TW200428785A - Fast frequency synthesizing and modulating apparatus and method - Google Patents

Abstract

A fast frequency synthesizing and modulating apparatus and method is provided, which includes a first phase lock loop (PLL) and a second phase lock loop. The first lock loop makes sure that the output modulated signal can keep the stability fixed according to a reference frequency signal with high precision. Then, the miss sampling of the transmission data can be improved. The second phase lock loop is linked to the microcomputer controller to pre-store the each control voltage of each band frequency into a master control panel. Then, the master control panel can provide a predetermined control voltage in accordance with the working frequency. By this way, the speed of the frequency hopping can be accelerated.

Description

200428785 V. Description of the invention (1) Technical field to which the invention belongs The present invention relates to a frequency hopping processing technology in a wireless communication system, and particularly to a fast frequency synthesis and modulation technology. Prior technologies As the world has become internationalized, the importance of communications technology has become increasingly important. If a major accident happens in a certain country, the convenience of communication can quickly send this message to all countries in the world and get assistance from all countries. In communication technology, wireless communication is the most attractive now. Because you want to transfer information between two places that are a little distance away but not connected by lines, there is no other more efficient way than wireless communication. In recent years, due to the rapid development of semiconductor technology, the use of digital 4 forms to process data has become more and more common. Therefore, most of the wireless communications used today choose to use digital form to process data. For traditional wireless digital communications, the digital data content at the transmitting end is converted into a radio-frequency analog signal for transmission, which is transmitted by the transmitter. At this time, if the receiver is adjusted to the same frequency as the radio frequency analog signal transmitted by the transmitter or is kept within an allowable error range, it can receive the radio frequency analog signal transmitted by the transmitter. Of course, after receiving this RF analog signal, the receiving end will convert the received RF analog signal into a digital form before processing. The basic phase-locked loop components traditionally used for frequency synthesis and modulation include: a phase detector, a frequency divider, and a voltage-controlled oscillator. In addition to receiving a reference frequency signal input, the phase detector is electrically connected To voltage controlled vibration

11210rwf.ptd Page 5 200428785 V. Description of the invention (2) Oscillator and frequency divider. The voltage controlled oscillator is responsible for outputting the oscillation signal. The phase detector is used to compare the phase of the input reference frequency signal and the signal output by the divider. The frequency divider divides the oscillating signal output by the voltage controlled oscillator and sends it to the phase detector. The voltage-controlled oscillator receives the signal output by the phase detector, provides an output signal after oscillation, and sends the output signal to the frequency divider. It is well known that quartz crystals have extremely stable resonance characteristics and very high selectivity (ie, Q value). When used on an oscillator, the output of the oscillator can maintain a very accurate and stable frequency, that is, high stability . However, the voltage-controlled oscillator used in the conventional phase-locked loop is not a crystal oscillator with high stability, so it needs to have a stable reference frequency and perform feedback frequency-locked operation. However, traditional phase-locked loops will lose data when the frequency is locked fast. In addition, in the traditional phase-locked loop, the modulation amount of the frequency band needs a loop cycle time to obtain the modulation amount data. In addition to the inability to control the precise amount of modulation, the frequency-locking speed also becomes difficult to grasp. In addition, the frequency divider uses a fixed value to perform the frequency division operation, which causes a problem that the frequency hopping speed between the high frequency band and the low frequency band is difficult to control. Based on the above, it can be known that when using a conventional single phase-locked loop for frequency synthesis and modulation, there will be the following disadvantages: (1) When the traditional single phase-locked loop encounters a fast frequency-locking speed, it will cause low frequency The modulation response is poor, so data and data cannot be transmitted normally, and even data loss may occur; (2) The traditional single phase-locked loop is difficult to control due to the modulation between the high and low frequency bands, and it is very difficult to master the frequency lock speed ;

