Surgery – Truss – Pad
Patent
1995-06-15
1997-05-27
Jastrzab, Jeffrey R.
Surgery
Truss
Pad
128903, 607 60, A61B 50402
Patent
active
056322798
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method of interference-tolerant heartbeat measurement, in which method the heartbeat signal of a person is measured from a suitable part of the body and transmitted as burst signals from a transmitting means to a receiver by means of talemetric data transmission, the transmitting interval of the burst signals being proportional to the measured heartbeat rate of the person.
Known telemetric transmitters of heartbeat measuring devices typically transmit a burst of about 5 kHz each time they have detected an ECG signal. The transmitting circuit consists of a simple resonance circuit, which is activated by means of transistor control. At certain intervals, for example at every fifth oscillation, a switch (transistor) in the transmitter closes and becomes conductive, whereupon the resultant current loads new energy into the magnetic field of the coil of the oscillating circuit. After a while when the switch opens, the current is switched off and the oscillating circuit is free for resonance vibration.
In heartbeat measurement, the transmitting unit transmits a signal each time the heart beats. The receiver counts the heartbeat rate on the basis of the time difference of successive transmitted signals. The method is in principle a method of time slot coding: the data to be transmitted is included in the transmission encoded in the time between the transmissions.
The known method described above is simple and reliable in circumstances free of interference. Individual disturbances may be filtered off by comparing the resultant heartbeat value to the previous results: if the new measurement result differs too much from the previous ones, it is probably caused by some external disturbance connected with the transmission/reception channel and may thus be eliminated from the measurement results.
However, if a wireless transmission of heartbeat data is performed in an environment with interference, the situation changes substantially. Thus a continuous irregular pulse sequence may arrive at the receiver, and it is difficult, often even impossible, to select the correct heartbeat signal from this sequence. Such a situation occurs easily when two or more users of heartbeat rate measurement devices are close to each other.
SUMMARY OF THE INVENTION
The purpose of this invention is to provide methods by means of which the aforementioned disadvantages are avoided and a simple coding of the heartbeat signal is achieved, so that the correct signals can be extracted from an incoming signal flow with interference in a reliable and exact manner without deteriorating the original accuracy of the timing of the signal.
In order to provide this, one embodiment of the method according to the invention is characterized in that the burst signal is amplitude-modulated with a frequency or a frequency sequence characteristic of the transmitter/receiver unit, on the basis of which the receiver recognizes bursts intended for it.
Another embodiment of the method according to the invention is characterized in that a phase-shift sequence characteristic of the transmitter/receiver unit is caused in the burst signal at desired intervals, the receiver recognizing bursts intended for it on the basis of this sequence.
A third embodiment of the method according to the invention is characterized in that the burst signal is amplitude-modulated with a number of different frequencies or frequency sequences, and that a number of different phase-shift sequences are caused in the burst signal at desired intervals, the receiver recognizing bursts intended for it on the basis of the combination formed by the amplitude modulation and the phase-shift sequences, the combination being individual to the transmitter/receiver unit.
Other preferred embodiments of the invention are characterized by what is disclosed in the appended claims.
The invention is thus based on one hand on the idea that the amplitude modulation caused by the control of the transmitting resonance circuit is clearly noticeable. When the
REFERENCES:
patent: 4625733 (1986-12-01), Saynajakangas
patent: 4944299 (1990-07-01), Silvian
patent: 4958645 (1990-09-01), Cadell et al.
patent: 5058581 (1991-10-01), Silvian
patent: 5127404 (1992-07-01), Wyborny
patent: 5414392 (1995-05-01), Schupak
patent: 5458123 (1995-10-01), Unger
Jastrzab Jeffrey R.
Polar Electro OY
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