JPH10209922A - Method, device for generating local oscillation frequency method and equipment frequency hopping spread spectrum communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a local oscillation frequency at high speed in the state of hopping inside a widely secured frequency range. SOLUTION: When any arbitrary frequency 41 is generated from a direct digital synthesis system synthesizer 10 at the same frequency interval as a local oscillation frequency 48 while defining its peak frequency as fd and synthesized with any one of frequencies 43-45 generated from respective synthesizers 21-23 as FMI+mFD (M:0,1,2... ... ..., M) through a frequency converter 25 later, within the wide frequency range, the desired local oscillation frequency 48 is generated at a high speed while extending a hopping distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
By synthesizing the frequency selected at the same time,
A local oscillation frequency generating method and apparatus in which the local oscillation frequency is generated as a frequency hopped state as desired, and further, a frequency hopping spread spectrum communication method in which such a local oscillation frequency generating method is adopted, Furthermore, the present invention relates to a frequency hopping spread spectrum communication device provided with such a local oscillation frequency generating device.

[0002]

2. Description of the Related Art In a so-called frequency hopping spread spectrum communication system, a spread spectrum communication is performed while a local oscillation frequency is sequentially switched according to a randomly determined order. The higher the switching frequency, that is, the higher the hopping speed, the better the anti-jamming and confidentiality. Therefore, in order to improve the anti-jamming property and confidentiality, a frequency synthesizer for generating a local oscillation frequency is required to have its output frequency switched at high speed within a wider frequency range. is the current situation.

[0003] In a conventional frequency hopping spread spectrum communication apparatus, a direct digital synthesis system is exclusively used as a synthesizer system capable of high-speed switching. As an example of a frequency synthesizer according to such a scheme, for example, “WHITE S
ERIES NO.57 Fundamentals and Applications of Spread Spectrum Communication Technology "
(March 13, 1987, published by Trikeps Co., Ltd., pp. 65-67), which is described below.

FIG. 4 shows a block diagram of an example of a frequency synthesizer in a conventional frequency hopping spread spectrum communication apparatus. As shown in the figure, in this example, the transmission device is shown as an example, but the situation is the same for the reception device. In this case, the transmission data 51 from the data generation unit 9 is converted into information 52 in a state where the information is modulated via the primary modulation unit 8, and the local oscillation frequency (DDS) from the digital synthesizer (DDS) 10 is directly converted by the frequency converter 7. Hopping synthesizer output frequency)
, The spread spectrum modulated signal 5
3 has been frequency-converted.

The operation of the direct digital synthesizer 10 will now be described in detail. For the sample value generating circuit 3, while the system clock 36 is generated from the clock generating circuit 1, the frequency The local oscillation frequency 48 to be output from the setting circuit 2
Is set as the frequency set value 31 =
It is updated and generated at regular intervals as (output local oscillation frequency [Hz] × 2 ^N ) / (frequency of system clock 36 [Hz]). Where N in the equation
Indicates the number of bits of the phase accumulator in the sample value generation circuit 3. Thus, in the sample value generation circuit 3, the frequency setting value 31 from the frequency setting circuit 2 is cumulatively added based on the system clock 36, so that the phase corresponding to the sample value 38 to be generated is used as a read address to the memory. It has been calculated. That is, the memory in the sample value generation circuit 3 includes:
The sample values for one cycle of the sine wave are stored in advance in the order of continuous addresses. Based on the calculated read address, the memory reads out the sample values 38 from the memory at the same read speed in the order of continuous addresses or in non-continuous addresses ( The addresses are read out in the order of the desired thinned-out state). The sample values 38 sequentially read out in this manner are converted into an analog sine waveform 39 having a local oscillation frequency 48 as a main component via a DA conversion circuit 4, and then output from a low-pass filter (LPF) 5 to an unnecessary component. This is obtained as the local oscillation frequency 48 from which the (harmonic components) have been removed. When reading from the memory, the larger the frequency setting value 31, that is, the larger the thinning interval of the read address, the higher the local oscillation frequency 48 is obtained from the direct digital synthesizer 10 as a high frequency. That is.

