Complex tone modulation

• US 3,895,316 A
• Filed: 08/29/1973
• Issued: 07/15/1975
• Est. Priority Date: 08/29/1973
• Status: Expired due to Term

• Current Assignee: Harry Fein
• Original Assignee: Harry Fein
• Inventors: Fein, Harry
• Primary Examiner(s): Brody, Alfred L.
• Application Number:
  US05/392,430
• Time in Patent Office: 685 Days
• Field of Search: 332/44,17,20,22,23R,23A,41,39,2 325/144,138,152 179/1N,2A,1AA,1ST 128/2.5P,2.5Q,2.5S,2.1B
• US Class Current: 332/120
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R
• CPC Class Codes: H03C 5/00 Amplitude modulation and angle modulation produced simultaneously or at will by the same modulating signal H03C7/00 takes precedence

Abstract

The generation of signals which vary in both frequency and amplitude in accordance with the amplitude of an information bearing input signal is disclosed. The invention thus relates to a complex tone generator wherein a monitored parameter is transduced into an electrical input signal which is employed to both frequency modulate a carrier signal in the audible frequency range and to amplitude modulate the frequency modulated carrier; the manner of amplitude modulation resulting in suppression of the unmodulated carrier.

Claims

1. A method for the production of audible signals which vary in both tone and magnitude in accordance with the amplitude of a monitored parameter, the amplitude of the monitored parameter varying at a sub-audible frequency, said method comprising the steps of:

transducing a monitored parameter which varies in amplitude at a sub-audible frequency into an electrical information bearing signal;

frequency modulating a carrier signal in the audible frequency range in accordance with the amplitude of the information bearing signal;

directly amplitude modulating the frequency modulated carrier signal with the information bearing signal while simultaneously suppressing the carrier signal in the absence of an information bearing signal; and

transducing the amplitude modulated signal into an audible signal.

2. The method of claim 1 wherein the step of amplitude modulating comprises:

multiplying the frequency modulated carrier signal by the information bearing input signal.

3. The method of claim 1 further comprising:

proportioning the information bearing input signal whereby a portion thereof is employed for frequency modulating the carrier signal and a portion thereof is employed for amplitude modulating the frequency modulated carrier signal.

4. The method of claim 2 further comprising:

proportioning the information bearing input signal whereby a portion thereof is employed to frequency modulate the carrier signal and a portion thereof is multiplied with the frequency modulated carrier signal.