JP2013201599A - Channelizer for frequency division multiplex signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a channelizer for a frequency division multiplex signal that respectively adjusts signal levels of all receiving channels and sufficiently secures a dynamic range of each channel.SOLUTION: A sampling rate of the frequency division multiplex signal via an A/D converter 11 and an orthogonal detector 12 is reduced by a decimation filter 13 to be converted into a baseband signal, a demultiplexer 14 demultiplexes a plurality of channel signals included in the baseband signal, and a switch 15 arranges the demultiplexed channel signals in arbitrary order and outputs the channel signals as time division multiplex signals. A channel gain adjuster 16 that determines magnitude of the signal level of each channel of the time division multiplex signal and increases/decreases the signal level of each channel according to a determination result is included. The time division multiplex signal obtained by adjusting the signal level of each channel is converted into the frequency division multiplex signal by a multiplexer 17 and outputted via an interpolation filter 18, an orthogonal modulation 19, and a D/A converter 20.

Description

  The present invention relates to a frequency division multiplexing technique used in multi-beam communication satellite communication, and relates to a frequency division multiplexing signal channelizer used in a communication system that needs to ensure a wide dynamic range of each beam or each channel.

In multi-beam communication, which is the subject of the present invention, a single communication satellite receives a plurality of beams transmitted from the ground, and a channel signal included in each beam using a channelizer or the like mounted on the communication satellite. The signal is frequency-converted into the feeder link band, rearranged to increase the frequency utilization efficiency of the feeder link, and transmitted to the ground station of the ground destination via the feeder link. ing.
FIG. 5 is an explanatory diagram showing the configuration of a conventional frequency division multiplexed signal channelizer. This figure shows a block configuration of a conventional frequency division multiplex signal channelizer mounted on a communication satellite, for example, and is a configuration example of an apparatus for inputting an IF band analog signal having N beams.
This channelizer is provided with N A / D converters 101, quadrature detectors 102, decimation filters 103, and demultiplexers 104, that is, for each received beam, for each channel included in each beam. It is configured to process the signal. This apparatus also includes a switch 105 for inputting signals output from the N demultiplexers 104, a multiplexer 106, an interpolation filter 107, a quadrature modulator 108, and a D / A converter 109.

Each A / D converter 101 converts the input analog signal of each channel in the IF band into a digital signal. This digital signal is input to the quadrature detector 102, has two orthogonal values, is decomposed into a real part and an imaginary part, and is converted into a baseband signal. The real part of this baseband signal is the I channel and the imaginary part is the Q channel, which are denoted as Ich and Qch, respectively.
The baseband signal composed of Ich and Qch is input to the decimation filter 103, down-sampled to a sampling rate of 1 / N, for example, and input to the duplexer 104.

  The duplexer 104 performs processing for converting the frequency-multiplexed signal (baseband signal composed of Ich and Qch) down-sampled as described above into a time-division multiplexed signal. When this conversion is performed, as a result, data indicated by the baseband signal is separated for each channel of Ich and Qch. The switch 105 collectively switches the data output from the N demultiplexers 104, rearranges the data in the order of the frequencies when output from the channelizer, and outputs the rearranged data.

  The multiplexer 106 converts each data input from the switch 105 so as to have a preset frequency, and performs frequency multiplexing for each channel. The interpolation filter 107 up-samples the signal output from the multiplexer 106 to M times the frequency and converts the signal into an IF band signal. The quadrature modulator 108 multiplexes Ich and Qch of the signal upsampled by the interpolation filter 107. The D / A converter 109 converts the digital signal output from the quadrature modulator 108 into an analog signal in IF band, and outputs the analog signal from the channelizer. The IF band signal output from the channelizer is converted to a transmission frequency to the ground, for example, and transmitted through a transmission means such as a modulator or an amplifier.

