RU2297175C2 - Physiological parameters monitoring system - Google Patents

Abstract

FIELD: medicine; measuring technique.

SUBSTANCE: system can be used at continuous viewing of several physiological parameters, for example, parameters characterizing cardiac and breathing activity of human operator including its dynamics through one communication channel, for example, at increased requirements claimed to measuring equipment, in particular, onboard of flying vehicle or under conditions of space flight. System has transmitting unit and receiving unit, which are connected with transmitting aerial and receiving aerial correspondingly. Transmitting unit has first and second detectors, first and second analog-to-digital converters, high frequency oscillator, phase manipulator, frequency manipulator and power amplifier. Receiving unit has radio receiver, demodulation unit and registration unit. Radio receiver has reference oscillator, second phase detector, control signal former, heterodyne, mixer and intermediate frequency amplifier. Demodulation unit has first, third and fourth phase detectors, phase doubler, first, second and third PLL units, first, second and third phase halver, frequency demodulator and adder. System provides increase in range of activity and increment in noise immunity due to usage of complex signals with combined phase and frequency manipulation at one carrier frequency.

EFFECT: improved characteristics of system.

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Description

The proposed system relates to medical information-measuring equipment and can be used for continuous monitoring through one communication channel simultaneously of several physiological parameters, for example, characterizing the activity of the cardiovascular and respiratory systems of the human operator, including in dynamics, for example, at elevated requirements for measuring equipment, in particular, on board an aircraft or in space flight conditions.

Known devices and systems for monitoring physiological parameters (ed. Certificate. USSR No. 1811380, 1814538; RF patents No. 2089094, 2128004, 1181258; Frolov MV Control of the functional state of a human operator. - M., Science, 1987, p. 40-42 and others).

Of the known devices and systems closest to the proposed system is the "Monitor system of physiological parameters" (RF patent No. 2089094, AB 5/02, 1993), which is selected as a prototype.

The specified system has improved operational characteristics, namely autonomy, independence from power sources, increased distance due to wireless communication with the receiving unit due to the introduction of additional elements connected in a certain way.

At the same time, the well-known system provides reliable reception of physiological signals only within a radius of a few tens of meters, which does not always meet modern requirements for such systems, including the ambulance system and the system of remote consultative centers.

An object of the invention is to increase the range and increase the noise immunity of the system by using complex signals with combined phase and frequency manipulation on a single carrier frequency.

The problem is solved in that in a monitor system of physiological parameters containing a transmitting unit, consisting of a first sensor and a high-frequency generator, with a transmitting antenna connected to the output of the transmitting unit and a receiving unit containing a receiving antenna, a radio receiver, the input of which is connected to the receiving antenna, a demodulation unit containing a first phase detector, and a registration unit, the outputs of which are connected to the outputs of the demodulation unit, the transmitting unit is made in the form of series-connected generators and a high frequency phase manipulator, the second input of which through the first analog-to-digital converter is connected to the output of the first sensor, a frequency manipulator, the second input of which through the second analog-to-digital converter is connected to the output of the second sensor, and a power amplifier, the output of which is connected to the transmitting antenna , the radio receiver is made in the form of a series-connected reference generator, a second phase detector, the second input of which is connected to the output of the third phase divider into two, shaper control the signal, the local oscillator, the mixer, the second input of which is connected to the receiving antenna, and the intermediate frequency amplifier, the demodulation unit is made in the form of series-connected to the output of the intermediate frequency amplifier of the phase doubler, the first PLL, the first phase divider into two and the frequency demodulator, the output of which connected to the first input of the registration unit, connected in series to the output of the phase doubler of the second PLL and the second phase divider into two, the output of which is connected to the second input of the frequency demo a regulator, the third input of which is connected to the output of the intermediate frequency amplifier, connected in series to the output of the phase doubler of the third PLL and the third phase divider, in series, connected to the output of the intermediate frequency amplifier of the first phase detector, the second input of which is connected to the output of the second phase divider , an adder, the second input of which is connected through the third phase detector to the outputs of the intermediate frequency amplifier and the third phase divider into two, and the fourth phase detector, w The second input of which is connected to the output of the third phase divider by two, and the output is connected to the second input of the registration unit.

The structural diagram of a monitor system of physiological parameters is presented in figure 1. Timing diagrams explaining the operation of this system are shown in figure 2.

The relative position of the symbol frequencies of complex QPSK-FSK signals is shown in Fig.3.

The system comprises a transmitting unit 2 and a receiving unit 8.

