JPH07143031A - Spread spectrum modulator and/or demodulator - Google Patents

Abstract

PURPOSE:To reduce the influence of interference disturbance due to the unrequired radiation of a circuit, etc., by constituting an SS modulator so as to perform FSK modulation and PSK modulation by switching by means of one switch. CONSTITUTION:The switch Sw1 is connected to a contact (a) in the case where the FSK modulation is performed, an information signal from an input terminal In1 is supplied to a voltage controlled oscillator 4. Therefore, an FSK modulation signal can be obtained from the oscillator 4. While the modulation signal is N-multiplied by a multiplier 6, it is subjected to 1/N2 frequency-division by means of a frequency divider 7, and is supplied to a spread code generator 8 as a clock signal. A generated spread code is supplied to an X-OR gate 9. At the gate 9, the spread code is subjected to phase inversion, and is supplied to a multiplier 11. SS modulation by multiplication is performed by the multiplier 11. In the case where PSK modulation is performed, the switch Sw1 is connected to a contact (b). In this way, since no input signal is supplied to the oscillator 4, SS modulated waves subjected to primary modulation is applied is outputted from the multiplier 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is spread spectrum (hereinafter referred to as S
S)) modulation and / or demodulation device, in particular SS
Frequency shift keying including FM modulation and demodulation in primary modulation in the modulator and primary demodulation in the SS demodulator, respectively (hereinafter referred to as FSK (Frequency Shift Keying))
Change, demodulation, and phase shift keying {hereinafter P (Phase) S
It is related to the SS modulation and / or demodulation device configured so that both the change and the demodulation can be easily switched.

[0002]

2. Description of the Related Art The primary modulation of information signals in radio transmission and communication using SS modulation and demodulation methods is usually FM modulation (when the information signal is an analog signal), FSK modulation (when it is also digital data), PSK modulation (same) is used. Then, SS in which PSK modulation is applied to the primary modulation
In communication, the primary demodulation is also PSK demodulation, and each is composed of dedicated modulation and demodulation circuits. Special cases for FSK modulation include MSK (Minimum Shift Keying) and G (Gau).
ssian filtered MSK, SS modulation and demodulation methods that perform such primary modulation normally and spread spectrum as secondary modulation and then perform data transmission, wireless communication, etc. are utilized in various fields by taking advantage of their characteristics. It has started, and recently it is being applied to the consumer equipment field.

As a specific example, a wireless LAN system adopting SS modulation and demodulation system, a digital mobile phone, or SS
GPS (Glo) is a modulated radio wave for satellite navigation system.
balPositioning System) In positioning (navigation) systems that receive and use satellite radio waves, dedicated modulation circuits and demodulation circuits are used, and signs of widespread use are beginning to appear.

GPS is a highly accurate satellite navigation system for military purposes developed mainly by the US Department of Defense, but a part of it is open to civilian use for positioning to detect the position of a moving object. It's being used. The user receives SS signal radio waves from 3 to 4 GPS satellites in a time division manner,
It is possible to know the current position of the user by obtaining the distance from the GPS satellite to the receiver (receiver) based on the radio wave propagation time, and there are many advantages such as accuracy and immediacy as compared with the conventional navigation system. With the expectation of its future potential and development potential, leading companies are proceeding with the development of GPS receivers.

In such a consumer GPS receiver, an SS modulated signal obtained by spreading-modulating a navigation message using a publicly-known spread code such as a C / A (Clear and Acquisition) code among radio waves transmitted from GPS satellites. Received and decrypted. The SS demodulation device of the present invention uses such G
Since it also has a function as a PS receiving device, the configuration of a part that can be used by the private sector in the configuration of the GPS satellite on the transmitting side will be briefly described with reference to FIG.

FIG. 2 shows a modulation transmitter 20 in a GPS satellite.
FIG. 3 is a block diagram showing the main part of C / A code generation, SS modulation, and the like. First, a very stable reference signal having a frequency of 10.23 MHz output from the atomic clock 13 for outputting a reference signal is supplied to a frequency multiplier (hereinafter abbreviated as “multiplier”) 14 and multiplied by N ₁ (= 154). Frequency = 1.5754
We have a 2 GHz L ₁ carrier. On the other hand, the reference signal is also supplied to the frequency divider 15, where it is divided into 1 / N ₂ (= 1/10) and then supplied to the C / A code generator 16 to generate the C / A code. There is. Therefore, the chip length of the C / A code generating clock signal is 1023 chips.

