CN1161601A - Frequency modulation and amplitude modulation repeated modulation theory - Google Patents

Abstract

The invention relates to a theory of frequency-amplitude remodulation. It consists of modulation circuit and demodulation circuit. In the process of modulation, the main oscillator and frequency modulator produces FM wave. Then, the FM wave is amplified and shaped by amplifier, amplitude limiter and low pass filter. At last, the amplitude modulator that receives the FM wave from the low-pass filter produces an amplitude-frequency modulated wave. In the process of demodulation, the amplitude leveller transforms the AM-FM wave into FM wave and detects the AM singnal. Then, the FM wave signal pass through the amplifier, the amplitude limiter and the low-pass filter. Finally, the frequency discriminator detects the FM signal. The characteristic is the amplitude-frequency remodulation. Advantages: high utilization ratio of equipment and channel, simple circuit, low energy consumption.

Description

Frequency modulation, amplitude modulation repeated modulation theory

The present invention relates to a kind of radio modulation theory, particularly a kind of frequency modulation, amplitude modulation repeated modulation theory.

At present, more representational radio modulation mode has four kinds, first kind is amplitude modulation(PAM), be called for short amplitude modulation, promptly the amplitude of carrier wave is with the big or small linear variation of modulation signal, this variation of carrier amplitude, carrying the information that modulation signal reflects, amplitude modulation is modulated than other, implements the simplyst, and band occupancy is the narrowest; Second kind is frequency modulation(FM), abbreviation frequency modulation, and promptly the instantaneous frequency of carrier wave changes linearly with the size of modulation signal; The third is a phase modulated, is called for short phase modulation, and promptly the instantaneous phase of carrier wave changes linearly with the size of modulation signal, no matter be frequency modulation, still phase modulation all is the phase angle that changes carrier wave, can be referred to as angle modulated, be called for short angle modulation, during angle modulation, the amplitude of carrier wave remains unchanged, and compares with Modulation and Amplitude Modulation, the major advantage of angle modulated is a strong interference immunity, and shortcoming is the frequency band broad; The 4th kind is pulse and digital modulation, pulse modulation is meant the paired pulses wave amplitude, width, the position, some parameters in these four parameters of repetition rate are modulated, be called pulse amplitude modulation (PAM) respectively, pulse width modulation (PWM), pulse position modulation (PPM), pulse frequency modulated (PFM), digital modulation is by to analog signal sampling, quantize, coding, form the process of one group of one group of code, it is divided into two kinds of pulse code modulation (pcm) and delta modulation (DM), when long-distance transmissions pulse or digital signal, also must carry out secondary modulation, promptly the pulse or the digital signal of modulation are modulated on the carrier wave again amplitude or phase angle that can modulated carrier, the maximum characteristics of digital signal, it is strong interference immunity, can realize time-division multiplex (promptly with the frequency Polymera) transmission, shortcoming is that its system is more more complex than other modulating system, the difficult realization of the time-division multiplex transmission of microwave band.

The objective of the invention is to release a kind of new radio modulation theory--frequency modulation, amplitude modulation repeated modulation theory, will be respectively independently frequency modulation, amplitude modulation two big wireless radio transmission modes combine, realize that a carrier wave carries two-way information, a machine is multiplexing, high efficiency strengthens the spatial channel utilance.

The object of the present invention is achieved like this: theoretical the same with other radio modulation, it divides modulation and demodulation two parts, modulating system comprises main shaking, frequency modulator, amplifier, amplitude limiter, low pass filter, amplitude modulator, frequency modulator is under main shake excitation and the modulation of first via modulation signal, form frequency-modulated wave, this frequency-modulated wave amplifies through amplifier, through amplitude limiter, low pass filter is removed the parasitic amplitude modulation that produces in frequency modulator, remove to promote amplitude modulator again, amplitude modulator forms frequency modulation under frequency-modulated wave excitation and the modulation of the second road modulation signal, the repetition modulating wave of two-way information is carried in amplitude modulation.Demodulating system is the inverse process of modulating system, and it comprises leveller, amplifier, amplitude limiter, low pass filter, frequency discriminator, and leveller is made of amplitude detector, phase inverter, equalizer, amplitude modulator,

Frequency modulation, amplitude modulation repeats modulating wave through leveller, detect am signals, it is the second road modulation signal in the modulating system, the waveform of this am signals and frequency modulation, the envelope that amplitude modulation repeats modulating wave is identical, if modulate frequency modulation with a just in time opposite modulation signal with this envelope, amplitude modulation repeats the amplitude of modulating wave, work as phase-aligned, modulation level is got when suitable, just can remove frequency modulation, amplitude modulation repeats the amplitude modulation component of modulating wave, recover the frequency-modulated wave of open width, the principle of leveller among the present invention that Here it is is utilized the am signals that has detected, through the phase inverter paraphase, remove to modulate amplitude modulator, frequency modulation, amplitude-modulated wave is adjusted time of delay through equalizer, sends into amplitude modulator, under the modulation of anti-phase am signals, produce the frequency-modulated wave of open width, this frequency-modulated wave amplifies through amplifier, through amplitude limiter, low pass filter removes parasitic amplitude modulation, detects frequency modulated signal through frequency discriminator again, i.e. first via modulation signal in the modulating system.