Some of the above-mentioned channelizers are provided with an IFFT filter bank and an FFT filter bank with variable bandwidths in order to support each carrier (channel) signal having various bandwidths (see Non-Patent Document 1). ).
In this apparatus, the received signal of each carrier is converted into a digital signal by an A / D converter, the transmission rate of each carrier is reduced by a down sampler, and input to the IFFT filter bank. This IFFT filter bank demultiplexes the input signal for each carrier and outputs it to the switch. This switch outputs each input signal to the FFT filter bank in a predetermined order. The FFT filter bank combines each signal input from the switch for each carrier, and outputs it to the up sampler. The up sampler increases the transmission rate of the signal of each carrier and outputs it to the D / A converter. Each of these carrier signals is converted into an analog signal by a D / A converter, and then converted into a communication frequency and transmitted to a transmission destination on the ground.

  The beam received by the communication satellite is formed by multiplexed analog signals. This analog signal is, for example, subjected to phase shift keying to represent digital data. In multiplex communication using this phase shift keying, digital values are determined in advance corresponding to each predetermined phase of an analog signal, and an arbitrary digital value is obtained by controlling the analog signal during communication to a desired phase. Is transmitted (see Non-Patent Document 2). Thus, if each data value is defined by a plurality of phases, it is possible to multiplex and transmit a plurality of values at the same frequency. For example, the above-mentioned Ich and Qch are multiplexed and transmitted. , Increase the transmission efficiency of large capacity data.

Fumihiro Yamashita, Hiroshi Kazama, Yoshinori Nakasuga “Proposal and Basic Operation Characteristics of Bandwidth Variable FFT Filter Bank for Communication Satellites” IEICE Transactions B Vol. J85-B No.12 pp-2290-2299 2002 12 Moon Fumio Takahata, Masayuki Yasunaga, Yasuo Hirata, Tomoki Ohsawa, and Junji Namiki “A PSK Group Modem for Satellite Communications” IEEE Journal on Selected Areas in Communications, Vol.SAC-5, No.4 May 1987

Since the conventional channelizer is configured as described above, it is possible to adjust the gain for each beam by setting the filter coefficient of the branching circuit, but if there is a difference in the reception level of each channel, the channel Since it cannot be adjusted every time, there is a problem that a sufficient dynamic range of each channel cannot be secured.
Further, even when a gain adjustment is performed for each received beam in the preceding stage of the A / D converter that converts the received analog signal of each channel into digital data, the input level of the A / D converter is adjusted. However, there is a problem in that it is not possible to individually adjust the gain of each channel included in the same reception beam.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a frequency-division multiplex signal channelizer that sufficiently adjusts the signal levels of all reception channels and sufficiently secures the dynamic range of each channel. And

  A frequency division multiplexed signal channelizer according to the present invention includes a duplexer that demultiplexes a plurality of channel signals included in the frequency division multiplexed signal, and a time division multiplexed signal in which the plurality of demultiplexed channel signals are arranged in an arbitrary order. A switch that outputs the signal, a channel gain adjuster that adjusts the signal level of each channel that forms the time division multiplexed signal output from the switch, and the time division multiplexed signal that is output from the channel gain adjuster from a predetermined frequency. And a channel level adjuster for determining the magnitude of the signal level of the channel forming the time division multiplexed signal, and the channel level determiner. A gain parameter that generates a gain parameter that increases or decreases the signal level of the channel according to the determination result of A parameter generator, and having a a level adjuster which performs increase or decrease of the signal level of the channel using the gain parameter.

  Also, an A / D converter that converts an analog signal that has been frequency-division multiplexed in the IF band into a digital signal, a quadrature detector that performs quadrature detection in the frequency-division multiplexed signal in the IF band that has been converted into the digital signal, A decimation filter that reduces the sampling rate of the frequency-division multiplexed signal of the IF band that has undergone the quadrature detection and converts it to a baseband signal, a demultiplexer that demultiplexes a plurality of channel signals included in the baseband signal, A switch that arranges the plurality of demultiplexed channel signals in an arbitrary order and outputs them as a time division multiplexed signal, a channel gain adjuster that adjusts the signal level of each channel forming the time division multiplexed signal output from the switch, and The time division multiplexed signal output from the channel gain adjuster is converted into a frequency division multiplexed signal having a predetermined frequency. A multiplexer that converts the frequency-division multiplexed signal converted by the multiplexer into an IF-band signal, and orthogonally modulates the IF-band frequency-division multiplexed signal converted by the interpolation filter. An orthogonal modulator; and a D / A converter that converts the frequency division multiplexed signal quadrature-modulated by the orthogonal modulator into an analog signal, and the channel gain adjuster includes a channel that forms the time division multiplexed signal. A channel level determiner that determines the magnitude of the signal level, a gain parameter generator that generates a gain parameter that increases or decreases the signal level of the channel according to the determination result of the channel level determiner, and the gain parameter And a level adjuster for increasing and decreasing the signal level of the channel.

