagram of an adjacent channel suppression circuit provided in the present invention;
fig. 3 is a third schematic diagram of the adjacent channel suppression circuit provided in the present invention;
fig. 4 is a flowchart illustrating an adjacent channel suppression method according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Fig. 1 is a schematic structural diagram of an adjacent channel suppression circuit provided in the present invention. The adjacent channel suppression circuit of the present invention is described below in conjunction with fig. 1. As shown in fig. 1, the adjacent channel rejection circuit includes: a first frequency conversion module 101, a filtering module 102 and a second frequency conversion module 103.
A first frequency conversion module 101, configured to down-convert an original signal received through an antenna into a first filtered signal according to a bandwidth of a target channel.
In particular, the output of the first frequency conversion module 101 may be connected with the filtering module 102. The input terminal of the first frequency conversion module 101 may be directly connected to the antenna, or may be connected to the antenna through another element (e.g., a power amplification element). An original signal received by an antenna is input to the first frequency conversion module 101 through an input end of the first frequency conversion module 101.
The original signal received by the antenna is a high-frequency signal of 5G Wi-Fi, wherein the high-frequency signal comprises a signal in a target channel and signals in other channels such as an adjacent channel and a secondary adjacent channel. Signals in the adjacent channel or the secondary adjacent channel can generate adjacent channel interference on signals in the target channel, and the data throughput of the target channel is reduced.
In a 5G Wi-Fi environment, theoretically, the frequency of the original signal received by the antenna may be 4910 MHz-5835 MHz, and the bandwidth of each channel included in the original signal may be 20MHz, 40MHz, or 80MHz, etc.
The first frequency conversion module 101 may down-convert a high-frequency original signal into an intermediate-frequency first filtered signal according to a bandwidth of a target channel, and send the first filtered signal to the filtering module 102 through an output end of the first frequency conversion module 101.
And the filtering module 102 is connected with the first frequency conversion module 101 and is configured to perform band-pass filtering on the first filtered signal to obtain a second filtered signal.
Specifically, the bandwidth of the filtering module 102 is smaller and may be the same as the bandwidth of the target channel, so that the second filtered signal includes the intermediate frequency signal corresponding to the signal in the target channel, and the intermediate frequency signals corresponding to the signals in the adjacent channel and the next adjacent channel of the target channel in the second filtered signal are fewer.
It should be noted that the Intermediate Frequency (IF) signal is a signal obtained by Frequency-converting a high Frequency signal. The frequency range of the intermediate frequency signal may be between 500MHz and 3 GHz.
And a second frequency conversion module 103, connected to the filtering module 102, for up-converting the second filtered signal into an output signal.
Wherein the frequency range of the original signal is the same as the frequency range of the output signal.
In particular, the second filtered signal may be sent to the second frequency conversion module 103 through an output of the filtering module 102. The second frequency conversion module 103 may up-convert the second filtered signal of the intermediate frequency into an output signal having the same frequency range as the original signal. The output signal comprises a signal in a target channel, and signals in adjacent channels and secondary adjacent channels of the target channel in the output signal are fewer.
In the prior art, a band-pass filter for performing band-pass filtering on an original signal received by an antenna has a bandwidth between 5GHz and 6GHz, which is much larger than the bandwidth of a target channel, an adjacent channel or a secondary adjacent channel. Therefore, in the prior art, a band-pass filter applied to a high-frequency signal is difficult to perform band-pass filtering on signals in different channels with smaller bandwidths, so that adjacent channel rejection of a target channel is lower, and data throughput of the target channel is reduced.
It should be noted that, the adjacent channel suppression circuit in the embodiment of the present invention may improve the adjacent channel suppression ratio of the target channel by accessing the original circuits of various receivers.
In particular, the access location of the adjacent channel suppression circuit may be between the antenna and an electrical element adjacent to the antenna. The input end of the adjacent channel suppression circuit is connected with the antenna, and the output end of the adjacent channel suppression circuit is connected with the electrical element. After the adjacent channel suppression circuit is connected to the original circuit of the receiver, the original signal received by the antenna is not directly input to the electrical element adjacent to the antenna, but is changed into an output signal which has the same frequency range as the original signal, comprises the signal of the target channel and comprises fewer signals of the adjacent channel and the secondary adjacent channel after passing through the adjacent channel suppression circuit, and then returns to the original circuit of the receiver to output the electrical element adjacent to the antenna.
