METHOD AND APPARATUS FOR MEASURING DELAY DISTORTION INCLUDING SIMULTANEOUSLY APPLIED MODULATED SIGNALS

• US 3,629,696 A
• Filed: 08/06/1968
• Issued: 12/21/1971
• Est. Priority Date: 08/06/1968
• Status: Expired due to Term

• Current Assignee: Bartelink Everhard H B
• Original Assignee: Bartelink Everhard H B
• Inventors: BARTELINK EVERHARD H B
• Application Number:
  US04/750,524
• Time in Patent Office: 1,232 Days
• US Class Current: 370/215
• CPC Class Codes: H04B 3/462 Testing group delay or phase shift, e.g. timing jitter

Abstract

A common modulating signal is applied to a plurality of carrier signals of differing frequency to provide signals with phase coincident modulation envelopes. These are simultaneously transmitted across transmission circuit being investigated, received at distant terminal, and individually demodulated. Phase separation between demodulated envelopes is ascertained as indication of delay distortion in transmission circuit.

Claims

1. A method for Measuring the delay distortion of a signal transmission circuit between spaced input and output points therein comprising the steps of modulating a plurality of different frequency carrier signals with the same modulating signal at the same frequency to produce modulated carrier signals having modulation envelopes of coincident phase, applying said modulated signals simultaneously to said input point for transmission over said circuit, receiving the modulated carrier signals at said output point, and determining any difference in phase between the modulation envelopes of said received signals.

2. A method according to claim 1, wherein the difference in phase is determined by the steps of separately demodulating each of the received signals, and then determining the phase difference between the demodulated signals.

3. A method according to claim 2, wherein at least three of said modulated different frequency carrier signals are applied to said input point, and the phase differences are determined directly between different pairs of the demodulated signals.

4. A method for measuring the delay distortion of a signal transmission circuit between spaced input and output points therein comprising the steps of modulating a plurality of different frequency carrier signals with the same modulating signal at the same frequency to produce modulated carrier signals having modulation envelopes of coincident phase, applying said modulated signals simultaneously to said input point for transmission over said circuit, receiving the modulated carrier signals at said output point, determining at the output point any difference in phase between the modulation envelopes of said received signals, and transmitting the information relative thereto back to said input point.

5. A method according to claim 4, wherein the information relative to said phase difference is subjected to the steps of being stored temporarily upon receipt at said output point and subsequently transmitted back to said input point upon termination of transmission from said input point.

6. Apparatus for measuring the delay distortion of a signal transmission circuit between spaced input and output points therein comprising means for supplying a plurality of carrier signals at different frequencies, a source of modulating signal, means for modulating each of said carrier signals with said modulating signal to produce modulated signals having modulation envelopes of the same frequency and coincident phase, means for applying said modulated signals simultaneously to said input point for transmission over said circuit, and means at said output point for determining any difference in phase between the modulation envelopes of said modulated signals as received thereat.

7. Apparatus according to claim 6, wherein said means at said output point comprises a plurality of demodulating channels, one for each of said modulated signals for the separate demodulating thereof, and means for determining the difference in phase between the demodulated signals obtained from said channels.

8. Apparatus according to claim 7, wherein each of said demodulation channels comprises:

filter means for selecting a different one of the modulated signals received at said output point, and a demodulator coupled to an output of said filter means for demodulating the corresponding selected modulated signal.

9. Apparatus according to claim 7, wherein each of said demodulation channels comprises:

filter means for selecting a different one of the modulated signals received at said output point, phase compensating means coupled to an output of said filter means for compensating for unequal phase shift in the different channels, and a demodulator coupled to an output of said phase compensating means for demodulating the corresponding selected modulated signal.

10. Apparatus according to claim 9, wherein there are more than two carrier signals and the means for determining the difference in phase between the demodulated signals comprises a Separate phase separation detector coupled to different pairs of said demodulators for receiving the demodulated outputs therefrom.

11. Apparatus according to claim 9, wherein the means for determining the difference in phase between the demodulated signals comprises a source of reference signal having the same frequency as said modulating signal, and a separate phase separation detector coupled to both said reference signal source and a different one of said demodulators for determining the phase difference between said reference signal and the demodulated output from the corresponding demodulator.

12. Apparatus according to claim 9, wherein the means for modulating comprise phase compensation means for compensating for unequal phase shift of the respective signals prior to application of the modulated signals to said input point for transmission.

13. Apparatus for measuring the delay distortion of a signal transmission circuit between spaced input and output points therein comprising means for supplying a plurality of carrier signals at different frequencies, a source of modulating signal, means for modulating each of said carrier signals with said modulating signal to produce modulated signals having modulation envelopes of the same frequency and coincident phase, means for applying said modulated signals simultaneously to said input point for transmission over said circuit, means at said output point for determining any difference in phase between the modulation envelopes of said modulated signals as received thereat, and means for transmitting the information relative to said phase difference back to said input point.

14. Apparatus according to claim 13, wherein there is further provided at the output point means for temporarily storing said information relative to said phase difference, and means for initiating said transmission back to said input point upon termination of transmission from said input point.

15. Apparatus according to claim 13, wherein the means for modulating comprise phase compensation means for compensating for unequal phase shift of the respective signals prior to application of the modulated signals to said input point for transmission.