11210twf.ptd Page 6 200428785 V. Description of the invention (3) (3) When the traditional single phase-locked loop is dense, the frequency hopping speed between the high frequency band and the low frequency band is too slow to meet the needs of the current communication era . SUMMARY OF THE INVENTION In view of this, the present invention is to improve the disadvantages of the prior art: 1. The problem of data loss when the low-frequency modulation response is poor; 2. The modulation amount is difficult to control; Problem. One of the effects of this invention is to provide a signal with high stability and flat modulation, which solves the problem of data loss; the second is to adjust the amount of modulation of the frequency and is easy to control; the third is to provide a preset voltage Speed up frequency hopping. The invention provides a fast frequency synthesizing and modulating device. The device includes a first phase locked loop and a second phase locked loop. The first phase-locked loop is based on the input data signal and a precise reference frequency signal to modulate and oscillate a modulation signal with the data loaded in the middle, and then output to the second phase-locked loop. The second phase-locked loop is connected after the aforementioned first phase-locked loop, and it oscillates an output modulation signal according to the modulation signal of the previously loaded data and a frequency-hopping reference frequency signal. The second phase-locked loop includes an output voltage-controlled oscillator, and the second phase-locked loop supplies a pre-biased voltage to the output voltage-controlled oscillator according to a pre-adjusted bias voltage data, so as to oscillate the Output modulation signal. In a preferred embodiment of the present invention, the first phase-locked loop includes: a first phase detector, a first voltage-controlled oscillator, a first frequency divider, and a second frequency divider. The first voltage-controlled oscillator is electrically connected to the first phase detection.

11210twf.ptd Page 7 200428785 V. Description of the Invention (4) The first frequency divider is connected to the first phase detector and the first voltage controlled oscillator. The first phase detector is used to compare a first reference frequency signal and a first frequency-divided signal, and then output a first voltage control signal. The aforementioned first reference frequency signal is a signal obtained by dividing the frequency of the accurate reference frequency signal by the second frequency divider. The first voltage-controlled oscillator is based on the aforementioned first voltage-controlled oscillation signal and the input data signal, and oscillates and modulates the modulation signal of the above-mentioned intermediate data. The first frequency divider divides the modulation signal of the previously loaded data described above to obtain a first frequency division signal. In addition, in a preferred embodiment of the present invention, the second phase-locked loop saves the In addition to the oscillator, it also includes a second phase detector, a loop filter, a first mixer, a first low-pass filter, a third frequency divider, a second mixer, and a second low-pass filter. Device. The loop filter is electrically connected to the second phase detector and the aforementioned output voltage-controlled oscillator; the first mixer is electrically connected to the output voltage-controlled oscillator; the first low-pass filter is electrically connected To the first mixer; the third frequency divider is electrically connected to the second phase detector; the second low-pass filter is electrically connected to the second mixer. The second phase detector is used to compare an intermediate frequency modulation signal and a second frequency division signal of the loaded data, and output an error signal. Among them, the intermediate frequency modulation signal of the previously loaded data is a signal obtained by processing the modulation signal of the middle loaded data. The loop filter obtains the second voltage-controlled signal after filtering the error signal. The first mixer obtains a first mixed signal after mixing the output modulation signal with a frequency hopping reference signal. First low-pass filter After filtering the aforementioned first mixed frequency signal, an output intermediate frequency data is obtained

11210twf.ptd Page 8 Λ / t 1 200428785 V. Description of the invention (5) Material signal. The third frequency divider divides the output intermediate frequency data signal obtained previously to obtain a second frequency division signal. The second mixer mixes the intermediate loaded data modulation signal output from the first phase-locked loop and the second reference frequency signal to obtain a second mixed signal. The second low-pass filter filters the second frequency mixing signal mentioned above to obtain the intermediate frequency modulation signal of the loaded data. The invention also introduces a method for fast frequency synthesis and modulation, which includes the following steps: firstly providing a high-stability accurate reference frequency signal; and then modulating and oscillating according to an input data signal and the aforementioned precise reference frequency signal An intermediate loaded data modulation signal; then provide a frequency hopping reference frequency signal and a pre-adjusted bias data; and provide a pre-set bias based on the pre-adjusted bias data mentioned above; and finally according to the intermediate loaded data The data modulation signal and the frequency-hopping reference frequency signal oscillate an output modulation signal. Among them, according to the pre-adjusted bias data, the aforementioned output modulation signal is quickly oscillated. In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is described below in detail with the accompanying drawings as follows: Embodiments The present invention proposes a fast Apparatus and method for frequency synthesis and modulation. FIG. 1 is a block diagram of a fast frequency synthesizing and modulating device according to a preferred embodiment of the present invention, which includes a first phase-locked loop 1200 and a second phase-locked loop 1300. FIG. 2 is a schematic block diagram of a circuit of a preferred embodiment of the first phase locked loop. FIG. 3 is a schematic circuit block diagram of a preferred embodiment of the second phase locked loop.

