RU2527487C2 - Apparatus for ultra-broadband radio communication with high noise-immunity - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to radio engineering, particularly high-speed radio communication systems which employ short-wave (SW) pulsed ultra-broadband signals. The technical result is achieved by using an additional wavelet filter of an ultra-broadband signal and selecting SW ultra-broadband signals in the form of complex Morlet wavelet coefficients, a harmonic modulated by a Gaussian function from a received useful signal. The apparatus for ultra-broadband radio communication with high noise-immunity includes: a receive/transmit switch (3), an ultra-broadband filter (4), a switch (23), a band-pass filter (22), an antenna (5), a buffer device (1), a delay device (27), an ultra-broadband pulse generator (2), a clock pulse sequence generator (19), a broadband clock signal amplifier (20), ultra-broadband low-noise amplifier (6), an analogue-to-digital converter (25), a clock signal wavelet filter (26), a clock unit (18), an attenuator (7), an ultra-broadband signal wavelet filter (28), signal channel time slot device (9), a signal channel threshold device (10), a signal channel buffer device (11), a signal channel threshold voltage generator (12), a noise channel time slot device (13), a noise channel threshold device (14), a noise channel buffer device (15), a noise channel threshold voltage generator (16), a processing and control unit (17).

EFFECT: higher noise-immunity of receiving SW ultra-broadband pulses via an ultra-broadband channel in interference conditions at low signal-to-noise ratio values of at least 10-15 dB.

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Description

The invention relates to radio engineering, in particular to high-speed radio communication systems (devices) using ultrashort pulsed (SRS) ultra-wideband (UWB) signals (UWB), in which the working frequency band and the average frequency of the signal spectrum are comparable in magnitude. Communication systems (devices) using ultra-wideband signals are described in a number of articles and patents. Examples include the pioneering development of UWB devices for a pulsed communication system, protected by US patents: [US 4,641,317 Spread Spectrum Radio Transmission System. Larry W. Fullerton. 12/03/84; US 5,677,927 Ultra wide Band Communication System and Method. Larry W. Fullerton; Ivan A. Cowie. 10/14/1997; US 5,687,169 Full Duplex Ultra wide Band Communication System and Method. Larry W. Fullerton. 11.24.1997]. These pulsed radio systems use one or more pulse subcarriers to transmit information. A pulsed radio receiver uses a cross-correlator that convolves a similar input signal with a reference signal, consisting of one hundred fifty to two hundred pulses synchronized in time with a known transmitter code. The correlator output voltage is integrated to recover the signal from noise and interference. However, certain restrictions are imposed on the level of distortion of the shape of the received signal, since when the UWB signal propagates, its shape changes depending on the reception / transmission distance. Due to the wide frequency band and ultra-short pulse duration, the requirements for synchronization accuracy in these systems are unusually high. In these well-known UWB systems, synchronization and auto-tuning signals are interconnected with the main information signals at the same energy level, and since the spectral density of all signals is at the noise level, the system is significantly susceptible to malfunctions. Entering into synchronism of such communication systems with UWB signals requires an unacceptably long time, because it is necessary to carry out an exhaustive search by temporarily shifting the synchronizing pulses with a step equal to half the duration of the UWB signal over the entire period of the synchronization signal. One of the areas for improving UWB systems proposed in [US 2003/0067963 Al Mode Controller For Signal Acquisition And Tracking In Ultra Wide Band Communication System. Timothy R. Miller, Gerard P. Lynch, Deepak M. Joseph. 04/10/2003], is the construction of digital systems with the processing of the input signal by reading a certain number of samples of signal and noise, determining the probability characteristics of signal and noise power levels with subsequent processing aimed at increasing the signal-to-noise ratio at the input of the actuator, however, a big gain with such processing was not achieved and it actually amounted to 2-3 dB. In the patent [US 2004/0156445 Al Ultra wide Band Communication System, Method, And Device With Low Noise Pulse Formation. John W. McCorkle. 08/12/2004] it was proposed to generate the emitted UWB signal to reduce the power of spurious emissions by using a signal in the form of biphasic wavelets obtained from the original code sequence using two-stage differentiating mixers, which reduces the radiation in the frequency band of the side lobes of the radiation spectrum. The essence of this invention is the use of wavelets to form the emitted UWB signal by the transmitter and is not related to the technical solution for the use of wavelet filtering in the present inventive device. Also known are high-speed communication systems with UWB signals without a carrier using ultra-fast threshold detection: [US 3662316 Shot Base Band Pulse Receiver. Kenneth W. Robbins 05/09/1972; US 3,728,632. Transmission and Reception System for Generation and Receiving Base Band Duration Pulse Communication System. Gerald F. Ross; 04/17/73; I.J. Immmoreev, A. A. Sudakov, "Ultra-Wideband Interference Resistant System for Secure Radio Communication with High Data Rate", ICCSC02, St. Petersburg, Russian Federation, June 2002, pp. 230-233; I.Ya. Immoreev, A.A. Sudakov, “Ultra-wideband noise-immune covert communication system with high data transfer rate”, Collection of reports of the All-Russian Scientific Conference. Murom, July 1-3, 2003 - Murom: Ed. - Printing Center MI VlSU, 2003, pp. 435-440]. For such communication systems using threshold detection, the distortion of the shape of the pulse signal during propagation and reception is not as critical as for systems using cross-correlators. The threshold detection of UWB signals with all relative simplicity allows for a higher information transfer rate. For threshold detection, it is necessary to have a sufficiently large signal to noise ratio (SNR) at the input of the threshold device. If the UWB receives a pulse signal with sufficient power at the input of the receiving device, it manifests itself in the form of a voltage exceeding the detection threshold level. However, this signal will not reflect the true shape of the received signal until the frequency band of the receiver is so wide as to reproduce the rise of the pulse front. The system is operable with a large signal to noise ratio.