The C / A code is the EX-OR gate 1
8, the exclusive OR operation (message modulation) with the navigation message given from the input terminal In2 is performed,
Further, in the multiplier 19, carrier modulation is performed by multiplication with the L ₁ carrier, and the result is transmitted from the transmitting antenna A ₂ . The clock signal for generating the above navigation message is 1
The frequency is 50 Hz, which is obtained by dividing 0.23 MHz by 1/204600. Since the P code modulated wave transmitted from the GPS satellite is not open to the public, detailed description thereof will be omitted.

As is clear from the above description, in the modulation / transmission unit 20 in the GPS satellite, the L ₁ carrier and C /
It has a synchronous relationship with the A code clock signal. By providing such a synchronization relationship, it is possible not only to reduce the influence of interference interference due to unnecessary radiation in the circuit elements that configure the device during modulation, reception and demodulation, but also to simplify the circuit configuration during SS demodulation. The possibility arises.

[0009]

As is well known, in the SS modulation and demodulation system, the demodulator side needs respective circuits for controlling the unique synchronization detection, synchronization acquisition, and synchronization holding.
In addition, since it is also related to the primary modulation method performed as pre-processing for SS modulation on the modulator side, a dedicated SS modulation and / or demodulation device corresponding to the primary modulation method used is required. However, even if the circuits are integrated, they are inevitably dedicated ICs, lack versatility, and hinder their future spread.

In view of the above conventional problems, the present invention has a part or main part of the configuration even if the primary modulation method is FM, PM (to analog signal) or FSK or PSK (to digital data). By implementing a sharable circuit, not only the conventional SS modulation and / or demodulation device but also GPS reception and demodulation can be shared, and S having high versatility SS modulation and SS demodulation is possible.
It is an object to provide an S modulator and / or an SS demodulator.

[0011]

In order to solve the above problems, the present invention provides an oscillator for oscillating and outputting a carrier wave for input information signal modulation, and the frequency of the output signal of the oscillator is multiplied by N ₁ and 1 / N _{2 respectively.} A frequency multiplier and a frequency divider, a spreading code generator that generates a spreading code such as a PN code or a C / A code using an output signal of the frequency divider as a clock, a power supply for supplying a DC bias, and a power supply side An arithmetic unit for performing a logical sum operation of the signal from the signal and the spread code, and the oscillator for transmitting the input information signal according to whether the primary modulation for the input information signal is PSK or FSK (including FM modulation), Alternatively, there is provided a spread spectrum modulator including a changeover switch for supplying the connection point between the power source and the arithmetic unit, and a multiplier for multiplying the output of the arithmetic unit and the output of the multiplier to spread the spectrum.

Further, the first local oscillator for outputting the local oscillation signal for frequency conversion, the multiplier for frequency-multiplying the local oscillation signal, and the local oscillation signal multiplied by the received SS modulated wave are used to multiply the frequency. A frequency conversion means for converting the intermediate frequency SS modulated wave to obtain an intermediate frequency SS modulated wave, a despreading means for despreading and demodulating the intermediate frequency SS modulated wave by multiplying a spreading code, and the level of the obtained despread demodulation output. Level discrimination circuit for discriminating between FSK and despread demodulation output
Demodulation means for primary demodulating a modulated wave (including FM modulated wave) or PSK modulated wave to obtain the original information signal, and a noise level detection circuit for detecting the level of noise included in the output of the demodulation means, and Depending on the type of the spread demodulation output signal, a control circuit that generates a control signal based on the output signal of either the noise level detection circuit or the level identification circuit, and the output of the phase locked loop that constitutes the demodulation means / N ₁ N ₂ frequency-divided signal and 1 / N ₂ frequency-divided signal of the output of the first local oscillator, arithmetic circuit, and second frequency signal that approximates the normal clock frequency Local oscillator of
A second changeover switch for changing over the connection from the second local oscillator to the arithmetic circuit side when a control signal is supplied from the control circuit, and a despreading means for generating a spread code by using the output of this changeover switch as a clock signal. Also provided is a spread spectrum demodulation device including a spread code generator for supplying to

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the SS modulation and / or demodulation device of the present invention will be described with reference to the drawings. FIG. 1 shows the basic configuration of an SS modulator (transmitter) 10 of the present invention, and FIG. 3 is a block diagram showing the basic configuration of an SS demodulator (receiver) 30 of the present invention. In a normal communication device, the SS modulation and demodulation device is equipped with both the SS modulation device 10 and the SS demodulation device 30, and the antennas A _1, A ₃ etc. are also used, but they should be designed individually. Is also possible,
Since actual communication is naturally performed between different communication devices, the SS modulation device 10 and the SS demodulation device 30 will be individually described below.

