KR101784313B1 - Compensation device for frequency deviation in wireless communication equipment - Google Patents

Abstract

The present invention relates to a frequency deviation compensation apparatus for a wireless communication apparatus, A low power amplifier for low power amplifying a received signal received through an antenna; A frequency down converter for converting the low power amplified received signal into a signal of an intermediate frequency mixed with a local oscillation signal and adjusting a frequency of the local oscillation signal to a control signal provided from the outside; Converts a signal of an intermediate frequency into a digital signal, converts it to a baseband signal, confirms a frequency deviation of the received signal, generates a control signal to compensate for the frequency deviation based on the determined frequency deviation, And a digital transmission / reception unit.

Description

TECHNICAL FIELD [0001] The present invention relates to a frequency deviation compensation apparatus for a wireless communication apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for compensating for a frequency deviation of a transmission / reception signal between wireless communication devices in a wireless communication device applicable to a base station of a mobile communication system, For example.

2. Description of the Related Art [0002] Recently, various studies have been conducted including a Multiple Input Multiple Output (MIMO) scheme and the like in order to more efficiently transmit more data in a limited frequency band to satisfy a service subscriber requiring a large amount of data service. In addition, in addition to a method of implementing a base station in units of existing macrocells, a plurality of base stations are implemented in units of a smaller cell (aka a small cell), thereby providing a data service intensively to a smaller number of subscribers And a small or very small base station for implementing the method.

In this case, the conventional method of connecting the base stations through the optical cable or the like increases the installation cost and difficulties due to the installation environment when the base station is connected to a plurality of small base stations. As a result, a system for connecting with each other through a wireless communication device between a base station and a small-sized base station has been required. Currently, the data capacity of a small cell can be effectively processed wirelessly, A communication apparatus using a millimeter wave (a very high frequency broadband millimeter wave) band is being applied.

However, 60 GHz and so on, which are applied in the millimeter wave band, are very high frequency bands, and the problems that are relatively uncomfortable in other radio communication technologies such as the 800 MHz band and the 2 GHz band which are the high frequency bands used in the conventional mobile communication system It has become important.

That is, when the frequency accuracy is not very precise in each of the local oscillators of two radio communication equipments transmitting and receiving signals in the millimeter wave band, frequency deviation occurs between the two radio communication equipments, Resulting in serious performance degradation and lowering the reliability of the communication system.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a frequency deviation compensation apparatus for reducing a frequency deviation between two wireless communication apparatuses, thereby improving the reliability of a communication system.

According to some embodiments of the present invention, there is provided an apparatus for compensating for frequency deviation of a wireless communication apparatus, the apparatus comprising: A low power amplifier for low power amplifying a received signal received through an antenna; A frequency down converter for converting the low power amplified received signal into a signal of an intermediate frequency by mixing with a local oscillation signal and adjusting a frequency of the local oscillation signal to a control signal provided from the outside; A control signal for converting the intermediate frequency signal into a digital signal and converting the intermediate frequency signal to a baseband signal, checking a frequency deviation with respect to the received signal, and compensating the frequency deviation based on the determined frequency deviation, And a digital transceiver for providing the frequency down-converter.

The local oscillator of the frequency down converter may be a voltage controlled crystal oscillator that generates a local oscillation signal adjusted to correspond to the control signal.

The digital transceiver includes a reference oscillator for generating a reference oscillation signal for generating a reference clock; A PLL (Phase Locked Loop) for generating an oscillation signal of the reference oscillator and generating a reference clock; An analog / digital converter operating according to a reference clock generated by the PLL and digitally converting the intermediate frequency signal; And a controller for receiving the digital signal converted from the analog-to-digital converter and converting the digital signal into a baseband signal, checking a direction in which the frequency deviation and the frequency are shifted in the baseband signal, And a signal processing circuit for outputting a control signal whose voltage value is adjusted based on the signal to the local oscillator of the frequency down converter.

Wherein the signal processing circuit comprises: a baseband converter for converting a digitally converted signal input from the analog-to-digital converter into a baseband signal using a reference clock provided from the PLL; A phase value calculator for calculating and outputting a phase value of a baseband signal output from the baseband converter; And a phase analyzer for analyzing a phase value output from the phase value calculator to determine a deviation degree of the received signal and a direction in which the frequency is shifted.

The phase analyzer may further include a phase comparator for comparing the phase of the received signal with a phase of the phase difference between the reference signal and the reference signal, .