Closest to the claimed technical solution is the communication system: [Patent for invention No. 2354048 RU “A method and communication system with fast entry into synchronism with ultra-wideband signals”, Kyshtymov G. A., Bondarenko V. V., Kyshtymov A. G., BIMP No. 12, 2009], taken as a prototype of the invention.

The known device contains a common, transmitting and receiving parts, the common part comprising a series-connected antenna, a receive / transmit switch, an ultra-wideband filter (UWBF) connected to the antenna, the first and second band-pass filters (PF) and the PF switch, the outputs and inputs of which are connected respectively, with the inputs / outputs of the bandpass filters, the inputs / outputs of which are connected to the antenna; the transmitting part comprises a buffer device and an ultra-wideband (UWB) pulse generator, a synchronization and information sequence generator (CIP) serially connected, an amplifier whose output is connected to the first input of the PF switch, a signal delay device connected between the output of the buffer device and the input of the UWB pulse generator, the output of the UWB pulse generator is connected to the first input of the receive / transmit switch, the receiving part contains serially connected ultra-wideband low-noise amplifier (UWB LNA), attenuator, power divider, signal channel time window device, signal channel threshold device and signal channel buffer device, the output of which is connected to the first input of the processing and control unit, noise channel time window device, channel threshold device noise and the buffer device of the noise channel, the output of which is connected to the second input of the processing and control unit, while the second output of the power divider is connected to the first input of the device a window of the noise channel, the second input of which is connected to the second output of the synchronization unit, the first output of which is connected to the second input of the device of the temporary window of the signal channel, in addition, the first output of the processing and control unit is connected by a bus to the inputs of the threshold voltage generators of the signal channel and the noise channel, with the first input of the synchronization unit, with the second inputs of the attenuator and the receive / transmit switch, the output of which is connected to the input of the UWB LNA, and the second output of the processing and control unit is connected to input b damper device, the output of the UWB pulse generator is connected to the first input of the receive / transmit switch, the outputs of the threshold voltage generators of the signal channel and the noise channel are connected respectively to the second inputs of the threshold devices of the signal channel and the noise channel, the input / output of the processing and control unit is the input / output of information connected in series to a low noise amplifier (LNA), an analog-to-digital converter (ADC) and a wavelet filter, the output of which is connected to the first input of the synchronization unit, which is It is equipped with a time window synchronization unit and is made with a second input to set it to its initial state, with the second inputs, ADC, wavelet filter and PF switch, as well as the input of the SIP driver, connected by a bus to the first output of the processing and control unit, the LNA input is connected to the output PF switch, in addition, the output of the wavelet filter is connected to the input of the synchronization unit, the outputs of which are respectively the outputs of the video pulses corresponding to the code "1", code "0" and the sync code.