  In addition, an A / D converter that converts a first frequency division multiplexed signal received through a user link and converted into an IF band analog signal into a digital signal, and a first frequency division converted into the digital signal A quadrature detector that performs quadrature detection of a multiplexed signal; a decimation filter that reduces the sampling rate of the first frequency division multiplexed signal that has undergone quadrature detection and converts the signal to a baseband signal; and a plurality of filters included in the baseband signal A demultiplexer for demultiplexing the channel signals, a switch for arranging the demultiplexed channel signals in an arbitrary order and outputting them as time division multiplexed signals, and each channel forming the time division multiplexed signals output from the switches A channel gain adjuster for adjusting the signal level of the signal and a time division multiplexed signal output from the channel gain adjuster with a predetermined frequency. A multiplexer that converts the signal into a frequency division multiplexed signal, an interpolation filter that converts the frequency division multiplexed signal converted by the multiplexer into an IF band signal, and an IF band that is converted by the interpolation filter. An orthogonal modulator for orthogonally modulating the frequency division multiplexed signal, a D / A converter for converting the frequency division multiplexed signal orthogonally modulated by the orthogonal modulator into an analog signal, and a first input to the A / D converter And a transmission means for transmitting a second frequency division multiplexed signal demultiplexed from one frequency division multiplexed signal to a ground station via a feeder link, and is transmitted from the communication satellite via a feeder link. Receiving means for receiving the second frequency division multiplexed signal, and converting the second frequency division multiplexed signal received by the receiving means via the feeder link into a time division multiplexed signal. Time-division multiplexed signal generation means, channel level determination means for determining the magnitude of the signal level of each channel forming the time-division multiplexed signal generated by the time-division multiplexed signal generation means, and the determination result of the channel level determination means In response, the ground station comprises gain parameter generation means for generating a gain parameter for increasing or decreasing the signal level of the channel, and gain parameter transmission means for transmitting the gain parameter to the communication satellite via a feeder link, The channel gain adjuster provided in the communication satellite acquires the gain parameter from the ground station received by the receiving means of the communication satellite via the feeder link, and is time-division output from the switch provided in the communication satellite. Use the gain parameter to increase or decrease the signal level of each channel that makes up the multiplexed signal. And a level adjuster that performs the operation described above.

According to the present invention, when the difference in the reception level of each frequency-multiplexed channel is large or when there is a level difference in the intensity of the received beam, the signal level of each channel can be adjusted appropriately, There is an effect that a large dynamic range can be secured in the channel signal.
Further, in satellite communication, even in a low C / N environment such as when the transmission power of the ground station is low or the positional relationship between the communication satellite and the ground station is unfavorable and fading occurs, interference or There is an effect that signal quality deterioration due to noise can be greatly reduced and the communication line can be maintained.

It is explanatory drawing which shows schematic structure of the channelizer for frequency division multiplex signals by the Example of this invention. It is explanatory drawing which shows the structure of the channel gain adjuster of FIG. It is explanatory drawing which shows operation | movement of the channel gain adjuster of FIG. It is explanatory drawing which shows the function which calculates | requires the gain parameter of a channel gain adjuster. It is explanatory drawing which shows the structure of the conventional channelizer for frequency division multiplexing signals.

Embodiments of the present invention will be described below with reference to the drawings.
(Example)
FIG. 1 is an explanatory diagram showing a schematic configuration of a frequency division multiplexed signal channelizer according to an embodiment of the present invention. This figure is a block diagram showing the configuration of a frequency division multiplexed signal channelizer 1 mounted on, for example, a communication satellite or the like. For each beam transmitted from the ground station, the same number of A / A D converter 11, a quadrature detector 12, a thinning filter 13, and a demultiplexer 14 are provided. The channelizer 1 illustrated here is configured to be able to process N reception beams.
The channelizer 1 also includes a switch 15 for inputting an output signal of each demultiplexer 14, a channel gain adjuster 16, a multiplexer 17, an interpolation filter 18, an orthogonal modulator 19, and a D / A converter 20. Yes.

