RU2486672C1 - Method of monitoring broadband signal delay and apparatus for realising said method - Google Patents

Method of monitoring broadband signal delay and apparatus for realising said method Download PDF

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RU2486672C1
RU2486672C1 RU2012105895/07A RU2012105895A RU2486672C1 RU 2486672 C1 RU2486672 C1 RU 2486672C1 RU 2012105895/07 A RU2012105895/07 A RU 2012105895/07A RU 2012105895 A RU2012105895 A RU 2012105895A RU 2486672 C1 RU2486672 C1 RU 2486672C1
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signal
connected
inverted
sample
inputs
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RU2012105895/07A
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Игорь Зенонович Климов
Анатолий Михайлович Чувашов
Андрей Николаевич Копысов
Алексей Александрович Богданов
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Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Ижевский государственный технический университет имени М.Т. Калашникова"
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Abstract

FIELD: radio engineering, communication.
SUBSTANCE: method of monitoring broadband signal delay involves generating two signals and filtering the obtained signals, the amplitude of which is proportional to the value of the correlation function between the reference signal and the received signal; comparing the obtained signals and correcting the time position of the reference signal relative to the received signal, and inverting the received signal before filtering, and switching the inverted and non-inverted signals, wherein a signal sample is formed, representing a keying pseudorandom sequence of binary symbols; a copy of the signal sample with a different time shift is formed from the signal sample; further, signals without broadband keying are generated form the non-inverted and inverted components of the original received signal. If a binary symbol of the copy of the signal sample is equal to 1, an inverted component of the received signal is used; if the binary symbol of the copy of the signal sample is equal to 0, an non-inverted component of the signal is used.
EFFECT: reducing losses associated with signal multiplication and simple processing scheme.
2 cl, 1 dwg

Description

The invention relates to the field of radio engineering, in particular to methods and devices for tracking the delay of broadband signals based on phase manipulation of pseudorandom code sequences used in radio communication systems operating in multipath channels and can be used in electronic communication systems using processing phase-shifted signals.

The system for tracking the time delay of the signal is used in digital communication systems with broadband signals. To obtain a stable quality of synchronization, such systems are based on the use of digital methods, while the control process is discrete, the parameters of the functional transformations are of constant value and a level of tracking quality is ensured, which is close to the calculated indicators. The operation of such a system is based on adjusting the time position (time delay) of the reference signal relative to the received signal in order to ensure maximum signal power at the system output. It is assumed that the problem of quickly determining the time delay of the signal relative to the reference one has already been previously solved, which allows combining the demodulating and modulating sequence with accuracy that ensures that the tracking system discriminates in order to obtain a sufficient level of the useful component of the error signal. The tracking procedure is designed to eliminate residual uncertainty in the delay and maintain synchronism in conditions when factors that lead to synchronization disturbances, namely additive interference, instability of clock frequencies, etc.

Known tracking methods are as follows. At each step, the received signal is multiplied by three copies of the signal, shifted relative to each other in time. The signals from the outputs of the second and third multipliers obtained as a result of multiplication by copies are filtered and squared. Thus, the values of the cross-correlation functions of the retarded and leading copies of the input signal are formed. The received signals are summed. At the output of the adder, a difference signal is generated that characterizes the time synchronization error. The temporary position of the copies of the signal from the output of the reference generator is changed until the error signal becomes zero. The input signal with the removed broadband modulation, containing information, is removed from the first multiplier.

The closest technical solution to the claimed invention is a device and a method for its implementation, described in the article by A. Gonzales, V. Ruis, M.I. Lopez, S. Valdeolmillos [Simulation of a tracking device for a second-order delay in multipath conditions. A. Gonzalez, B. Ruiz, M.I. Lopez, C. Valdeolmillos. Simulation of a second order delay locked loop in multipath environment. IEEE 0-7803-1266-X / 93].

A disadvantage of the known methods are. significant losses associated with the multiplication of two broadband radio signals, which leads to energy losses of up to 10 dB (Noise-like signals in information transmission systems. Edited by VB Pestryakov, Moscow: Sovetskoe Radio, 1973, p. 263).