First, the SS modulator 10 of FIG. 1 will be described. This is an amplifier 2 having a low output impedance, a changeover switch (hereinafter abbreviated as "switch") Sw1 for system selection, and a voltage as a typical example of an oscillator. Controlled oscillator (V
CXO) 4, DC bias supplier including DC power supply E ₁ , multiplier 6, frequency divider 7, spread code generator (PNG)
8. EX-O which is an arithmetic unit for performing (exclusive) OR operation
R gate 9, multiplier 11 and LPF (low pass filter) 12
And the like, and these are connected as shown in the drawing.

Of the above components, the multiplier 6, frequency divider 7, PNG 8, EX-OR gate 9 and multiplier 11 are
The multiplier 14, the frequency divider 15, the C / A code generator 16, and the EX-OR gate 18 of the modulation / transmission unit 20 shown in FIG.
Since they have the same functions as the multiplier 19 and the multiplier 19, detailed description thereof will be omitted. However, a spreading (PN) code other than the C / A code is generated in the PNG 8 so as not to interfere with the radio waves from the GPS satellites. The switches Sw1 and S
The switches Sw2 to Sw4 in the S demodulator 30 are artificially switched according to the application, and the contact a is FM, FSK (MS
The contact b is for PSK.

Next, the modulation operation of the SS modulator 10 will be described with reference to FIG. 1 in the case where FSK (including FM modulation) modulation is first performed as the primary modulation. In that case, since the switch Sw1 is connected to the contact a as shown in the figure, the information signal such as an analog signal or digital data from the input terminal In1 is supplied to the voltage controlled oscillator 4 through the amplifier 2 and the switch Sw1. Therefore, in the voltage controlled oscillator 4, an FSK modulation signal obtained by modulating a carrier wave of a specific frequency with an information signal (FM modulation signal in the case of an analog signal)
Is obtained.

The modulated signal is supplied to the multiplier 6 and N
While being multiplied by _1, it is also supplied to the frequency divider 7, where 1 /
The spread code generator 8 is divided into N ₂ and used as a clock signal.
Is supplied to. The spread code generated based on this clock signal is supplied to the EX-OR gate 9,
Since only the DC voltage from the DC bias supplier 5 is applied to the other input terminal of the gate 9, the spread code is only phase-inverted here and is supplied to the multiplier 11 via the LPF 12. Therefore, in the multiplier 11, the above N ₁
SS modulation by multiplication with the multiplied FSK modulation signal (or FM modulation signal) is performed, and SS modulation is performed from the transmission antenna A _1.
It is transmitted as a modulated wave.

The clock signal for generating the spread code is
Since it is obtained based on the carrier wave (the output of the voltage controlled oscillator) that is FSK (FM) modulated by the information signal, the cycle of the clock signal and the spread code changes accordingly, but the multiplier 1
Since the spreading code and the FSK (FM) modulated signal supplied to 1 are in a synchronous relationship with each other, the SS operation can be performed without any trouble.

Next, the case where PSK (or PM) modulation is performed as the primary modulation will be described. In this case switch Sw1
Is connected to the contact b, so that the input signal is not supplied to the voltage controlled oscillator 4, so that the carrier wave is simply output from the voltage controlled oscillator 4 as a reference signal and multiplied by N _{1 by the} multiplier 6 to obtain a multiplier. 11 is supplied to the spread code generator 8 as a clock signal (the cycle is unchanged) and is divided into 1 / N ₂ by the frequency divider 7 and is supplied to the spread code generator 8 to generate the spread code. Output to one input terminal of the gate 9.

By the way, the DC voltage supply circuit 5 includes the amplifier 2
Since it is disabled by being affected by the low output impedance of the EX-OR gate 9, the information signal is directly supplied to the other input terminal of the EX-OR gate 9, where SS modulation by exclusive OR operation with the spread code is performed. (So-called direct diffusion without primary modulation) is performed. The obtained SS modulation signal is supplied to the multiplier 11 via the LPF 12, where the carrier modulation is performed by multiplication with the reference signal (carrier wave) multiplied by N ₁ and the SS modulation wave that is also subjected to the primary modulation. Is output from the transmission antenna A ₁ .