The A / D converter 11 has, for example, a function of inputting an analog signal converted into an IF band frequency by a beam receiving unit (not shown) mounted on a communication satellite, and converting the analog signal into a digital data signal. I have.
The quadrature detector 12 has a function of separating the signal output from the A / D converter 11 into a real part and an imaginary part.
The decimation filter 13 has a function of reducing the transmission speed of the signal output from the quadrature detector 12 and converting an IF band signal into a baseband signal.
The demultiplexer 14 has a function of demultiplexing the baseband signal output from the decimation filter 13 and separating and extracting the signal (data) of each channel.

The switch 15 has a switch matrix configuration, for example, and has a function of inputting signals output from the duplexers 14 and outputting these signals as time division multiplexed signals.
FIG. 2 is an explanatory diagram showing the configuration of the channel gain adjuster of FIG. The channel gain adjuster 16 includes a multiplier 30 that sequentially inputs signals output from the switch 15 and a gain parameter setting table 31 that stores gain parameters used by the multiplier 30 for arithmetic processing. The channel gain adjuster 16 includes, for example, the multiplier 30 and the gain parameter setting table 31 described above as level adjusters for increasing and decreasing the level of the channel signal. Equipped with a bowl.
The multiplexer 17 has a function of converting the time division multiplexed signal output from the channel gain adjuster 16 into a frequency division multiplexed signal for each channel.

The interpolation filter 18 has a function of upsampling the signal frequency-multiplexed by the multiplexer 17 and converting the signal into an IF band signal.
The quadrature modulator 19 has a function of modulating the real part and the imaginary part of the signal output from the interpolation filter 18 for each channel.
The D / A converter 20 has a function of converting the output signal of the interpolation filter 18 into an analog signal in the IF band.

Next, the operation will be described.
For example, a communication satellite that receives a multi-beam transmitted from a source ground station via a user link reduces the communication frequency of each received beam to a predetermined IF band frequency using a receiving unit (not shown). Let The channelizer 1 of the present embodiment receives the signals of each beam converted to the IF band frequency described above, demultiplexes and extracts each signal included in the beam, and outputs a signal according to a predetermined standard specified by the communication system. Are rearranged, and after adjusting the level of each signal, the combined signal is converted into the frequency band of the feeder link and transmitted to the destination ground station.
The A / D converter 11 shown in FIG. 1 is provided for each received beam as described above. For example, the A / D converter (1) 11 is an analog signal of the beam 1 converted into the IF band. Similarly, the A / D converter (N) 11 inputs an analog signal of the beam N. Here, each part which processes the signal of beam 1 is illustrated and demonstrated.

The A / D converter (1) 11 converts the content of the input beam 1 into a signal represented by digital data.
The quadrature detector (1) 12 performs quadrature detection of the signal output from the A / D converter (1) 11, and is orthogonally modulated so that the amplitude change and the phase change of the signal can be discriminated independently. The two values are separated into real part Ich and imaginary part Qch.
The decimation filter (1) 13 performs downsampling of the IF band signal output from the quadrature detector (1) 12 so that, for example, the sampling rate is 1 / N (N is the number of received beams). The transmission rate is reduced and converted to a baseband signal.

The duplexer (1) 14 separates the baseband signal output from the decimation filter (1) 13 into each channel. In other words, the beam 1 subjected to frequency division multiplexing is separated for each channel.
Each demultiplexer 14 converts a frequency division multiplexed signal into a time division multiplexed signal using, for example, Fourier transform. The frequency-multiplexed signal is obtained by multiplexing a plurality of channels, and a signal in which each channel is time-division multiplexed in an arbitrary time unit is generated by the above conversion. That is, each channel included in the beam is separated by the demultiplexer (1) 14 to the demultiplexer (N) 14, and a signal representing each time-division multiplexed channel is output to the switch 15.

