JP3192592B2 - Spread spectrum communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication system for simultaneously transmitting two different types of spread spectrum signals by sharing the same frequency band.

[0002]

2. Description of the Related Art The direct spread spectrum communication system is
In a primary modulator, a carrier wave supplied from an oscillator is subjected to normal modulation such as FSK (frequency shift keying) or PSK (phase shift keying) with an information signal, and a secondary modulator (spread modulator) is applied to the modulation output. In (2), the secondary modulation is further performed with the spreading code generated by the spreading code generation circuit, and the spectrum is spread over an extremely wide band as compared with the band of the information signal spectrum and transmitted. Conventionally, various systems for simultaneously transmitting a modulated signal having a narrow-band signal spectrum to such a direct system spread spectrum signal have been proposed. One of such systems is disclosed in Japanese Patent Publication No. 7-83347. The proposed method was proposed. The communication system disclosed in Japanese Patent Publication No. 7-83347 is realized by a circuit configuration shown in FIG. That is, the transmitting side is composed of a spread spectrum modulator 1, a narrow band signal modulator 2, an adder 3, and a transmitting antenna 4, and the receiving side is a receiving antenna 5, an amplifier 6, a spread spectrum demodulator 7, a narrow band signal demodulator. 8.

[0003] The spread spectrum modulator 1 has an input terminal 1
Data signal d (t) input from 1 and carrier wave oscillator 12
Is supplied to the primary modulator 13 for primary modulation to obtain a narrow-band signal a (t) having a bandwidth of BW1. This narrow band signal a (t) is supplied to a spread modulator 16 which is a secondary modulator. On the other hand, a spreading code clock generator 14 is provided, and a clock having a frequency fT from the clock generator 14 is supplied to a spreading code generator 15 to generate a spreading code s (t) and supply it to a spreading modulator 16. The spread modulator 16 multiplies and modulates the narrow band signal a (t) by the spread code s (t) to obtain a spread spectrum modulated signal v (t), which is supplied to the adder 3.

[0004] The narrow band signal modulating section 2 has an input terminal 21a,
Data signals ga (t), gb input from 2b,.
(t),... gn (t) and carrier wave oscillators 22a, 22b,.
., F2n from the second band 2n.
.. 23n to perform first-order modulation, and narrow-band signals ba (t), bb (t),.
Get n (t). Then, the narrow band signals ba (t), bb (t),
... bn (t) are supplied to the adder 3. The adder 3 generates the spread spectrum modulated signal v (t) and the narrow band signals ba (t) and bb.
The transmission signal x (t) to which (t),... bn (t) is added is transmitted via the transmission antenna 4.

[0005] The transmission signal x transmitted from the transmission antenna 4
(t) is received by the receiving antenna 5 and then supplied to the spread spectrum demodulation unit 7 and the narrow band signal demodulation unit 8 via the amplifier 6.

The narrow band signal demodulation unit 8 converts the signal from the amplifier 6 into a narrow band signal ba (t), bb
The center frequencies f2a, f2b,... f2n of (t),... bn (t), and the passband width to the same BW2 as the bandwidth of the narrowband signals ba (t), bb (t),. Set band pass filter 81
a, 81b,... 81n and pass through a narrow-band signal demodulator 8
82a, 82b,... 82n. Since the signals input to the narrowband signal demodulators 82a, 82b,... 82n do not include the component of the spread spectrum modulated signal v (t), the spread spectrum modulated signal v (t) is
It does not interfere with the demodulation of a (t), bb (t),... bn (t). Thus, only the demodulated signals of the narrow band signals ba (t), bb (t),... Bn (t) are extracted from the output terminals 83a, 83b,.

The spread spectrum demodulation unit 7 supplies the signal from the amplifier 6 to the despread modulator 74 after passing the signal through the band-pass filter 71. Bandpass filter 71
Is for removing signals outside the band of the spread spectrum modulated signal v (t). A clock having a frequency fT is generated from the spreading code clock generator 72 and supplied to the spreading code generator 73, and the spreading code s (t) is supplied from the spreading code generator 73 to the despreading modulator 74. Despread modulator 7
In step 4, the product modulation of the received signal x (t) and the spreading code s (t) is performed to despread the received signal x (t). The signal y (t) after the despread modulation passes through a band-pass filter 75 having a center frequency of f1 and a pass bandwidth of BW1, and then is supplied to a primary demodulator 77 receiving an oscillation signal from a local oscillator. The signal is demodulated, and unnecessary frequency components are further removed by a low-pass filter 78, and then extracted from an output terminal 79. In this spread spectrum communication system, the spectrum of the spread spectrum modulated signal v (t) and the narrow band signal ba
The feature is that there is a certain relationship between the spectrums of (t), bb (t),... bn (t). The relationship was as described below.

