JPS58103247A - Receiving device - Google Patents

Abstract

PURPOSE:To secure synchronism quickly within a hopping pattern period with simple constitution of a receiver without using any synchronism searching mode, by deciding the presence or absence of the demodulating and wave detecting output of a spread spectrum code and giving phase control to the generation of the output of a local reference wave. CONSTITUTION:A local reference wave is delivered from a frequency synthesizing circuit 7 of a receiving device of a frequency hopping communication system and then mixed with the spread spectrum signal supplied through a receiving antenna 1 at a frequency mixing circuit 2. Then the spread signal is demodulated. The signal demodulated at the circuit 2 is amplified at an IF amplifying circuit 3 and receives a wave detection at an envelope curve wave detecting circuit 4. This wave detection output is integrated at an integration circuit 5 and applied to a control circuit 6. At the same time, the wave detection output of the circuit 4 is applied to the circuit 6. Then the state of synchronism is detected by the circuit 6 between the local reference signal and the diffusing signal which is supplied to the circuit under the control of a program which is previously incorporated. The pattern phase of the output of a pattern generating circuit 8 is controlled by the output of the circuit 6. Then the output of the circuit 8 is applied to the circuit 7, and the synchronism is secured quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiving device, and particularly to a receiving device in a frequency hopping communication system using a spread spectrum signal based on frequency hopping modulation.

Spect 2 transmits and receives information using radio waves, spreads it over multiple bands, which is much wider than the frequency bandwidth required to transmit the information, converts the signal by fc times, and transmits and receives it. Broadband communication systems have recently become well known.

Frequency hopping modulation is one of the modulation methods used in the spectrum-spreading method, in which the carrier frequency to be transmitted is adjusted to a certain frequency according to the pattern of the code sequence specified in advance depending on the purpose of communication. It shifts, or hops, from one element of a set to another element of another set, and the information to be sent is incorporated into the above-mentioned code sequence or hopping frequency.

In a receiving device that receives such a spectrum spread signal, it is necessary to demodulate this signal by dividing it into two levels.

The M1 stage is after the spread spectrum code of the signal which is spread by frequency hopping modulation, whereby the signal is spread by spectrum despreading to recover the spectrum and frequency band.

Second stage pi*Fi A signal containing information after the first stage.

This is the demodulation of the so-called baseband signal, which extracts additional information and corresponds to normal post-processing.

In the decoding required for these receptions, the input signal encoded by the received frequency hopping plexus is
It must be accurately synchronized with the reference signal of the receiving device in two respects: the position of the code sequence pattern and the rate of generation of this pattern.

The reference signal referred to here is a local reference wave required in the demodulation of stage II, which is performed to mix with the input signal, despread the spectrum spread signal by correlation, and restore the state before spreading. . The input received signal is multiplied with this local reference wave, that is, correlated to demodulate the spectrum spread code. The spread spectrum code is a pseudorandom noise code (
(hereinafter referred to as PN code), for example, the longest linear code (hereinafter referred to as M
M-sequence codes) and other codes including M-sequences are used, and usually, such codes modulated by information are used. In addition, when spreading a signal with a large information rate, that is, a signal with a wide baseband width, or when you want to increase the margin against interference, band spreading is used. It is necessary to use a high-speed code sequence such as megabits.

The carrier frequency corresponds to the code bag of the code sequence as,
That is, the set of frequencies is synchronized with the change of code state.
Hopping between.

Generally, in a communication system using a frequency hopping method, holopink frequencies to be hopping are several thousand or more frequencies f1. fl, fs...i
n, and these hopping frequencies are a combination of many types of transmittances specified by the communication purpose,
That is, it is transmitted in a hopping pattern corresponding to the spreading code. Further, the transmission duration of each hopping frequency forming this hopping pattern is called a chip, and each chip is usually set to be equal.

When demodulating such an input spread spectrum signal, correlation may be performed using a local reference wave consisting of a hopping frequency and a spread spectrum code synchronized with the signal and before being modulated by information. In this case, what causes the 1% interstitial hearing is the synchronization of the input spread spectrum signal and the local reference wave, that is, the synchronization of the input spread code and the code of the local reference wave. This synchronization usually deviates due to transmission conditions between receivers and receivers, shifts due to door frequency, etc. Therefore, it is necessary to match this synchronization j by some method to match the spread code of the input spread spectrum false code with the local code of the local reference wave, so that the correlation can be performed correctly.

Conventionally, this method of synchronizing the woodcutter has generally been carried out as follows.

