Measuring the transmission quality of a phase difference modulated carrier

• US 3,924,188 A
• Filed: 05/06/1974
• Issued: 12/02/1975
• Est. Priority Date: 05/04/1973
• Status: Expired due to Term

• Current Assignee: Rudolf Hofbauer
• Original Assignee: Rudolf Hofbauer
• Inventors: Hofbauer, Rudolf
• Primary Examiner(s): Libman, George H.
• Application Number:
  US05/467,122
• Time in Patent Office: 575 Days
• Field of Search: 178/67,69A 325/67,65,363 179/175.3 324/77R,103
• US Class Current: 375/224
• CPC Class Codes: H04L 1/206 for modulated signals
• CPC Class Codes: H04L 27/22 Demodulator circuits; Receiver circuits

Abstract

A method for measuring the transmission quality of pulse controlled, phase difference modulated data signals is described. Phase scanning pulses are produced which occur in the centers of the consecutive modulation sections. The phase difference modulated carrier is subject to amplitude modulation by band limitation, and modulation sections of the phase difference modulated carrier are assigned to modulation sections of the amplitude signal. Scanning pulses occurring in the centers of the modulation sections of the amplitude signal are derived from the phase scanning pulses. By means of the aforementioned scanning pulses, instantaneous values of the amplitude signal are sampled and measured. The maximum and minimum instantaneous values which occur during an observation period are stored by corresponding measured values, and the difference between the two measured values is formed and serves as a measure for transmission quality.

Claims

1. In a data transmission system wherein message signals are transmitted using phase difference modulation in a pulsecontrolled manner and in consecutive modulation sections, said phase difference modulated carrier being subject to amplitude modulation by band limitation, wherein phase scanning pulses, occurring in the centers of consecutive modulation sections, are produced and wherein an amplitude demodulator produces an amplitude signal, modulation sections of said phase difference modulated carrier being assigned to modulation section of said amplitude signal, a method for measuring the quality of the transmitted signals, comprising:

deriving scanning pulses from said phase scanning pulses, occurring in the centers of the modulation sections of the amplitude signal, sampling and measuring instantaneous values of said amplitude signal using said scanning pulses, storing measured values corresponding to maximum and minimum instantaneous values of said amplitude signal occurring during an observation period and forming the difference between said maximum and minimum values, which difference serves as a measure of the transmission quality.

2. The method defined in claim 1 comprising the additional step of:

displaying said difference on a visual display device,

3. The method defined in claim 1 comprising the additional step of:

indicating said difference on a pointer-type indicating instrument.

4. The method defined in claim 1 comprising the further step of:

correcting the transmitted signal by means of said difference.

5. In a data transmission system having means for pulse controlled transmitting and receiving message signals by means of phase difference modulation of a carrier signal, said phase difference modulated carrier being subject to amplitude modulation by band limitation, means for producing phase scanning pulses, which occur in consecutive modulation sections and an amplitude demodulator for producing an amplitude signal, modulation sections of said phase difference modulated carrier being assigned to modulation sections of said amplitude signal, the improvement comprising:

delay means for producing scanning pulses from said phase scanning pulses, first and second scanning circuit means having, respectively, first and second inputs, said first inputs being connected to receive said amplitude signal and said second inputs being connected to receive said scanning pulses, said first and second scanning circuits being constructed to sample instantaneous values of said amplitude signal using said scanning pulses and to store the maximum and minimum instantaneous values occurring during an observation period and difference forming circuit means connected to receive said stored maximum and minimum instantaneous values and to form a signal corresponding to the difference between them.

6. The improved data transmission system defined in claim 5 wherein said difference forming circuit means comprises first and second resistances and a diode, a first terminal of said first resistance being connected to a first output of said difference forming circuit means, a first terminal of said second resistance being connected to a second output, said diode being connected between second terminals of said first and second resistances.