The device selected as the closest analogue contains three parallel processing branches, the first of which contains a multiplier, at the output of which an information signal appears, which is contained in the input broadband signal, and the second and third - series-connected multiplier, filter and quadrator in each processing branch in this case, the multiplier and filter in the second and third processing branches perform the function of correlators, at the output of which the values of the cross-correlation functions of the input signal are formed la and its retarded and leading copies, and also contains a pseudo-random sequence generator, an adder, a low-pass filter in the feedback ring and a controlled generator. When the received signal and the signal generated by the pseudo-random sequence generator are temporarily out of sync, the values of the correlation functions are not equal in the lead and lag channels. At the output of the adder there is a difference signal characterizing the error of the time synchronization. The temporary position of the reference oscillator is changed until the error signal becomes zero.

A disadvantage of the known device is its high technical complexity, since additional blocks are required to receive a broadband signal with unknown random parameters, for example, for a random initial phase of the signal in the correlation receiver, a second (quadrature) channel containing the same blocks and an envelope allocation scheme are required.

The task to which the proposed method is directed is to simplify the processing circuit of a broadband signal.

The technical result achieved by the implementation of the proposed method consists in a new approach to constructing a processing circuit using as a sample a directly manipulating sequence and removing broadband modulation using inversion of individual elements of the original signal.

This problem is achieved by the fact that in the method of tracking the delay of a broadband signal, which includes the formation of two responses to a sample of a broadband signal, comparing the received responses and adjusting the temporal position of the reference signal relative to the received signal, the signal inversion and switching operations are introduced before filtering.

The task for which the proposed device is intended is to reduce the losses introduced by the processing circuit.

The technical result achieved by the implementation of the proposed device is to reduce the number of circuit elements.

This task is achieved by the fact that in the tracking device for delaying a broadband signal containing a filter, a sample generator, a subtracting device and a control device, an inverting amplifier and demanipulation and processing units are additionally introduced at the beginning of the circuit. Each of the demanipulation and processing blocks contains a managed switch and a selective narrow-band filter, while the signal outputs of the managed switches are connected to the corresponding filter inputs, the switch inputs are the inputs of the demanipulation and processing block, and the filter outputs are the outputs of the demanipulation and processing blocks.

A method for tracking the delay of a broadband signal is as follows. The received signal, consisting of the sum of the phase-shifted signal and interference, is inverted in amplitude. Broadband modulation is removed from the received signal under the control of a signal sample as follows. A signal sample is generated, which is a manipulating sequence of binary characters 0 and 1. 3 copies of the signal with different time offsets are formed from the sample. Next, 3 signals are generated with the removed broadband manipulation of non-inverted and inverted elements of the original received signal as follows. If the binary symbol of the sample copy is 1, the inverted element of the received signal is used; if the binary symbol of the copy of the sample is 0, the non-inverted signal element is used. The duration of the binary symbols of the sample coincides with the duration of the element of the broadband signal. Signals from filters corresponding to retarded and leading copies are detected and subtracted. The difference proportional to the difference in power allocated by the selection filters is fed to the control unit position of the manipulating sequence on the time axis with respect to the received signal. The temporary position of the signal sample from the output of the generator is adjusted to equalize the signal powers at the outputs of the selection filters, depending on the sign of the difference. Due to the symmetry of the autocorrelation function of the broadband signal with respect to the zero shift, the equilibrium point corresponds to the supply to the input of the managed switch corresponding to the zero shift, a copy of the sequence matched by the delay with the manipulating sequence of the received broadband signal. Therefore, the additive mixture of the demodulated signal (narrowband) containing useful information and interference will be removed from the output of the corresponding filter. With zero delay mismatch, the information signal is extracted from the additive mixture without reducing its power.

Functional diagram of a tracking device operating by the proposed method is presented in figure 1.

The device contains:

1 - amplifier with direct and inverse outputs,

2 1 ... 2 3 - managed switches,

3 1 ... 3 3 - selective narrow-band filters,

4 1 , 4 2 - detectors,

5 - subtractive device,

6 - block control shift of the signal sample,

7 - manipulator sequence generator,

8 1 , 8 2 - elements of discrete delays.