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• Refer to Figures i and 2 at the same time, where the first phase-locked loop includes the first phase-suppressor detector 1 2 10, the first voltage-controlled oscillator 1 2 2 0, the first divider 1 2 2 5 and the second frequency divider 1 2 0 5. The connection situation is that the first voltage-controlled oscillation is If 2 0, which is connected to the first phase detector 丨 2 丨 〇; the first frequency divider 丨 2 2 5 is connected to the first phase detector 丨 2丨 〇 and the first voltage-controlled oscillator 202 are used to synchronize the signal with an accurate reference frequency according to the input data signal and oscillate an intermediate data modulation signal. It achieves one of the purposes of outputting the data modulation signal with two stable and flat data modulation signals. & With reference to Figures 1 and 3 at the same time, the second phase-locked loop includes a multi-frequency "k voltage controlled oscillator 1 3 2 0 and a frequency-locked loop. The aforementioned frequency-locked loop includes: a first phase detector 3 3 〇, a loop filter 1 3 1 5, a first mixer 1 345, a first low-pass filter 134 〇, and a third frequency divider 1325, second low-pass filter 1 3 1 0, second mixer 315, digital / analog conversion bias circuit 1 3 3 5 and multi-band voltage controlled oscillator 3 2 0. The connection situation is that the loop filter 1 3 1 5 is electrically connected to the second phase detector 丨 3 3 〇 and the multi-band voltage-controlled vibration state 1 3 2 0, and the first mixer 1 3 4 5 is electrically connected The multi-band voltage-controlled oscillator is 1 3 2 0; the first low-pass filter 1 3 4 0 is electrically connected to the first mixer 1 3 4 5; the third frequency divider 1 3 2 5 is electrically connected to the first The two-phase detector 3 3 0; the second low-pass filter 1 3 1 0 is electrically connected to the second mixer 3 3 5. Its work is to generate an output modulation signal based on a modulated signal in the middle of the loaded data and a frequency hopping reference frequency signal. Another work is to provide a pre-bias voltage to a multi-band voltage controlled oscillator based on a pre-biased bias data. Because of the combination of the second phase-locked loop and the microcomputer to achieve one of the purposes of accelerating the frequency hopping speed, the modulation amount of the frequency can be fine-tuned and easily controlled and suppressed.

200428785 V. Description of the invention (7) Benefits of noise control. Here, the rate of the first phase-locked loop is firstly determined by the feedback loop and the feedback loop's required stability bit detector 1 2 1 0. The first parameter 1 1 3 Q divided by the frequency signal has a temperature system that can make the vibration frequency range. This temperature Compensa temperature coefficient communication technology body oscillator radio frequency analogy. On the one hand, the frequency oscillation is provided to the electric number 1. 2 3 5 The frequency of the most stable oscillator is usually highly compensated for the oscillation of ted C r, and none. The most basic device for the receiver of the temperature signal and the pulse generator. To discuss the first phase-locked loop, please refer to Figure 2 for a schematic block diagram of a preferred embodiment. The phase characteristics of the oscillation frequency are determined, and the stability of the oscillation frequency is related to the change of frequency. In order to achieve the requirements of the present invention, the first phase is used in the first phase-locked loop. Its function is to compare the first reference frequency signal 1 2 3 0 and the first phase, and then output the first voltage control signal 1 2 4 0. The aforementioned signal 1 2 3 0 is obtained by dividing a temperature-compensated crystal oscillator number by a second frequency divider 1 2 0 5. The resonance characteristics and very high selectivity (Q value) of quartz crystals give a very accurate and stable frequency. Available crystals range from several kHz to hundreds of MHz and have resonance frequencies of 1 or 2 p p m / ° C. In order to achieve the high stability of the crystal oscillator 1130 (Temperature ystal Oscillator, TCX0), it is recommended to use a lower device to achieve one of the purposes of high stability. In fact, both the transmitter and the receiver will be equipped with a temperature-compensated crystal-compensated crystal oscillator. In addition to keeping the frequency emitted by the transmitter within a permissible range, it can also be used with As a basis for the solution. The function of this book is to output and use various signal waveforms. The first voltage controlled oscillator 1 2 2 0 accepts the first phase