By the adjacent channel suppression circuit in the embodiment of the invention, the suppression capability of the adjacent channel signal of the target channel can be improved by 3-8 dB, and the suppression capability of the adjacent channel signal of the secondary channel can be improved by more than 18 dB.
According to the embodiment of the invention, the first frequency conversion module is used for down-converting a high-frequency original signal into an intermediate-frequency first filtering signal, so that the filtering module with a smaller bandwidth is used for filtering the first filtering signal to obtain a second filtering signal, the second frequency conversion module is used for up-converting the second filtering signal into an output signal with the same frequency range as that of the original signal, signals in an adjacent channel or a secondary adjacent channel can be effectively filtered, the adjacent channel rejection ratio of a target channel can be improved, the adjacent channel interference of the target channel can be improved, and the data throughput of the target channel can be improved.
Fig. 2 is a second schematic structural diagram of the adjacent channel suppression circuit provided in the present invention. The adjacent channel suppression circuit of the present invention is described below in conjunction with fig. 2. As shown in fig. 2, the filtering module 102 in the adjacent channel rejection circuit includes: a plurality of filtering sub-modules 201.
Each filtering submodule 201 corresponds to a different bandwidth.
Specifically, each filtering submodule 201 in the filtering module 102 may correspond to a different bandwidth. The filtering submodule 201 has different corresponding bandwidths and center frequencies, and the filtering submodule 201 can perform filtering in different frequency ranges.
The filtering module 102 in the embodiment of the present invention is described below by way of an example.
The filtering module 102 may include three filtering sub-modules 201, and the three filtering sub-modules 201 may correspond to 20MHz, 40MHz, and 80MHz bandwidths, respectively. The filtering submodule 201 corresponding to the 20MHz bandwidth may include a radio frequency SAW filter with a model SF2208E, the center frequency is 1227MHz, and the frequency range is 1207 MHz-1247 MHz; the filtering submodule 201 corresponding to the bandwidth of 40MHz may include a radio frequency SAW filter with the model of SF2211E, the center frequency is 1200MHz, and the frequency range is 1160 MHz-1240 MHz; the filtering submodule 201 corresponding to the 80MHz bandwidth may include a radio frequency SAW filter with a model SF2393E, a center frequency of 1570MHz, and a frequency range of 1490MHz to 1650 MHz.
And the filtering submodule 201 is configured to perform band-pass filtering according to a bandwidth corresponding to the filtering submodule 201.
Specifically, different filter sub-modules 201 have different bandwidths, and allow different frequency ranges of signals to pass through. The filtering submodule 201 may perform band-pass filtering on the passed signal according to a bandwidth corresponding to the filtering submodule 201.
According to the embodiment of the invention, the signals passing through the filtering submodules are subjected to band-pass filtering through the plurality of filtering submodules respectively corresponding to different bandwidths in the filtering module, so that the intermediate frequency signals with a smaller frequency range can be subjected to band-pass filtering, and the adjacent channel suppression circuit can be suitable for adjacent channel suppression of target channels with different bandwidths.
Based on the content of the foregoing embodiments, the local oscillation signal generating module 202.
The local oscillation signal generating module 202 is connected to the first frequency conversion module 101 and the second frequency conversion module 103, and configured to generate a local oscillation signal according to the bandwidth of the target channel, the center frequency of the target channel, and the center frequency of the filtering module 102, and send the local oscillation signal to the first frequency conversion module 101 and the second frequency conversion module 103, respectively.
The local oscillation signal generating module 202 may generate a local oscillation signal according to the center frequency of the filtering module 102 and the center frequency of the target channel.
Specifically, the frequency of the first filtered signal obtained by the first frequency conversion module 101 down-converting the original signal needs to match the center frequency of the filtering module 102. By calculating the difference between the center frequency of the target channel and the center frequency of the filtering module 102, the frequency of the required local oscillator signal can be obtained. According to the frequency of the local oscillation signal, the local oscillation signal generating module 202 may generate the local oscillation signal of the frequency.