Wherein the phase analyzer comprises: a sampling window corresponding to a predetermined time interval for analyzing the phase state of the phase value; It is possible to operate in consideration of a preset threshold value as a criterion for determining that the deviation of the received signal is within the normal range.

According to some other embodiments of the present invention, the present invention provides a frequency deviation compensation apparatus for a wireless communication apparatus, A low power amplifier for low power amplifying a received signal received through an antenna; A frequency down converter for converting the low power amplified received signal into a signal of an intermediate frequency by mixing with a local oscillation signal and adjusting a frequency of the local oscillation signal to a control signal provided from the outside; And a digital transceiver for converting the intermediate frequency signal into a digital signal, converting the intermediate frequency signal to a baseband signal, checking a frequency deviation of the received signal, and converting the baseband signal based on the determined frequency deviation .

The digital transceiver includes a reference oscillator for generating a reference oscillation signal for generating a reference clock; A PLL (Phase Locked Loop) for generating an oscillation signal of the reference oscillator and generating a reference clock; An analog / digital converter operating according to a reference clock generated by the PLL and digitally converting the intermediate frequency signal; The PLL operates according to a reference clock generated by the PLL, converts the digital signal converted from the analog-to-digital converter into a baseband signal, confirms a direction in which the frequency deviation and frequency are shifted in the baseband signal, The baseband signal conversion operation can be performed.

Wherein the signal processing circuit comprises: a baseband converter for converting a digitally converted signal input from the analog-to-digital converter into a baseband signal using a reference clock provided from the PLL; A phase value calculator for calculating and outputting a phase value of a baseband signal output from the baseband converter; And a phase analyzer for analyzing a phase value output from the phase value calculator to determine a direction in which the deviation and frequency of the received signal are shifted and outputting a control signal to the baseband converter; The base band converter may perform the baseband signal conversion operation according to the control signal.

As described above, the frequency deviation compensation apparatus in the wireless communication apparatus according to the embodiments of the present invention can reduce the frequency deviation between the two wireless communication apparatuses, thereby improving the received signal processing performance and improving the reliability of the communication system have.

FIG. 1 is a block diagram of an example in which a frequency deviation reduction scheme, which is basically considered to reduce a frequency deviation, is applied in a wireless communication apparatus for processing a millimeter wave band
FIG. 2 is a block diagram illustrating a frequency deviation compensation apparatus in a wireless communication apparatus for processing a millimeter wave band according to an embodiment of the present invention.
FIG. 3 is a detailed block diagram of a main part of the signal processing circuit in FIG. 2
FIGS. 4A to 4C are graphs showing graphs showing the phase value generation state according to the frequency deviation of various conditions in the operation of the signal processing circuit of FIG. 3. FIG.
5 is a flowchart illustrating an operation flow for compensating for frequency deviation in a wireless communication apparatus for processing a millimeter wave band according to an exemplary embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be appreciated that those skilled in the art will readily observe that certain changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims. To those of ordinary skill in the art.

FIG. 1 is a block diagram of an exemplary application of a frequency deviation reduction scheme, which is basically considered to reduce a frequency deviation in a wireless communication apparatus for processing a millimeter wave band, . Referring first to FIG. 1, a structure that can be considered as a primary consideration for reducing a frequency deviation in a wireless communication apparatus for processing a millimeter wave band will be described first.

1 includes a low noise amplifier (LNA) 102 for low-power amplifying a reception signal of a millimeter wave band received through a millimeter wave band reception antenna ANT to process a reception signal )Wow; A first filter (104) which receives an output from the low power amplifier (102) and performs filtering of the millimeter wave band to remove unnecessary waves; A frequency down converter 110 which receives the output of the first filter 104 and converts the millimeter wave signal into a signal having an intermediate frequency by mixing the signal with the local oscillation signal; A second filter 122 for receiving the output of the frequency down converter 110 and filtering the intermediate frequency band to remove unnecessary waves; And a digital transceiving unit (DTU) 130 for receiving the output of the second filter 122, converting the digital signal into a digital signal, and converting the digital signal into a baseband signal.

