MULTIPLE CARRIER PHASE MODULATED SIGNAL GENERATING APPARATUS

• US 3,806,811 A
• Filed: 01/20/1972
• Issued: 04/23/1974
• Est. Priority Date: 01/20/1972
• Status: Expired due to Term

• Current Assignee: Wallace T. Thompson
• Original Assignee: Wallace T. Thompson
• Inventors: Thompson, Wallace T.
• Primary Examiner(s): Mayer, Albert J.
• Application Number:
  US05/219,363
• Time in Patent Office: 824 Days
• Field of Search: 178/67,66 324/77B 325/45,47,141-148,126,133,134,163,363,153,310,320,58,67 328/16,17 331/76,78,17R,132,172,173 332/14,16,23
• US Class Current: 455/110
• CPC Class Codes: H04B 1/04 Circuits

Abstract

Signal generator for use in testing FM communication receivers including a triggered free-running multivibrator which may be synchronized to operate at a frequency equal to the spacing between adjacent channels of the FM receiver and an audio oscillator. The outputs of the multivibrator and the audio oscillator are coupled to a step recovery diode which produces a spectrum of a plurality of harmonics of the frequency of the multivibrator, each of which is phase modulated by the output of the audio oscillator.

Claims

1. Multiple carrier phase modulated signal generating apparatus including in combination first oscillator means operable to produce a signal of a basic frequency at an output connection;

second oscillator means operable to produce a signal of a modulation frequency at an output connection; and

spectrum generating-phase modulating means including a step recovery diode having an input electrode coupled to the output connection of the first oscillator means through a capacitance operable to block the modulation frequency and coupled to the output connection of the second oscillator means through a filtering means operable to pass the modulation frequency and block the basic frequency and having an output electrode, said spectrum generating-phase modulating means being operable to generate a plurality of harmonics of the basic frequency and to phase modulate each of the harmonics of the basic frequency by the modulation frequency;

whereby a plurality of output signals are produced at the output electrode of the step recovery diode, each output signal being a harmonic of the basic frequency phase modulated by the modulation frequency.

2. Multiple carrier phase modulated signal generating apparatus in accordance with claim 1 wherein said first oscillator means includes a triggered free-running multivibrator employing two cross-coupled inverter circuits;

and said second oscillator means includes a free-running multivibrator employing two cross-coupled inverter circuits.

3. Multiple carrier phase modulated signal generating apparatus in accordance with claim 2 including signal shaping means connected to the output connection of the spectrum generating-phase modulating means and operable to attenuate the plurality of output signals from the spectrum generating-phase modulating means by an amount inversely related to the frequency of the output signals whereby differences in the amplitudes of the output signals are reduced.

4. Multiple carrier phase modulated signal generating apparatus in accordance with claim 3 including an output terminal;

and diode switch means coupled between the output connection of the signal generating-phase modulating means and the output terminal and operable to permit output signals to be passed to the output terminal only when a forward biasing potential is applied to the diode switch means.