The switch 15 has a function of receiving the signals of the respective channels output from the duplexers (1) 14 to (N) 14 and temporarily storing the signals of a plurality of channels.
The switch 15 stores the signals input from the demultiplexers 14 by itself, rearranges them in the order in which they can be transmitted without delay to the user link transmission destination, and outputs them. Specifically, for example, considering the transmission speed and data size, each of the above-mentioned stored values in accordance with the conditions for rearranging so that the frequency utilization efficiency of the feeder link is increased at the stage of multiplexing at the later stage. Output signals in order. By outputting the signal of each channel in this way, the time-division multiplexed signal is input to the channel gain adjuster 16.
The switch 15 is set with the above-described priority conditions and the like by an external control signal. That is, when the channelizer 1 is mounted on a communication satellite, the order of channels to be transmitted to the destination ground station is set by a control signal acquired from, for example, a feeder link ground station via the communication means of the communication satellite. Is done.

  FIG. 3 is an explanatory diagram showing the operation of the channel gain adjuster of FIG. The channel gain adjuster 16 inputs the signal of each channel output from the switch 15 as a time division multiplexed signal to the multiplier 30, and uses the multiplier 30 to set the gain parameter stored in the gain parameter setting table 31. The signal of the channel is multiplied to adjust the signal level of the channel.

The channel gain adjuster 16 operates as follows.
A gain parameter corresponding to the signal of each channel is stored in the gain parameter setting table 31 in advance. When a signal of any channel is input to the multiplier 30, a gain parameter corresponding to the channel is read from the gain parameter setting table 31, and a multiplication process is performed.
Specifically, for example, signals and data of channel 1 (hereinafter referred to as CH1) to channel n (hereinafter referred to as CHn) are sequentially input to the channel gain adjuster 16. The data of CH1 to CHn are time-division multiplexed from the switch 15 and output in succession. Data from CH1 to CHn is sequentially input to the multiplier 30 at a predetermined interval, and gain parameters corresponding to CH1 to CHn are appropriately read from the gain parameter setting table 31.

  The multiplier 30 inputs a gain parameter corresponding to the input CH in synchronization with the data of each CH input from the switch 15, and performs multiplication processing of the data of the CH and the gain parameter. Similarly, each data from CH2 to CHn is sequentially input, and gain parameters corresponding to CH2 to CHn read from the gain parameter setting table 31 are sequentially input, and multiplication processing of the data of each CH and the gain parameter is performed. Do. By this multiplication processing, the signal level indicated by the data of each CH becomes the same. That is, the difference in signal level indicated by the data of each CH output from the multiplier 30 is smaller than the difference in signal level indicated by the data of each CH input to the multiplier 30. FIG. 3 shows the concept of data processing of N channels. There are a case where N pieces are processed simultaneously in parallel and a case where N pieces are sequentially processed at high speed.

  FIG. 4 is an explanatory diagram showing a function for obtaining a gain parameter of the channel gain adjuster. The channel gain adjuster 16 obtains a gain parameter corresponding to the channel signal before inputting the arbitrary channel signal to the multiplier 30. Specifically, the channel gain adjuster 16 includes n channel level determiners 32 and channel gain parameter generators 33 corresponding to, for example, CH1 to CHn, and generates and sets gain parameters for each channel.

For example, the channel level determination unit (CH1) 32 receives CH1 data sequentially output from the switch 15, and compares the signal level indicated by this data with a preset reference level. Using this comparison result, a CH1 signal level adjustment amount, that is, a CH1 level signal indicating the level increase / decrease level is generated and output to the channel gain parameter generator (CH1) 33.
As shown in FIG. 4, the channel level determination unit (CH1) 32 inputs Ich and Qch of the same channel sequentially output from the switch 15, and inputs the value of Ich here as P and the value of Qch as Qch. Then, the signal level of CH1 is obtained by the calculation (a) of (P ² + Q ² ) ^1/2 , and this signal level is compared with the reference level.

  This reference level is stored and held by the channel level determination unit (CH1) 32 itself. Similarly, each of the channel level determination unit (CH2) 32 to the channel level determination unit (CHn) 32 stores and holds a reference level. The reference level is stored and set in advance in each channel level determination unit 32. For example, when the channelizer 1 is mounted on a communication satellite, the reference level may be set from the ground station via a feeder link. The reference level may have the same value common to each channel, or may have a different value for each channel set according to the characteristics of each channel signal.