[0006]

However, in the conventional frequency synthesizer, the upper limit of the frequency of the system clock is limited by the upper limit operation speed of the memory in the sample value generation circuit. The hopping frequency range is also limited. In other words, the frequency range (DC to several MHz) of the local oscillation frequency obtained from the frequency synthesizer, and accordingly, the maximum frequency as the upper limit is kept small. In general, in order to further improve the anti-jamming and confidentiality characteristics of the frequency hopping method, it is necessary to secure a large frequency range of the local oscillation frequency and to switch quickly within the frequency range. However, the conventional frequency synthesizer cannot secure a sufficiently large frequency range of the local oscillation frequency.

A first object of the present invention is to provide a local oscillation frequency generating method capable of generating a local oscillation frequency at high speed in a hopped state within a largely secured frequency range. A second object of the present invention is to provide a local oscillation frequency generator capable of generating a local oscillation frequency at high speed in a hopped state within a largely secured frequency range. A third object of the present invention is to provide a frequency hopping spread spectrum communication method capable of performing spread spectrum communication in a state in which anti-jamming property and confidentiality are further improved. A fourth object of the present invention is to provide a frequency hopping spread spectrum communication apparatus capable of performing spread spectrum communication in a state where anti-jamming and confidentiality are further improved.

[0008]

Local oscillation frequency generation method in the object SUMMARY OF THE INVENTION or a frequency hopping spread spectrum communication method, basically, any frequency at the same frequency interval and the local oscillation frequency is directly as the highest frequency f _d, When the generation is enabled by the digital synthesizing method, the first frequency corresponding to the frequency set value is generated every time the frequency set value is updated and set in time series, while f _min + M · f _d (M: 0, 1, 2, ...
.., M), the second frequency corresponding to the frequency set value is generated each time the frequency set value is updated and set in time series. This is achieved by synthesizing the second frequency and the first frequency while generating a desired local oscillation frequency.

Further, as the local oscillation frequency generator, or frequency hopping spread spectrum communication apparatus of the above objects, basically, any frequency at the same frequency interval and the local oscillation frequency by a direct digital synthesis system as the maximum frequency f _d A first frequency generating means for generating a first frequency corresponding to the frequency set value each time the frequency set value is updated and set in a time-series manner, if f _min + M · f _d (M: 0, 1, 2,...)
.., M), the second frequency corresponding to the frequency set value is generated each time the frequency set value is updated and set in time series. Generating a desired local oscillation frequency by synthesizing a second frequency generating means, and combining the second frequency from the second frequency generating means and the first frequency from the first frequency generating means. Or to configure a local oscillation frequency generator to include at least
Alternatively, as means for generating a desired local oscillation frequency in a state of high-speed frequency hopping, this is achieved by providing a local oscillation frequency generator configured as described above.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, before entering into a specific description of the present invention, an outline thereof will be described. A local oscillation frequency generator (hopping synthesizer) according to the present invention includes:
Basically, two kinds of frequency generating means are included, and the output frequency from each of these frequency generating means is synthesized by the frequency synthesizing means, whereby a local oscillation frequency is generated as desired. As the type of the frequency generating means, the first frequency generating means (DDS
System continuously variable frequency generating means) and the second for coarse frequency setting
Frequency generating means (discrete frequency generating means). Of these frequency generating means, the first frequency generating means can set the frequency at the same frequency interval as the desired local oscillation frequency. The switching speed is equivalent to the DDS according to the prior art. In the second method, the output frequency can be discretely generated up to a high frequency so that the output frequency from the second frequency generating means is converted into a desired local oscillation frequency. The frequency is set to be equal to or higher than the highest frequency that can be generated by the first frequency generating means. Further, in order to secure a large frequency interval before and after the frequency switching, that is, a hopping distance, two or more types of frequencies are always set in a stable output state from the second frequency generating means prior to the frequency switching. In addition, at the time of actual switching, any one of them is selected as a synthesis target. The frequency switching timing for the first frequency generating means and the frequency selection output timing for the second frequency generating means are set to the same timing, so that the local oscillation frequency is generated in a state where the frequency is hopped as desired. It is.