The transmitting unit 2 consists of a series-connected high-frequency generator 5, a phase manipulator 4, the second input of which through the first analog-to-digital converter 3 is connected to the output of the first sensor 1, the frequency manipulator 15, the second input of which is connected to the output through the second analog-to-digital converter 13 the second sensor 11, and the power amplifier 16, the output of which is connected to the transmitting antenna 6.

The receiving unit 8 consists of a radio receiver 9 connected in series to the receiving antenna 7, a demodulation unit 10, and a recording unit 14.

The radio 9 contains a reference oscillator 17 connected in series, a second phase detector 18, the second input of which is connected to the output of the third phase divider 29 into two, a control signal shaper 19, a local oscillator 20, a mixer 21, the second input of which is connected to a receiving antenna 7, and an amplifier 22 intermediate frequency.

The demodulation unit 10 contains a phase doubler 23 connected in series to the output of the intermediate frequency amplifier 22, a first PLL (phase locked loop) 24, a first two phase divider 27, and a frequency demodulator 30, the output of which is connected to the first input of the recording unit 14, connected in series to the output of the phase doubler 23, the second PLL unit 25 and the second phase divider 28 into two, the output of which is connected to the second input of the frequency demodulator 30, the third input of which is connected to the output of the intermediate frequency amplifier 22, after The third PLL unit 26 and the third phase divider 29 are connected to the output of the phase doubler 23 and the third phase divider 29 is connected in series to the output of the intermediate frequency amplifier 22, the first phase detector 12, the second input of which is connected to the output of the second phase divider 28, the adder 32, the second input which through the third phase detector 31 is connected to the outputs of the intermediate frequency amplifier 22 and the second phase divider 29 into two, and a fourth phase detector 33, the second input of which is connected to the output of the second phase divider 29 into two with the second input of the registration unit 14.

The monitoring system of physiological parameters works as follows.

The sensor 1 of the transmitting unit 2 provides registration of the activity of the human cardiovascular system, and the sensor 11 provides registration of the activity of the human respiratory system.

The sensor 1 contains electrodes that are mounted on the observed person (athlete, transport driver, worker, astronaut, pilot, patient with various cardiovascular disorders and diseases, etc.).

The sensor 11 also contains electrodes, which are also mounted on the observed person.

Analog-to-digital converters 3 and 13 convert the measured parameters characterizing the activity of the cardiovascular and respiratory systems of the observed person into digital modulating codes M ₁ (t) (Fig. 2, a) and M ₂ (t) (Fig. 2, b ) respectively.

These modulating codes are sequentially fed to the second inputs of the phase 3 and frequency 11 manipulators, thereby forming a complex signal with combined phase (QPSK) and frequency (FSK) keying.

Uc (t) = Vc · Cos [(2πfn (t) · t + φk (t)], 0≤t≤Ts,

where Vc, Tc is the amplitude and duration of the signal;

fn (t) = {f ₁ , f ₂ } is the manipulated component of the frequency that displays the law of frequency manipulation in accordance with the modulating code M ₂ (t) (Fig. 2, b), while fn (t) = const for nτе < t <(n + 1) · τэ and can change abruptly Δf at t = nτэ, i.e. at the borders between elementary premises (n = 1, 2, ..., N ₁ );

φк (t) = {0, π} is the manipulated component of the phase that displays the law of phase manipulation in accordance with the modulating code M ₁ (t) (Fig. 2, a), while φк (t) = const at Кτэ <t < (K + 1) on the boundaries between elementary premises (K = 1, 2, ..., N ₂ ).

This signal, after amplification in the power amplifier 16, is radiated by means of the transmitting antenna 6, captured by the receiving antenna 7, and fed to the first input of the mixer 21, to the second input of which the voltage of the local oscillator 20

Ug (t) = Vg Cos (2πfgt + φg).

At the output of the mixer 21, voltages of combination frequencies are generated. The amplifier 22 is allocated the voltage of the intermediate (differential) frequency (figure 2, c).

Upr (t) = Vpr · Cos [2πfprn (t) · t + φк (t)], 0≤t≤Tc,

where fprn (t) = fn (t) -fg is the intermediate frequency,

Vpr = 1 / 2K ₁ · Vc · Vg;

To ₁ - gear ratio of the mixer.