As a result of the comparison, when there is no difference between the signal level obtained by the calculation (a) and the reference level, it is assumed that the gain parameter is set as the origin in advance, and a CH1 level signal indicating this value is generated. To do. The gain parameter in this case indicates that the channel signal level increase / decrease process is not executed.
As a result of the comparison, when the signal level obtained by the calculation (a) is larger than the reference level, the gain parameter is changed to a value obtained by subtracting a predetermined set width from the set value with the above origin. A CH1 level signal indicating the value is generated. The gain parameter in this case indicates that the signal level of the channel is reduced by a predetermined amount.
As a result of the comparison, when the signal level obtained by the calculation (a) is smaller than the reference level, the gain parameter is changed to a value obtained by adding a predetermined setting width to the setting value with the above origin. A CH1 level signal indicating the value is generated. The gain parameter in this case indicates that the signal level of the channel is increased by a predetermined amount.

  The reference level is a level set in advance for each channel. Specifically, when the D / A converter 20 shown in FIG. 1 converts the digital data to generate an analog signal, the analog signal is at a level that falls within the dynamic range of the D / A converter 20. The reference level is a value that is statistically predicted and set based on the number and characteristics (properties) of signals included in the output beam.

The channel gain parameter generator (CH1) 33 generates a CH1 gain parameter using the contents of the CH1 level signal input from the channel level determiner (CH1) 32, and writes data representing this parameter in the gain parameter setting table 31. (Set).
The gain parameter generated here is obtained by multiplexing, for example, a bit signal composed of a plurality of bits indicating the increase / decrease amount of the signal level and an identification signal indicating the signal position of CH1 output from the switch 15. Further, the gain parameter has a value for adjusting the signal level of each channel to a level set (defined) in advance.

The gain parameters stored in the gain parameter setting table 31 are input to the multiplier (1) 30 as described above and used for signal level adjustment of CH1.
Similarly to the above description, the respective signal levels of CH2 to CHn are determined by the channel level determiner (2) 32 to the channel level determiner (n) 32, and the CH2 level signal to CHn level signal are respectively generated. Also, using these signals, the channel gain parameter generator (2) 33 to the channel gain parameter generator (n) 33 generate gain parameters for the respective channels, and these gain parameters are stored in the gain parameter setting table 31. Write.
The gain parameter is generated before the channel signal corresponding to the gain parameter is input to the multiplier 30 and stored in the gain parameter setting table 31.

For example, when the channelizer 1 is mounted on a communication satellite, the gain parameter described above is generated by the gain parameter generator 33 mounted on the communication satellite, but a similar gain parameter is generated on the ground station side. It is also possible to configure.
As described above, the frequency division multiplexed signal received by the communication satellite is converted into a time division multiplexed signal. The time position of the signal of each channel in this time division multiplexed signal, that is, the timing at which each process is performed can also be recognized by the ground station. That is, according to the processing operation on the communication satellite side, for example, a gain parameter can be generated on the ground station side and transmitted to the communication satellite to adjust the signal level of each channel.

When a channelizer 1 or the like is mounted on a communication satellite, a frequency division multiplex signal received by the communication satellite via a user link, that is, a frequency division multiplex signal input to the A / D converter 11 of the channelizer 1 is transmitted to the communication satellite side. The provided transmission means demultiplexes. Next, the transmission means converts the frequency division multiplexed signal (A) demultiplexed from the frequency division multiplexed signal acquired from the user link into a frequency within the feeder link band, and transmits it to the ground station via the feeder link. Send.
In addition, the above ground station side receives receiving means for receiving the frequency division multiplexed signal (A) demultiplexed by the communication satellite via the feeder link, and the frequency division multiplexed signal (A) is time-division multiplexed signal. Time-division multiplexed signal generating means for converting to (B) is provided. This time-division multiplexed signal generating means includes a configuration similar to the A / D converter 11, the quadrature detector 12, the thinning filter 13, the demultiplexer 14, the switch 15 and the like, and the same. It has a function.