The spreading code is a maximum period sequence code having a spreading code length of N bits generated by using a clock pulse having a frequency fT. Data signal d (t) input from input terminal 11
, BW1 <fT / N (1), and data signals ga (t), gb (t),... Gn (t) input from the input terminals 21a, 2b,. ) Are modulated by the narrowband modulators 23a, 23b,... 23n, the bandwidth BW2 of the narrowband signals ba (t), bb (t),... Bn (t) is BW2 <fT / N−BW1 (2) Is a condition. Then, with respect to the center frequency f1 of the spread spectrum modulation signal v (t), the narrow band signal b
a (t), bb (t),... bn (t) are arranged at frequency positions represented by f1 ± (1 + 2m) fT / 2N... (3), and simultaneously with the spread spectrum modulated signal v (t). Transmitted.

By the way, the spectrum of the spread spectrum modulated signal v (t) represented by the above equation (1) appears as a set of spectrums having a bandwidth of BW1 at intervals of fT / N, as shown in FIG. In addition, narrow-band signals ba (t) and bb having a bandwidth BW2 satisfying the condition of the above equation (2)
When (t),... bn (t) are arranged at the frequency positions represented by the above equation (3), the result is as shown in FIG. According to this spread spectrum communication method, as shown in FIG. 16, a spread spectrum modulated signal v (t) and narrow band signals ba (t), bb
(t),... bn (t) are transmitted at the same time without overlapping spectrums. Therefore, the narrow band signal demodulation unit 8
Then, the spread spectrum modulation signal v (t) and the narrow band signal ba
(t), bb (t),... bn (t) are converted to band-pass filters 81a to 81
1n, and the spread spectrum modulated signal v (t)
, Without receiving the interference of the narrow band signals ba (t), bb (t),.
bn (t) is demodulated. The spread spectrum demodulation unit 7
In the spread spectrum modulation signal v (t)
Converges to the original narrowband signal a (t) and narrowband signal ba
(t), bb (t),... bn (t) are spread, but the spectra of both signals after despreading do not overlap. For this reason,
The narrow-band signals a (t) are narrow-band signals ba (t), bb (t),.
The primary demodulation can be performed without receiving the interference of (t), and the interference rejection ability far exceeds the spreading processing gain.

[0010]

However, the conventional communication system has the following problems. Due to radio laws,
The frequency band in which transmission of a spread spectrum modulated wave (hereinafter referred to as an SS modulated wave) is permitted is an ISM (In
It is a frequency band in which electromagnetic waves are radiated from various devices, such as a dustrial Scientific Medial) band, and the propagation environment of electromagnetic waves is often not very good. In such a frequency band, narrow band signals ba (t), bb (t),... Bn (t) transmitted simultaneously with the spread spectrum modulated signal v (t).
Has been directly affected by jamming waves from other devices (for example, unnecessary radiation noise radiated from a microwave oven), and has not been able to obtain sufficient communication quality.
In the case of a frequency band in which the transmission of the SS modulated wave is permitted, the intensity of the electromagnetic wave to be transmitted is restricted not only by the total power but also by the law in terms of the peak power. For this reason, when trying to perform communication using a normal narrow-band modulated signal, only weaker radio waves can be transmitted than the SS radio, and as a result, there has been a problem that the communication quality is further deteriorated.

On the other hand, frequency hopping (hereinafter referred to as FH-S
Called S. ), When a large number of wireless devices are arranged in the same wireless area, another FH is used.
A problem is that data transmission errors occur due to the "hit" phenomenon of radio waves transmitted from SS radios. In particular, when frequency hopping is performed at timings independent of each other in a narrow communication area, there is a problem that collision between radio transmission and reception frequencies cannot be controlled between radio devices, and transmission errors increase.

According to the first to third aspects of the present invention, the frequency hopping modulated signal can be transmitted simultaneously with the direct spread spectrum modulated signal without interfering with each other, and the spreading processing gain of both signals can be greatly improved. , A synchronous timing signal of a frequency hopping modulation signal can be transmitted by a spread spectrum modulation signal, thereby improving transmission efficiency and frequency utilization efficiency,
Further, the present invention provides a spread spectrum communication system having an excellent ability to remove interference with interference waves from other devices.