After the local oscillation signal generating module 202 generates the local oscillation signal, the local oscillation signal is sent to the first frequency conversion module 101, so that the first frequency conversion module 101 may mix the local oscillation signal with the original signal to obtain a first filtering signal of the intermediate frequency.
The local oscillator signal generating module 202 may further send the local oscillator signal to the second frequency conversion module 103, so that the second frequency conversion module 103 may mix the original signal with the second filtered signal of the intermediate frequency to obtain an output signal with a frequency range the same as that of the original signal.
It should be noted that the local oscillation signal generating module 202 in the embodiment of the present invention may include a programmable voltage controlled oscillator of the TRF3765, where a frequency range of the local oscillation signal output by the programmable voltage controlled oscillator is 300MHz to 4.8 GHz. The programmable voltage controlled oscillator may generate the local oscillation signal according to the bandwidth of the target channel, the center frequency of the target channel, and the center frequency of the filtering module 102 (or the corresponding filtering submodule 201 having the same bandwidth as the bandwidth of the target channel), and send the local oscillation signal to the first frequency conversion module 101 and the second frequency conversion module 103, respectively.
According to the embodiment of the invention, the local oscillator signal is generated by the local oscillator signal generating module according to the bandwidth of the target channel, the central frequency of the target channel and the central frequency of the filtering module, and is respectively sent to the first radio frequency module and the second radio frequency module, so that the first radio frequency module and the second radio frequency module respectively mix the local oscillator signal with the original signal and the second filtering signal, the down-conversion of the original signal and the up-conversion of the second filtering signal are realized, and the requirement of signal frequency conversion when the adjacent channel of the target channel is inhibited can be met.
Based on the content of the above embodiments, the method further includes: a first switching module 203.
And the first switching module 203 is respectively connected to the first frequency conversion module 101 and each of the filtering sub-modules 201, and is configured to switch the first filtered signal into the corresponding filtering sub-module 201 having the same bandwidth as the target channel.
Specifically, the first switching module 203 may include one input terminal and a plurality of output terminals, and the input terminal can only be conducted with one output terminal.
The input end of the first switching module 203 is connected to the output end of the first frequency conversion module 101, and each output end of the first switching module 203 is connected to each filtering sub-module 201.
The first switching module 203 may switch the first filtering signal into the filtering submodule 201 having the same bandwidth as the target channel according to the bandwidth of the target channel and the bandwidth of the filtering submodule 201, so that the filtering submodule 201 may filter the first filtering signal, retain the intermediate frequency signal corresponding to the signal in the target channel, and effectively filter the intermediate frequency signals corresponding to the signals in other channels, such as the adjacent channel and the secondary adjacent channel.
It should be noted that the first switching unit in the embodiment of the present invention may include a single-pole multi-throw switch, an input end of the single-pole multi-throw switch is connected to an output end of the first frequency conversion module 101, and each output end is connected to each filter submodule 201. In the embodiment of the present invention, the first filtering signal may be switched into the corresponding filtering sub-module 201 with the same bandwidth as the target channel by controlling the GPI/O.
It should be noted that GPI/O is a short term for General Purpose input/output (General Purpose I/O), and its pins can be freely used by user through program control.
According to the embodiment of the invention, the first filtering signal is switched into the corresponding filtering submodule with the same bandwidth as the target channel through the first switching module, so that the filtering submodule can filter the first filtering signal, the adjacent channel suppression circuit is suitable for adjacent channel suppression of the target channels with different bandwidths, and the adjacent channel suppression ratio of the target channel can be improved.
Based on the content of the above embodiments, the second switching module 204.
The second switching module 204 is connected to each of the filtering sub-modules 201 and the second frequency conversion module 103, and is configured to transmit a second filtering signal output by any one of the filtering sub-modules 201 to the second frequency conversion module 103.
Specifically, the second switching module 204 may include a plurality of inputs and an output.
Each input end of the second switching module 204 is connected to each filtering sub-module 201, and the output end of the second switching module 204 is connected to the second frequency conversion module 103.