11210twf.ptd Page 11 200428785 V. Description of the invention (8) The first voltage-controlled signal 1 2 4 0 output by the detector 1 2 1 0 oscillates with the input data signal and modulates an intermediate data-containing modulation The variable signal is output to the second phase-locked loop. The first frequency divider 1 2 2 5 is responsible for dividing the frequency-modulated signal carrying data in the middle and outputting the first frequency division signal 1 2 3 5 to the first phase detector 1 2 1 0. The second frequency divider 1 2 0 5 is controlled by a frequency division data, and divides the accurate reference frequency signal output by the temperature compensated crystal oscillator 1 1 3 0 to obtain the first reference frequency signal 1 2 3 0. Because the first phase-locked loop uses a highly accurate reference frequency signal for modulation, the accuracy of the data transmitted on the modulation signal output by the first phase-locked loop can be determined. Next, the second phase locked loop is discussed. Please refer to FIG. 3 for a schematic block diagram of a second embodiment of the second phase locked loop. The second phase detector 1 3 3 0 is used to compare the t-frequency modulation signal of the loaded data output by the second low-pass filter 1 3 1 0 with the third frequency divider 1 3 2 5 After the second frequency division signal 1 3 6 5 is output, an error signal is output to the loop filter 1315. The filter has the function of frequency selection, that is to say, it can pass signals in a specific frequency range and block signals outside the frequency range. Such a filter ideally has two frequency bands. Among them, the transmission gain of one frequency band is one, that is, the pass-band of the filter; the transmission gain of the other frequency band is zero, that is, the stop band of the filter (s t 0 p-b a n d). Of course, the higher the filter selectivity (Q value), the smaller the harmonic component of the sine wave output, and the more accurate the filtered waveform is. The loop filter we use in the second phase-locked loop requires 4 gen. Mobile, therefore using a variable frequency wide loop filter,

112101 w f. Ptd Page 12 200428785 V. Description of the invention (9) It is used to respond to various frequency signals. Then, the loop filter 1 3 1 5 filters the error signal output by the second phase detector 1 3 3 0 To obtain the second voltage control signal 1 3 6 0. The first mixer 1 3 4 5 mixes the output modulation signal of the multi-band voltage controlled oscillator 1 3 2 0 with the frequency hopping reference frequency signal to obtain a first mixed signal 1 3 7 0. Among them, the frequency hopping reference frequency signal mentioned above is a signal output by a frequency hopping synthesizer after receiving a control instruction for controlling frequency data. The first mixed frequency signal 1 3 7 0 obtained earlier is input to the first low-pass filter 1 3 4 0, and an output intermediate frequency signal is obtained after filtering by the filter. This intermediate frequency signal passes through the third frequency divider 1 3 2 After frequency division, the second frequency division signal 1 3 6 5 is obtained and input to the second phase detector 1 3 3 0. The second mixer 1 3 0 5 mixes the modulated data-carrying signal output from the first phase-locked loop with the second reference frequency signal 1 1 3 5 to obtain a second mixed signal 1 3 5 5. This second frequency mixing signal 1 3 5 5 is input to a second low-pass filter and a wave filter 1 3 1 0. After this filtering, wave filter and wave, an intermediate frequency modulation signal with the previously mentioned data is obtained. The second phase detector 1 3 3 0 is input to perform a phase comparison operation. In addition, the second phase-locked loop also includes a digital / analog conversion pre-bias circuit 1 3 3 5. According to the pre-bias data, a pre-bias is provided to the multi-band voltage-controlled oscillator 1 3 2 0. Thereby, the output modulation signal is rapidly oscillated. Due to the combination of the second phase-locked loop and the microcomputer, the control voltage of the entire operating frequency can be adjusted in advance, and the obtained voltage can be stored in the main control board in advance. When the frequency hopping function is activated, the main control board will provide the required preset voltage according to the size of the operating frequency to achieve one of the purposes of accelerating the frequency lock speed. Here, the multi-band voltage controlled oscillator 1 3 2 0 is used as the output voltage controlled oscillator to make

11210twf.ptd Page 13 200428785 V. Description of the Invention (ίο). Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes and retouch without departing from the spirit and scope of the present invention. The scope of protection of the invention shall be determined by the scope of the attached patent application.

