RU64392U1 - RANGE MEASURER - Google Patents

Abstract

The utility model relates to digital computing and can be used mainly in radar systems (radars) for measuring ranges to a target based on one processor, as well as in other areas of technology, including the use of electromagnetic radiation other than radio waves. The range meter contains series-connected analog-to-digital converter (ADC), the first and second storage devices (memory), as well as the first and second multipliers, the first and second adders, an inverter, an adder-drive, a digital signal processing processor (DSP). The ADC input is the input of the device. The second memory is made with the possibility of sequential access as FIFO. It is also connected to the first and second inputs of the first multiplier, and the output is connected to the first and second inputs of the second multiplier; the output of the first multiplier is connected to the first input of the first adder, to the second input of which the output of the accumulator-accumulator is connected; the output of the second multiplier through an inverter is connected to the first input of the second adder, the second input of which is connected to the output of the first adder, and the output is connected to the input of the adder-drive, the output of which is connected to the input of the DSP, the output of which is the output of the device. 1 n.a. f-ly, 4 ill.

Description

The utility model relates to digital computing and can be used mainly in radar systems (radars) for measuring ranges to a target based on one processor, as well as in other areas of technology, including the use of electromagnetic radiation other than radio waves.

In digital receivers of modern radars processing large digital arrays, the classical method for detecting signals carrying information about the range to the target is carried out on the basis of devices for correlation analysis and optimal filtering, in particular, using multichannel digital processing of small digital arrays (channel spacing ) [one]. The disadvantage of the classic device for radar range measurement is its multi-channel nature, which significantly complicates the hardware implementation based on the construction of specialized multiprocessor systems.

A digital range estimation device is known, comprising a first analog-to-digital converter (ADC), the output of which is connected to the input of the first memory device, a second ADC, the output of which is connected to the input of the second memory, a digital signal processing processor (DSP), a digital processor module signal processing for a rough range estimate (DSP module), a cyclic signal shaper containing the first adder, the third memory and the second adder connected in series, while the inputs of the first and second ADCs are combined and I are input to the device, the output of the first memory is connected to the first inputs of the first adder of the cyclic signal generator and the DSP module, and the output of the second memory is connected to the second inputs of the first adder of the cyclic signal generator and the DSP module, the output of the second adder of the cyclic signal generator is connected to the first input of the DSP, to the second input of which the first output of the DSP module is connected, the second output of which and the output of the DSP are, respectively, the first and second outputs of the device.

A time-limited, time-controlled receiver strobe signal containing the useful signal reflected from the target, noise and interference, is digitized as a sequence of digital codes and the sequences of digital samples are stored in the form of two coherent numerical samples of length L samples. If the probe signal is not modulated, then coherent numerical samples are added up and overlapping Δn samples are formed from the obtained sequence

a sequence of numbers of length equal to the number N of samples of the probe signal. For each of the obtained sequences, the Fourier spectral density function is determined and compared with a threshold value. By the value of the magnitude and coordinates of the threshold excess of the Fourier spectral density function, the sign of the presence of the signal reflected from the target in the strobe, the Doppler frequency offset and the position of the sequence of 2N samples containing the samples of the reflected signal — the interval of linear convolutions — are determined. A rough estimate of the range is determined from them with an accuracy corresponding to the overlap interval Δn. If the probe signal is modulated, then coherent numerical samples of 2N samples length are formed and summed. The resulting sequence is remembered, by elementwise addition of the first and second halves of this sequence, a cyclic signal is generated with a length of N samples, fast cyclic convolution calculations are performed using the fast Fourier or Hartley transform, the values and coordinates of the threshold excess of convolution values are determined to within the reference, by which radial range to the target with an accuracy corresponding to the digitization interval of the reflected signal [2].

The reason that impedes the achievement of the technical result indicated below when using the well-known digital range estimation device is its relatively low speed, due to the considerable complexity and computational costs associated with determining the linear convolution interval. This, in turn, requires the use of a large volume of complex and expensive DSPs.