As described above, the SS modulator 10 of the present invention
Then, one switch Sw1 is used for FSK modulation and PSK modulation.
It can be carried out by switching. Further, the carrier (carrier wave) and the spread code clock signal are in a synchronous relationship as described above, and the carrier and the C / A code clock signal are also in a synchronous relationship in the modulating section in the GPS satellite.
By providing such a synchronization relationship, not only the influence of interference interference due to unnecessary radiation of the circuit can be reduced at the time of modulation and reception demodulation to be described later, but there is a possibility that the circuit configuration for SS demodulation can be simplified.

Next, the configuration and demodulation operation of the SS demodulator 30 of the present invention will be briefly described with reference to FIG. In the figure, reference numerals 24 and 26 are conversion means (mixer) for converting the SS modulated wave received by the receiving antenna A ₃ into an intermediate frequency spread spectrum modulated wave, and 48 is a spread code generator, which are the GPS satellites shown in FIG. When receiving the radio wave from the modulation / transmission unit 20 in, a C / A code, which is a kind of (special) spread code, is generated, and the radio wave from the SS modulation device 10 of the other machine shown in FIG. 1 is received. In this case, the PN code is generated. In addition, the phase comparator 36, LF
(Loop filter) 37 and VCO (voltage controlled oscillator)
A phase locked loop (PLL circuit) 35 is formed by 38. Further, a portion surrounded by a broken line including the phase-locked loop 35 is a demodulation means (primary demodulation circuit) for primary demodulating an FSK modulated wave (including an FM modulated wave) or a PSK modulated wave which is a despread demodulation output. There are 40 configurations.

By the way, the multiplication number N _{1a of} the first multiplier 29
And the multiplication number N _{1b of} the second multiplier 21 are N _1a + N _1b = N
₁ (the multiplication number in the multiplier 6 of the SS modulator 10). Also, the switches Sw2 to Sw4 are set to 1
If the next modulation is FM or FSK (including MSK or GMSK), it is connected to the contact a, and if it is PSK, it is connected to the contact b. Therefore, it is convenient to configure the switches Sw2 to Sw4 with one interlocking switch. A level identification circuit 52, a noise level detection circuit 53, a control circuit 54, a changeover switch Sw1 and the like are provided as means for obtaining the control signal for spread spectrum synchronization acquisition. The other detailed components will be described below. Specify it together with the operation description.

The SS modulated wave received by the receiving antenna A ₃ is supplied to the first frequency conversion mixer (multiplier) 24 via the BPF 22 and the RF amplifier (intermediate frequency amplifier) 23. On the other hand, the local oscillation signal output from the local oscillator (TCXO) 28 is multiplied by N _1a and N _1b by the multiplier 29 and the multiplier 21, respectively, and is supplied to the mixers 24 and 26, respectively. Then SS
A first frequency conversion of the modulated wave is performed to obtain a first intermediate frequency signal. The carrier frequency of the SS modulated wave is 1.
Above 5 GHz, the frequency of this intermediate frequency signal is hundreds (200
~ 600) MHz.

This intermediate frequency signal is supplied to the mixer 26 for second frequency conversion via the BPF 25, where the second frequency is multiplied by the output of the multiplier 21 (N _1b multiplied local oscillation signal). A conversion is performed to obtain a second intermediate frequency signal. The second intermediate frequency signal is supplied to the despreading multiplier 31, where the spreading code from the spreading code generator 48 (C / A code code when receiving GPS satellite radio waves, other PN code). } Despreading demodulation is performed. The obtained despread demodulation output (first-order modulated wave) is the BPF.
32, amplifier (AGC amplifier or limiter amplifier) 33
Is supplied to the multiplier 34 and the like for performing FSK demodulation and PSK demodulation as primary demodulation.

