Engineering topics
Publications and source records attributed to Hubbard, W. P..
Vibration analyis is nondestructive and noninvasive. Transistor isolated from heat (or cold) of surroundings by filament suspension. Filaments made of polyester are (0.005 in) 0.127 mm in diameter. Transistor lead wires are wrapped around certain filaments. Applicable for testing filament mounts too delicate for testing by tension probes.
Component holder speeds examination of matched pairs. Transistors are oriented for two perpendicular x-ray views. Second view obtained by simply flipping block around corner near components, while corner remains in contact with film. Procedure allows inspection of up to 50 pairs - two views of each pair - on single x-ray film in same time previously required for 1 unmounted pair.
Digital circuitry automatically demodulates received radio-frequency ranging signals for phase comparison with transmitted signal. All digital circuitry makes system more stable than analog predecessor and makes automatic operation easier and simpler.
An apparatus for demodulation and correlation of a code modulated 10 MHz signal is presented. The apparatus is comprised of a sample and hold analog-to-digital converter synchronized by a frequency coherent 40 MHz pulse to obtain four evenly spaced samples of each of the signal. Each sample is added or subtracted to or from one of four accumulators to or from the separate sums. The correlation functions are then computed. As a further feature of the invention, multipliers are each multiplied by a squarewave chopper signal having a period that is long relative to the period of the received signal to foreclose contamination of the received signal by leakage from either of the other two terms of the multipliers.
The use of a 1 MHz range code and a narrow-passband IF filter reduces waveform distortion error by a factor of as much as 20. Along with this improvement in ranging precision, ranging accuracy is enhanced by nullifying many errors caused by equipment vagaries. The IF filter and concomitant modification of ranging system software (and in the case of the planetary ranging assembly, hardware) are the most cost-effective way of improving the current generation ranging system.
Pocket sized transmitter, frequency modulated by crystal derived tones, with integral loop antenna provides police with easy operating alert signal communicator which uses patrol car radio to relay signal. Communication channels are time shared by several patrol units.