The essence of the utility model is as follows. Its task is to simplify the range meter and expand its capabilities while significantly reducing the volume, complexity and cost of hardware implementation. The technical result obtained by the implementation of the utility model is expressed in increasing the speed of the range meter.

The specified technical result is achieved by the fact that in the known digital range estimation device containing an analog-to-digital converter (ADC), the input of which is the input of the device, the first storage device (memory), the input of which is connected to the output of the ADC, the first and second adders, a digital processor signal processing (DSP), the output of which is the output of the device, according to the utility model, the second memory, the first and second multipliers, an inverter, an adder-drive are introduced, while the input of the second memory is connected to the output of the first Y, first and second inputs of said first multiplier and an output - to the first and second inputs of the second multiplier; the output of the first multiplier is connected to the first input of the first adder, to the second

the input of which the output of the accumulator-drive is connected; the output of the second multiplier through the inverter is connected to the first input of the second adder, the second input of which is connected to the output of the first adder, and the output to the input of the adder-drive, the output of which is connected to the input of the DSP.

The second memory is made with the possibility of sequential access as FIFO.

The utility model is illustrated by drawings, in which: FIG. 1 is a structural diagram of a range meter; figure 2 - illustration of the formation of a sequence of samples of the current energy spectrum of the signal; figure 3 - current energy spectrum of the signal; figure 4 - block diagram of the algorithm of the DSP.

Range meter (figure 1) contains a series-connected ADC 1, first 2 and second 3 memory, the input of which is also connected to the first and second inputs of the first multiplier 4 ₁ , and the output to the first and second inputs of the second multiplier 4 ₂ . The output of the first multiplier 4 _{1 is} connected to the first input of the first adder 6 ₁ , to the second input of which the output of the accumulator-accumulator 7 is connected. The output of the second multiplier 4 _{2 is} connected through the inverter 5 to the first input of the second adder 6 ₂ , the second input of which is connected to the output of the first adder 6 ₁ , and the output is with the input of the accumulator-drive 7, the output of which is connected to the input of the DSP 8. The input of the device is the input of the ADC 1, which is connected to the corresponding output of the receiver, for example, radar (not shown in the diagram), the output is the output of DSP 8 The described device TVO performed on the known elements of digital technology. In particular, the second memory 3 can be made in the form of a register with sequentially connected memory cells and parallel transfer of their contents and direct access to the first and last memory cell with the possibility of sequential access of the type "first entered - first left" (FIFO) [3] . DSP 8 is made according to well-known rules on the logical elements of digital technology, its structure is clear from the flowchart of the operation algorithm shown in Fig.4.

Range meter works as follows. An analog signal x (t) is received at the ADC input 1 from the output of the radar receiver, the duration of which is limited by the time gate of the receiver - T. At the ADC 1 output, a sequence of samples x (i · Δt) is formed, with a length L = Т ÷ Δt, where "÷" - the operation of integer division, which is recorded in the first memory 2 in the form of a numerical array x _i (figure 2), fed to the input of the second memory 3, the first and second inputs of the first multiplier 4 ₁ . Next, the current energy spectrum (TES) of the signal is formed according to the recurrence formula proposed by the authors:

,

where E ₀ = 0, T ₁ ≤i≥T ₂ ;

