Method for measuring RF pulse rise time, fall time and pulse width

• US 5,805,460 A
• Filed: 06/13/1997
• Issued: 09/08/1998
• Est. Priority Date: 10/21/1994
• Status: Expired due to Fees

• Current Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Original Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Inventors: Greene, Elliott J., Lo, Pei-Hwa
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): Stamber, Eric W.
• Application Number:
  US08/874,001
• Time in Patent Office: 452 Days
• Field of Search: 364/486, 364/487, 364/569, 324/617, 327/14, 327/31, 368/118
• US Class Current: 702/79
• CPC Class Codes: G01R 29/02 Measuring characteristics of individual pulses, e.g. deviation from pulse flatness, rise time or duration

Abstract

A method for measuring the rise/fall time and pulse width of RF pulses using multi-purpose, commercial-off-the-shelf test devices, such as an RF signal down converter, a digitizer and a signal processor. The method is based on digitizing the RF signals and developing an average sample pulse waveform. The rise/fall time and pulse width are then calculated from data points on the sample waveform. The method is suitable for real-time calculations of the rise/fall time and pulse width.

Claims

1. A method for measuring pulse characteristics of a pulsed RF signal comprising:

(a) down converting said pulsed RF signal to an intermediate pulse stream signal having an intermediate frequency;

(b) sampling said down converted signal over a selected number of cycles at a selected sampling frequency such that the intermediate frequency is greater than 50% of the sampling frequency, but less than the sampling frequency whereby the sampling collects a data set comprising one or two data points per cycle of the intermediate frequency wherein said data set represents a single pulse;

(c) collecting multiple data sets;

(d) collecting within each of said data sets, data points before, during and after each pulse;

(e) averaging said data sets to obtain a sample pulse envelope comprising baseline points, a rising edge, a pulse plateau and a falling edge; and

(f) calculating one or more of said pulse characteristics consisting of rise time, fall time and pulse width.

2. The method of claim 1 wherein step (f) comprises the steps:

(a) calculating the time associated with the data points representing 10 percent of the rising edge above said baseline point;

(b) calculating the time associated with the data points representing 90 percent of the rising edge above said baseline point; and

(c) calculating said rise time by subtracting the time associated with said rising edge 10 percent level from the time associated with said rising edge 90 percent level.

3. The method of claim 1 wherein step (f) comprises the steps:

(a) calculating the time associated with the data points representing 10 percent of the falling edge above said baseline point;

(b) calculating the time associated with the data points representing 90 percent of the falling edge above said baseline point; and

(c) calculating said fall time by subtracting the time associated with said falling edge 10 percent level from the time associated with said falling edge 90 percent level.

4. The method of claim 1 wherein step (f) comprises the steps:

(a) calculating the time associated with the data points representing 50 percent of both the rise edge and fall edge above said baseline point; and

(b) calculating said pulse width by subtracting the time associated with said rising edge 50 percent level from the time associated with said falling edge 50 percent level.