It should be noted that only one filtering submodule 201 in the filtering module 102 has a signal passing through, and a second filtering signal output by any filtering submodule 201 in the filtering module 102 may be transmitted to the second frequency conversion module 103 through the second switching module 204.
According to the embodiment of the invention, the second switching module is used for transmitting the second filtering signal output by any filtering submodule to the second frequency conversion module, and the second filtering signal output by any filtering submodule in the filtering module can be transmitted to the second frequency conversion module.
Fig. 3 is a third schematic diagram of the adjacent channel suppression circuit according to the present invention. The adjacent channel rejection circuit of the present invention is described below in conjunction with fig. 3. As shown in fig. 3, the adjacent channel rejection circuit further includes: a first low noise amplification module 301, a first radio frequency filtering module 302, a second radio frequency filtering module 303 and a second low noise amplification module 304.
The first low noise amplification module 301 is connected to the antenna and the first rf filtering module 302, respectively.
Specifically, the power of the original signal received by the antenna is small. The first low noise amplification module 301 may be used as a pre-amplifier to amplify the power of the original signal to obtain a power-amplified original signal. Due to the characteristics of the first low noise amplification module 301, the signal-to-noise ratio of the power amplified original signal is small.
The low noise amplifier sends the power amplified original signal to the first rf filtering module 302. The first rf filtering module 302 filters the power-amplified original signal, so as to effectively filter the interference signal outside the bandwidth range, and obtain the power-amplified and filtered original signal.
It should be noted that, after being amplified by the low noise amplifier, the original signal received by the antenna not only includes signals of other channels, such as the target channel, an adjacent channel of the target channel, and a secondary adjacent channel, but also may include an interference signal outside the 5G Wi-Fi frequency band or an interference signal generated by the first low noise amplification module 301.
It should be noted that the bandwidth of the first rf filter module 302 is between 5GHz and 6GHz, and signals with a frequency range between 5GHz and 6GHz can be allowed to pass through.
The first rf filtering module 302 is connected to the first frequency conversion module 101.
The first rf filtering module 302 sends the power-amplified and filtered original signal to the first frequency conversion module 101, so that the first frequency conversion module 101 can down-convert the filtered original signal into a first filtered signal.
The second rf filtering module 303 is respectively connected to the second frequency conversion module 103 and the second low noise amplification module 304.
The second frequency conversion module 103 may send the output signal to the second rf filtering module 303. The second radio frequency module filters the output signal, so that interference signals outside a bandwidth range can be effectively filtered, and the filtered output signal is obtained.
It should be noted that the output signal not only includes the signal of the target channel, but also may include an interference signal generated by the first frequency conversion module 101, the filtering module 102, or the second frequency conversion module 103.
It should be noted that the bandwidth of the second rf filter module 303 is between 5GHz and 6GHz, and signals with a frequency range between 5GHz and 6GHz can be allowed to pass through.
After obtaining the filtered output signal, the second rf filtering module 303 sends the filtered output signal to the second low noise amplifying module 304. The second low noise amplification module 304 may amplify the filtered output signal to obtain a filtered and power amplified output signal.
The second low noise amplification module 304 may send the filtered and power amplified output signal to electrical components in the receiver that would otherwise be connected to the antenna.
According to the embodiment of the invention, the power of the original signal is amplified by the first low-noise amplification module, the original signal with the amplified power is filtered by the first radio frequency filtering module, the corrected original signal can be provided for the adjacent channel inhibition of the target channel, the intermediate frequency signal corresponding to the signal in the adjacent channel or the secondary adjacent channel in the first filtering signal can be effectively filtered, the output signal is filtered by the second radio frequency filtering module, the power of the output signal is amplified by the second low-noise amplification module, the adjacent channel inhibition ratio of the target channel can be further improved, and the data throughput of the target channel can be further improved.
Fig. 4 is a flowchart illustrating an adjacent channel suppression method according to the present invention. The adjacent channel suppression method of the present invention is described below in conjunction with fig. 4. As shown in fig. 4, the adjacent channel suppression method includes: step 401, down-converting an original signal received through an antenna into a first filtered signal according to a bandwidth of a target channel.
It should be noted that the main execution body of the adjacent channel suppression method in the embodiment of the present invention is the adjacent channel suppression circuit in any of the above embodiments.