Here, the primary modulation on the transmitting side is FM,
In the case of FSK modulation, the switches Sw2 to Sw4 are connected to the contact a as described above. Therefore, since the DC voltage is applied to the multiplier 34 from the DC power source (DC bias voltage source) E ₂ , the FSK (or FM) modulated wave which is the despread demodulation output is directly compared in the phase locked loop 35. And is supplied to the multiplier (multiplier) 36. Generally, the phase locked loop is used for demodulating the FM modulated wave or the FSK modulated wave, and in that case, the error output of the phase comparator 36 is a loop filter (LF).
Although it is obtained as a demodulation output via 37, in the configuration of the present invention, the phase of the output of the VCO 38 and the FM (or FSK) modulated wave is compared by the multiplier 39 for demodulation. Therefore, demodulation information is obtained from the multiplier 39 via the LPF 47 and output from the output terminal Out1.

On the other hand, when the primary modulation is PSK modulation, the switches Sw2 to Sw4 are connected to the contact b, so that the multiplier 3
In 4, the demodulation information from the LPF 47 and the PSK modulated wave from the amplifier 33 are multiplied, and the output becomes a signal in which the phase change information has disappeared. The multiplication output is supplied to the multiplier 36 (phase locked loop 35). Since the phase locked loop 35 functions as a tracking filter, the output of the VCO 38 is a high-quality reproduced carrier signal with few noise and information leakage components. Become. After the phase of the reproduced carrier signal is shifted by 90 ° (π / 2 radian) in the phase shift circuit 51, the multiplier 39 performs synchronous demodulation by multiplication with the input PSK modulated wave, and demodulates from the output terminal Out1 via the LPF 47. It is output as information.

Next, the principle of generating the clock signal necessary for generating the spread code for despread demodulation will be described. In the SS demodulator 30 of the present invention, the mixer 2 is used as described above.
Since frequency conversion is performed (twice) in 4 and 26, the synchronization relationship between the carrier and the spread code clock signal is lost. Therefore, in order to avoid this loss phenomenon, the SS demodulator 30 is devised as follows.

First, for frequency conversion in the mixers 24 and 26, the local oscillation signals from the local oscillator 28 are frequency-multiplied by the multipliers 29 and 21, respectively, and the respective multiplication numbers N _1a and N _1b are used. A relationship of N ₁ = N _1a + N _1b is provided between the SS side modulator 10 and the multiplication number N ₁ . Further, the frequency f _k and carrier frequency fc of the spread code clock signal in the SS modulator 10 and the multiplication numbers N _1a and N _1b have a relationship of fc = N ₁ N ₂ f _k . Therefore, assuming that the local oscillation signal is fo, the carrier frequency f _i of the demodulation primary modulation wave is as follows. _{f i = fc -N 1 fo =} N 1 N 2 f k -N 1 fo .............................. (1)

Therefore, in order to regenerate the clock signal f _k , the frequency division output obtained by dividing the carrier frequency by 1 / N ₁ N ₂ and 1 / N ₂ of the local oscillation signal are divided by local oscillation. It is sufficient to detect the sum frequency of the signal frequency. That is, if the reproduced clock signal frequency is f _{k '} , then f _k' = {1 / (N ₁ N ₂ )} × (N ₁ N ₂ f _k −N ₁ fo) + (fo / N ₂ ) = f _k − (Fo / N ₂ ) + (fo / N ₂ ) = f _k …………………… (2), and the clock signal in which the synchronization relationship is not lost can be reproduced.

In the actual circuit configuration, the output of the VCO 38 is divided into 1 / N ₁ N ₂ by the frequency divider 41, and f _k- (fo /
N ₂ ). Furthermore, by the peripheral ₂ binary 1 / N and supplies a local oscillation signal to the frequency divider 43, to obtain the fo / N _2. Therefore, the outputs of the frequency dividers 41 and 43 are EX-O.
It is supplied to the R gate 42 (may be an adder) to take the sum frequency, and the clock signal is reproduced via the BPF 44 and the amplifier 45. Therefore, the clock signal f at the time of modulation
_The clock signal f _{k ′} equal to _k is obtained from the output terminal Out2.

Next, the synchronization detection and the synchronization acquisition which are indispensable for SS synchronization will be described. After the power of the apparatus main body is turned on, the switch Sw5 is initially connected to the oscillator 46 side, and the frequency fs of the oscillation signal is selected as f _k ± Δf. Therefore, a spread code is generated using this oscillation signal as a clock, and the spread code length is changed by sliding (fine-adjusting) the frequency fs, and the level of the despread output is low (almost 0) in the non-correlation period. Correlation points whose levels suddenly increase occur in bursts, and it is necessary to quickly detect the instantaneous correlation points (center of the correlation part).