The disadvantage of the device of the prototype is the low noise immunity of receiving SC UWB pulses through an ultra-wideband channel under the influence of interference and loss of operability of the device with a comparable signal power and noise at the receiver input.

The technical result, to which the invention is directed, is to increase the noise immunity of receiving UWB IC pulses through an ultra-wideband channel under the influence of interference at low signal-to-noise ratios by at least 10-15 dB.

The specified technical result is achieved by the fact that in an ultra-wideband radio communication device with increased noise immunity, comprising a series-connected analog-to-digital converter, a synchronization signal wavelet filter, a synchronization unit, a noise channel time window device, a noise channel threshold device, a noise channel buffer device, and a processing unit and controls, serially connected buffer device, delay device, UWB pulse generator, receive / transmit switch, over Iro-band filter and antenna, serially connected signal channel time window device, threshold signal channel device and signal channel buffer device, the output of which is connected to the second input of the processing and control unit, synchronization pulse train driver, broadband synchronization signal amplifier, switch and band-pass filter the output of which is connected to the input of the antenna, as well as an attenuator, a threshold voltage generator of the channel with a signal whose output is connected to the second input of the threshold device of the signal channel, a threshold voltage generator of the noise channel, the output of which is connected to the second input of the threshold device of the noise channel, while the first output of the processing and control unit is connected to the input of the buffer device, and the second common output is connected to the second inputs of the receive / transmit switch, the analog-to-digital converter, the wavelet filter of the synchronizing signal, the synchronization unit and the inputs of the attenuator, the driver of the synchronizing signal pulse sequence, the driver of the threshold voltage of the signal channel and the driver of the threshold voltage of the noise channel, and the second output of the synchronization unit is connected to the second input of the device of the temporary window of the signal channel, an additional UWB signal filter is introduced, the input of which is connected to the output of the attenuator, the first output is connected to the input devices of the time window of the signal channel, and the second output is connected to the input of the device of the time window of the noise channel, the input of the ultra-wideband low-noise amplifier is connected to the switch output transmission / reception, and ultra-wideband low-noise amplifier output - to the first input of the analog-to-digital converter.

The essence of the invention lies in the fact that in the inventive device, the reception of synchronizing NW and UWB information IC pulse signals is carried out in a common, ultra-wideband channel, which simplifies the scheme. The introduction of an additional second wavelet filter UWB SK signals makes it possible to increase the noise immunity of the inventive device via an UWB channel by at least 10-15 dB at low signal-to-noise ratios by isolating the signal at the output of the wavelet filter in the form of wavelet transform coefficients. Ultimately, this leads to the achievement of the claimed technical result.

An ultra-wideband radio communication device with increased noise immunity (Figure) contains: a receive / transmit switch (3), an ultra-wideband filter (UWBF) (4), a switch (23), a band-pass filter (22), an antenna (5), a buffer device (1) , delay device (27), UWB pulse generator (2), synchronization pulse generator (19), broadband synchronization signal amplifier (20), ultra-wide low-noise amplifier (6), analog-to-digital converter (25), wavelet filter of the synchronization signal (26 ), synchronization unit (18), attenuator (7), UWB signal wavelet filter (28), signal channel time window device (9), signal channel threshold device (10), signal channel buffer device (11), threshold voltage conditioner signal channel (12), noise channel time window device (13), noise channel threshold device (14), noise channel buffer device (15), noise channel threshold voltage generator (16), processing and control unit (17).

The analytical representation of the time-frequency filtering of non-stationary signals carried out by the wavelet filter (28) can be interpreted as the scalar product of the analyzed signal s (t) and the basis function ψ (t).

$$W_{\mathrm{AT}P}(a,b)=\underset{-\infty }{\overset{\infty }{\int }}s(t){\psi }_{a,b}(t)dt,\text{(one)}$$

where w _{a, b} (t) is the mother wavelet, from which the whole family of basic decomposition functions is formed using contractions (extensions) and shifts:

$${\psi }_{a,b}(t)=a^{-\mathrm{one}/2}\psi \left(\frac{t-b}{a}\right)\text{, (2)}$$

where a is the wavelet scale (analogous to the central frequency of the extracted signal), b is the wavelet shift along the time axis t.