The input of the amplifier 1 is the input circuit of the tracking device. The outputs of the amplifier are connected to the corresponding signal inputs of the managed switches 2 1 ... 2 3 . Each managed switch 2 1 ... 2 3 has two signal inputs, one signal output and one control input. Non-inverse inputs of managed switches 2 1 ... 2 3 are connected in parallel and connected to the non-inverting output of amplifier 1. Inverse inputs of managed switches 2 1 ... 2 3 are connected in parallel and connected to the inverting output of amplifier 1. The control inputs of switches 2 1 ... 2 2 are connected to the circuit outputs series-connected elements of discrete delays 8 1 and 8 2 . Moreover, the control inputs of the switches 2 1 and 2 3 are connected to the outputs of the corresponding delay elements 8 1 and 8 2 connected in series with each other, the control input of the last switch 2 3 is connected to the input of the delay element 8 2 and to the output of the manipulating sequence generator 7. The outputs of the managed switches 2 1 ... 2 3 are connected to the inputs of the selection filters 3 1 ... 3 3 . The outputs of the selection filters 3 1 and 3 3 are connected to the inputs of the detectors 4 1 and 4 2 . The outputs of the detectors are connected to the inputs of the device 5 subtraction. The output of the subtraction device 5 is connected to the input of the control unit 6 by shifting the signal sample. The output of the sample shift control unit 6 is connected to the input of the manipulating sequence generator 7. The output of the manipulator sequence generator 7 is connected to the input of the discrete delay element 8 2 and to the control input of the switch 2 3 .

The proposed device implements the described method as follows. The received signal, consisting of the sum of the useful signal and interference, is fed to an amplifier 1 with direct and inverse outputs, which from the original signal generates an inverted and non-inverted amplitude signal. From the output of the amplifier, the signals are fed to the inputs of the managed switches 2 1 ... 2 3 . Managed switches 2 1 ... 2 3 carry out the switching of one of the inputs to the output by the signals at the control inputs. The chain of discrete delays 8 1 and 8 2 forms 2 copies of the signal samples shifted relative to the original signal received from the generator 7 of the manipulating sequence. The signal from the output of element 8 2 is synchronized with the input signal, the signal received directly from the generator of the manipulating sequence, and the signal at the output of the delay element 8 1 are a lagging and leading copy of the received signal. The value of the tuning step is determined by the sampling frequency and for the total number of tuning steps N, the duration of the main lobe of the autocorrelation function of the broadband signal ΔТ, the value of the tuning step is determined as the ratio Δt = ΔT / N. The amount of shift between the leading copy and the copy with zero shift, as well as the amount of shift between the late copy and the copy with zero shift, is set to a multiple of the adjustment step. Copies of signal samples from the manipulating sequence generator and from the discrete delay circuit 8 1 and 8 2 are fed to the control inputs of the switches 2 1 ... 2 3 and control the switching of inputs. If the binary symbol of the copy of the sample is 1, the inverse input of the switch is connected to the output of the switch, if the binary symbol of the copy of the sample is equal to 0, the non-inverse input of the switch is connected to the output of the switch for a time corresponding to the duration of the element of the broadband signal. Thus, at the outputs of switches 2 1 ... 2 3 , 3 signals are formed with broadband manipulation removed. The received signals are filtered by selection filters 3 1 ... 3 3 , the passband of which corresponds to the band occupied by a simple narrow-band signal with removed phase shift keying. The detectors emit an envelope of signals from the outputs of the filters 3 1 and 3 3 . Thus, at the outputs of the detectors 4 1 and 4 2 , the values of the cross-correlation functions of the delayed and leading copies of the input signal are formed. The signals from the detectors 4 1 and 4 2 are fed to the subtraction device 5, in which the received signals are compared with each other. From the output of the subtraction device 5, the signal is supplied to the control unit 6 by shifting the signal sample. In the control unit 6, depending on the sign of the received signal difference, a decision is made on the direction of the shift of the temporary position of the de-manipulating pulse sequence, clocking the manipulating sequence generator 7. The temporary position of the signal sample from the output of the generator is adjusted to equalize the signal powers at the outputs of the selection filters 3 1 and 3 3 . This provides tracking of the delay of the broadband signal.

An example of an implementation of a detection device is a processing circuit on a Sharc ADSP 21364 signal processor. The signal processing units, including switching, filtering, detection, summation, are executed in the form of algorithms implemented in software.

The proposed method for tracking the delay of a broadband signal can simplify the processing circuit of broadband signals and reduce processing losses, which improves the quality of synchronization.