That is, the local reference wave is mixed by a frequency mixing circuit, and the frequency hopping signal converted into an intermediate cylinder wave number by correlation is amplified by an intermediate frequency amplifier circuit, and then input to a baseband demodulation circuit to demodulate information. Output. In this case, the signal output from the detector of the baseband demodulation circuit is input to the synchronization detection circuit, and the phase of the local code of the local reference wave can be destroyed by periodically changing the speed of the driving clock signal by a certain minute amount. A synchronization search is performed so that both codes jump and slide, and then a synchronization judgment [! The synchronization state is determined by 2I Ayu, and when it is found that synchronization is established, the F'i four-period search operation is stopped. The time from the start of the synchronization search to stop + ht must be completed while the input signal and the local reference wave are at or near the maximum correlation point. From this condition, it is necessary to determine whether the input signal is a human signal or the threshold level of the receiving device. Near signal S to noise N ratio 87
When N is bad, KFi requires a lot of synchronization search time.

Once synchronization has been achieved, it is then necessary to maintain synchronization by keeping the speed of the local code of the local reference wave accurately aligned with the speed of the spreading code of the input signal. Stiff,
ti is usually performed by a synchronization tracking circuit called a delay lock circuit. This delay lock circuit also has m-type variations, but as a substitute, two series of frequency mixing circuits, intermediate frequency nI width circuits, envelope detection circuits, etc. are prepared in advance, and these two series and The code speed fFi of the local reference wave to be mixed is delayed by a certain specified number of 6 for one side, resulting in 9 signals.0 This specific delay 11 can be set freely, and is usually overcome by 1 or 2 bits. , change the polarity of one of the two output information of the envelope detection rotation obtained by kneading to make it the opposite phase, and pass the sum of these two outputs as the control signal of the drive phase clock oscillator of the station S reference wave. By using the local reference wave to track the sign of the input signal,
The midpoint between the maximum point and the branch point of the composite correlation l4i1 number by the receiving circuit of 1 is captured, and the human signal is tracked by offsetting it by half of slow #, t.

In this way, synchronization is generally maintained by performing synchronization search and synchronization tracking using very complicated methods, and then outputting to the baseband demodulation circuit. However, such conventional methods of synchronization search and tracking require a search mode for synchronization, and it is not always possible to acquire synchronization within the period of the hopping pattern. Therefore, it takes a long time to synchronize, requires a complicated circuit configuration, and when the S/N of the input signal is in a hurry, the time required is several times the pattern period. Considering the number of hopping patterns, the required time is The disadvantage is that time is larger than others.

The main feature of the present invention is that, in a receiver for a spectrum spread signal based on frequency hopping, a further stage is employed in which the phase of output generation of a local reference wave is controlled by demodulating a spread spectrum code and determining the presence or absence of a detection output. By providing f, synchronization search mode is not required, and synchronization can be performed quickly within the turn period within the Houpi period (and in particular, interference by Cvv waves can be automatically avoided, and chips in chip units can be easily synchronized. It is an object of the present invention to provide a receiving device having a simple configuration, which is difficult to malfunction and is not prone to malfunction.

44 of the present invention, a frequency hopping communication system in which the frequency is changed (hopped) according to a predetermined time series (hopping pattern) to convey a message of misfortune. A frequency synthesizer that outputs a local reference wave that demodulates (despreads) the spread spectrum signal by mixing with
#! Output from the spectrum spectrum 2m spread signal frequency synthesis (b) path. Aya wave number mixing Itl that mixes with the 3s reference wave
ll omitted, and the intermediate fkj output from the drum number connection path.
An intermediate frequency amplification circuit 41M that amplifies the wave number false signal and an envelope detection circuit that detects the output of the intermediate frequency amplification circuit 41M.
2IIIii11, an integrating circuit that integrates and smoothes the output of the envelope@detection circuit, and outputs the resultant output, and II Ji! dvt
Controls the frequency and output turn of the local reference wave output from the number synthesis circuit a control circuit which detects the synchronization state of the human force spread spectrum signal and the local reference wave by means of these two outputs under the control and control of the block diagram, and controls the phase of the output of the pattern generation circuit; The present invention will be described in detail with reference to a 0th order 1 plane configured with .

FIG. 1 is a block diagram showing one example of the present invention. In this embodiment, the input signal 101 manually input from the receiving antenna l is a spectrum spread signal subjected to frequency hopping modulation, and is a spread spectrum code using a PN code whose code is changed according to the information to be transmitted. And this sign! The anti-beast is based on the number of hopping waves sent in the hopping pattern of the pivot foot.