In the spectrum of this signal with a continuous phase and an index of frequency manipulation

mf = (f ₂ -f ₁ ) τэ = 0.5

the symbol frequencies f ₁ and f _{2 are} suppressed. The indicated symbolic frequencies are determined as follows (figure 3):

f ₁ = fcp-1 / (4τэ) - signal frequency corresponding to the symbol + "1";

f ₂ ⁼ fcp + 1 / (4τэ) - signal frequency corresponding to the symbol - "1";

fcp = f ₀ = fpr = (f ₁ + f ₂ ) / 2 - average ("imaginary") signal frequency.

Since the symbol frequencies f ₁ and f _{2 are} suppressed in the spectrum of the received complex QPSK-FSK signal, the radio 9 monitors the average ("imaginary") frequency fcp.

After frequency conversion, the voltage Upr (Fig.2, c) from the output of the intermediate frequency amplifier 22 is supplied to the first input of the frequency demodulator 30 and to the inputs of the phase doubler 23, phase detectors 12 and 31.

When the phase is doubled, the received complex signal acquires the frequency manipulation index mf = 1 and its continuous spectrum is transformed into three discrete components 2f ₁ , 2f ₂ and 2f ₃ . Using the PLL 24, 25 and 26, the discrete components are filtered, and frequency dividers 27, 28 and 29 ensure that the frequencies of the synchronization signals and the received signal correspond. At the outputs of the frequency dividers 27, 28 and 29, harmonic oscillations are formed (figure 2, g, d, e):

U ₁ (t) = Vpr Cos2πf ₁ t,

U ₁ (t) = Vpr Cos2πf ₂ t,

U ₃ (t) = Vpr Cos2πf ₃ t, 0≤t≤Tc,

which are fed to the inputs of the frequency demodulator 30 and phase detectors 12, 31 and 33.

From the output of the frequency demodulator 30, the binary sequence M ₂ ′ (t) (FIG. 2, h) transmitted using frequency manipulation is fed to the first input of the registration unit 14.

At the outputs of the phase detectors 12 and 31, the following low-frequency voltages are generated, respectively:

U ₄ (t) = V ₄ · Cos [2π (f ₃ -f ₁ ) · t + φк (t)],

U ₅ (t) = V ₄ · Cos [2π (f ₂ -f ₃ ) · t-φк (t)], 0≤t≤Tc,

where V ₄ = 1 / 2K ₂ · Vpr ² ;

K ₂ - transfer coefficient of phase detectors;

which are summed in the adder 32

U _Σ (t) = V _Σ · Cos [2πf ₃ · t-2π (f ₂ -f ₁ ) / 2 · t + φк (t)] · Cos [2π (f ₂ -f ₁ ) / 2],

where V _Σ = 2V ₄ .

This voltage is supplied to the information input of the phase detector 33, to the reference input of which harmonic oscillation U ₃ (t) is supplied from the output of the phase divider 29 into two. The output of the phase detector 33 is formed of a low-frequency voltage [figure 2, g, M ₁ '(t)]

Un (t) = Vн Cos [2πf ₃ · t-2π (f ₂ + f ₁ ) / 2 · t + φк (t)] = Vн Cosφк (t), 0≤t≤Tc,

where Vн = 1 / 2К ₂ · V _Σ · V _ol ;

f ₃ - (f ₁ + f ₂ ) / 2 = 0,

proportional to the modulating code M ₁ (t) (figure 2, a).

This voltage is supplied to the second input of the registration unit 14.

To ensure the symmetry of the frequencies f ₁ and f ₂ relative to the frequency f _{0 of the} reference oscillator 17, a phase-locked loop system is used, consisting of a reference oscillator 17, a phase detector 18 and a control signal shaper 19.

Voltage reference generator 17

U ₀ (t) = V ₀ Cos2πf ₀

and the voltage U ₃ (t) from the output of the phase divider 29 into two is supplied to the inputs of the phase detector 18 and compared in phase. If these voltages differ in phase, then a voltage is generated at the output of the phase detector 18. Moreover, the amplitude and polarity of this voltage depend on the degree and direction of the deviation of the intermediate frequency fpr = f ₃ from the frequency f _{0 of the} reference oscillator 17. This voltage through the driver 19 of the control signal acts on the local oscillator 20, changing its frequency f _g so that the symmetry of the frequency of the reference generator relative to the symbolic frequencies f ₁ and f ₂ (f ₀ = fpr).