In parallel, the first and second inputs of the second multiplier 4 ₂ receive a number from the N-th cell of the memory register of the second memory 3. The result of multiplication from the output of the first multiplier 4 _{1 is} fed to the input of the first adder 6 ₁ , its second input receives a numerical value from the output of the adder - accumulator 7. The result representing the sum of two numbers, from the output of the first summer 6 ₁ goes to the first input of the second summer 6, ₂ to the second input of which the numerical value output from the inverter 5, obtained by inverting the (number of sign change) p result, incoming from the output of the second multiplier April _2. From the output of the second adder 6 _{2, the} result of the summation is fed to the input of the adder - drive 7 and the numbers obtained in it are sequential readings of TPPs (Fig. 3), which, in the order of their calculation, are sequentially fed to the input of DSP 8. Here, according to the algorithm shown in Fig. 4, each sample from successively obtained TES values is compared with the maximum value from its previous samples and if the new sample exceeds the existing maximum, then it is stored as a new maximum value of TES together with the corresponding reference number. Otherwise, the previous maximum value of the TPP and its reference number are saved. The obtained maximum value of the reference energy spectrum MaxЕ is compared with the threshold value Ерr, which can be taken as any value of the energy spectrum E _i in the interval (М-N <i> М + N), where the received signal is absent, or a priori. If the threshold is exceeded, i.e. the fulfillment of the condition MaxE-Еrr≥So, where the value So = N / 2 corresponds to the minimum value of the TEC of the reflected signal, one judges the presence of a useful signal from the target in the sequence of samples. The range R to the target is determined by the formula:

,

where M is the reference number of the signal corresponding to the largest sample of the TPP;

Δt is the sampling interval of the analog-to-digital conversion;

t ₀ - the beginning of the temporary gate of the receiver;

C is the speed of propagation of radio waves in free space (speed of light).

As can be seen from the flowchart of FIG. 4, all the technical components included in it are digital and constitute the nomenclature of a typical DSP, for example, processors such as TMSXXX, ADSPXXX, etc. Therefore, in general, a ranging device can be made on the basis of a single processor.

Example. Let L = 4096 = 4N, N = 1024 = 2 ^r , r = 10. Estimation of the number of Ks arithmetic

operations necessary for the implementation of the claimed device can be written in the form:

Kc = (L-N) (2 + 2 + 1 + 1 + 1) = 18N,

those. to calculate one TESS reference, it is necessary to perform two operations of multiplication, two operations of addition, one operation of subtraction. To find the maximum TESS, you must perform one comparison operation and one assignment operation.

An estimate of the number Kn of arithmetic operations necessary for the implementation of the prototype can be written as:

Kn = (8 + 3) Kbpf≈550N,

where is the estimate of the FFT account [1, 2] Kbpf = (N / 2) r · 10.

In the prototype, to determine the position of linear convolutions or roughly determine the range, it is necessary to calculate eight FFT algorithms, and to accurately calculate the range, it is necessary to calculate three FFT algorithms corresponding to the calculation of the fast cyclic convolution algorithm.

The given performance estimates show that, according to this criterion, the claimed range meter is approximately 30 times more effective than its prototype. Obviously, an advantage in the technical implementation of the claimed solution.

Information sources:

1. Rabiner L., Gould B. Theory and application of digital signal processing. M., "WORLD", 1978.

2. RU 2264650, G06F 17/14, G01S 13/26, 2005.

3. Novozhilov O.P. Fundamentals of digital technology / study guide. - M .: IP Radio-Soft, 2004, pp. 322-327.

Claims (2)

1. The range meter containing an analog-to-digital converter (ADC), the input of which is the input of the device, the first storage device (memory), the input of which is connected to the output of the ADC, the first and second adders, a digital signal processing processor (DSP), the output of which is the device output, characterized in that the second memory, the first and second multipliers, an inverter, an accumulator-drive are introduced, while the input of the second memory is connected to the output of the first memory, the first and second inputs of the first multiplier, and the output to the first and second inputs of the WTO horn multiplier; the output of the first multiplier is connected to the first input of the first adder, to the second input of which the output of the accumulator-accumulator is connected; the output of the second multiplier through the inverter is connected to the first input of the second adder, the second input of which is connected to the output of the first adder, and the output to the input of the adder-drive, the output of which is connected to the input of the DSP. 2. The range meter according to claim 1, characterized in that the second memory is made with the possibility of sequential access of the FIFO type.