Here, as a specific example of the operation, a certain time t
From 1 to t2, if the frequency f _d1 is output from the first frequency generation means and the frequency f ₁ is output from the second frequency generation means, (f _d1 + f
A local oscillation frequency having a frequency of ₁ ) is obtained. Further, in the next time t2 -t3, the frequency f _d2 from the first frequency generating means, the second is then if the frequency f ₂ is outputted, from the frequency synthesizing means, (f _d1 + f A local oscillation frequency having a frequency of ₂ ) can be obtained. At this time, if the frequency generation range of the first frequency generation means is up to (f _dmin -f _dmax ), the frequency interval between the frequencies f ₁ and f ₂ is always
(F _dmax −f _dmin ) or more. As a result, a local oscillation frequency can be generated in a hopping state within a wider frequency range while having a hopping speed equivalent to that of the DDS according to the related art.

Now, the present invention will be described in detail with reference to FIG.
1 shows a block configuration of an example of a local oscillation frequency generator according to the present invention. As shown in the figure, it is shown as being provided in a frequency hopping spread spectrum communication apparatus (transmitting apparatus), but the situation is the same when it is provided in a receiving apparatus. In this case, the local oscillation frequency generator (hopping synthesizer) 26 includes a DDS 10 as a first frequency generator and PLL type synthesizers 21 to 23 as a second frequency generator.
And multiplexer 16, frequency converter 25 and band pass filter (BPF) as frequency synthesis means
24, DDS10, PLL system synthesizers 21 to 2
3 and a control circuit 6 for collectively controlling the multiplexer 16
It is composed of Among these components, the DDS 10 has the same configuration as that shown in FIG. 4, except that the frequency setting value 31 is set by the control circuit 6. The frequency division ratio setting values 32 to 34 as frequency setting values for the PLL synthesizers 21 to 23 are also set by the control circuit 6. As will be understood from FIG. 2 to be described later, the PLL type synthesizers 21 to 23 always operate in such a manner that any two of them are already in the frequency lock-in completed state and the other one is in the frequency lock-in state. The phase synchronization operation is updated by the division ratio setting values 32 to 34 from the control circuit 6, and the two PLs already in the frequency pull-in completed state
The output frequency from each of the L-system synthesizers is given as a selected output frequency 46 to the frequency converter 25 sequentially from the multiplexer 16 by a selection control signal 35 from the control circuit 6. As a result, in the frequency converter 25, the selected output frequency 46 and the output frequency 41 from the DDS 10 are synthesized, and the synthesis result 47 is obtained as desired as the local oscillation frequency 48 via the band-pass filter 24. is there. However, the number of PLL synthesizers is not limited to three, but may be four or more.
It is also possible to provide. The number may be determined appropriately in consideration of frequency pull-in characteristics and simplification in configuration.

Here, the local oscillation frequency generator 26
The operation in one example will be described below with reference to FIG. That is, the frequency range of the local oscillation frequency 48 output from the local oscillation frequency generator 26 is represented by f
Assuming that the highest frequency among the output frequencies 41 from the _{min to} f _max and the DDS 10 is f _d , as the output frequency 43 from the PLL synthesizer 21, the following n kinds of f ₁₁ to f _1n minutes can be set.

F ₁₁ = f _min f ₁₂ = f _min + f _d : f _1n = f _min + (n−1) f _d Similarly, the output frequency 44 from the PLL system synthesizer 22 is a division ratio set value. 33, the following n ways f _{21 to} f _2n can be set.