[0013]

According to the first aspect of the present invention,
The signal bandwidth BW1 is determined by a maximum period sequence code having a spreading code length of N bits generated by using a clock pulse having a frequency fT.
Transmits a direct spread spectrum modulated signal whose spectrum is spread by multiplying and modulating a narrow band signal represented by BW1 <fT / N, and the bandwidth BW2 is related to the relation of BW2 <fT / N-BW1. When expressed by the formula, a narrow-band signal having a bandwidth BW2 different from the narrow-band signal is expressed by f1 ± (1) with respect to the center frequency f1 of the direct system spread spectrum modulation signal.
+ 2m) fT / 2N (where m is 0 and a positive integer), a frequency hopping modulation signal hopping to a frequency position indicated by the following equation is transmitted simultaneously with the direct spread spectrum modulation signal, and the frequency hopping modulation signal is Hopping at a timing based on the correlation synchronization timing of a direct spread spectrum modulation signal.

According to a second aspect of the present invention, the signal bandwidth BW1 is set to BW1 <fT by a maximum period sequence code having a spreading code length of N bits generated by using a clock pulse having a frequency fT.
/ N to transmit a direct spread spectrum modulated signal whose spectrum is spread by multiplying and modulating a narrow band signal represented by / N, and the bandwidth BW2 is changed to BW
When expressed by the relational expression 2 <fT / N-BW1, a narrow-band signal having a bandwidth BW2 different from the narrow-band signal is
The center frequency is f1 ± (1 + 2m) fT / 2 with respect to the center frequency f1 of the direct system spread spectrum modulated signal.
N (where m is 0 and a positive integer) a frequency hopping modulated signal that hops to a frequency position indicated by an equation is transmitted at the same time as a direct spread spectrum modulated signal, and the frequency hopping modulated signal is a direct spread spectrum signal. It is to hop at a timing based on a synchronization timing transmitted by a spread modulation signal.

According to a third aspect of the present invention, in the spread spectrum communication system according to the first or second aspect, when demodulating a direct spread spectrum modulated signal, simultaneously transmitted signals are despread and the center frequency is directly adjusted. The purpose of the present invention is to perform demodulation after passing through a band-pass filter having the same center frequency f1 as the spread spectrum modulation signal and a pass bandwidth of BW1.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) This embodiment relates to claims 1 and 3.
An embodiment corresponding to FIG. As shown in FIG. 1, a transmitting-side device is connected to a spread-spectrum modulator (hereinafter referred to as D
This is referred to as an S-SS modulator. ) 100, frequency hopping spread spectrum modulator (hereinafter, referred to as FH-SS modulator) 110, adder 121, transmission antenna 122
, And the receiving-side apparatus includes a receiving antenna 123, an amplifier 124, and a direct system spread spectrum demodulation unit (hereinafter, referred to as DS).
-Referred to as an SS demodulation unit. ) 130, and a frequency hopping type spread spectrum demodulation unit (hereinafter, referred to as an FH-SS demodulation unit) 140.

The DS-SS modulator 100 includes an information signal input terminal 101, a carrier oscillator 102, and a primary modulator 10
3, a spread code clock generator 104, a spread code generator 105, and a spread modulator 106 as a secondary modulator. The FH-SS modulator 110 includes a transmission data input terminal 111, a narrow band modulator 112, Hopping code generator 113, frequency synthesizer 114, and mixer 1
15.

The DS-SS demodulator 130 includes a band-pass filter 131, a spread code clock generator 132, a spread code generator 133, a despread modulator 134, a band pass filter 135, a local oscillator 136, and a primary demodulator. 137,
Low-pass filter 138 and reception data output terminal 139
The FH-SS demodulator 140 includes a bandpass filter 141, a narrowband signal demodulator 142, a reception data output terminal 143, a mixer 144, a hopping synchronization circuit 145, a hopping code generator 146, and a frequency synthesizer 147. are doing.

The DS-SS modulator 100 converts an information signal d (t) input from an information signal input terminal 101 into a frequency f 1 from a carrier oscillator 102 in a primary modulator 103.
First-order modulation by the carrier wave. Thereby, the information signal d
(t) is modulated into a narrow-band signal a (t) having a center frequency f1 and a modulated bandwidth BW1. Here, for example, f1
= 2484 MHz and BW1 = 30 kHz as an example. The narrow band signal a (t) is
To supply. Further, the spreading code generator 105 is based on a clock signal of frequency fT supplied from the spreading code clock generator 104 and has a maximum periodic sequence code s (t) (hereinafter referred to as M sequence) having a chip rate fT and a spreading code length N. , And is supplied to the spread modulator 106.