Specifically, the first frequency conversion module in the adjacent channel rejection circuit may down-convert an original signal received through the antenna into a first filtered signal according to a bandwidth of the target channel.
The original signal received by the antenna is a high-frequency signal of 5G Wi-Fi, wherein the high-frequency signal comprises a signal in a target channel and signals in other channels such as an adjacent channel and a secondary adjacent channel. Signals in the adjacent channel or the secondary adjacent channel can generate adjacent channel interference on signals in the target channel, and the data throughput of the target channel is reduced.
In a 5G Wi-Fi environment, theoretically, the frequency of the original signal received by the antenna may be 4910 MHz-5835 MHz, and the bandwidth of the channel included in the original signal may be 20MHz, 40MHz, or 80MHz, etc.
The first frequency conversion module can convert a high-frequency original signal into a first filtering signal of an intermediate frequency in a down-conversion mode according to the bandwidth of the target channel, and sends the first filtering signal to the filtering module in the adjacent channel suppression circuit, so that the filtering module can perform band-pass filtering on the first filtering signal.
In particular, the bandwidth of the filtering module is smaller and may be the same as the bandwidth of the target channel. Therefore, when the filtering module performs band-pass filtering on the first filtering signal, the band-pass filtering may be performed on the intermediate frequency signal corresponding to the signal in the current channel and the intermediate frequency signal corresponding to the signal in the adjacent channel or the secondary adjacent channel of the current channel to obtain the second filtering signal. The second filtered signal includes intermediate frequency signals corresponding to signals in the target channel, and the intermediate frequency signals corresponding to signals in adjacent channels and secondary adjacent channels of the target channel in the second filtered signal are fewer.
It should be noted that the Intermediate Frequency (IF) signal is a signal obtained by Frequency-converting a high Frequency signal. The frequency range of the intermediate frequency signal may be between 500MHz and 3 GHz.
Wherein the frequency range of the original signal is the same as the frequency range of the output signal.
Specifically, the second frequency conversion module in the adjacent channel rejection circuit may up-convert the second filtered signal of the intermediate frequency into an output signal having the same frequency range as the original signal. The output signal comprises a signal in a target channel, and signals in adjacent channels and secondary adjacent channels of the target channel in the output signal are fewer.
In the prior art, a band-pass filter for performing band-pass filtering on an original signal received by an antenna has a bandwidth between 5GHz and 6GHz, which is much larger than the bandwidth of a target channel, an adjacent channel or a secondary adjacent channel. Therefore, in the band-pass filter applied to high-frequency signals in the prior art, it is difficult to perform band-pass filtering on signals in different channels with different bandwidths, so that the adjacent channel rejection of a target channel is relatively low, and the data throughput of the target channel is reduced. It should be noted that, in the adjacent channel suppression method in the embodiment of the present invention, the suppression capability of the adjacent channel signal of the target channel can be improved by 3-8 dB, and the suppression capability of the next adjacent channel signal can be improved by more than 18 dB.
According to the embodiment of the invention, the high-frequency original signal is converted into the intermediate-frequency first filtering signal through down-conversion, so that the second filtering signal is obtained after the first filtering signal is filtered, and the second filtering signal is up-converted into the output signal with the same frequency range as the original signal, so that the signals in the adjacent channel or the secondary adjacent channel can be effectively filtered, the adjacent channel rejection ratio of the target channel can be improved, the adjacent channel interference of the target channel can be improved, and the data throughput of the target channel can be improved.
Based on the content of the foregoing embodiments, performing band-pass filtering on the first filtered signal to obtain a second filtered signal specifically includes:
and performing band-pass filtering on the first filtering signal through a corresponding band-pass filter with the same bandwidth as that of the target channel to obtain a second filtering signal.
In particular, the filtering submodule in the adjacent channel rejection circuit may comprise a band pass filter.
The plurality of band pass filters may correspond to a plurality of different bandwidths. The band-pass filters have different corresponding bandwidths and different center frequencies, and the band-pass filters can filter different frequency ranges. The bandpass filter in the embodiment of the present invention is described below by way of an example.