In the present invention, in demodulating the primary modulated wave,
In the case of FM demodulation and FSK demodulation, the noise in the demodulation output is minimized at the correlation point, and the noise is supplied to the noise level detection circuit 53. In the case of PSK demodulation,
Focusing on the fact that the level of the despread output becomes maximum at the correlation point, the level identification circuit 52 performs that level to detect the correlation point and perform synchronization acquisition. The obtained detection signal is supplied to the control circuit 54 via the switch Sw3, is converted into a control signal here, and switches the switch Sw5 so that the clock signal from the amplifier 45 is supplied to the spread code generator 4.
8 is supplied, the SS synchronization becomes normal and held.

By the way, a CPU (not shown) or the like is required to receive the GPS satellite radio wave and calculate the positioning information. However, in order to exchange the information signal necessary for the exchange with the CPU. , Output terminals Out2, Out3 and input terminals
In5 is used. That is, in order to obtain the reproduction atomic clock frequency, the frequency of the output signal of the terminal Out2 may be multiplied by 10 by a multiplier (not shown), and the C / A code is naturally output from the terminal Out3 so that each GPS signal is output. When it is desired to select a spread code equivalent to the C / A code unique to the satellite, the control signal is supplied from the terminal In5.

As described above, also in the demodulation device 30 having such a configuration, it is possible to easily carry out the FSK demodulation and the PSK demodulation by switching the three switches Sw2 to Sw4 (or one interlocking switch). TCXO28, multiplier 2
1, 29; BPF 22, 25, 27, 32; multiplier 2
4, 26, 31; LPF 47, 49 and PLL 35, etc.
Many circuits are shared.

The above is the SS modulator 10 and the SS of the present invention.
The basic operation principle of the demodulation device 30 will be described. Next, a more specific operation of the SS modulation device 10 in the case of handling data composed of digital signals as information signals will be briefly described with reference to FIG. To do. FIG. 4 is a block diagram of an SS modulator 10 'as a modified example, in which 1 is a data processing unit, 63 is a frequency divider, and the same components as those of the basic configuration shown in FIG. The detailed description thereof will be omitted.

As is apparent from FIG. 4, the frequency divider 63 divides the clock signal for spread code generation in the PNG8 into 1 / N.
_The frequency is divided into ₃ and supplied to the data processing unit 1, so that the data clock signal and the spread code have a synchronous relationship. Particularly, when the PSK modulated wave is SS-modulated, the spread code length and the 1-bit period of the data are made equal, or the 1-bit width of the data is made an integral multiple of the spread code length, and the data and the spread code clock signal are As is well known, the effect of being able to reduce the leakage component of the diffusion component generated in the demodulation information output is obtained by maintaining the synchronization relationship between and.

By configuring the apparatus of the present invention as shown in FIG. 4, not only in PSK modulation but also in FSK (or FM) modulation, the 1-bit width of data and the spread code length can be associated with each other in a synchronous relationship. Therefore, the leakage of the diffused component during the output of the demodulation information is reduced. In the actual configuration example,
For example, when the spread code length is 127 chips, the frequency division number N ₃ of the frequency divider 63 is 127 (or a positive multiple thereof).

5 is a block diagram of a further modification 10 ″ of the SS modulator of the present invention. In the figure, 3 is an encoder (or A / D converter), and 64 is a frequency divider. As can be inferred from this figure, the handling of the signal when an analog signal such as voice is supplied as the information signal from the input terminal In4 is shown, that is, the encoder 3 digitizes the input signal. , A synchronization relationship is provided between the encoding clock signal and the spread code.For example, when the spread code length is 127 chips, the frequency division number N ₄ in the frequency divider 64 is N ₂ × 127 (or That is a positive multiple.

Finally, as a modified example of the SS demodulator, a circuit configuration capable of performing a specific operation in decoding an information signal will be briefly described with reference to the main block diagram of FIG. In the figure, 65 is a frequency divider {the frequency divider 63 of the SS modulator 10 '
Is the same as the frequency division number of the above}, 67 is a decoder (or a data processing unit), 61 is an LPF that transmits only information signals, and the same components as those of the SS demodulator 30 shown in FIG. The detailed description thereof will be omitted.

As shown in the drawing, the clock signal for generating the spread code is divided into 1 / N ₃ by the frequency divider 65, and this is divided by the decoder 6
7, the demodulated output from the LPF 47 is subjected to operations such as decoding (D / A conversion) and data processing corresponding to the data processing unit 1 of the SS modulator 10 '.