This is a spread spectrum code based on this PN code.It is a book that has been converted into a spread spectrum code that can be easily deciphered by anyone who knows the original code, and the information is digitized. The original code, that is, the PN code, is inverted each time the value changes in polarity from @1@ to 10@ or vice versa from 10 to 111.

The hopping frequency number is a sequence of hopping patterns corresponding to this converted code sequence, and is transmitted one after another for each frequency number, that is, for each chip. Therefore, if the receiving side knows the likely code sequence, it despreads the spectrum-2m spreading code by adding the original code, the PN code, to the composite code to which the information 111s has been added. By extracting the number of cycles and baseband demodulating it, it is possible to obtain two more pieces of information.

Such an input spread spectrum signal 101 input from antenna 1 Fis 'J! In order to demodulate the spread spectrum signal, which is one stage of demodulation, the signal is input to the frequency mixer 2 along with a local reference wave 701 output from the frequency synthesis circuit 7, which will be described later, and the correlation is calculated by multiplying the two to obtain the spectrum 2. 4NWA of the system spreading code is performed. In this embodiment, the spectrosim spreading code of the input signal 101 is a PN code that is shaped by information, so @IM
The local code of the local reference wave output from number synthesis circuit-7 is PN.
The frequency mixer 2 is a double-balanced mixer-type two-pigeon wave mixing circuit, which inputs the input signal 101 and the local reference wave 701, multiplies them, and spreads the spectrum by their cross-correlation. The code is despread by 1 and a despread signal is output.

However, in this embodiment, the despread signal output from the frequency mixer 2 undergoes heterotine correlation with an intermediate cylinder wave number lower than the frequency of the input signal. Therefore, the number of hopping frequencies that is always higher than the local reference wave 701Fi and the input signal 101 by this intermediate frequency fIy is PN.
It is assumed that the code string corresponds to the code string.

In this heterodyne correlation, the bandwidth of the spread spectrum signal is restored, and the hopping frequency of the input signal 101 containing information is always /ltK Toshishi. By preventing direct frequency leakage, etc., and controlling the frequency and bandwidth of this four-way circuit, it is highly resistant to interference, interference, etc. This is for the purpose of

Frequency synthesis 1 is about 7Fi, which generates a local reference wave 701 for correlating with the input signal 101 input to the frequency mixer 2 = This local reference wave 701 is the input signal 1
The original code before transformation of 01, that is, the PN code, has a local code, always has a frequency higher than the number of hopping cycles of the input signal 101 by f = ν, has the same speed as the input signal 101 And, it is necessary that the signal is always in -J period with this signal.O This pigeon wave number synthesis excitation 7 synthesizes a large number of @ wave numbers by mixing the number of cycles of the decimal in various combinations. This is a so-called direct synthesis type frequency synthesizer that outputs a synthesized frequency by switching at an island speed in response to a control signal 801 output from a pattern generation circuit 8, which will be described later.

The pattern generation circuit 8 separates the code generation circuit using a feedback type 7-foot register from the driving clock signal, and eliminates the PN code by the code generation circuit, and also generates the PN code by the code generation circuit. By controlling the speed, it is possible to arbitrarily convert the code to 1jA degrees.

The feedback type shift register of the code generation circuit includes an n-stage shift register that can be arbitrarily determined according to the desire, and a plurality of r! Logic for returning logical combinations to the input board (
b) It is possible to set an arbitrary code of a sequence with a maximum length of 21-1 bits.

As a result, each PN code is output in accordance with the transmission code.

Therefore, it can be used as a single sequence code to utilize the maximum number of bits, and the 0 pattern generation time #P18Fi, which is a combination of M sequence codes and is used as the first code With such positive acid, the same PN code g as the transmitting side PN code is output, and
Further, in correspondence with the PN code, it is outputted to the subwave number unit ab approximately 7 as a fine wave number setting code 'lr control signal 801 corresponding to Kariden's Hola Pig pattern. The frequency synthesis circuit 7 that receives this output has the same PN code as the transmitting side, and also has the same PN code as f! A local reference wave 701 with a frequency higher than ν is output and input to the frequency mixer 2 manually.

The pattern phase of the hopping pattern generation is controlled by the control signal 601 under the control of a preset program of the control 1 Ayu 6 that controls the synchronized operation of the entire receiving device. and control the pattern generation speed, and set the sequence of hopping patterns that should be generated.