112101 w f. Ptd Page 14 200428785 Brief description of the diagram The first diagram is a block diagram showing a fast frequency synthesis and modulation device; the second diagram is a circuit block diagram showing a preferred embodiment of the first phase-locked loop Intent, and FIG. 3 is a schematic circuit block diagram showing a preferred embodiment of the second phase locked loop. Description of graphical symbols: 1 1 1 0: control signal decoder 1 1 2 0: buffer amplifier 1 1 2 5: frequency doubling tuner 1 1 3 0: temperature compensated crystal oscillator Yu 1 1 3 5: second reference Frequency signal 1 1 4 0: Frequency hopping synthesizer 1 1 4 5: Transmitter module 1 2 0 0 · First phase locked loop 1 2 0 5: Second frequency divider 1 2 1 0: First phase detection Detector 1 2 2 0: first voltage controlled oscillator 1 2 2 5: first frequency divider 1 2 3 0: first reference frequency signal 1 2 35: first frequency division signal 1 2 4 0 Voltage control signal 1 3 0 0: Second phase locked loop 1 3 0 5: Second mixer

11210twf.ptd Page 15 200428785 Brief description of the diagram 13 10 Second low-pass filter 13 15 Loop filter 13 20 Multi-band voltage controlled oscillator 1325 Second frequency divider 13 30 Second phase detector 1335 Digital / analog Conversion pre-bias circuit 1340 first low-pass filter, wave filter 1345 first mixer 13 55 second frequency mixing signal 1365 second frequency dividing signal 13 60 second voltage control signal 1370 first frequency mixing signal

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Claims (1)