In the above description, the receiving antenna A ₃
The two mixers (multipliers) 24 and 26 are used as means for converting the frequency of the SS modulated wave received by the above into an intermediate frequency spread spectrum modulated wave.
As a means for supplying a conversion signal to the local oscillator (TC
XO) 28 from the local oscillation signal to N _1a and N _{1b, respectively.}
The first and second multipliers 29 and 21 for multiplying are used. With this configuration, more reliable conversion is possible. However, when N _1a or N _1b is a relatively small integer, N _1a + N _1b = N ₁ (the multiplier 6 of the SS modulator 10 is used. It is also possible to use only one multiplier having a multiplication number of 1). In that case, only one mixer for frequency conversion is required, and the BPF 25 is unnecessary. On the contrary, it is theoretically possible to provide three or more multipliers and mixers.

[0043]

According to the present invention, the SS modulator is FM modulation or FSK modulation (MSK modulation, GMSK) as the primary modulation.
(Including modulation) and PSK modulation can be easily switched by a switch, and the SS demodulator can easily perform primary demodulation of both FM demodulation, FSK demodulation and PSK demodulation as primary demodulation with a switch. Not only can it be performed by switching to, but it can also be used for reception and demodulation of GPS satellite radio waves, so it has the advantage of opening up a wide range of applications. Further, since the circuits of each modulation system can be commonly used, an integrated circuit having a wide range of applications can be realized.

Further, since the device of the present invention can simplify the circuit structure of the SS demodulation device in particular, it can be sufficiently satisfied in the application in the consumer field without being integrated into a circuit, and a great effect can be obtained. Furthermore, in terms of specific performance, even in the case of a digital coded information signal, a synchronization relationship can be provided between the digital coding clock signal and the spread code regardless of the primary modulation method. By making the 1-bit length of the digital code equal to or a multiple of the spreading code length,
It is possible to minimize the leakage of spreading components that occur in demodulation information,
Has various excellent features.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing a basic configuration example of an SS modulation device of the present invention.

FIG. 2 is a block configuration diagram showing a main part of a modulation transmission unit in a GPS satellite that can be transmitted to the SS demodulation device of the present invention.

FIG. 3 is a block configuration diagram showing a basic configuration example of an SS demodulation device of the present invention.

FIG. 4 is a block diagram showing a modification of the SS modulator of the present invention.

FIG. 5 is a block diagram showing another modification of the SS modulator of the present invention.

FIG. 6 is a block configuration diagram showing a main part of a modified example of the SS demodulation device of the present invention.

[Explanation of symbols]

1 ... Data processing unit, 2, 23, 33, 45 ... Amplifier, 3
... Encoder, 38, 4 ... Voltage controlled oscillator, 5 ... DC bias supplier, 6, 21, 29 ... Multiplier, 7, 41, 4
3 ... Frequency divider, 8, 48 ... Spreading code generator, 9, 42 ... E
X-OR gate, 10 ... SS modulator, 11, 24, 2
6, 31, 34, 36, 39 ... Multipliers, 12, 47, 4
9 ... LPF (low-pass filter), 20 ... GPS satellite modulation / transmission unit, 22, 25, 27, 32, 44 ... BPF (bandpass filter), 28, 46 ... Local oscillator, 30 ... SS demodulator, 35 … Phase locked loop, 37… Loop filter, 4
0 ... Primary demodulation circuit, 51 ... Phase shift circuit, 52 ... Level identification circuit, 53 ... Noise level detection circuit, 54 ... Control circuit, 6
3 to 65 ... Frequency divider, 67 ... Decoder (data processing unit),
A ₁ ~A ₃ ... antenna, E _1, E ₂ ... DC power supply, Sw1~S
w5 ... Changeover switch.