The present invention will distinguish independently frequency modulation, amplitude modulation two big RI radio intelligence carrier transmission modes combine, release a kind of new frequency modulation, amplitude modulation repeated modulation theory, this modulation theory is applied in the transmitter, make a transmitter finish the effect of two transmitters, reduced energy resource consumption, and solved crowded this key issue of spatial channel, especially in expensive satellite communication, use this theory in the satellite television, more demonstrate its economic worth and social value, wide application of the present invention, the radio theory there is bigger breakthrough, circuit is simple, is suitable for ground and satellite communication, TV is extensively promoted the use of.

Fig. 1 is a modulating system block diagram of the present invention;

Fig. 2 is a demodulating system block diagram of the present invention;

Fig. 3 is the block diagram of leveller among the present invention;

Fig. 4 is that frequency modulation, amplitude modulation repeat modulating wave modulated process oscillogram;

Fig. 5 is a modulating system schematic diagram of the present invention;

Fig. 6 is a demodulating system schematic diagram of the present invention.

The invention will be further described below in conjunction with drawings and Examples.

Embodiment:

The present invention includes modulation and demodulation two parts, modulating system block diagram as shown in Figure 1, frequency modulator is at main excitation and the first via modulation signal u of shaking _o(t) under the modulation, form frequency-modulated wave, in the present embodiment, the main signal that shakes is the high_frequency sine wave signal, modulation signal is an analog signal, main shaking also can be called exciter, the circuit of finishing this part is a lot, the LC oscillator is arranged, negative resistance oscillator, quartz oscillator, microwave solid state oscillator and frequency synthesizer etc., the frequency modulator strictness should be frequency modulator, and its circuit has several, varactor frequency modulation is arranged, reactance-tube frequency modulation etc., frequency-modulated wave amplifies through amplifier, through amplitude limiter, low pass filter is eliminated parasitic amplitude modulation, remove to promote amplitude modulator, amplifier herein is the high frequency small signal amplifier, and kind is a lot, the transistor resonance amplifier is arranged, wide-band amplifier, parametric amplifier etc., the circuit of finishing the amplitude limit function has diode clipper, the field effect transistor amplitude limiter, differential pair amplitude limiter etc., low pass filter has the LC low pass filter, the RC low pass filter, active low-pass filter etc., amplitude modulator encourages at frequency-modulated wave, under the modulation of the second road modulation signal u (t), produces frequency modulation, amplitude modulation repeats modulating wave A (t), the amplitude modulator strictness should be amplitude modulator, and its circuit has the transistor amplitude modulator, the electron tube amplitude modulator, Multiple Modulation amplitude modulator etc., frequency modulation, the mathematic(al) representation that amplitude modulation repeats modulating wave is $A\left(t\right)=[A_0+\mathrm{ku}\left(t\right)]\cos [{\mathrm{\ω}}_{0}t+k_f{\∫}_0^t{u}_0\left(\mathrm{\τ}\right)\mathrm{d\τ}]$ In expression formula, A _oCarrier amplitude during for no amplitude modulation, ω ₀Be the main angular frequency that shakes, the angular frequency when promptly not having frequency modulation, K, Kf are proportionality constant, u _o(t) be frequency modulated signal, u (t) is an am signals, and Fig. 4 is the modulated process oscillogram that frequency modulation, amplitude modulation repeat modulating wave, establishes modulation signal for simple sinusoidal, and cosine signal, Fig. 4 (a) are the carrier signal A when not having modulation _o(t)=A ₀Cos ω ₀T, Fig. 4 (b) is frequency modulated signal u _o(t)=U _oCos Ω t, Fig. 4 (c) are that main shaking is activated at frequency modulated signal u _o(t) frequency-modulated wave that forms under the modulation