[0015] _{f 21 = f min + nf d} f 22 = f min + (n + 1) f d: f 2n = f min + (2n-1) f d output frequency 45 from the PLL synthesizer 23 also divide ratio n as f ₃₁ follows the set value 34 ~f
_3n minutes can be set.

F ₃₁ = f _min + 2nf _d f ₃₂ = f _min + (2n + 1) f _d : f _3n = f _min + (3n-1) f _d where n is to be output from a single PLL-type synthesizer is the number of the output frequency, the highest frequency f _d DDS
10 and PLL system synthesizers 21 to 23, f
if obtaining the local oscillation frequency 48 in the frequency range of _min ~f _max, the value of the _{n, n = (f max -f} min) / f
_d / (number of PLL-type synthesizers).

The operation will be described more specifically.
As shown, at time t1, the PLL-N synthesizer 21, already frequency retraction of the frequency f ₁₁ is also even the PLL synthesizer 22, already frequency f ₂₁
And the local oscillation frequency 48 is set as the frequency f between the times t1 and t2.
Assuming that _m1 is output, as the frequency setting value 31 for the DDS 10 from the control circuit 6, the frequency setting value 31 =
The value calculated as (output frequency f _d1 [Hz] × 2N) / (system clock frequency f _CLK [Hz]) is set. Here, N is the number of bits of the phase accumulator in the DDS 10. The frequency setting value 31 allows the DDS 10 to set the frequency setting value 31
In which the frequency f _d1 corresponding is outputted as the output frequency 41. On the other hand, in parallel with the output of the frequency f _d1 , the output frequency 44 from the PLL synthesizer 22, that is, the frequency f ₂₁ is selected as the selected output frequency 46 from the multiplexer 16 by the selection control signal 35 from the control circuit 6. This is what has been output. Accordingly, the frequency component (f ₂₁ + f _d1 ), (f ₂₁ −) is obtained as a synthesis result 47 between the frequencies f _d1 and f ₂₁ by the frequency converter 25.
f _d1) but simultaneously obtained, among these components, by the latter component is removed by the band-pass filter 24, frequency components _{(f2 1 + f d1) (} = f m1) is obtained as a local oscillator frequency 48 Things. Subsequent time t2
In ~t3 Further, from DDS10, to the frequency f _d2 is output as the output frequency 41, and at the same time the frequency setting value 31 is set from the control circuit 6, the selection control signal 35 from the control circuit 6 to the multiplexer 16 , And the multiplexer 16 outputs the frequency f ₁₁ from the PLL synthesizer 21 as the selected output frequency 46. As a result, the bandpass filter 2
4, the frequency component (f ₁₁ + f _d2 ) (= _{fm 2} ) is obtained as the local oscillation frequency 48. Furthermore,
At subsequent time t3 t4, the same under control by the control circuit 6, as a result of the frequency f ₂₁ is synthesized from the frequency f _d3 and PLL-N synthesizer 22 from DDS10, the frequency component (f ₂₁ + f _d3) (= _Fm3 ) is obtained as the local oscillation frequency 48.

As can be seen from FIG. 2, during the period from time t1 to t4, the PL is set by the frequency division ratio set value 34 from the control circuit 6.
Although only the L-system synthesizer 23 is in the frequency lock-in state, from time t4 to time t7, only the PLL system synthesizer 21 is in the frequency lock-in state by the division ratio setting value 32, and the time t7 Between t10 and t10, the PLL system synthesizer 2
At this time, each of the PLL type synthesizers 21 to 23 has one of the frequency synchronizing states, while the other two have the frequency synchronizing state. It is in the state where the retraction is completed. Therefore, even after time t4, the output frequency and the DDS from each of the two PLL synthesizers in the frequency lock-in completed state.
The local oscillation frequency 48 can be generated as desired by successively combining the output frequency 41 with the output frequency 41.