The frequency down-converter 110 may include, for example, a local oscillator 114 implemented with an oven controlled crystal oscillator to generate a local oscillation signal; And a frequency mixer 112 for mixing down the local oscillation signal supplied from the local oscillator 114 and the received signal of the millimeter wave output from the first filter 104 and down-converting the received signal into an intermediate frequency signal, Lt; / RTI >

The DTU 130 includes a reference oscillator 138 which is implemented as a voltage controlled crystal oscillator and generates a reference oscillation signal for generating a reference clock of the corresponding digital transceiver 130, Wow; A PLL (Phase Locked Loop) 136 for receiving an oscillation signal of the reference oscillator 138 and generating a reference clock for operation of the digital transceiver 130; An analog-to-digital converter (ADC) 132 that operates in accordance with a reference clock generated by the PLL 136 and converts the intermediate frequency signal provided from the second filter 122 to a digital signal; For example, a field programmable gate array (FPGA), receives the converted digital signal from the analog-to-digital converter 132, and generates a baseband signal And a signal processing circuit 134 that performs a digital signal processing operation such as converting the signal to a digital signal.

The wireless communication equipment for processing the millimeter wave band as shown in FIG. 1 may be employed in, for example, a small base station or a repeater of a small cell, and may be configured to receive a wireless signal transmitted to a macro base station or another small base station . In the above description, the internal components for processing the received signal in the wireless communication equipment for processing the millimeter wave band are described as an example, but in addition, the components for processing the transmission signal may be added to the wireless communication equipment I will understand. At this time, the transmission and reception signals are transmitted and received through the antenna ANT shown in FIG. 1, and a configuration for separating transmission and reception signals such as a duplexer (not shown) is provided between the antenna ANT and the low- So as to separate the transmission signal and the reception signal. In the above description, the first filter 104 is provided at the rear end of the low-power amplifier 102, but may be provided at the front end of the low-power amplifier 102, and may be omitted in some cases. Likewise, the second filter 122 may be omitted.

As shown in FIG. 1, internal components for processing a received signal of a wireless communication device for processing a millimeter wave band may be similar to components for processing a received signal of a conventional wireless communication device.

However, in order to reduce the frequency deviation in the wireless communication equipment that processes the millimeter wave band, the local oscillator 114 is implemented with a very precise frequency accuracy. For example, considering a case where a baseband signal of 1 MHz is multiplied by a millimeter wave band of about 60 GHz, the final millimeter wave signal in which the oscillation frequency of the transmission side or the reception side is multiplied by an error of about several Hz, , A deviation may occur in units of KHz. For example, the local oscillator 114 has a structure sealed by a constant temperature oven (i.e., an oven), thereby maintaining a constant temperature state so as not to be influenced by characteristics due to the ambient temperature, and an oven controlled crystal oscillator (OCXO).

However, the structure shown in FIG. 1 basically corresponds to a scheme for reducing the frequency deviation between the transmitting side and the receiving side by maximizing the frequency accuracy individually on the transmitting side and the receiving side, respectively. Such a scheme has a limitation in actively coping with the frequency deviation which is inevitably generated between the transmitting side and the receiving side. In addition, the above-described structure has a problem in that it requires an oven-controlled crystal oscillator, which is relatively expensive and complex equipment, in order to maximize the frequency accuracy at the transmitting side and the receiving side.

FIG. 2 is a block diagram of a frequency shift compensation apparatus applied to a wireless communication apparatus for processing a millimeter wave band according to an embodiment of the present invention, and shows a basic structure for processing a received signal in a wireless communication apparatus. Referring to FIG. 2, a wireless communication apparatus according to an embodiment of the present invention may be configured to transmit a reception signal of a millimeter wave band received through a millimeter waveband receiving antenna ANT to a low power amplification A low power amplifier (LNA) 202; A first filter 204 that receives an output from the low power amplifier 202 and performs filtering on a millimeter waveband to remove unwanted waves; A frequency down converter 210 receiving the output of the first filter 204 and converting the millimeter wave band signal into a local oscillation signal and converting the signal into an intermediate frequency signal; A second filter 222 that receives the output of the frequency down converter 210 and performs filtering of an intermediate frequency band to remove unwanted waves; And a digital transmission / reception unit (DTU) 20 for receiving the output of the second filter 222, converting the digital signal into a digital signal, and converting the digital signal into a baseband signal.

2, unlike the structure of FIG. 1, the frequency down-converter 210 is implemented as a voltage-controlled crystal oscillator, and performs an external control (that is, A local oscillator 214 for generating a local oscillation signal, which is regulated by voltage control; And a frequency mixer 212 for mixing the local oscillation signal supplied from the local oscillator 214 with the reception signal of millimeter wave output from the first filter 204 and down-converting the received signal into an intermediate frequency signal.