As an example, a chip rate fT = 10 MH
z, the case of the spreading code length N = 63 will be described. The spread modulator 106 converts the narrowband signal a (t) into an M-sequence code s
(t), and the center frequency is 2484 MHz.
Direct spread spectrum modulated signal (hereinafter, DS-S
It is called an S modulation signal. ) Output v (t). DS-SS
The modulated signal v (t) is a set of discrete spectrums centered on the frequency f1 and in which the spectrum whose bandwidth is BW1 is arranged at a frequency interval of fT / N.
In the case of this example, as shown in FIG. 2, a spectrum centered at f1 = 2484 MHz and having a bandwidth BW1 = 30 kHz is a set of spectra arranged at fT / N, that is, at intervals of approximately 159 kHz.

The FH-SS modulator 110 modulates the information signal gm (t) input from the transmission data input terminal 111 with a narrow band modulator 112, and has a center frequency fx and a bandwidth B
A narrow band modulated wave bm (t) of W2 is set. On the other hand, according to the hopping code from the hopping code generator 113, the frequency synthesizer 114 has an output frequency f2m = fy ± (1 + 2m) fT / 2N (4) (where m is 0 or a positive integer). The signal f shown
Output 2m. Here, the center frequency fx of the narrow-band modulated wave bm (t) and fy in the above equation (4) indicating the output frequency of the frequency synthesizer 114 have a relationship represented by fx + fy = f1 (5).

Now, since f1 = 2484 MHz,
For example, fx = 300 MHz and fy = 2184 MHz. fx and fy need only satisfy the relationship of the above equation (4) and are not limited to this frequency.

The two signals b having such a frequency relationship
m (t) and f2m (t) are frequency-converted by the mixer 115, and the frequency at which the output frequency fz is fz = fx + fy ± (1 + 2m) fT / 2N = f1 ± (1 + 2m) fT / 2N (6) A hopping signal (hereinafter, referred to as an FH-SS signal) cm (t) is output. In the above equation (6), m takes a value of either 0 or a positive integer, and the value of m changes under the control of the hopping code generator 113. In addition, the part of “±” in the above equation (6) is also determined by the control of the hopping code generator 113.

Here, in the above equation (6), the case where the "±" portion is + and m changes in the range of 1 to 10 will be described as an example. From the above equation (6), f1 = 2484 MH
z, fT = 10 MHz, N = 63, m = 1, 2, 3, ...
Substituting 9 and 10, the frequency is 2484.2381MHz,
2484.3968MHz, 2484.5556MHz,… 2485.5079MHz, 2485.6
It becomes 667 MHz. The output signal cm (t) of the mixer 115 is
One of the 10 waves is selectively output, and the selected frequency is changed by hopping with time. The time for staying at one frequency and the order in which the frequencies are selected are determined by the hopping code output from the hopping code generator 113.

The output signal of the mixer 115, ie,
The FH-SS signal cm (t) is as shown in FIG. However,
FIG. 3 shows all the spectrums output at m = 1 to 10 at the same time. In practice, only one of these spectrums is transmitted at a certain moment. The DS-SS modulated signal v (t) thus generated and FH
-SS signal cm (t) is added by the adder 121 to obtain a signal x
(t) is output from the antenna 122. The spectrum of the output signal x (t) is as shown in FIG. However,
The spectrum of the FH-SS signal cm (t) indicated by oblique lines in the drawing shows all the spectrums output at m = 1 to 10 at the same time as in the case of FIG. Only one of the spectra will be output. The above is the operation of the transmitting device, but the operation of the receiving device is as follows.

The output signal x (t) from the transmitting device is received by the antenna 123, amplified by the amplifier 124,
It is supplied to the SS demodulation unit 130 and the FH-SS demodulation unit 140. In the DS-SS demodulation section 130, the received signal x
(t) is passed through a band-pass filter 131 to obtain DS-SS
Only the signal within the main lobe band of the modulated signal is supplied to despread modulator 134. On the other hand, the spreading code generator 133
10 MH generated from spread code clock generator 132
An M-sequence signal sr (t) having a spreading code length N = 63 is generated based on the clock of z and supplied to the despreading modulator 134.
The spreading code s generated by the spreading code generator 133
r (t) is the same code as the spread code s (t) generated by the spread code generator 105 of the DS-SS modulator 100. Although not shown, the spread code clock generator 1
32 and the despreading modulator 134 are accompanied by a synchronization acquisition circuit, a synchronization tracking circuit, and the like.
The synchronization of the spread code of the S modulated wave is detected and the synchronization is maintained. Therefore, the spreading code sr (t) generated in the receiving device is the same as the spreading code s (t) generated in the transmitting device, and has the same phase.