Claims (7)

[Claims] 1. An oscillator that oscillates and outputs a carrier wave for modulating an input information signal, and a frequency of an output signal of the oscillator is N _{1 respectively.}
A multiplier and a divider for multiplying and dividing by 1 / N _2, a spread code generator for generating a spread code such as a PN code or a C / A code using an output signal of the divider as a clock, and a DC bias. The power supply to be supplied, an arithmetic unit for performing a logical sum operation of the signal from the power supply side and the spread code, and whether the primary modulation for the input information signal is PSK or FSK (including FM modulation). In accordance with the changeover switch for supplying the input information signal to the oscillator or the power supply side, and means for multiplying the output of the arithmetic unit and the output of the multiplier to spread the spectrum, a plurality of primary modulations are provided. A spread spectrum modulation device, characterized in that it is configured to perform various types of modulation. 2. When the input information signal is digital data, the output signal of the frequency divider is further frequency-divided into an integer related to the spreading code length in the spreading code generator.
2. The spread spectrum modulation apparatus according to claim 1, further comprising: the frequency divider of claim 1 and a data processing section that performs a predetermined signal processing on the digital data using the output signal of the second frequency divider as a clock. 3. When the input information signal is an analog signal, the output signal of the oscillator is further frequency-divided into an integer related to the spread code length in the spread code generator.
2. The spread spectrum modulation apparatus according to claim 1, further comprising: the frequency divider and the encoder for converting the analog signal into a digital signal by using the output signal of the second frequency divider as a coding clock. 4. A first local oscillator for outputting a local oscillating signal, a multiplier for multiplying the frequency of the local oscillating signal, and a spread spectrum modulated wave received by frequency conversion by multiplication with the output of the multiplier. Frequency conversion means for obtaining a frequency spread spectrum modulated wave, despreading means for multiplying the intermediate frequency spread spectrum modulated wave by a spread code to perform despread demodulation, and level identification for identifying the level of the obtained despread demodulation output signal A circuit, a primary demodulation means for demodulating an FSK (including FM) modulated wave or a PSK modulated wave which is a despread demodulation output signal to obtain an original information signal, and noise included in the output of the primary demodulation means. And a noise level detection circuit for detecting the level of the control signal, and a control signal is generated based on the output of either the noise level detection circuit or the level identification circuit according to the type of the despread demodulation output signal. A control circuit and an arithmetic circuit for logically operating a signal obtained by dividing the output of the phase-locked loop constituting the primary demodulation means by 1 / N ₁ N ₂ and a signal obtained by dividing the local oscillation signal by 1 / N ₂ A second local oscillator that outputs a signal of a frequency close to a regular clock; and a changeover switch that switches the connection from the second local oscillator to the arithmetic circuit side when a control signal is supplied from the control circuit. , A spread code generator for generating a spread code using the output of the change-over switch as a clock signal and supplying the spread code to the despreading means.
A spread spectrum demodulation device that surely demodulates the original information signal regardless of whether the next modulation is FSK modulation (including FM modulation) or PSK modulation. 5. A demodulation means for primary demodulating an FSK (including FM) modulated wave or a PSK modulated wave that is a despread demodulation output is an FSK (including FM) modulated wave or a PSK modulated wave that is a despread demodulation output. A first and second multiplier supplied with
A phase locked loop for obtaining a phase locked output based on the multiplication output from the first multiplier, and the phase locked output or a signal obtained by phase shifting the phase locked output by a predetermined amount according to the type of modulation in the despread demodulation output signal. A second selector switch for selecting any of the above, a third multiplier for performing primary demodulation by multiplying the output signal from the second selector switch and the modulated signal, and the third multiplier Of the constant voltage or the output of the low-pass filter depending on the type of modulation in the despread demodulation output signal, a low-pass filter that transmits only necessary frequency components from the output of The spread spectrum demodulation device according to claim 4, further comprising a third changeover switch for supplying either one to the first multiplier, so that a plurality of types of demodulation can be performed. 6. The output of the demodulation means is decoded when the original information signal on the modulation and transmission side is an analog signal with respect to the signal obtained by the demodulation means for primary demodulating the despread demodulation output signal. D / A converter), and in the case of digital data subjected to predetermined signal processing, a data processing section that performs data processing corresponding to the signal processing, and a data processing section for the data processing section from the arithmetic circuit. The spread spectrum demodulation device according to claim 4 or 5, further comprising a frequency divider that divides the frequency of the output signal by a predetermined amount. 7. As a means for obtaining the intermediate frequency spread spectrum modulated wave by frequency-converting the received spread spectrum modulated wave, n (n is an integer) mixers, and the sum of the multiplication numbers of each mixer is N _1. 7. The frequency converter according to claim 4, further comprising: a plurality of multipliers, wherein the outputs of the first local oscillator are frequency-multiplied by the multipliers and supplied to each of the mixers. The spread spectrum demodulation device according to any one of the items.