The local oscillator 214 of the frequency down-converter 210 adjusts the frequency of the local oscillation signal by a control signal (i.e., voltage control) provided from the DTU 230. The digital transceiver 230 checks the frequency deviation of the received signal and outputs a control signal for compensating the deviation to the local oscillator 214 of the frequency down converter 210 based on the frequency deviation.

1, for example, a voltage controlled crystal oscillator may be used to generate the reference clock of the corresponding digital transceiver 230. In this case, A reference oscillator 238 for generating an oscillation signal that is a reference for harm; A PLL 236 receiving the oscillation signal of the reference oscillator 238 and generating a reference clock for operation of the digital transceiver 230; An analog-to-digital converter (ADC) 232 operating according to the reference clock generated by the PLL 236 and digitally converting an intermediate frequency signal provided from the second filter 222; For example, a field programmable gate array (FPGA), receives the converted digital signal from the analog-to-digital converter 232, and generates a baseband signal And a signal processing circuit 234 for performing a digital signal processing operation such as conversion to a digital signal.

In the above-described configuration, the signal processing circuit 234 may further comprise a signal processing circuit 234, which, in accordance with an embodiment of the present invention, further identifies the direction in which the frequency deviation and the frequency are shifted in the baseband signal for the received signal, To the local oscillator 214, which may be embodied as the voltage controlled crystal oscillator of the frequency down converter 210. The control oscillator 214 of FIG.

3 is a detailed block diagram of a main part of the signal processing circuit 234 in FIG. 2. Referring to FIG. 3, the detailed configuration and operation of the signal processing circuit 234, which can be implemented by an FPGA, will be described . 3, the signal processing circuit 234 converts the digitally converted signal (complex signal) input from the analog-to-digital converter 232 into a baseband signal (complex signal) using the reference clock provided from the PLL 236 baseband signal to a baseband signal. The baseband converter 302 may be implemented as a complex multiplier composed of an NCO (Numerically Controlled Oscillator) or the like.

The signal processing circuit 234 is configured to perform an arctangent (ARC TAN) calculation function using, for example, a CORDIC (Coordinate Rotation Digital Computer) algorithm, A phase value calculator 304 for calculating and outputting a phase value (for example, an arc tangent value) of the band signal; And a phase analyzer 306 for receiving the phase value output from the phase value calculator 304 and analyzing the received phase value to determine a deviation degree of the received signal and a direction in which the frequency is shifted.

The signal processing circuit 234 is supplied with a control signal having a voltage value appropriately set to compensate for the deviation based on the degree of deviation and the frequency shift direction output from the phase analyzer 306 to a local oscillator 214 And a control signal generator (not shown) for adjusting the oscillation signal of the local oscillator 214 may be provided. For example, when the local oscillator 214 is implemented as a voltage-controlled crystal oscillator, the voltage value of the control signal may be appropriately set within 0 to 5 V, and a control signal for adjusting the oscillation signal in units of 0.5 V Lt; / RTI > The control signal generator may be implemented in the signal processing circuit 234, but may be separately implemented in the digital transceiver 230.

The phase analyzer 306 in the signal processing circuit 234 is configured to determine the degree of deviation of the received signal and the direction in which the frequency has shifted by analyzing the time-varying state of the phase value output from the phase value calculator 304. At this time, the variation graph of the phase value shows different characteristics depending on the degree of deviation of the received signal and the direction in which the frequency is shifted. By analyzing such characteristics, the degree of deviation and the direction of the frequency shift can be grasped.

As shown in FIG. 4A, for example, when a deviation occurs to the right relative to a reference frequency (that is, a reference frequency of the receiving-side wireless communication device) (that is, And the received reference frequency is higher than the frequency), the variation graph of the phase value shows a waveform corresponding to a sawtooth wave having a period in which the waveform linearly increases relatively slowly with respect to time. This sawtooth waveform shows a sudden return back to the initial value when a certain maximum value is reached.

If the received signal deviates leftward relative to the reference frequency (i.e., when the reference frequency received from the transmitting equipment is lower than the agreed reference frequency), as shown in FIG. 4B, A waveform corresponding to a sawtooth wave having a period in which the waveform linearly decreases relatively slowly with respect to time appears. This sawtooth waveform shows a sudden return back to the initial value when a certain minimum value is reached.