To implement the filters, a complex Morlet wavelet was chosen - a harmonic modulated by the Gaussian function:

$${\psi }_a(x)=\exp \frac{-x^2}{2}\cos \left(ax\right).\text{(3)}$$

A digital wavelet filter (28) can be implemented on programmable logic integrated circuits (FPGAs) of Vertex II Pro XC2VP70 by Xilinx (see, for example, Malla S. Wavelets in signal processing: Transl. From English - M .: Mir, 2005 - pp. 276 - 303).

Device ultra-wideband radio communications with increased noise immunity works as follows. At the beginning of the communication session, a calibration cycle for determining the noise level in the receive channel and a cycle for setting your own data and the data of the subscriber in the receiver and transmitter are carried out. The transmitter emits into the free space a complex signal consisting of a pulsed ultra-wideband signal for transmitting information and a wideband FSK SIP signal, the frequency band of which is located below the boundary of the UWB signal working band. A signal intended for transmission in the form of an encoded sequence of impulses of the service channel, as well as other audio and video information, is fed to the input “I / O” of the processing and control unit (17). The processing and control unit (17) sets the reception codes on the control bus in the synchronization unit (18) and transmission codes in the SIP driver of the high-frequency signal (19). After analyzing the interference situation, the threshold voltage codes of the signal channel and the noise channel are set similarly to the prototype, the code of the receive / transmit switch 3 and the switch code (23) are set to “transmission” mode. In the “transmission” mode, the output of the UWB pulse generator (2) is connected to the UWBF (4), the output of the broadband signal amplifier (20) is connected via a switch (23) to the bandpass filter (22), and the signal input of the ultra-wideband low-noise amplifier (6), through the switch (3) is connected to the UBPF filter (4). The transmission code corresponds to the subscriber's address, and the reception code corresponds to the own address of the transmitting device. After the calibration of threshold devices (10, 12) is completed, a search is performed to enter the synchronism of the subscriber receiver and transmitter. For this, the processing and control unit (17) provides a synchronizing sequence of UWB pulses through a buffer (1), a delay device (27) to the input of the UWB generator (2), which contains information about the subscriber’s code, the code of the requested transmitter and the code for the temporary location of each fragment SIP. Each component of the UWB synchronization sequence of pulses corresponds in a certain way to a separate fragment of the SIP of the service channel sequence. This allows, on the one hand, to determine the beginning and end of the CIP sequence using several accepted components of the UWB signal synchronization sequence, and, on the other hand, knowing the moments of changing the frequency of the FSK signal to synchronize the time window of the UWB signal receiver, thereby increasing its noise immunity. The amplified BB signal of the SIP driver of the high-frequency signal (19) from the output of the amplifier (20) through the circuit formed in the "transmission" mode, enters the antenna (5) and is broadcast. The time intervals between the SIP video pulses (that is, between the moments of the frequency change of the FSK clock signal) are multiples of the period of the UWB signal pulses, while they are synchronized at these moments. The generated clock signal through the buffer device (1) starts the UWB pulse generator (2) with a delay τ and, through the circuit formed in the “transmission” mode, excites the antenna (5), which emits the UWB signal into the air together with the BSC. The transmission of the clock signal is repeated one more time and then, in the requesting transceiver device, the processing and control unit (17) switches the receive / transmit switch (3) to the “receive” state, that is, the antenna (5) and UWBF (4) are connected to the ultra-wide low-noise input amplifier (24). In the process of receiving the transmitted signal by a similar subscriber device, the complex signal, which is composed of the BSS synchronization, UWB signal and noise, is converted into a discrete signal by an ultra-fast ADC (25), received by the antenna (5) and amplified by an ultra-wideband low-noise amplifier (6), fed to the input of the wavelet filter (26) and through the attenuator (7) to the input of the UWB wavelet filter (28). In the synchronization circuit at the output of the wavelet filter (26), a short voltage drop is allocated corresponding to the frequency change front of the FSK signal. The voltage drop synchronizes the output gates of the synchronization unit (18), and the time intervals between the output gates are a multiple of the time gaps to the allocated synchronizing fronts of the frequency change. The first output of the synchronization block (18) gates the time window of the signal channel at the corresponding moments of the arrival of the UWB pulse from the output of the wavelet filter (28). When a received and amplified UWB pulse is received in the time window of the signal channel, the threshold device (10) of the signal channel is triggered and passes the signal through the buffer device (11) of the signal channel to the input of the processing and control unit (17). The difference of the claimed device from the prototype is the use of one common LNA (6) and one common ultra-wideband ADC (25) to amplify and analog-to-digital conversion of the service NW and information IC UWB signal. Upon receipt of a signal from the output of the wavelet filter (28), two channels of the receiving device carry out parallel reception of the SC UWB signal. One channel is used to assess the signal level, the second - to assess the level of external noise. The basis of each channel is a sensitive threshold device (10) of the signal channel and a sensitive threshold device (14) of the noise channel. Reception in the signal and noise channels is carried out in the corresponding time intervals (time windows) provided by the devices (9) and (13) time windows of the signal and noise, respectively. Reception of a signal in the window, the duration of which is not much longer than the duration of the SC UWB pulse, allows you to further provide increased noise immunity. From the output of the wavelet filter (28), the signal processed by the devices (9) and (13) of the time windows of the signal and noise enters the threshold device (10) of the signal channel and the threshold device (14) of the noise channel. From the output of the threshold devices (10) and (14), through the corresponding buffer elements (11) and (15), the signals are fed to the inputs of the processing and control unit (17). The signal processor of the processing and control unit (17) analyzes the level of the received signal and received noise, enables or disables the operation of the synchronization circuit, and adjusts the threshold voltage supplied to the detector in accordance with a given detection criterion. In this communication system, the ideal observer criterion is used, in which the threshold voltage is set equal to half the maximum voltage of the received pulse of the informative signal. For automatic adjustment of the threshold voltage, the probability of error per bit of the received signal is estimated and, depending on the processing results, the sensitivity of the receiver is adjusted by adjusting the thresholds in the drivers (12), (16) of the threshold voltage of the signal channels and noise via the control bus. The dynamic range of the receiver is adjusted using the attenuator (7). According to the results of the analysis, the operation of the synchronization unit (18) is also controlled. As mentioned above, before starting work, the receiver is calibrated for external noise. The main tasks of calibration are the installation of reference voltages supplied to the threshold devices of the signal and noise channels. After analyzing the noise environment, threshold voltage codes are set for the threshold device (10) and (14). Calibration is carried out after turning on the receiver power and after signal loss in the operating mode.