FIG. 3 is a block diagram showing another example of the local oscillation frequency generator according to the present invention. As shown in the drawing, a substantial difference from the one shown in FIG. 1 is that frequency multipliers 62 to 64 and a crystal oscillator 61 are provided instead of the PLL type synthesizers 21 to 23. In this case, the output frequency 65 from the crystal oscillator 61 is multiplied by the frequency multiplying circuit 62 based on the coefficient set value 69 from the control circuit 6, and an output frequency 66 in a multiplied state is obtained. ing. The output frequency 66 from the frequency multiplying circuit 62 is further multiplied by a frequency multiplying circuit 64 based on a coefficient set value 71 to obtain an output frequency 68 in a multiplied state. Further, the output frequency 65 from the crystal oscillator 61 is also multiplied by a frequency multiplying circuit 63 based on a coefficient set value 70 different from each of the coefficient set values 69 and 71, and the output frequency is multiplied and output. 67 are obtained. Thus, the output frequency 65 from the crystal oscillator 61
, The output frequencies 66 to 68 having different frequencies are obtained by directly or indirectly multiplying the frequencies. One of the output frequencies 66 to 68 is From the control circuit 6
Is selected and output as the selected output frequency 46 by the selection control signal 35 from. At this time, if the update timing of the selected output frequency 46 is made the same as that of the output frequency 41 and the coefficient setting values 69 to 71 for the frequency multipliers 62 to 64 are updated as desired, a desired local oscillation The frequency 48 is obtained. More specifically, for example, while the frequency multiplying circuits 62 and 64 are a series a and the frequency multiplying circuit 63 is a series b, while the output frequency 67 from the series b is selectively output from the multiplexer 16, the coefficient setting for the series a is performed. While the output frequencies 66 and 68 are updated by updating the values 69 and 71, while the output frequency from one of the series is selectively output, the output frequency from the other series is changed. If it is updated, the selected output frequency 46 is discretely obtained from the multiplexer 16 within a wider frequency range.

[0020]

As described above, according to the first and second aspects, there is provided a local oscillation frequency generating method capable of generating a local oscillation frequency at high speed in a hopped state within a largely secured frequency range. According to the third aspect, a local oscillation frequency generator capable of generating a local oscillation frequency at a high speed in a hopped state within a largely secured frequency range is further provided according to a fourth aspect. A frequency hopping spread spectrum communication method capable of performing spread spectrum communication in a state in which anti-jamming property and confidentiality are further improved is further improved in the case of claim 5, in which anti-jamming property and confidentiality are further improved. In this state, frequency hopping spread spectrum communication apparatuses capable of performing spread spectrum communication can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a local oscillation frequency generator according to the present invention.

FIG. 2 is a diagram for explaining an operation of an example of the local oscillation frequency generator.

FIG. 3 is a block diagram showing another example of a local oscillation frequency generating apparatus according to the present invention;

FIG. 4 is a diagram showing a block configuration of an example of a frequency synthesizer in a frequency hopping spread spectrum communication apparatus according to the related art.

[Explanation of symbols]

6 control circuit, 10 direct digital synthesizer (DDS), 16 multiplexer, 21-23 ...
PLL type synthesizer, 24 ... band pass filter,
25 frequency converter, 26 local oscillation frequency generator (hopping synthesizer), 61 crystal oscillator, 62
~ 64 ... frequency multiplier

Claims (5)