The despread signal ar (t) output from the despread modulator 134 is as follows: ar (t) = sr (t) × (t) (7) Here, the spreading code sr (t) in the receiving device
Is the same code as the spreading code s (t) generated in the transmitting apparatus, and if phase synchronization is established, sr (t) = s (t) (8). ) Expression: ar (t) = s (t) tcm (t) + v (t)｝ = s (t) ｛cm (t) + s (t) a (t)｝ = s (t) cm (t ) + S ² (t) a (t) = s (t) cm (t) + a (t) (9) FIG. 5 shows the spectrum of only the second term = a (t) in the above equation (9).

On the other hand, the first term in the above equation (9) = s (t)
cm (t) indicates that the FH-SS signal cm (t) is a signal directly spread by the spreading code s (t). m = 1
In this case, the instantaneous spectrum of the FH-SS signal cm (t) is the spectrum of the hatched portion when m = 1 in FIG. 4, and the product of this and s (t) is the spectrum shown in FIG. Similarly, the product of s (t) and cm (t) when m = 10 is as shown in FIG. As described above, the frequency component generated by the component of the first term in the above equation (9) is ± 5 from f1 = 2484 MHz regardless of m.
It appears at a frequency position separated by 9 kHz or more. m
FIG. 8 shows the spectrum of the signal ar (t) when = 1.

As shown in FIGS. 6 and 7, even if the value of m changes, the frequency position of the spectrum generated by the component of the first term of the above equation (9) does not change. Only the level of the spectrum component changes. The component of the second term in the above equation (9) is f1 = 2484
Although it appears as a spectrum having a bandwidth of ± 15 kHz centered on MHz, the component of the first term of the above equation (9) has a space of at least about 44 kHz irrespective of the value of m.

The frequency component despread signal ar (t)
Are output from the despread modulator 134 and pass through the band-pass filter 135. The pass band width of this band pass filter 135 is ± 15 kHz centering on 2484. Therefore, the output of the band-pass filter 135 is only the component of the second term of the above equation (9), and the spectrum is as shown in FIG. Here, the bandpass filter 1 is actually used.
When creating 35, it is difficult to create a combination of the center frequency and the pass bandwidth as described above. In such a case, an intermediate frequency circuit may be provided so that the frequency can be converted and a band-pass filter having a lower center frequency can be used. 5 by the band pass filter 135.
The received signal converged to the frequency band shown in FIG.
After being demodulated at 37, it is output from a reception data output terminal 139 via a low-pass filter 138.

In the FH-SS demodulation section 140,
The received signal is provided to a mixer 144 where it is mixed with the output of a frequency synthesizer 147. According to the hopping code from the hopping code generator 146, the frequency synthesizer 147 controls the frequency synthesizer 11 of the transmitting apparatus.
A signal having the same frequency as that of No. 4 is generated in the same hopping order. The hopping code generator 146 is controlled by the synchronization circuit 145 and is synchronized with the frequency hopping signal component included in the received signal. That is, the frequency synthesizer 147 is the frequency synthesizer 114 of the transmitting apparatus.
, Signals of the same frequency are successively generated at the same timing. The signal generated by the frequency synthesizer 147 in this manner is transmitted to the frequency synthesizer 114 of the transmitting apparatus.
Is synchronized, the output is the same as the output f2m of the frequency synthesizer 114.

The spectrum of the received signal input to the mixer 144 is the same as the spectrum of the transmitted signal.
As shown in FIG. The mixer 144 calculates the product of the received signal and the output f2m of the frequency synthesizer 147. For example, when m = 1, from the above equation (4),
f2m = 2184.2381 MHz, and a spectrum appears at a frequency position obtained by translating the spectrum shown in FIG. 4 by f2m on the frequency axis. In this case, a spectrum occurs at both the + f2m direction and the -f2m direction with respect to the frequency of FIG. 4, but FIG. 9 shows only the frequency component related to -f2m.

Similarly, when m = 10, the above (4)
From the equation, f2m = 2185.6667 MHz is obtained, and FIG.
The spectrum appears at a frequency position where the spectrum shown in (1) is translated by f2m on the frequency axis. in this case,
Although a spectrum is generated for both the + f2m direction and the -f2m direction with respect to the frequency of FIG. 4, FIG. 10 shows only the frequency component related to -f2m.

As described above, the output signal bmr of the mixer 144
(t) indicates that the FH-SS signal component is fx = 300M regardless of the value of m if hopping synchronization is established.
It converges within a band of ± 20 kHz centering on Hz. In contrast, DS-S transmitted simultaneously with the FH-SS signal
The S signal component fluctuates right and left around 300 MHz depending on the value of m, but a discrete spectrum always appears at the same frequency position. And 300MH
Even if the frequency component is closest to z, as shown in FIGS. 9 and 10, no spectrum component appears at a frequency position within about 44 kHz from 300 MHz.

