Electronic ausculscope

• US 4,731,849 A
• Filed: 07/30/1986
• Issued: 03/15/1988
• Est. Priority Date: 07/30/1986
• Status: Expired due to Fees

• Current Assignee: Decitel Cardiol Acoustics South Carolina Corporation
• Original Assignee: Decitel Cardiol Acoustics South Carolina Corporation
• Inventors: Bloomfield, John W. III
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Schroeder, L. C.
• Application Number:
  US06/890,502
• Time in Patent Office: 594 Days
• Field of Search: 381/67, 128/715
• US Class Current: 381/67
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R

Abstract

A battery source of dc voltage continuously energizes digital circuitry for controlling operation of analog signal processing circuitry including a microphone preamplifier, an automatic gain control amplifier, a bandpass section and an output buffer driving audio reproducing equipment. The analog signal processing circuitry is energized on select command from the battery source through a switched on power supply. Automatic operation of the gain control amplifier may be disabled and the bandpass section by-passed in response to other select commands.

Claims

1. In an electronic ausculscope having a pick-up transducer, a preamplifier to the transducer, automatic gain control means connected to the preamplifier for variable amplification of audio signals transmitted from the transducer, speaker means for reproducing the audio signals amplified by the automatic gain control means, output buffer means operatively by connected to the automatic gain control means for driving the speaker means and bandpass means connected to the automatic gain control means for limiting transmission of the amplified audio signals to selected bandpass frequencies, the improvement comprising selectively controlled supply means for powering the preamplifier and the output buffer means in response to command signals and selectively controlled gate means connected to the output buffer means and the automatic gain control means for by-pass of the bandpass means.

2. The improvement as defined in claim 1 wherein said power supply means includes a power continuously powering the automatic gain control means and the gate means at a relatively high voltage, switching control means continuously powered by the source at said high voltage for generating said command signals, power splitting means connected to the source for powering the preamplifier at a relatively low voltage in response to said command signals and selective switch means connected to the switching control means for initiating said generation of the command signals and controlling operation of the gate means.

3. The improvement as defined in claim 2 including selectively operated means for disabling operation of the automatic gain control means as a variable gain amplifier.

4. The improvement as defined in claim 3 including grounding means connected to the power splitting means for maintaining a constant reference level for the high and low voltages supplied by the power source and the switching control means, said constant reference level being equal and opposite in polarity to the relatively low voltage.

5. The improvement as defined in claim 4 wherein the output buffer means includes an output amplifier powered in response to the command signals and ground establishing circuit means connected to the grounding means in series with the output amplifier and the speaker means in delayed response to the command signals.

6. The improvement as defined in claim 5 including indicator means powered simultaneously with the output amplifier of the buffer means and connected to the automatic gain control means and the gate means for indicating the operational thereof.

7. The improvement as defined in claim 6 including mode selector means connected to the gate means for by-passing the bandpass means either by each actuation of the selective switch means or alternate actuation of the selective switch means.

8. The improvement as defined by claim 7 wherein the selective switch means includes a power select switch and a bandpass select switch, said switching control means having separate circuit portions respectively connecting the power and bandpass select switches to the power splitting means and the gate means.

9. The improvement as defined by claim 8 wherein the disabling means is connected to that circuit portion of the switch control means to which the power splitting means is connected.

10. The improvement as defined in claim 9 wherein the automatic gain control means includes an operational amplifier interconnecting the preamplifier and the bandpass means and feedlock loop means connected to the operational amplifier for varying signal gain therethrough as an inverse function of input signal amplitude below a predetermined amplitude limit.

11. The improvement as defined in claim 1 including selectively operated means for disabling operation of the automatic gain control means as a variable gain amplifier.

12. The improvement as defined in claim 11 wherein the automatic gain control means includes an operational amplifier interconnecting the preamplifier and the bandpass means and feedback loop means connected to the operational amplifier for varying signal gain therethrough as an inverse function of input signal amplitude below a predetermined amplitude limit.

13. The improvement as defined in claim 2 including grounding means connected to the power splitting means for maintaining a constant reference level for the high and low voltages supplied by the power source and the switching control means, said constant reference level being equal and opposite in polarity to the relatively low voltage.

14. The improvement as defined in claim 13 wherein the output buffer means includes an output amplifier powered in response to the command signals and ground establishing circuit means connected to the grounding means in series with the output amplifier and the speaker means in delayed response to the command signals.

