Vintage 1967-04

Michael Cowley Jack H Lepoff

Mike Cowley received his BS and MS degrees in electrical engineering from the University of Notre Dame in 1959 and 1961, respectively. In 1965 he received the Ph.D. degree in electrical engineering from Stanford University, where he was employed as a research assistant in quantum electronics. Before coming to hp associates in 1965, he taught electrical engineering for a year at the University of California at Santa Barbara, and worked as a consultant in physical electronics. Since joining hp...

As ocean research becomes more sophisticated greater precision in temperature measurement is needed

Benjamin Franklin was able to locate and chart the Gulf Stream by hauling buckets of water on deck and measuring its temperature. Today, many northbound ships locate themselves in the Gulf Stream by towing thermometers, then take advantage of the current. This is only one of many uses for ocean temperature data. Life in the sea, ocean currents, tidal changes, acoustic transmission, radiation absorption and heat loss are reflected by even minute ocean temperature variations. Oceanographic...

Balanced Mixer Analysis

In a balanced mixer in which the two diodes are operated at different bias voltages, some of the higher-power coefficients in the power series expansion of one diode's current function can be made to cancel the corresponding coefficients in the other diode's current function. Cancellation is the reason for the improved IM rejection of the balanced mixer of Fig. 3. Cancellation of intermodulation is an apparent contradiction of balanced-mixer theory, which predicts summation of this response2....

Quartz Thermometer

Prior to the introduction of the quartz sensor either resistance elements or thermistors were used. These may be biased with a constant current to produce a dc voltage to operate a voltage-controlled oscillator, or used in phase shift networks to influence the frequency of an RC oscillator. In either case the stability of the frequency conversion is influenced by other circuit elements in addition to the sensor itself. The quartz temperature sensor takes advantage of the characteristic of a...

Improved Intermodulation Rejection in Mixers

Intermodulation distortion, always a problem in mixer design, can be largely prevented by a careful choice of bias and power levels. Intermodulation has always been one of the most pernicious forms of spurious response in superheterodyne receivers. It is a pleasure to be able to report that this type of interference can now be vastly reduced by proper design of the mixing element of the receiver and by a proper choice of the dc operating points of the mixer diodes. By means of the recently...