Fig. 4 (d) is at frequency-modulated wave A for amplitude system system signal u (t)=U ' sin Ω 1t Fig. 4 (e) _o(t) promote down, the frequency modulation that forms under modulation signal u (t) amplitude modulation, amplitude modulation repeat modulating wave A (t).Demodulating system is the inverse process of modulating system, demodulating system block diagram as shown in Figure 2 is made of leveller, amplifier, amplitude limiter, low pass filter, frequency discriminator, leveller detects am signals u (t) on the one hand, convert frequency modulation, amplitude-modulated wave A (t) to frequency-modulated wave on the one hand, this frequency-modulated wave amplifies through amplifier, through amplitude limiter, low pass filter is eliminated parasitic amplitude modulation, detect frequency modulated signal through frequency discriminator, kam-frequency circuit has the phase place frequency-discriminating circuit, ratio frequency-discriminating circuit etc.Fig. 3 leveller block diagram that drawn, in Fig. 3 (a), one road frequency modulation, amplitude-modulated wave A (t) is through amplitude detector, detect am signals u (t), the part of u (t) is given amplitude modulator through the anti-phase am signals of the anti-phase formation of phase inverter, another road frequency modulation, amplitude-modulated wave is delayed time through equalizer, give amplitude modulator, under the modulation of reverse am signals, form frequency-modulated wave, phase inverter can be used the coupling transformer paraphase, also can use the paraphase of single-stage common-emitter amplifier, in Fig. 3 (b), the anti-phase am signals that utilizes the negative polarity amplitude detector to detect--u (t), directly modulate amplitude modulator, with frequency modulation, amplitude-modulated wave A (t) converts frequency-modulated wave A to _n(t), the circuit of amplitude detector has multiple, and the beat-frequency detection device is arranged, product detector etc., equalizer is a kind of delay circuit, and just in time opposite with frequency modulation, amplitude-modulated wave envelope phase in the amplitude modulator with the phase place that guarantees anti-phase am signals, equalizer is made of some filters.For at a distance, high-quality, the transmission RI radio intelligence, modulation signal adopts complicated digitally encoded signal, leveller among the present invention can only be to modulation less than 100% frequency modulation, amplitude modulation repeats modulating wave and carries out open width, therefore, the modulation of amplitude modulator must be less than 100% in the modulating system, because modulating system of the present invention, demodulating system is in different frequency ranges, different indexs, transmit under the various different situations of dissimilar modulation signals, the physical circuit that adopts is different, and the each several part in the block diagram also can be used multi-form circuit and realize under identical conditions, here do not introduce one by one, as example, Fig. 5 a certain modulating system schematic diagram of the present invention that drawn, Fig. 6 a certain demodulating system schematic diagram of the present invention that drawn, in Fig. 5, with transistor BG1 is that core constitutes local oscillation circuit, is that core constitutes the frequency modulator circuit with di-cap BG2, with transistor BG3, BG4, BG5 is that core constitutes amplifier circuit, with transistor BG6, BG7, BG8 is that core constitutes amplitude limiter circuit, with L1, L2, C1, C2, constituting low pass filter, is that core constitutes the amplitude modulator circuit with triode BG9, in Fig. 6, with diode BG11 is that core constitutes the amplitude detector circuit, with L3, L4, C3, C4, constituting equalizer, constitute phase inverter with coupling transformer B, is that core constitutes modulation circuit with triode BG12, with triode BG13, BG14, BG15 are that core constitutes amplifier circuit, with transistor BG16, BG17, BG18 is that core constitutes amplitude limiter circuit, with L5, and L6, C5, C6 constitutes low pass filter, and with diode BG19, BG20 is that core constitutes kam-frequency circuit.

Claims (4)

1. frequency modulation, amplitude modulation repeated modulation theory, it comprises modulating system and demodulating system, shake by main, frequency modulator, amplifier, amplitude limiter, low pass filter, the modulating system that amplitude modulator is formed is characterized in that: first via modulation signal and the main signal that shakes are delivered in the frequency modulator, formed frequency-modulated wave, this frequency-modulated wave amplifies through amplifier, remove parasitic amplitude modulation through amplitude limiter, low pass filter, remove to promote amplitude modulator, frequency-modulated wave promotes amplitude modulator under the modulation of the second road modulation signal, form the repetition modulating wave of frequency modulation, amplitude modulation portability two-way information, its mathematic(al) representation is: $A\left(t\right)=[A_0+\mathrm{ku}\left(t\right)]\cos [{\mathrm{\ω}}_{0}t+\mathrm{kf}{\∫}_0^t{n}_0\left(\mathrm{\τ}\right)\mathrm{d\τ}]$ Demodulating system comprises leveller, amplifier, amplitude limiter, low pass filter, frequency discriminator, it is characterized in that: frequency modulation, amplitude modulation repeat modulating wave through leveller, on the one hand, detect am signals, it is the second road modulation signal in the modulating system, with frequency modulation, amplitude-modulated wave converts frequency-modulated wave on the one hand, and this frequency-modulated wave amplifies through amplifier, through limitting every device, low pass filter removes parasitic amplitude modulation, detects frequency modulated signal through frequency discriminator again, i.e. first via modulation signal in the modulating system.

2. according to claim 1 described frequency modulation, amplitude modulation repeated modulation theory, it is characterized in that: the first via, the second road modulation signal are digitally encoded signal.

3. according to claim 1 or 2 described frequency modulation, amplitude modulation repeated modulation theory is characterized in that: the frequency-modulated wave of isolating single modulation with leveller from FMAM repetition modulating wave.

4. according to the described frequency modulation of claim 1.2.3., amplitude modulation repeated modulation theory, it is characterized in that using with quadrat method and can release phase modulation, amplitude modulation repeated modulation theory.

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