The mixer 14 having such a frequency component
The output signal bmr (t) of No. 4 passes through the band-pass filter 141. The band pass filter 141 has a center frequency of 300 MHz and a pass bandwidth of ± 20 kHz. Therefore, the signal that has passed through the band-pass filter 141 is D
All the S-SS signal components (spectrum components in white portions in FIGS. 9 and 10) are removed, and only FH-SS signal components (spectral components in hatched portions in FIGS. 9 and 10) remain. The signal br (t) extracted by passing through the band-pass filter 141 in this manner is converted into a narrow-band signal demodulator 142
After that, it is output from the reception data output terminal 143.

The FH-SS modulator 110 of the transmitting device
The hopping code generator 113 receives the timing signal from the spread code generator 105 of the DS-SS modulator 100 as a signal line 151, an A contact of the switching circuit 152, and a signal line 153.
And a timing signal is supplied from the spread code generator 133 of the DS-SS demodulation unit 130 of the receiving side device via the signal line 154, the B contact of the switching circuit 152, and the signal line 153. . The timing signal from the spreading code generator 105 uses a DS-SS transmission timing signal as a timing signal, and the timing signal from the spreading code generator 133
33 from the DS-SS synchronization circuit (not shown) inside
-The SS reception timing signal is used as the timing signal. The hopping code generator 113 generates a hopping signal in synchronization with the timing signal. The signal line 154 is also connected to the FH
-Also connected to the hopping synchronization circuit 145 of the SS demodulation unit 140.

Here, an example of the operation will be described assuming that there are three radios A to C having the circuit configuration of FIG. 1. For example, in the radio A, the switching circuit 152 is connected to the A contact side. Set it. Then, the DS-SS modulator 100 of the own station
Generates a frequency hopping signal maintaining a constant phase relationship with the phase of the spreading code generated by the spreading code generator 105. This state is shown in FIG. FIG.
2 shows an example in which an M-sequence signal is used as a spreading code of S-SS modulation section 100. In the case of the M-sequence code, the autocorrelation value becomes maximum for each code cycle, and the autocorrelation values in other phases are small and constant. Radio A
In synchronization with the phase of the spreading code generated in the own station, for example, as shown in FIG. 11, f1 → f2 → f3 →
The communication frequencies are hopped in the order of... → f9 → f10 → f1 → f2 →.

On the other hand, in the radios B and C other than the radio A, the DS-SS signal transmitted from the radio A is received and the spread code generator 1 in the DS-SS demodulator 130 is received.
The spread code is synchronized by obtaining the correlation value of the spread code in the DS-SS synchronization circuit built in the device 33. Therefore, in the wireless devices B and C, the phase information of the spread code of the wireless device A can be known similarly to the wireless device A. Therefore, the radio B is, for example, as shown in FIG.
When the phase of the spreading code of the DS-SS signal of
The communication frequency is hopped in the order of f3 → f4 → f5 →... → f1 → f2 → f3 → f4 →. Similarly, the radio C also has f9 → f10 → f1 →... → f7 → f8 → f9 → f
Hops communication frequencies in the order of 10 →….

As shown in FIG. 11, both the radio B and the radio C perform frequency hopping using the same hopping code as that of the radio A, but the hopping phases of the three radios are shifted from each other. However, there is no occurrence of a “hit” in which the communication frequencies collide with each other. Also, the spectrum of the DS-SS signal transmitted by the radio A and the radios A, B, C
Have no frequency bands overlapping each other. Therefore, the DS-S transmitted by each of the three radios A, B, and C
Both the S signal and the FH-SS signal are transmitted without overlapping their spectra.

(Second Embodiment) In this embodiment, an embodiment corresponding to claims 2 and 3 will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and different parts will be described. As shown in FIG. 12, a hopping timing generator 107 is provided in the DS-SS modulator 100, and the hopping timing generator 107 transmits data at a fixed time interval to transmission data input from the information signal input terminal 101. Information is interrupted and frequency hopping is performed by the signal line 161, the switching circuit 16
The signal is supplied to the hopping code generator 113 of the FH-SS modulator 110 via the A contact 2 of FIG. The hopping timing generator 107 is connected to the information signal input terminal 101.
Is supplied to the primary modulator 103 as an information signal d (t). DS-SS demodulation unit 1
30 through the low-pass filter 138 to the reception data output terminal 139, and the FH-SS through the signal line 163 and the B contact of the switching circuit 162.
The signal is supplied to the hopping code generator 113 of the modulator 110 and the FH-SS demodulator 14 is supplied via the signal line 163.
0 hopping synchronization circuit 145.