The adjacent channel suppression circuit may include three band pass filters, and the three band pass filters may correspond to 20MHz, 40MHz, and 80MHz bandwidths, respectively. The band-pass filter corresponding to the 20MHz bandwidth can comprise a radio frequency SAW filter with the model SF2208E, the center frequency is 1227MHz, and the frequency range is 1207 MHz-1247 MHz; the band-pass filter corresponding to the 40MHz bandwidth can comprise a radio frequency SAW filter with the model SF2211E, the central frequency is 1200MHz, and the frequency range is 1160 MHz-1240 MHz; the band-pass filter corresponding to the 80MHz bandwidth may include a radio frequency SAW filter of SF2393E, the center frequency is 1570MHz, and the frequency range is 1490MHz to 1650 MHz.
Different bandpass filters have different corresponding bandwidths and allow different frequency ranges of signals to pass through. The band-pass filter may perform band-pass filtering on the passed signal according to a bandwidth corresponding to the band-pass filter.
Specifically, according to the bandwidth of the target channel and the band-pass of the band-pass filter, the first filtering signal may be input to the band-pass filter having a corresponding bandwidth that is the same as the bandwidth of the target channel, so that the band-pass filter may filter the first filtering signal, and effectively filter signals of other channels such as an adjacent channel and a secondary adjacent channel while retaining the signal of the target channel.
The embodiment of the invention performs band-pass filtering on the first filtering signal through the corresponding bandwidth filter with the bandwidth same as the new bandwidth of the target to obtain the second filtering signal, can perform band-pass filtering on the first filtering signal with a smaller frequency range, can be suitable for adjacent channel suppression of target channels with different bandwidths, and can improve the adjacent channel suppression ratio of the target channel.
Based on the content of the foregoing embodiments, before down-converting the original signal received through the antenna into the first filtered signal according to the bandwidth of the target channel, the method further includes:
and acquiring a local oscillator signal according to the bandwidth of the target channel, the central frequency of the target channel and the central frequency of the band-pass filter.
If the bandwidth of the target channel is judged to be the same as that of the band-pass filter according to the bandwidth of the target channel, a local oscillation signal can be generated through a local oscillation signal generation module in the adjacent channel suppression circuit.
Specifically, the frequency of a first filtered signal obtained by down-converting an original signal by the first frequency conversion module needs to be matched with the center frequency of the band-pass filter. The frequency of the required local oscillator signal can be obtained by calculating the difference between the center frequency of the target channel and the center frequency of the band-pass filter. The local oscillator signal generating module may generate a local oscillator signal of a corresponding frequency.
It should be noted that, in the embodiment of the present invention, after the frequency of the required local oscillation signal is obtained according to the bandwidth of the target channel, the center frequency of the target channel, and the center frequency of the band-pass filter, the local oscillation signal of the corresponding frequency sent by the external electrical element may also be received.
Correspondingly, down-converting an original signal received through an antenna into a first filtered signal according to the bandwidth of the target channel, specifically including:
and mixing the original signal with the local oscillator signal to obtain a first filtering signal.
After the local oscillation signal is obtained, the local oscillation signal and the original signal are mixed by a first frequency conversion module in the adjacent channel suppression circuit, and a first filtering signal of the intermediate frequency is obtained.
It should be noted that the local oscillation signal generating module in the embodiment of the present invention may include a programmable voltage controlled oscillator of the TRF3765, where a frequency range of the local oscillation signal output by the programmable voltage controlled oscillator is 300MHz to 4.8 GHz.
According to the embodiment of the invention, the local oscillator signal is obtained according to the bandwidth of the target channel, the central frequency of the target channel and the central frequency of the filtering module, and is mixed with the original signal, so that the down-conversion of the original signal is realized, the frequency of the required local oscillator signal can be obtained according to the bandwidth of the target channel, the central frequency of the target channel and the central frequency of the filtering module, the local oscillator signal with the corresponding frequency can be obtained, the down-conversion of the original signal can be realized through the mixing of the local oscillator signal and the original signal, and the requirement of signal frequency conversion when the adjacent channel of the target channel is inhibited can be met.
