ROY WALTER LEWALLEN
Pilots at 152 Ave, Beaverton, OR

5629703, May 13, 1997

Aug 9, 1995

8/512797

Roy W. Lewallen - Beaverton OR

Tektronix, Inc. - Wilsonville OR

H03M 112

341155

A spectrum analyzer (10, 70) employs a method of reducing the amplitude of harmonic and spurious signals (102, 104, 112) introduced into a frequency-domain output spectrum by, for example, nonlinearities in a mixer (12, 78) or an ADC (20, 92). The method employs acquiring and digitizing a normal time-domain data record of an input signal, transforming the time-domain data record to a normal frequency-domain record (30), and storing the normal record. Next, a local oscillator (14, 76) driving the mixer is frequency shifted, and an additional time-domain data record is acquired, digitized, transformed, and stored to produce a shifted frequency-domain data record (40). Then, the shifted data record is mathematically realigned (50) with the normal data record and the normal and realigned data records are combined to produce a frequency-domain data record (60) having reduced harmonic and spurious signal amplitudes. The method preferably employs multiple frequency shifts of the local oscillator and a corresponding number of acquisitions, digitizations, transformations, realignments, and averages.

5122734, Jun 16, 1992

Jul 19, 1990

7/555212

Roy W. Lewallen - Beaverton OR

Tektronix, Inc. - Beaverton OR

G01R 1320, H03K 1700

324121R

A method and apparatus prevents unwanted synchronization from obstructing a data acquisition instrument operator's view of N multiplexed signals synchronized to a high speed system clock being used to trigger an instrument through a prescaler with a fixed prescaling factor M, where N and M are related by a common factor. During a time while the instrument, for example, an oscilloscope, is ignoring trigger input information, a desynchronizing signal is applied to the prescaler, causing it to miss a random number of counts or causing it to count incorrectly. Thus, when the oscilloscope resumes triggering it is likely to be synchronized to a different combination of the multiplexed signals. This technique can be applied to individual data points or to records containing a number of data points. By accumulating a number of records obtained in this way and superimposing them on the display, or by simply displaying them very rapidly so that the averaging effects of the human eye cause them to appear to be superimposed, these composite records effectively include complete information about the full set of multiplexed signals.

4924110, May 8, 1990

Sep 8, 1988

7/241686

John B. Rettig - Portland OR
Jonathan Lueker - Portland OR
John E. Carlson - Portland OR
Stanley P. Kaveckis - Aurora OR
Roy W. Lewallen - Beaverton OR

Tektronix, Inc. - Beaverton OR

H03K 402, H03K 512, H03K 501, H03K 1756

307227

A step generator for producing steps having constant edge parameters while driving varying loads includes a pair of DC coupled low speed diode switches for slowly switching the output load current. A pair of capacitors provide an AC coupled high speed input for rapidly, but temporarily, switching the output load current until the sustaining action of the low speed diode switch has occurred. A pair of resistor divider circuits in each of the low speed diode switches maintains a relatively constant reverse bias voltage across the diodes coupled to the capacitors. The high speed switching threshold is maintained at a relatively constant level which produces an output voltage step with constant edge parameters and no overshoot.