The registration unit 14 may be a personal computer with two analog-to-digital converters built-in or additionally included at its input, the inputs of which are the inputs of the registration unit 14, and a set of corresponding known algorithms, such as, for example, digital filtering, statistical processing, analysis of individual components signal (intervalometry), as well as various service functions (long-term recording, storage, sorting and comparison of information, display options, etc.). Such an implementation of the registration unit 14 allows for a better separation of complex physiological signals from the outputs of the demodulation unit 10 into components, to reduce the influence of interference, artifacts, etc. and expand operational amenities.

Thus, the proposed system in comparison with the prototype provides an increase in the range and increase the noise immunity of the system. This is achieved by using complex signals with combined phase and frequency shift keying on a single carrier frequency.

Complex signals with combined phase and frequency manipulation on a single carrier frequency open up new possibilities in the technique of transmitting physiological parameters characterizing the activity of the cardiovascular and respiratory systems of a human operator over long distances.

These signals allow the use of a new type of selection - structural selection. This means that there is a new opportunity to separate signals operating in the same frequency band and at the same time intervals.

Among other problems, the solution of which largely determines the further progress of radio communications, should include the problem of establishing reliable communication in channels in the presence of a multipath nature of the propagation of radio waves. The presence of multipath propagation of radio waves leads to a distortion of the received signals, which complicates the reception and reduces the reliability of the transfer of physiological parameters characterizing the activity of the cardiovascular and respiratory systems of the human operator.

Attempts to overcome the harmful effects of multipath have been made for a long time. These include diversity reception, signal selection by time and angle of arrival, corrective coding, and some other methods. However, all of them do not provide a fundamental solution to the problem.

Due to its good correlation properties, a complex QPSK-QPSK signal can be “folded” into a narrow pulse, the duration of which is inversely proportional to the used bandwidth. Choosing such a frequency band so that the duration of the “convoluted” pulse is shorter than the delay time, it is possible to separately receive pulses arriving at the receiving point in various ways, and by summing their energy, it is also possible to increase the noise immunity of receiving complex FMN-FMN signals. Thus, the indicated problem gets a fundamental solution.

From the point of view of detection, complex QPSK-FSK signals have high energy and structural secrecy.

The energy secrecy of these signals is due to their high compressibility in time and spectrum with optimal processing, which reduces the instantaneous radiated power. As a result, a complex signal at the receiving point may be masked by noise and interference. Moreover, the energy of a complex signal is by no means small, it is simply distributed over the time-frequency domain so that at each point in this region the signal power is less than the power of noise and interference.

The structural secrecy of complex QPSK-QPSK signals is due to a wide variety of their forms and significant ranges of parameter changes, which makes it difficult to optimize or at least quasi-optimal processing of complex QPSK-Qmn signals of an a priori unknown structure in order to increase the sensitivity of the receiver.

Claims (1)

A physiological parameter monitoring system comprising a transmitting unit consisting of a first sensor and a high-frequency generator, with a transmitting antenna connected to the output of the transmitting unit, and a receiving unit consisting of a receiving antenna, a radio receiver, the input of which is connected to the receiving antenna, a demodulation unit containing the first a phase detector, and a recording unit, the inputs of which are connected to the outputs of the demodulation unit, characterized in that the transmitting unit is made in the form of series-connected high-hour generator of a phase manipulator, the second input of which through the first analog-to-digital converter is connected to the output of the first sensor, a frequency manipulator, the second input of which through the second analog-to-digital converter is connected to the output of the second sensor, and the power amplifier, the output of which is connected to the transmitting antenna, a radio receiver made in the form of a series-connected reference generator, a second phase detector, the second input of which is connected to the output of the third phase divider into two, shaper control signal the oscillator, the local oscillator, the mixer, the second input of which is connected to the receiving antenna, and the intermediate frequency amplifier, the demodulation unit is made in the form of series-connected to the output of the intermediate frequency amplifier of the phase doubler, the first phase locked loop (PLL), the first phase divider into two and frequency a demodulator, the output of which is connected to the first input of the registration unit, connected in series to the output of the phase doubler of the second PLL and the second phase divider into two, the output of which is connected to the second input a frequency demodulator house, the third input of which is connected to the output of an intermediate frequency amplifier, connected in series to the output of the phase doubler of the third PLL and the third phase divider, connected in series to the output of the intermediate frequency amplifier of the first phase detector, the second input of which is connected to the output of the second phase divider into two, an adder, the second input of which through the third phase detector is connected to the output of the intermediate frequency amplifier and the fourth phase detector, the second input is cerned connected to the output of the third divider into two phases, and an output coupled to a second input of the recording unit, the second input of the third phase detector coupled to the output of the third divider into two phases.

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