[Claims] 1. A local oscillation frequency generating method in which a desired local oscillation frequency is generated by synthesizing two types of frequencies sequentially and simultaneously selected in time series, wherein the local oscillation frequency is the same as the local oscillation frequency. When an arbitrary frequency can be generated as the highest frequency fd by the direct digital synthesis method at intervals, the first frequency corresponding to the frequency set value is updated every time the frequency set value is updated and set in time series. While f _min + M · f _d (M:
.., M), each time the frequency setting value is updated and set in time series, the frequency setting value corresponds to the frequency setting value. A local oscillation frequency generating method for generating a desired local oscillation frequency by synthesizing the second frequency and the first frequency while generating the second frequency. 2. A local oscillation frequency generating method in which a desired local oscillation frequency is generated by synthesizing two types of frequencies sequentially and simultaneously selected in time series, wherein the local oscillation frequency is the same as the local oscillation frequency. When an arbitrary frequency can be generated as the highest frequency fd by the direct digital synthesis method at intervals, the first frequency corresponding to the frequency set value is updated every time the frequency set value is updated and set in time series. While f _min + M · f _d (M:
0, 1, 2,..., M) when at least any two frequencies are desirably and preliminarily selected and are generated in a stable state. Every time the frequency setting value is updated and set in time series, the second frequency corresponding to the frequency setting value is selected as one of the two frequencies, and the second frequency and the second frequency are selected. 1. A local oscillation frequency generating method in which a desired local oscillation frequency is generated by synthesizing the frequency of the local oscillation frequency. 3. A local oscillation frequency generating apparatus for generating a desired local oscillation frequency by synthesizing two types of frequencies sequentially and sequentially selected in time series, wherein the local oscillation frequency is the same as the local oscillation frequency. When an arbitrary frequency can be generated as the highest frequency fd by the direct digital synthesis method at intervals, the first frequency corresponding to the frequency set value is updated every time the frequency set value is updated and set in time series. First frequency generating means for generating f _min +
When an arbitrary frequency defined as M · f _d (M: 0, 1, 2,..., M) is allowed to be generated, every time the frequency set value is updated and set in time series. A second frequency generating means for generating a second frequency corresponding to the frequency set value; a second frequency from the second frequency generating means; and a first frequency from the first frequency generating means. And a frequency synthesizing means for generating a desired local oscillation frequency by synthesizing the local oscillation frequency. 4. A transmission-side apparatus transmits a spread-spectrum modulated signal at a frequency-hopped local oscillation frequency, while a reception-side apparatus transmits a frequency-hopped local-oscillation signal from a transmission-side apparatus. a frequency hopping spread spectrum communication method to be received by the frequency, at least transmitting-side apparatus, either in the receiving device, direct digital arbitrary frequency as the highest frequency f _d at the same frequency interval and the local oscillation frequency When generation is enabled by the combining method, the first frequency corresponding to the frequency set value is generated every time the frequency set value is updated and set in time series, while f _min + M · f _d (M: 0, 1, 2,...,…,
When an arbitrary frequency defined as M) is allowed to be generated, every time the frequency set value is updated and set in time series, the second frequency corresponding to the frequency set value is generated. A frequency hopping spread spectrum communication method in which a desired local oscillation frequency is generated as a frequency hopping state by combining the second frequency and the first frequency. 5. A transmitting device for transmitting a spread spectrum modulated signal using a frequency hopped local oscillation frequency,
Alternatively, a frequency hopping spread spectrum communication device as a receiving device that receives a spread spectrum modulated signal from the transmitting device at a frequency hopped local oscillation frequency, wherein a desired local oscillation frequency is frequency-hopped at a high speed. as a means for generating a state, if any frequency at the same frequency interval and the local oscillation frequency is the occurrence Allowed by the direct digital synthesis system as the highest frequency f _d, updated and set a time-series manner the frequency setting value A first frequency generating means for generating a first frequency corresponding to the frequency setting value each time the frequency setting is performed, and f _min +
If an arbitrary frequency defined as M · f _d (M: 0, 1, 2,..., M) can be generated,
Every time the frequency setting value is updated and set in time series, a second frequency generating means for generating a second frequency corresponding to the frequency setting value, and a second frequency generating means from the second frequency generating means.
Frequency hopping provided with a local oscillation frequency generating device including at least a frequency synthesizing means for generating a desired local oscillation frequency by synthesizing the frequency of the first frequency and the first frequency from the first frequency generating means. Spread spectrum communication equipment.