Further, on the above-mentioned ground station side, channel level determination means and channel gain parameter generation means similar to the above-described channel level determination unit 32 and channel gain parameter generation unit 33 are provided as components of the channelizer 1, respectively.
The channel level determination means compares the signal level of each channel constituting the time division multiplexed signal output from the time division multiplexed signal generation means with the reference level in the same manner as the channel level determination unit 32.
The gain parameter generation unit generates a gain parameter in the same manner as the channel gain parameter generator 33 according to the comparison result of the channel level determination unit.

  On the ground station side, the gain parameter generated by the gain parameter generation means is transmitted to the communication satellite via the feeder link by the transmission means of the ground station, and the channel gain adjuster 16 via the reception means of the communication satellite. To input. The transmission means of the ground station that transmits the gain parameter and the reception means of the ground station that receives the demultiplexed frequency division multiplexed signal (A) are communication means used by the ground station for the feeder link. . The communication satellite transmitting means for transmitting the frequency division multiplex signal (A) and the communication satellite receiving means for receiving the gain parameter are communication means used by the communication satellite for the feeder link.

  The channel gain adjuster 16 used here uses the gain parameter generated by the channel gain parameter generation means provided in the above-mentioned ground station to adjust the signal level of each channel forming the time division multiplexed signal output from the switch 15. A level adjuster that increases and decreases is provided. This level adjuster is configured by the multiplier 30 and the gain parameter setting table 31 described above. Here, the channel gain adjuster 16 mounted on the communication satellite does not include the channel level determination unit 32 and the channel gain parameter generator 33.

Each channel signal that has been increased or decreased by the channel gain adjuster 16 and has a predetermined signal level is input to the multiplexer 16 and subjected to frequency division multiplexing so as to have a predetermined frequency for each channel. The multiplexer 16 converts the time division multiplexed signal output from the channel gain adjuster 16 into a frequency multiplexed signal using, for example, inverse Fourier transform.
The interpolation filter 18 up-samples the signal output from the multiplexer 17 to a frequency M times, and converts the signal from the baseband to the IF band.

The quadrature modulator 19 performs quadrature modulation that multiplexes Ich and Qch of the signal output from the interpolation filter 18.
The D / A converter 20 converts the IF band signal in the digital data format output from the quadrature modulator 19 into an analog signal and outputs the analog signal to the outside of the channelizer 1.
Thereafter, the signal in the IF band is converted into a signal in a frequency band for satellite communication, for example, by a transmission unit (not shown) and transmitted to a transmission destination (such as a ground station) via a user link.

As described above, according to the frequency division multiplexed signal channelizer of this embodiment, the received signal level of each channel is compared with a predetermined reference level, and the signal level of each channel is increased or decreased according to the comparison result. As a result, a large dynamic range can be secured for the signal of each channel, and the communication quality can be stabilized.
In addition, it is possible to secure a communication line even when the C / N environment is not good. In satellite communication, when the transmission power of the ground station is weak, or between the communication satellite and the ground station, Alternatively, the communication state can be maintained even when there is a factor that causes a communication failure in the vicinity thereof.
In addition, by configuring the gain parameter for adjusting the signal level of each channel to be generated on the ground station side, the reception level of each channel received by the communication satellite can be appropriately adjusted at the ground station. In addition, the number of devices mounted on the communication satellite can be reduced, and the mounting weight and mounting space can be suppressed.

  The channelizer for frequency division multiplex signals according to the present invention can adjust the signal level of each channel from the received transmission source and transmit it to the transmission destination in a relay means such as a communication satellite. Suitable for required multiple signal communication.

1 channelizer 11, 101 A / D converter 12, 102 quadrature detector 13, 103 decimation filter 14, 104 demultiplexer 15, 105 switch 16 channel gain adjuster 17, 106 multiplexer 18, 107 interpolation filter 19, 108 Quadrature modulator 20, 109 D / A converter 30 multiplier 31 gain parameter setting table 32 channel level determiner 33 channel gain parameter generator

Claims (3)