4A and 4B show a sampling window w corresponding to a section for actually analyzing the waveform characteristic in the graph of the variation of the phase values, and the sampling window may be set to an appropriate size in advance. The phase analyzer 306 continuously checks the waveform characteristics of the sampling window w, that is, the variation degree, the increase or the decrease characteristic of the phase values, thereby continuously determining the deviation of the received signal and the direction of the frequency shift. At this time, there may be an error in determining the deviation of the received signal in a period in which the sawtooth waveform rapidly varies between the maximum value and the minimum value. In order to solve such an error, the phase analyzer may perform the above determination operation more than 3 times, for example, and operate with reliability for the result when the determination result is the same.

Meanwhile, the phase analyzer 306 can consider that there is no deviation in the received signal when the degree of variation of the phase values within the sampling window w is within a preset threshold value. For example, in an ideal case where there is no deviation in the received signal at all, the phase value variation characteristic will have a direct current (DC) characteristic. 4C shows a waveform corresponding to the phase value variation characteristic when it is judged that there is no deviation of the received signal, that is, when it is judged that it is within a preset threshold value. In this case, for example, a waveform corresponding to the variation characteristic of the phase value is shown as an example when the reception signal deviation is 100 Hz. As shown in FIG. 4C, when the deviation of the received signal is relatively small, the deviation of the received signal may be considered to be within the normal range. That is, in this case, the threshold value is appropriately set in advance so that the degree of variation of the phase values is within the threshold value. Of course, when more precise operation is required, a high performance resolution may be applied to compensate for the frequency deviation.

5 is a flowchart illustrating an operation for compensating for frequency deviation in a wireless communication apparatus for processing a millimeter wave band according to an exemplary embodiment of the present invention. Referring to FIG. 2 and FIG. 3, the digital transmission / The signal processing circuit 234 of FIG. Referring to FIG. 5, a description will be made of an 'AFC (Auto Frequency Control)' which is a frequency deviation compensation operation according to an embodiment of the present invention. First, in step 402, A sampling window which is a section for checking the variation of the threshold value and the phase value is set in advance. The threshold value and the sampling window may be fixedly set in advance before performing the frequency deviation compensation operation according to the present invention, so that the step 402 may not be actually performed.

In step 404, a difference between a maximum value and a minimum value of the phase values in the sampling window is determined and it is determined whether the result is less than or equal to the threshold value. If it is determined that the difference between the maximum value and the minimum value of the phase value is equal to or less than the threshold value as a result of the determination in step 404, the operation is terminated while the deviation of the received signal is within the normal range. If the difference between the maximum value and the minimum value of the phase value exceeds the threshold value The process proceeds to step 406. [

In step 406, it is determined whether the phase value in the corresponding sampling window is increasing. The operation of step 406 is to determine whether the waveform of the phase value has the sawtooth shape shown in FIG. 4A. If it is determined in step 406 that the phase value is increasing, the process proceeds to step 407. If the phase value is not increased (i.e., the phase value is decreased), the process proceeds to step 408.

In step 407, a frequency deviation corresponding to the difference between the maximum value and the minimum value of the phase value is checked, and the control voltage of the voltage controlled crystal oscillator (OCXO) as shown in FIG. 2 is set to a level corresponding to the frequency deviation By a preset level). On the other hand, in step 408, the voltage control crystal oscillator (OCXO) control voltage is increased to a level corresponding to the frequency deviation (or a predetermined level). After the operations of steps 407 and 408 are performed, the process returns to step 404, and the above steps are repeated. Thus, the processes are repeated until it is determined that the deviation of the received signal is within the normal range. .

5, a frequency deviation compensation operation according to an embodiment of the present invention may be performed. In addition, in another embodiment of the present invention, in addition to the operation in FIG. 5 described above, Can be performed. For example, in another embodiment of the present invention, instead of decreasing or increasing the voltage-controlled crystal oscillator (OCXO) control voltage corresponding to the frequency deviation in steps 407 and 408 of FIG. 5, And adjusts the operation of the same baseband converter 302.

That is, in another embodiment of the present invention, when operations 407 and 408 of FIG. 5 are performed, the operation of a numerically controlled oscillator (NCO) constituting the baseband converter 302 to compensate for the frequency deviation So as to generate a so-called 'AFC signal'. The 'AFC signal' may be set to a value corresponding to the frequency deviation, and the NCO performs an operation in consideration of the frequency deviation (that is, adding or subtracting the AFC signal) according to the received reference frequency, To compensate for the frequency deviation.

As shown in FIGS. 2 to 5, embodiments of the present invention basically analyze a received signal and adaptively compensate for the frequency deviation. In such a structure, the frequency deviation can be compensated for effectively . In addition, such a structure can be realized with relatively simple and low-cost because the local oscillator 214 can be implemented not as an oven-controlled crystal oscillator but as a voltage-controlled crystal oscillator.