FIG. 13 shows a state in which the hopping timing generator 107 interrupts data transmission at regular time intervals and transmits information to the hopping code generator 113 for frequency hopping. The transmission data input from the information signal input terminal 101 is temporarily interrupted for a time width tf at a cycle every time tH. During this time tH, FH-S
Signals fa, fb, fc,... Fi, fj (hereinafter referred to as fx signals) indicating that the hopping timing of the S signal has arrived are transmitted. As described above, the transmission data and the signals fa, fb, fc,.
The signal d (t) in which i and fj are alternately repeated is DS-SS
It is modulated and transmitted wirelessly. Here, the operation will be described by taking as an example a case where three wireless devices A, B, and C are communicating with each other using different wireless devices. In the wireless device A, the switching circuit 162 is switched to the A contact side.
Therefore, a timing signal synchronized with the fx signal sent from the Hopping timing generator 107 is output from the signal line 161.
The signal is supplied to the hopping code generator 113 via the contact A of the switching circuit 162. Therefore, in the radio A, the hopping timing of the FH-SS modulator 110 is synchronized with the fx signal transmitted from the DS-SS modulator 100, as shown in FIG.

On the other hand, the other radios B and C operate as follows. The switching circuit 162 has switched to the B contact side. The DS-SS demodulation section 130 receives the received DS-SS
The SS signal is demodulated, and the arrival timing of the fx signal transmitted from the wireless device A is known. The signal obtained by demodulating the DS-SS signal is supplied to the hopping code generator 113 via the signal line 163 and the B contact of the switching circuit 162. As a result, the hopping code generator 113 sets the DS-SS demodulation unit 1
The FH-SS modulator 1 of the own station at a timing synchronized with the signal fx obtained from the received demodulated data supplied from
Perform 10 hops. Therefore, as shown in FIG. 13, the hopping timings of the radios B and C coincide with the hopping timings of the radio A.

In this operation, the hopping timing signal fx transmitted from the radio A includes information on the hopping frequency itself. Therefore, the signal fa,
The content of each signal is made different, such as fb, fc,..., fi, fj, so that the hopping frequency can be specified. However, in each of the radios A, B, and C, the setting of which frequency should be changed when the hopping timing signal fx is received is set in advance to a different content for each radio. For example, as shown in FIG. 13, when the radio A outputs the hopping timing signal fa, it hops to the frequency f1, and the radio B transmits the hopping timing signal f.
a when receiving the hopping timing signal fa, the radio C hops to the frequency f3.
Hopping to By repeating such an operation, each wireless device performs a frequency hopping operation. This method uses F
This is used in the case of a so-called low-speed frequency hopping scheme in which the frequency hopping cycle of the H-SS modulator 110 is longer than the time width of one bit of transmission data.

Radio B and radio C both perform frequency hopping using the same hopping code as radio A,
Since the phases of hopping of the three wireless devices are shifted from each other, there is no occurrence of a “hit” in which communication frequencies collide. Also, the spectrum of the DS-SS signal transmitted by the radio A and the FH-SS transmitted by the radios A, B, and C
The spectrums of the signals do not overlap with each other in frequency band. Therefore, between the three wireless devices A, B, and C, both the DS-SS signal and the FH-SS signal transmitted by the wireless devices are transmitted without overlapping their spectra.

[0045]

As described above, according to the first to third aspects of the present invention, the frequency hopping modulation signal and the direct type spread spectrum modulation signal do not overlap in the frequency band, and therefore the frequency hopping modulation signal and the direct type spread spectrum signal are not used. The modulated signals can be transmitted simultaneously without any interference between them. Moreover, it is possible to obtain a good reception state that greatly exceeds the spread processing gain of both signals. In addition, the synchronization timing signal of the frequency hopping modulation signal can be transmitted by the direct method spread spectrum modulation signal transmitted simultaneously with the frequency hopping modulation signal, and the hopping timing of each frequency hopping method spread spectrum radio is completely synchronized. Can be transmitted. Therefore, in the same system, collision of communication frequencies in frequency hopping, that is, hit does not occur at all, so that extremely efficient transmission can be realized, and frequency use efficiency can be improved. Further, all signals to be transmitted are spread spectrum modulated, and have excellent interference removal capability against interference radio waves from other devices.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a spectrum of a direct spread spectrum modulation signal according to the embodiment;

FIG. 3 is a diagram showing an example of a spectrum of a frequency hopping modulation signal in the embodiment.

FIG. 4 is a diagram showing an example of a spectrum of a transmission signal output from the antenna of the transmitting device according to the embodiment.