Claims (3)

1. A method for tracking the delay of a broadband signal, including generating two signals and filtering the received signals, the amplitude of which is proportional to the correlation function between the reference signal and the received signal, comparing the received signals and adjusting the temporal position of the reference signal relative to the received signal, characterized in that the received signal before filtering the inverted and non-inverted signals are inverted and switched, while the operation of removing broadband modulation is performed and, namely, a signal sample is formed, which is a manipulating pseudo-random sequence of binary symbols, copies of the signal sample are generated from the signal sample with a different time shift, then signals with the removed broadband manipulation are formed from non-inverted and inverted elements of the original received signal, and if the binary symbol copy of the signal sample is 1, then use the inverted element of the received signal, if the binary symbol of the copy of the signal sample is 0, then use a non-inverted signal element.
2. A device for tracking the delay of a broadband signal, containing a filter, a sample generator, a subtracting device and a control device, characterized in that an inverting amplifier and demanipulation and signal processing units are additionally introduced at the beginning of the circuit, the input of the amplifier is the input of the tracking device, the outputs of the amplifier are connected the corresponding signal inputs of the blocks of demanipulation and processing, non-inverse inputs of the blocks of demanipulation and processing are combined in parallel and connected to a non-inverting output amplifier, inverse inputs of the demanipulation and processing units are combined in parallel and connected to the amplifier's output output, the control inputs of the demanipulation and processing units are connected to the outputs of the circuit of discrete delay elements connected in series, the control inputs of the demanipulation and processing units are connected to the outputs of the corresponding delay elements connected in series between by itself, the control input of the last block of demanipulation and processing is connected to the input of the delay element and to the output of the gene the manipulator sequence, the outputs of the managed switches are connected to the inputs of the selection filters, the outputs of which are connected to the inputs of the subtraction device through the detectors, and the output of the subtraction device is connected to the input of the shift sample control unit of the signal, the output of the sample shift control unit is also connected to the input of the manipulation sequence generator, output which is connected to the input of the discrete delay element and to the control input of the demanipulation and processing unit.
3. The device according to claim 2, characterized in that each of the demanipulation and processing units contains a managed switch and a selective narrow-band filter, while the signal outputs of the managed switches are connected to the corresponding filter inputs, the inputs of the switch are inputs of the de-manipulation and processing unit, the outputs of the filters are outputs of blocks of demanipulation and processing.
RU2012105895/07A 2012-02-17 2012-02-17 Method of monitoring broadband signal delay and apparatus for realising said method RU2486672C1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2667483C2 (en) * 2016-11-28 2018-09-20 Акционерное общество "Концерн "Созвездие" Method of highly-precise monitoring wideband signal delay and apparatus for realising said method

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3947634A (en) * 1974-11-21 1976-03-30 Ncr Corporation System for synchronizing local pseudo-noise sequence to a received baseband signal
US5347536A (en) * 1993-03-17 1994-09-13 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Multipath noise reduction for spread spectrum signals
GB2313750A (en) * 1996-05-31 1997-12-03 Daewoo Electronics Co Ltd Digital delay locked loop
US5850420A (en) * 1995-10-06 1998-12-15 Sextant Avionique Wideband receiver for the measurement of distance by pseudo-random code signals
RU2128398C1 (en) * 1997-08-13 1999-03-27 Закрытое акционерное общество "Кодофон" Device for tracing signal delay
RU2157593C1 (en) * 1999-06-24 2000-10-10 Гармонов Александр Васильевич Method for tracing signal delay and device which implements said method

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3947634A (en) * 1974-11-21 1976-03-30 Ncr Corporation System for synchronizing local pseudo-noise sequence to a received baseband signal
US5347536A (en) * 1993-03-17 1994-09-13 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Multipath noise reduction for spread spectrum signals
US5850420A (en) * 1995-10-06 1998-12-15 Sextant Avionique Wideband receiver for the measurement of distance by pseudo-random code signals
GB2313750A (en) * 1996-05-31 1997-12-03 Daewoo Electronics Co Ltd Digital delay locked loop
RU2128398C1 (en) * 1997-08-13 1999-03-27 Закрытое акционерное общество "Кодофон" Device for tracing signal delay
RU2157593C1 (en) * 1999-06-24 2000-10-10 Гармонов Александр Васильевич Method for tracing signal delay and device which implements said method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2667483C2 (en) * 2016-11-28 2018-09-20 Акционерное общество "Концерн "Созвездие" Method of highly-precise monitoring wideband signal delay and apparatus for realising said method

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