Based on the content of the foregoing embodiments, up-converting the second filtered signal into an output signal specifically includes:
and mixing the second filtering signal with the local oscillation signal to obtain an output signal.
After the local oscillation signal is obtained, the original signal and the second filtering signal of the intermediate frequency may be mixed by the second frequency conversion module in the adjacent channel suppression circuit, so as to obtain an output signal with the same frequency range as that of the original signal.
According to the embodiment of the invention, the up-conversion of the second filtering signal is realized by mixing the local oscillation signal and the second filtering signal, and the requirement of signal frequency conversion when the adjacent channel of the target channel is inhibited can be met.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. An adjacent channel suppression circuit, comprising: the device comprises a first frequency conversion module, a filtering module and a second frequency conversion module;
the first frequency conversion module is used for converting the original signal received by the antenna into a first filtering signal in a down-conversion mode according to the bandwidth of the target channel;
the filtering module is connected with the first frequency conversion module and is used for carrying out band-pass filtering on the first filtering signal to obtain a second filtering signal;
the second frequency conversion module is connected with the filtering module and is used for up-converting the second filtering signal into an output signal;
wherein the frequency range of the original signal is the same as the frequency range of the output signal.
2. The adjacent channel suppression circuit according to claim 1, wherein the filtering module comprises: a plurality of filtering sub-modules;
each filtering submodule corresponds to different bandwidths respectively;
and the filtering submodule is used for carrying out band-pass filtering according to the bandwidth corresponding to the filtering submodule.
3. The adjacent channel suppression circuit according to claim 1, further comprising: a local oscillator signal generating module;
the local oscillator signal generating module is respectively connected with the first frequency conversion module and the second frequency conversion module, and is configured to generate a local oscillator signal according to the bandwidth of the target channel, the center frequency of the target channel, and the center frequency of the filtering module, and respectively send the local oscillator signal to the first frequency conversion module and the second frequency conversion module.
4. The adjacent channel suppression circuit according to claim 2, further comprising: a first switching module;
the first switching module is respectively connected with the first frequency conversion module and each filtering submodule, and is configured to switch the first filtering signal into the corresponding filtering submodule with a bandwidth that is the same as the bandwidth of the target channel.
5. The adjacent channel suppression circuit according to claim 2, further comprising: a second switching module;
the second switching module is respectively connected with each filtering submodule and the second frequency conversion module, and is configured to transmit the second filtering signal output by any one of the filtering submodules to the second frequency conversion module.
6. The adjacent channel suppression circuit according to claim 5, further comprising: the device comprises a first low-noise amplification module, a first radio frequency filtering module, a second radio frequency filtering module and a second low-noise amplification module;
the first low-noise amplification module is respectively connected with the antenna and the first radio frequency filtering module;
the first radio frequency filtering module is connected with the first frequency conversion module;
the second radio frequency filtering module is respectively connected with the second frequency conversion module and the second low noise amplification module.
7. An adjacent channel suppression method, comprising:
down-converting an original signal received through an antenna into a first filtered signal according to the bandwidth of a target channel;
performing band-pass filtering on the first filtering signal to obtain a second filtering signal;
up-converting the second filtered signal into an output signal;
wherein the frequency range of the original signal is the same as the frequency range of the output signal.
8. The adjacent channel suppression method according to claim 7, wherein the band-pass filtering the first filtered signal to obtain a second filtered signal specifically includes:
and performing band-pass filtering on the first filtering signal through a corresponding band-pass filter with the same bandwidth as that of the target channel to obtain the second filtering signal.
9. The adjacent channel suppression method according to claim 8, wherein before the down-converting the original signal received through the antenna into the first filtered signal according to the bandwidth of the target channel, the method further comprises:
acquiring a local oscillator signal according to the bandwidth of the target channel, the central frequency of the target channel and the central frequency of the band-pass filter;
correspondingly, the down-converting an original signal received through an antenna into a first filtered signal according to the bandwidth of the target channel specifically includes:
and mixing the original signal with the local oscillation signal to obtain the first filtering signal.
10. The adjacent channel suppression method according to claim 9, wherein the up-converting the second filtered signal into an output signal specifically comprises:
and mixing the second filtering signal with the local oscillation signal to obtain the output signal.
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