FIG. 5 is an output signal a from a primary modulator of a direct spread spectrum modulation section of a transmitting apparatus according to the embodiment.
The figure which shows the spectrum of the 2nd term a (t) of (t) and (9) formula.

FIG. 6 is a diagram showing a signal spectrum of a first term s (t) cm (t) of Expression (9) when the frequency hopping modulation signal is m = 1 in the embodiment.

FIG. 7 is a first term s (t) cm (t) of equation (9) when the frequency hopping modulation signal is m = 10 in the embodiment.
The figure which shows the signal spectrum of FIG.

FIG. 8 is a diagram showing a signal spectrum of the despread signal ar (t) when the frequency hopping modulation signal is m = 1 in the embodiment.

FIG. 9 shows a component appearing in the vicinity of 300 MHz in the signal spectrum of the signal bmr (t) output from the mixer of the frequency hopping type spread spectrum demodulation unit when the frequency hopping modulation signal is m = 1 in the embodiment. FIG.

FIG. 10 shows a signal bmr (t) output from the mixer of the frequency hopping type spread spectrum demodulation unit when the frequency hopping modulation signal is m = 10 in the embodiment.
FIG. 3 is a diagram showing components appearing in the vicinity of 300 MHz in the signal spectrum of FIG.

FIG. 11 is a diagram showing an autocorrelation value of a direct spread spectrum modulation signal of one radio and a hopping frequency of each radio when the embodiment is applied to three radios.

FIG. 12 is a block diagram showing a second embodiment of the present invention.

FIG. 13 is a diagram showing transmission data of one wireless device by a direct spread spectrum modulation signal and a hopping frequency of each wireless device when the embodiment is applied to three wireless devices.

FIG. 14 is a block diagram showing a conventional example.

FIG. 15 is a diagram showing a spectrum of a direct spread spectrum modulation signal in the conventional example.

FIG. 16 is a diagram showing a frequency arrangement in the conventional example.

[Explanation of symbols]

 Reference Signs List 100 spread spectrum modulator 103 primary modulator 105 spread code generator 106 spread modulator 110 frequency hopping spread spectrum modulator 112 narrow band modulator 113 hopping code generator 130 direct spread spectrum Demodulation unit 131 Band pass filter 133 Spread code generator 134 Despread modulator 137 Primary demodulator 140 Frequency hopping spread spectrum demodulation unit 141 Band pass filter 142 Narrow band signal demodulator 146 Hopping code Generator

Claims (3)

(57) [Claims] A signal bandwidth BW1 is multiplied by modulating a narrow-band signal represented by BW1 <fT / N by a maximum period sequence code having a spreading code length of N bits generated by using a clock pulse having a frequency fT. A direct spectrum spread modulated signal whose spectrum is spread is transmitted, and when the bandwidth BW2 is represented by a relational expression of BW2 <fT / N-BW1, the bandwidth BW2 is different from the narrowband signal. The frequency position of the narrow-band signal is represented by the following formula: The center frequency of the narrow-band signal is represented by f1 ± (1 + 2m) fT / 2N (where m is 0 and a positive integer) with respect to the center frequency f1 of the direct spread spectrum modulation signal. A frequency hopping modulation signal hopping to the direct system spread spectrum modulation signal is transmitted at the same time as the frequency hopping modulation signal. , Spread spectrum communication system, wherein, characterized in that the hopping timing on the basis of the correlation synchronization timing of the direct system spread spectrum modulation signal. 2. The signal bandwidth BW1 is multiplied by modulating a narrow-band signal represented by BW1 <fT / N by a maximum period sequence code having a spreading code length of N bits generated by using a clock pulse having a frequency fT. A direct spectrum spread modulated signal whose spectrum is spread is transmitted, and when the bandwidth BW2 is represented by a relational expression of BW2 <fT / N-BW1, the bandwidth BW2 is different from the narrowband signal. The frequency position of the narrow-band signal is represented by the following formula: The center frequency of the narrow-band signal is represented by f1 ± (1 + 2m) fT / 2N (where m is 0 and a positive integer) with respect to the center frequency f1 of the direct spread spectrum modulation signal. A frequency hopping modulation signal hopping to the direct system spread spectrum modulation signal is transmitted at the same time as the frequency hopping modulation signal. , Spread spectrum communication system, wherein, characterized in that the hopping timing on the basis of the synchronization timing transmitted by the direct method spread spectrum modulation signal. 3. When demodulating a direct system spread spectrum modulated signal, simultaneously transmitted signals are despread and the center frequency is the same as the center frequency f1 of the direct spread spectrum modulated signal and the pass bandwidth is BW1. 3. The spread spectrum communication system according to claim 1, wherein demodulation is performed after passing through a band-pass filter.