As described above, the configuration and operation of the frequency deviation compensation apparatus in the wireless communication apparatus according to the embodiments of the present invention can be performed. While the present invention has been described with respect to specific embodiments thereof, Can be carried out without departing from the scope. Accordingly, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by equivalents of the claims and the claims.

Claims (10)

1. A frequency deviation compensation apparatus for a wireless communication apparatus,
A low power amplifier for low power amplifying a received signal received through an antenna;
A frequency down converter for converting the low power amplified received signal into a signal of an intermediate frequency by mixing with a local oscillation signal and adjusting a frequency of the local oscillation signal to a control signal provided from the outside;
A control signal for converting the intermediate frequency signal into a digital signal and converting the intermediate frequency signal to a baseband signal, checking a frequency deviation with respect to the received signal, and compensating the frequency deviation based on the determined frequency deviation, And a digital down-converter,
The local oscillator of the frequency down-
And a voltage controlled crystal oscillator for generating a local oscillation signal adjusted in accordance with the control signal,
The digital transmission /
A reference oscillator for generating a reference oscillation signal for generating a reference clock;
A PLL (Phase Locked Loop) for generating an oscillation signal of the reference oscillator and generating a reference clock;
An analog / digital converter operating according to a reference clock generated by the PLL and digitally converting the intermediate frequency signal;
And a controller for receiving the digital signal converted from the analog-to-digital converter and converting the digital signal into a baseband signal, checking a direction in which the frequency deviation and the frequency are shifted in the baseband signal, And a signal processing circuit for outputting a control signal whose voltage value is adjusted based thereon to the local oscillator of the frequency down converter,
Wherein the signal processing circuit comprises:
A baseband converter for converting the digital-converted signal input from the analog-to-digital converter into a baseband signal using a reference clock provided from the PLL;
A phase value calculator for calculating and outputting a phase value of a baseband signal output from the baseband converter;
And a phase analyzer for analyzing a phase value output from the phase value calculator to determine a deviation degree of the received signal and a direction in which the frequency is shifted.
delete delete delete The apparatus of claim 1,
Wherein the phase deviation calculator analyzes the time phase of the phase value output from the phase value calculator to determine a deviation degree of the received signal and a direction in which the frequency is shifted.
6. The apparatus of claim 5,
When the phase state of the received signal has a characteristic corresponding to a sawtooth having a period of linearly increasing or decreasing with respect to time, it is regarded that the received signal is deviated rightward or leftward relative to the reference frequency Of the frequency deviation.
7. The apparatus of claim 6,
A sampling window corresponding to a preset time interval for analyzing the phase state of the phase value;
And operates in consideration of a preset threshold value as a criterion for determining that the deviation of the received signal is within a normal range.
1. A frequency deviation compensation apparatus for a wireless communication apparatus,
A low power amplifier for low power amplifying a received signal received through an antenna;
A frequency down converter for converting the low power amplified received signal into a signal of an intermediate frequency by mixing with a local oscillation signal and adjusting a frequency of the local oscillation signal to a control signal provided from the outside;
And a digital transceiver for converting the intermediate frequency signal into a digital signal, converting the intermediate frequency signal to a baseband signal, checking a frequency deviation of the received signal, and converting the baseband signal based on the determined frequency deviation,
The digital transmission /
A reference oscillator for generating a reference oscillation signal for generating a reference clock;
A PLL (Phase Locked Loop) for generating an oscillation signal of the reference oscillator and generating a reference clock;
An analog / digital converter operating according to a reference clock generated by the PLL and digitally converting the intermediate frequency signal;
The PLL operates according to a reference clock generated by the PLL, converts the digital signal converted from the analog-to-digital converter into a baseband signal, confirms a direction in which the frequency deviation and frequency are shifted in the baseband signal, And a signal processing circuit for performing a conversion operation of the baseband signal,
Wherein the signal processing circuit comprises:
A baseband converter for converting the digital-converted signal input from the analog-to-digital converter into a baseband signal using a reference clock provided from the PLL;
A phase value calculator for calculating and outputting a phase value of a baseband signal output from the baseband converter;
And a phase analyzer for analyzing a phase value output from the phase value calculator to determine a direction in which the deviation and frequency of the received signal are shifted and outputting a control signal to the baseband converter;
Wherein the baseband converter performs the operation of converting the baseband signal according to the control signal. delete delete

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