200428785 6. Scope of patent application 1. A fast frequency synthesizing and modulation device, including a first phase locked loop for modulating and oscillating an intermediate load based on an input data signal and an accurate reference frequency signal Data modulation signal; and a second phase-locked loop, coupled to the first phase-locked loop, for oscillating an output modulation signal based on the intermediate data modulation signal and a frequency hopping reference frequency signal Wherein, the second phase-locked loop includes an output voltage-controlled oscillator, and the second phase-locked loop supplies a pre-biased voltage to the output voltage-controlled oscillator according to a pre-adjusted bias voltage data to rapidly oscillate the output. Modulation signal. 2. The fast frequency synthesizing and modulating 4 device as described in item 1 of the scope of patent application, wherein the first phase-locked loop includes: a first phase detector for comparing a first reference frequency signal and a first A frequency division signal and outputting a first voltage control signal, wherein the first reference frequency signal is obtained according to the precise reference frequency signal; a first voltage control oscillator coupled to the first phase detector, Configured to oscillate and modulate the intermediate loaded data modulation signal according to the first voltage control signal and the input data signal; and a first frequency divider coupled to the first phase detector and the first A voltage-controlled oscillator is used to divide the frequency of the intermediate data modulation signal to obtain the first frequency division signal. 3 · The device for fast frequency synthesis and modulation as described in item 2 of the scope of patent application, wherein the first phase locked loop further includes a second frequency divider for receiving control of a frequency division data, Divide the precise reference frequency signal to 11210twf.ptd Page 17 200428785 6. Scope of patent application The first reference frequency signal is obtained. 4. The fast frequency synthesizing and modulating device according to item 2 of the scope of patent application, wherein the first voltage controlled oscillator is a voltage controlled quartz oscillator. 5. The fast frequency synthesizing and modulating device according to item 1 of the scope of patent application, wherein the output voltage controlled oscillator quickly oscillates the output modulation signal according to a second voltage control signal and the pre-set bias voltage, The second phase locked loop further includes: a second phase detector for comparing an intermediate frequency modulation signal of a loaded data with a second frequency division signal, and outputting an error signal, wherein the loaded data is The frequency modulation signal is obtained according to the intermediate data modulation signal; a loop filter is coupled to the second phase detector and the output voltage-controlled oscillator to filter the error signal to obtain The second voltage-controlled signal; a first mixer coupled to the output voltage-controlled oscillator for mixing the output modulation signal with the frequency-hopping reference frequency signal to obtain a first frequency-mixed signal A first low-pass filter coupled to the first mixer for filtering the first frequency mixing signal to obtain an output intermediate frequency data signal; and a third frequency divider coupled to The second phase detector and the first A low-pass filter is used to divide the output intermediate frequency data signal to obtain the second divided frequency signal. 6. The fast frequency synthesizing and modulating device as described in item 5 of the scope of patent application, wherein the second phase locked loop further comprises: 11210twf.ptd Page 18 200428785 6. Patent application scope-a second mixer for mixing the intermediate data modulation signal with a second reference frequency signal to obtain a second mixed signal; and A second low-pass filter is coupled to the second mixer to filter the second mixed signal to obtain the IF modulated signal of the loaded data. 7. The fast frequency synthesizing and modulating device as described in item 6 of the scope of patent application, further comprising a frequency doubling tuner for doubling the precise reference frequency signal to obtain the second reference frequency signal. 8. The fast frequency synthesizing and modulating device as described in item 7 of the scope of patent application, further comprising a buffer amplifier whose input terminal is connected to the precise reference frequency signal and its output terminal is connected to the frequency doubling tuner. 9. The fast frequency synthesizing and modulating device according to item 5 of the scope of patent application, wherein the second phase-locked loop further includes a digital analog conversion pre-bias circuit for using the pre-bias bias data, The pre-bias is supplied to the output voltage controlled oscillator. 10. The fast frequency synthesizing and modulating device according to item 5 of the scope of patent application, wherein the loop filter is a variable frequency wide loop filter. 11. The fast frequency synthesizing and modulating device as described in item 5 of the scope of patent application, wherein the output voltage controlled oscillator is a multi-band voltage controlled oscillator. 1 2. The fast frequency synthesizing and modulating device as described in item 1 of the scope of patent application, which is coupled to a frequency hopping synthesizer, which is controlled by a control frequency data and outputs different frequency The frequency hopping reference frequency signal. 1 3. The fast frequency synthesizing and modulating device as described in item 1 of the scope of patent application, further comprising a high-stability oscillator to provide the accurate reference frequency 11210twf.p t d page 19 200428785 VI. Patent application rate signal. 14. The fast frequency synthesizing and modulating device according to item 13 of the scope of patent application, wherein the high-stability oscillator is a temperature-compensated crystal oscillator. 1 5. — A method for fast frequency synthesis and modulation, including the following steps: providing one of the accurate reference frequency signals with high stability; modulating and oscillating an intermediate load based on an input data signal and the accurate reference frequency signal Data modulation signal; providing a frequency-hopping reference frequency signal and a pre-biased bias data; providing a pre-bias voltage based on a pre-biased bias data; and a modulation signal and the frequency hopping based on the intermediate loaded data An output modulation signal is oscillated with reference to the frequency signal, and the output modulation signal is quickly oscillated according to the pre-set bias voltage. 16. The method as described in item 15 of the scope of patent application, wherein the step of modulating and oscillating the intermediate data modulation signal includes the following steps: obtaining a first reference according to the precise reference frequency signal Frequency signal; frequency dividing the intermediate data modulation signal to obtain a first frequency division signal; detecting and comparing the first reference frequency signal and the first frequency division signal to output a first voltage control signal; And according to the first voltage control signal and the input data signal, oscillate and modulate the intermediate loaded data modulation signal. 11210twf.ptd Page 20 200428785 VI. Patent application scope 17 • The method described in item 16 of the patent application scope, wherein the step of obtaining the first reference frequency signal is to divide the precise reference frequency signal by The first reference frequency signal is obtained. 18. The method as described in item 15 of the scope of patent application, wherein the step of oscillating the output modulation signal includes the following steps: mixing the output modulation signal with the frequency hopping reference frequency signal to obtain a A first mixed frequency signal; filtering the first mixed frequency signal to obtain an output intermediate frequency data signal; and dividing the output intermediate frequency data signal to obtain a second divided frequency signal. Modulate the intermediate frequency modulated signal according to the intermediate loaded data to obtain an intermediate frequency modulated signal of the loaded data; detect and compare the intermediate frequency modulated signal of the loaded data and the second frequency division signal, and output an error signal; The error signal is filtered to obtain a second voltage control signal; and the output modulation signal is quickly oscillated according to the second voltage control signal and the pre-set bias voltage; The method described above, wherein the step of obtaining the frequency modulated signal of the loaded data comprises the following steps: mixing the intermediate loaded data modulated signal with a second reference frequency signal to obtain a second mixed signal; And filtering the second mixing signal to obtain the IF modulation signal of the loaded data. 11210twf.ptd Page 21 200428785 112101 w f. P t ci p. 22