The output of frequency synthesis 1 and 2 is a group of pulses with a chest wave number of tS1] which is output in a time series corresponding to the information included in the input signal 101, and after being amplified by the IP amplification circuit 3,
It is output one after another at chip intervals corresponding to the hopping wave number. This intermediate frequency is output as a spectrum spreading code: Ql harmonic output 302 by a control signal 602 in the control book of the control program of 'm1pl@s when the reception signal is synchronized with the input signal. Then, for information demodulation, baseband modulation (b) is output to output information by baseband demodulation. However, normally, the spreading code of the input signal 101 and the local code of the local reference wave 701 are
If the synchronization is out of sync, we will detect the synchronization status and
Synchronization must be adjusted accordingly.

In this embodiment, the output of the IFtllii device 3 is sent to the envelope detector I2J approximately 4, the envelope detection of the intermediate frequency of the IF amplifier 3 is performed, and the output after detection is sent to the integrating circuit 5 and the control circuit 6. do.

The hopping frequencies of the output system signal 101 of the envelope detection (b) path 4 are output one after another in chip units according to the sequence of the hopping pattern.

Integral path 5 consists of a simple integrator consisting of a capacitor and a resistor; 7. By assembling the L butt trigger, the detection output colored thin line for each chip input from the envelope sensor 1 and 4 is integrated, smoothed, and added to the /unit trigger using an emitter circuit. The rise time of the integrator depends on the time constant determined by the capacitors and resistors used, which is also related to the time of PJ Xlj m output and therefore also to the operating threshold voltage of the trigger, and is determined by the pre-specified optimum The Schmitt trigger is a level detector for the input signal, and if the output of the 1,000 meter envelope detection exceeds the set trigger level, -
An output corresponding to the detection of the period is generated. The signal input from the envelope detection output 4 corresponds to the hopping wave number sent out in chip units of the hopping pattern, and the integrator successively integrates the detection outputs sent in chip units. Therefore, the output of the integrator increases its level in accordance with the time constant, and when it reaches the trigger level of the trigger, the Schmitt trigger operates, and this output corresponds to the synchronized state, and the control circuit 1i1f! Sent on 18th.

The trigger force level of this trigger (that is, the human power level detection threshold 7 hold level) is also related to the time constant of the integrator in the previous stage, and is set according to the required first-period detection speed.Therefore, The level setting is not set so that all the pins 7' in the hopping pattern are input and activated, but the level is set to a threshold 7 hold level where a certain number of chip 7' inputs are activated and output, and the integrator Corresponding to the characteristics of The output of the hopping pattern must have a threshold of 7 hold level Km and generate an output. Therefore, the propagation situation between the transmitter and the receiver, for example, the multipath problem that differs depending on the number of waves,
In case of chip loss that occurs accidentally, an output is generated without directly responding.

On the other hand, the envelope N1 - the output 40 after detection output from the detector 4
] directly input to the control circuit 6. Therefore, this detection output 401 is directly inputted to the housing ahyu 6 in the case of chip-by-chip loss.

The control (1141 (b)) path 6 receives the output signal 401 directly input from the envelope detection circuit 4 and the signal output from the integrator (b) 5, and outputs these two signals under the control of 70 grams. The human power is compared and the judgment is V. These two human powers are input to the control circuit 6 in the following state.

That is, the output signal 401 input directly from the envelope detection 1 path 4 and the output signal 401 input directly from the autumn equinox h#e15
501 means whether all the signals are on, one of them is off, or both of them are off.

The hopping pattern has chips known in advance.

If the S/N ratio of the input signal is good, there is no interference, interference a, etc., and the signal is synchronized with the local fundamental III wave, both of the above two outputs will be output normally. However, when an unspecified number of techno receptions are accidentally lost due to accidental interference or a temporary drop in 87N, the output signal from the envelope-wave circuit 4 is turned off each time the 401Fi chip is missing. Due to the autumnal equinox effect, the output signal 401 output from the horizontal branch 4-way 5 remains on until chip missing #r reaches the pre-specified trigger operation threshold 7 hold, and this output 501F: The signal is input to the control circuit 6.

In addition, continuous states due to missing chips or out of synchronization, or @! When the signal is generated due to a mixed state or a conscious interference wave such as a 0W wave, the outputs 401 of envelope-transverse waves 1 and 4 are turned off, and the outputs 401 of equinoxes 1 and 5 are turned off. Even with the equinox effect caused by the horizontal separator, the Schmidt trigger's thread 7 hold level was not exceeded.
Therefore, the output 501 of the integrating circuit 5 is also turned off.