Claims (1)

An ultra-wideband radio communication device with increased noise immunity, comprising a low-noise amplifier, an analog-to-digital converter, a wavelet filter of a synchronizing signal, which generates a short voltage drop at the output corresponding to the frequency change front of the FSK signal, synchronization unit, noise channel time window device, channel threshold device noise buffer device of the noise channel and the processing and control unit, series-connected buffer device, device latency, UWB pulse generator, receive / transmit switch, the second output of which is connected to the low-noise amplifier input, an ultra-wideband filter and an antenna, serially connected signal channel window device, signal channel threshold device and signal channel buffer device, the output of which is connected to the second input of the block processing and control, serially connected shaper of a synchronizing pulse sequence, amplifier of a broadband synchronizing signal, switch a detector and a band-pass filter, the output of which is connected to the input of the antenna, as well as an attenuator, a driver of the threshold voltage of the signal channel, the output of which is connected to the second input of the threshold device of the signal channel, a driver of the threshold voltage of the noise channel, the output of which is connected to the second input of the threshold device of the noise channel, wherein the first output of the processing and control unit is connected to the input of the buffer device, and the second common output is a control bus and connected to the second inputs of the switch, receiving / transmitting, analog-to-digital converter, synchronization signal wavelet filter, synchronization block, inputs of the synchronizing pulse sequence driver, signal channel threshold voltage generator, noise channel threshold voltage generator and attenuator control input, the signal input of which is combined with the wavelet filter input synchronization signal, and the second output of the synchronization unit is connected to the second input of the device of the time window of the signal channel, characterized in that the UWB signal wavelet filter is additionally introduced, the input of which is connected to the attenuator output, and the output is connected to the combined inputs of the signal channel time window device and the noise channel time window device.