System for the acoustic announcement of a periodic movement by means of ultrasonic power

The invention concerns a system for the acoustic announcement of the movement a surface moved by surfaces in living organisms by sending ultrasonic power and receiving of the Uhraschallenergie reflected by and by deriving electrical signals representative for the surface movement from the reflected Uhraschallenergie. It is already a method well-known for indirect Blutdruckmessung, with which Öffnungsund Schließbewegung of a Arterienwand under external pressure application is measured thereby that the signals are seized, from the double shift between a Uhraschallsignal sent to the Arterienabschnitt which is at pressure and by the moved Arterienwand reflected signal resulted. Normally the doppler signals are measured automatically and evaluated. If however due to lower measuring blood pressure values the Arterienwand moves relatively slowly, then the doppler signals are in a frequency range, in which spurious signals obstruct the automatic measurement. Contrary to an automatic analysis system the human ear is able to differentiate a rhythmic clay/tone from coincidental Störslgnalen to. Accordingly it would be thus possible to seize the doppler signals with the hearing provided that they were supplied in an audible form. Regarding the blood pressure measuring method discussed above that would mean that the doppler signals, which would lie for very low blood pressure values below the audible frequency would have to be converted into signals with a well audible frequency. The invention is the basis the task to make equipment available for the UltraschaUdiagnostik with which signals, which have a frequency within the range or below the border of the audibility, can be converted into signals with one deudich audible frequency. According to invention this reached by means for the production of a clear rhythmic signal sequence within the audio frequency range from the measured signals, as the amplitude of an audio frequency with the measured signals is modulated. This can be for example realised by the use of a modulation unit, in the one certain audio frequency with the doppler signal is modulated and a suitable gain control, which makes it possible to seize and differentiate from the noise to the rhythmic signal sequence of the heart impulses from the output signals. In the following a remark example of the invention is more near descriptive on the basis the designs. It shows Fig.1 a block diagram of the arrangement of the individual parts of the equipment and Fig.2 according to invention a diagram of the characteristic tension processes in different points of the equipment according to invention. A signal with low frequency, for example coming from a Diskfiminatoransgang, becomes as input signal over the input terminal --11-- a gain control unit --12--- supplied, which essentially contains a potentiometer for adjustment of the squelch. The exit of the gain control unit --12-- is with a 10-cycle per second filter --13-- connected, which serves to eliminate slowly running NuUpunktschwankungen. To the exit of the filter --13-- is an automatic gain control unit --14-- attached, to the one feedback line --15-- of the exit --22-- flihrt. In addition the unit possesses --14--- an entrance --16--, for example a switch, in order to operate the automatic gain control, which is not normally in enterprise, manueil. The automatic gain control --14-- is followed of a bidirectional rectifier --17--, its exit with the entrance of a modulation stage --18-- is connected. In addition is with the Modulationsstu£e --18-- a Oszlllator --19-- coupled, the one continuous sine signal of 200Hz produces. The exit of the modulation stage is over an amplifier --21-- with the output terminal --22-- connected, to which for example headphones or a loudspeaker can be attached. The function mode of the managing described equipment is to be described now on the basis an ultrasonic blood pressure measuring system of the initially discussed kind. In this case comes to the input terminal --11-- signal put on of a frequency discriminator, with which a doppler signal was measured, which is representative for the modulation, which erf'ährt a sent carrier frequency by the movement of the Arterienwand. With the equipment according to invention signals with any frequency can be processed; its main advantage is however best evident, if one regards the frequency range below the audibility. At low blood pressure values (under 60 or 70mm) the doppler signals have a frequency within the range of 10 to 20 cycles per second, which can hear and not from Störsignahn differentiate the ear of a carrier frequency when using approximately two MIIz. The observer uses appropriately headphones or a loudspeaker, those to the output terminal --22-- are coupled. With the help of the gain control unit --12-- the noise is stopped to a scarcely audible distance. The observed Arterie of the patient is pinched off perfectly with external pressure (seal), so that no an arterial Wandbewegnng of indicating signals, but only coincidental spurious signals at the entrance of the equipment to arise. If the external pressure is reduced, first arise by the arterieUe wall movement produced signals at the systolic point of the patient. In Fig.2 these are, from the doppler frequency discriminator the input terminal --11-- supplied signals shown, whereby the signal --31-- a series of 20 cycle per second signals and the signal --32-- coincidental disturbances represents. With the help of the 10Hz-Filters --13-- all frequencies are eliminated below 10 cycles per second, in order to avoid a Nullpunktdd£t. The signals of the automatic gain control unit become subsequently, --14-- supplied, those with manual operation by means of entrance ---16-- the signal amplitude on a pre-determined height limits. After the double-way rectifying the signal shown in Fig.2b becomes --33-- the modulation stage --18-- supplied, in that it the 200Hz-Generatorfrequenz --34-- modulated. The amplitude continuous 200 of the cycle per second signal, which is shown in Fig.2c, is appropriately regulated before the measurement on a height, straight with which it is still audible when the absence input signals. At the output terminal --22-- received modulation product --35-- is shown in Fig.2d. In such a way received signals make it for the observer possible to recognize and easily from the noise to differentiate the rhythmic signal sequence of the arising heart impulses according to approximately three to four impulses. Since the acoustic signals mark the movement of the Arterienwand, Blutdmckwerte can be easily measured now, as the observer at the same time reads off the manometer connected with the seal. As soon as the observer seized the systolic impulses, it operates the switch manually --16--, around the automatic gain control --14-- in enterprise to set and in such a way one by the increasing intensity of the following signals produced over-regulation to avoid. It is natural that in place of the generator --19-- produced 200 cycle per second frequency each suitable frequency in the audio range to be used can. Another variant of the invention would arise for example as a result of the use of a Gegentaktmodulators in place of the bidirectional rectifier.