Therefore, when the output signal 401 of the envelope detection circuit 4 input to the control path 6 and the output signal 501 of the autumn equinox gIllb5 are both off, the spread code of the input signal 101 of the receiver and the local reference wave 701 It can be assumed that the synchronization with the local code of When off, it can be considered as an accidental, temporary loss of a small number of chips.

In response to such an input state, the control circuit #66 controls the I! When it is found that both of the two manual inputs are off using the i-logical circuit, that is, no output is obtained from the envelope detection circuit 4 or the integral 1 or 5, this state is set under the control of the built-in program. is determined to be out of synchronization, outputs a control signal 601 to control the clock signal generation (b) of pattern generation 1g path 8, cuts off the clock signal generation speed, and outputs the local code and therefore the local reference wave 401. It stops for a specific short period of time, and immediately after that, the hopping pattern is traced chip by chip again to ensure that one of the inputs is turned on, and the synchronization is performed while controlling the clock signal generation speed of the pattern generation circuit 8. Perform retention.

According to this method, it is possible to accurately detect not only when the synchronization is out of order, but also when a chip is missing or continues to occur due to continuous interference, interference, etc. It is also possible to identify it as missing. Also, there is interference even if it is continuous.

By suspending the Fi reception state for a certain period of time in response to interference, it becomes easy to quickly re-synchronize after that, and the reception state can be continued in the event of a temporary chip loss.

These operations can also basically be performed on a single chip basis.

Further, as described above, the present invention detects the output of the envelope detector at an intermediate frequency corresponding to the degree of the synchronization state, and compares this with the output integrated over a specific number of chips of the hopping pattern to determine the reception state. I decided to maintain the synchronized state while throwing it away! A modification of this example in which #Fe is used is also considered to be a yuzu glaze.

For example, in this embodiment, the input signal 101 is a PN code, but it may also be a different combination code by combining the λ1 sequence.

In addition, when the control circuit 6 generates an output corresponding to the on/off of the input signal, the 1m gate circuit also outputs when either of the two people is on, and even in this state, the reception is turned off. This can also be done conveniently by Flrfu.

Furthermore, in this embodiment, the stock distribution circuit 5 is configured with a single integrator and a Schmitt trigger, and the threshold level of the circuit 11 is raised in accordance with the S/N of the signal input to this circuit. It is also possible to easily implement a plurality of integrating circuits switched into three stages of , medium, and low, and any of these modified colors can be easily implemented without departing from the gist of the present invention.

As explained above, according to the present invention, in a receiving device for a spread spectrum signal using frequency hopping variation,
By providing a simple means of demodulating the spread spectrum code and determining the presence or absence of the detection output and controlling the phase of the output of the local reference wave, the FIJ period search mode is not required and the process can be performed quickly within the hopping pattern period. A receiving device 1 that is resistant to interference, interference, etc., has an extremely simple configuration, is capable of synchronizing, and can automatically avoid interference especially due to CVv waves, is difficult to malfunction due to missing chips, and has an extremely simple configuration.
This has the effect of achieving 1.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. l...Receiving antenna, 2...Frequency mixing circuit, 3...IP amplifier circuit, 4...
Envelope detection circuit, 5...Integrator circuit, 6...
...Control circuit, 7...Frequency synthesis circuit, 8...
... Noku turn occurs Naka 1 road. 〆−

Claims (1)

[Claims] In a frequency hopping communication receiving device that communicates information by changing (hopping) the frequency according to a predetermined time series (hopping pattern), this spread spectrum signal is demodulated (despread) by mixing it with the input spread spectrum signal. a frequency synthesis circuit that outputs a local reference wave that outputs a local reference wave and is capable of externally controlling the frequency of the local reference wave; and a frequency mixing circuit that mixes the spread spectrum signal and the local reference wave output from the frequency synthesis circuit. , an intermediate frequency amplification circuit for amplifying the intermediate frequency signal output from the frequency mixing path, an envelope detection circuit for detecting the output of the intermediate frequency amplification circuit, and integrating and smoothing the output of the envelope detection circuit. an integrating circuit for outputting, a pattern generating circuit for controlling the frequency and output pattern of the local reference wave output from the frequency synthesis circuit, and a built-in logger for receiving the output of the envelope detection circuit and the output of the integrating circuit. and a control circuit that detects the N-phase state of the input spread spectrum signal and the local reference wave under the control of the two channels and controls the pattern phase of the output of the pattern generation circuit. A receiving circuit that uses this as mold.