A duplexer for demultiplexing a plurality of channel signals included in the frequency division multiplexed signal;
A switch for arranging the plurality of demultiplexed channel signals in an arbitrary order and outputting them as a time division multiplexed signal;
A channel gain adjuster for adjusting the signal level of each channel forming the time division multiplexed signal output from the switch;
A multiplexer that converts the time division multiplexed signal output from the channel gain adjuster into a frequency division multiplexed signal having a predetermined frequency;
With
The channel gain adjuster is
A channel level determiner for determining the magnitude of the signal level of the channel forming the time division multiplexed signal;
A gain parameter generator that generates a gain parameter that increases or decreases the signal level of the channel according to a determination result of the channel level determiner;
And a level adjuster that increases or decreases the signal level of the channel using the gain parameter. An A / D converter that converts an analog signal that has been frequency-division multiplexed in the IF band into a digital signal;
A quadrature detector that performs quadrature detection of the frequency-division multiplexed signal in the IF band converted into the digital signal;
A decimation filter that reduces the sampling rate of the frequency-division multiplexed signal of the IF band that has undergone the quadrature detection and converts it to a baseband signal;
A duplexer for demultiplexing a plurality of channel signals included in the baseband signal;
A switch for arranging the plurality of demultiplexed channel signals in an arbitrary order and outputting them as a time division multiplexed signal;
A channel gain adjuster for adjusting the signal level of each channel forming the time division multiplexed signal output from the switch;
A multiplexer that converts the time division multiplexed signal output from the channel gain adjuster into a frequency division multiplexed signal having a predetermined frequency;
An interpolation filter that converts the frequency division multiplexed signal converted by the multiplexer into a signal in the IF band;
An orthogonal modulator for orthogonally modulating the frequency division multiplexed signal of the IF band converted by the interpolation filter;
A D / A converter that converts the frequency division multiplexed signal orthogonally modulated by the orthogonal modulator into an analog signal;
With
The channel gain adjuster is
A channel level determiner for determining the magnitude of the signal level of the channel forming the time division multiplexed signal;
A gain parameter generator that generates a gain parameter that increases or decreases the signal level of the channel according to a determination result of the channel level determiner;
And a level adjuster that increases or decreases the signal level of the channel using the gain parameter. An A / D converter that converts the first frequency division multiplexed signal received through the user link and converted into an analog signal in the IF band into a digital signal;
A quadrature detector for performing quadrature detection of the first frequency division multiplexed signal converted into the digital signal;
A decimation filter that reduces the sampling rate of the first frequency division multiplexed signal subjected to the quadrature detection and converts it into a baseband signal;
A duplexer for demultiplexing a plurality of channel signals included in the baseband signal;
A switch for arranging the plurality of demultiplexed channel signals in an arbitrary order and outputting them as a time division multiplexed signal;
A channel gain adjuster for adjusting the signal level of each channel forming the time division multiplexed signal output from the switch;
A multiplexer that converts the time division multiplexed signal output from the channel gain adjuster into a frequency division multiplexed signal having a predetermined frequency;
An interpolation filter that converts the frequency division multiplexed signal converted by the multiplexer into a signal in the IF band;
An orthogonal modulator for orthogonally modulating the frequency division multiplexed signal of the IF band converted by the interpolation filter;
A D / A converter that converts the frequency division multiplexed signal orthogonally modulated by the orthogonal modulator into an analog signal;
Transmitting means for transmitting a second frequency division multiplexed signal demultiplexed from the first frequency division multiplexed signal input to the A / D converter to a ground station via a feeder link;
For communication satellites,
Receiving means for receiving a second frequency division multiplexed signal transmitted from the communication satellite via a feeder link;
Time division multiplexed signal generating means for converting the second frequency division multiplexed signal received by the receiving means via the feeder link into a time division multiplexed signal;
Channel level determining means for determining the magnitude of the signal level of each channel forming the time division multiplexed signal generated by the time division multiplexed signal generating means;
Gain parameter generating means for generating a gain parameter for increasing or decreasing the signal level of the channel according to the determination result of the channel level determining means;
Gain parameter transmitting means for transmitting the gain parameter to the communication satellite via a feeder link;
In the ground station,
The channel gain adjuster provided for the communication satellite is:
Obtaining a gain parameter from the ground station received by the receiving means of the communication satellite via a feeder link;
A frequency-division multiplex signal channelizer comprising a level adjuster that uses the gain parameter to increase or decrease the signal level of each channel forming a time-division multiplex signal output from a switch provided in the communication satellite.

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