JPS6131919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for modulating two types of analog signal information, particularly analog signal information corresponding to any two of brain waves, blood pressure waves, etc. detected from a living body. This paper relates to a modulation/demodulation method in a medical 2-channel telemeter that uses both modulation and pulse duty modulation.

Conventionally, medical telemeter devices can be roughly divided into those for research and those for patient monitoring. Among these, the ones for research use handle various biological analog signals at the same time, which inevitably leads to an increase in the size of the Ikioi device itself. Furthermore, although devices for patient monitoring do not handle various biological analog signals at the same time, their functions require that they can be used continuously for long periods of time, and that they are small and consume low power.

Looking at the devices for patient monitoring that have been used in the past, the reality is that most of them handle only one type of biological analog signal that is considered to be the most important among various biological analog signals. However, given the importance of patient monitoring and recent demands, it is desirable to handle multiple types of biological analog signals as much as possible, even while satisfying the above functions even for patient monitoring. That is clear. To achieve this, functions are multiplied, but even if the number of channels is simply increased, if the number of subcarriers is increased in accordance with the number of channels, as seen in conventional 2-channel devices, the circuit will need to be multiplied. This is undesirable because it increases complexity, increases power consumption, and increases the size of the device itself.

An object of the present invention is to continuously remotely monitor two types of biological analog signals over a long period of time under low power consumption without reducing transmission accuracy.

For this purpose, the present invention converts one type of biological analog signal into a frequency modulated wave using a voltage controlled oscillator, and then this frequency modulated wave is further subjected to pulse duty modulation by a comparator using another type of biological analog signal. It is characterized by the following. The main carrier is frequency-modulated or pulse-amplitude modulated using the modulated wave obtained in this manner, and then transmitted.The receiving side demodulates this and separates and outputs each biological analog signal.

Hereinafter, the present invention will be explained with reference to FIGS. 1 to 4.

First, an overview of the present invention will be explained with reference to block diagrams of embodiments shown in FIGS. 1 and 2. In these figures, the dotted line display portion is a portion related to a conventional 1-channel patient monitoring telemeter device, and the other portions are portions added according to the present invention.

According to these figures, analog detection signals from a living body are amplified to a modulation level by input amplifiers 3, 4 via corresponding input terminals 1, 2. Of these, the output A of the input amplifier 3 controls the voltage controlled oscillator 5 to change the oscillation frequency of its triangular wave output. That is, the output A becomes a frequency modulated wave (FM modulated wave). Its center frequency is chosen to be 2KHz, for example. The frequency modulated wave thus obtained is compared with the output of the input amplifier 4 by a comparator 6, and after being subjected to pulse duty modulation, the main carrier modulator 7 performs frequency modulation or amplitude modulation of the main carrier. The output of the main carrier modulator 7 is transmitted via a radio transmitter 8 to a transmitting antenna 9.
It is then emitted into the air as radio waves.

The radio waves emitted into the air in this way are received by the radio receiver 11 via the receiving antenna 10 shown in FIG.
demodulated into a pulse wave. In order to obtain a signal corresponding to output A from this pulse wave, that is, an analog detection signal applied to input terminal 1, the pulse wave is
It is passed through the FM demodulation circuit 13. The pulse wave is subjected to frequency discrimination, and a voltage proportional to the frequency deviation from the carrier center frequency is obtained from the output terminal 15 as an analog detection signal. On the other hand, the output of the main carrier demodulator 12 is passed through a low-pass filter 14. This allows subcarriers, e.g.
Noise components outside the 2KHz component transmission band are removed,
A voltage corresponding to the pulse duty is obtained from the output terminal 16 as an analog detection signal applied to the input terminal 2.

3a to 3c illustrate the principles of frequency modulation and pulse duty modulation. according to this,
The changes from Fig. 3a to Fig. 3b and from Fig. 3c to Fig. 3d are frequency modulation, and the changes from Fig. 3a to Fig. 3c and from Fig. 3b to Fig. 3d is pulse duty modulation. The period in Figure 3a is τ
Then, the marks in FIGS. 3a to 3d are τ/2, τ/4, τ/6, and τ/12, respectively. On the other hand, the third
Since there are two pulse trains in Figures b and d, the total pulse width of the mark is from Figure 3a to Figure 3b,
There is no change from FIG. 3c to FIG. 3d. In other words, frequency modulation does not affect pulse duty modulation, and even if the pulse duty is modulated from FIG. 3a to FIG. 3c and from FIG. 3b to FIG. 3d, there is no change in the frequency. Each of them can have information independently. The present invention utilizes this.

FIG. 4 is a simplified example of the input/output waveforms of the main parts in FIG. 1. according to this,
While the frequency of the frequency output C of the voltage controlled oscillator 5 changes in response to the magnitude of change in the analog detection signal applied to the input terminal 1, the output C changes to the output B corresponding to the other analog detection signal. Since the signal is pulse duty modulated, the output D of the comparator 6 becomes as shown in the figure. That is, the output D
A change in the frequency of the pulse train in the input terminal 1 causes a change in the analog detection signal applied to the input terminal 1, and a change in the duty factor of the pulses corresponding to each frequency causes a change in the analog detection signal applied to the input terminal 2. Since the output D corresponds to changes, two types of analog detection signals are included in the output D. Therefore, if only this output D is sent and demodulated and separated on the receiving side, each analog detection signal will be separated, thereby avoiding complication of the modulation-related circuit on the transmitting side. I can do it. This means that even though the number of analog detection signals handled has increased, the number of circuits has not increased significantly.
This also means that it is possible to reduce the power consumption and size of the device itself.

As explained above, according to the present invention, two analog detection signals are combined into a single signal using frequency modulation and pulse duty modulation, and while this combined signal is transmitted from the transmitting side, the receiving side This composite signal is demodulated and separated into two original analog detection signals.

Therefore, not only can a conventional 1-channel telemeter device be implemented as a 2-channel telemeter device by adding only a few circuit elements, but the device itself can also be made smaller and consume less power.

[Brief explanation of the drawing]

1 and 2 are block diagrams of the transmitting side and receiving side of the embodiment of the present invention, respectively. FIG. 3 is a diagram explaining the principle of the present invention. FIG. 4 is the input/output waveform of the main part in FIG. 1. It is a diagram. 3, 4...Input amplifier, 5...Voltage controlled oscillator, 6
…Comparator, 7…Main carrier modulator, 8
...Radio transmitter, 11...Radio receiver, 12...Main carrier demodulator, 13...FM demodulation circuit, 14...Low pass filter.

Claims (1)

[Claims] 1 converting one biological analog detection signal amplified to a modulation level into a frequency modulated wave, and pulse duty modulating the modulated wave by the other biological analog detection signal amplified to a modulation level;
The main carrier is frequency-modulated or amplitude-modulated using the modulated wave obtained by this modulation and then wirelessly transmitted from the transmitting side, while the received frequency-modulated wave or amplitude-modulated wave is demodulated on the receiving side. , characterized in that the frequency of the demodulated signal obtained by the demodulation is discriminated to obtain the one biological analog detection signal, and at the same time, the demodulated signal is passed through a bottom band filter to obtain the other biological analog detection signal. Modulation and demodulation method for medical 2ch telemeter.