15. The improvement as defined in claim 14 including indicator means powered simultaneously with the output amplifier of the buffer means and connected to the automatic gain control means and the gate means for indicating the operational conditions thereof.

16. The improvment as defined in claim 2 including mode selector means connected to the gate means for by-passing the bandpass means either by each actuation of the selective switch means or alternate actuation of the selective switch means.

17. The improvement as defined in claim 2 wherein the selective switch means includes a power select switch and a bandpass select switch, said switching control means including separate circuit portions respectively connecting the power and bandpass select switches to the power splitting means and the gate means.

18. The improvement as defined in claim 17 including selectively operated means for disabling operation of the automatic gain control means as a variable gain amplifier.

19. The improvement as defined in claim 18 wherein the selectively operated disabling means is connected to that circuit portion of the switching control means to which the power splitting means is connected.

20. In an electronic ausculscope having a pick-up transducer, an output speaker and bandpass means operatively interconnecting the transducer and the speaker for transmission of audio signals to the speaker, the improvement comprising selectively controlled power supply means for powering the ausculscope in response to command signals and gate means connected to the bandpass means for selective by-pass thereof during processing of the audio signals transmitted between the transducer and the speaker, said bandpass means including a plurality of filters having different predetermined bandpass frequencies and a common predetermined Q factor.

21. In an electronic ausculscope having a pick-up transducer, an output and bandpass amplifier means operatively interconnecting the transducer and the speaker for limiting transmission of audio signals to selected bandpass frequencies, the improvement comprising selectively controlled power supply means for powering the ausculscope in response to command signals and gate means connected to bandpass amplifier means for selective by-pass thereof during processing of the audio signals transmitted between the transducer and the speaker, said power supply means including a power source continuously powering the gate means, switching control means continuously powered by the source for generating said command signals and signal conducting means connecting the switching control means to the gate means for by-passing the bandpass amplifier means in response to said command signals.

22. In an electronic ausculscope having a pick-up transducer, an output speaker and amplifier means for transmitting audio signals from the transducer to the speaker, the improvement comprising a power source continuously powering the amplifier means at a predetermined operating voltage, switching control means continuously powered by the source for generating command signals, powered splitting means responsive to said command signals for estabishing a reference ground level, loop means operatively connected to said amplifier means in response to the establishment of said reference ground level for varying signal gain as an inverse function of input signal amplitude below a predetermined amplitude limit and selectively operated means for transmitting the command signals to the feedback loop means to enable operation thereof.

23. In a signal processing device having an input, an output, analog circuit means operatively interconnecting the input and output for processing signals transmitted therebetween and selectively controlled digital circuit means producing command signals for controlling operation of the analog circuit means, the improvement comprising power means connected to the digital circuit means for continuous energization thereof at an operating voltage and switch controlled supply means continuously energized by the power means for energization of the analog circuit means in response to the command signals, said analog circuit means including an audio amplifier and a bandpass circuit, said input comprising a microphone connected to the amplifier and said output comprising a speaker and an output buffer connecting the bandpass circuit to the speaker.

24. The improvement as defined in claim 23 including ground means connected to the digital circuit means and means operated by the switch controlled supply means for generating a reference voltage level applied to the ground means of a polarity opposite to said operating voltage.

25. The improvement as defined in claim 24 wherein the digital circuit means includes signal gate means for selectively connecting the audio amplifier to the output buffer in by-pass relation to the bandpass circuit, feedback loop means connected to the audio amplifier for varying signal gain therethrough as an inverse function of input signal amplitude below a predetermined amplitude limit, a pair of select signal switches, and means connected to said switches for generating said command signals.

26. The improvement as defined in claim 23 wherein the digital circuit means includes signal gate means for selectively connecting the audio amplifier to the output buffer in by-pass relation to the bandpass circuit, feedback loop means connected to the audio amplifier for varying signal gain therethrough as an inverse function of input signal amplitude below a predetermined amplitude limit, a pair of select signal switches, and means connected to said switches for generating said command signals.

27. In an electronic ausculscope having a microphone, output speaker means for audio reproduction of sounds picked up by the microphone and bandpass means operatively interconnected between the microphone and the speaker means for selectively processing the sounds picked up prior to said audio reproduction thereof, including a plurality of filters having different predetermined bandpass frequencies and a predetermined Q factor.