Koss Corporation

Bahr Technologies, Inc.

Neil K Fortney

Dennis E Bahr

Kendall E Post

Manfred W Suhr

Erich T Ziemann

Tom Blandino

Michael Skroch

An acoustical transducer unit mountable in a speaker enclosure with a speaker opening adapted to face a user's ear, and a method for manufacturing the transducer. The transducer has a pair of opposing plates spaced apart a predetermined distance and a diaphragm physically connected and positioned between the plates, though electrically separated from the plates. The plates are adapted to be connected to an audio signal source, while the diaphragm receives a bias voltage. The transducer is mounted in the enclosure facing outward toward the speaker opening. The diaphragm is formed of a flexible substrate material such as MYLAR.TM.. A substantially infrared transparent material is deposited onto each side of the substrate in a thin layer to arrive at a transducer which is at a much higher level of performance than those of the prior art. The deposited material is infrared transparent so as to permit the deposition process to proceed without substantial damage or distortion to the diaphragm. Because the deposited metal is transparent to infrared energy, the diaphragm may be thinner than 5.0.times.10 meters, resulting in a transducer having substantially improved frequency response due to the thinness and low mass of the diaphragm.

Electrostatic acoustic transducer having extremely thin diaphragm

A circuit for monitoring and indicating the outut level of an energy source, such as the voltage level of a battery. The circuit includes a triangle wave generator, and a comparison circuit for comparing the triangle wave form to the battery output level and generating a comparison signal. A dual color LED set displays the comparison signal. The diode set is activated in one color when the battery signal is greater than the triangle wave form, while the other color diode is activated when the battery signal is less than the triangle wave form. When the frequency of the triangular wave is two Hertz, the LED set produces discernable flashes between the first color LED and the second color LED when the battery signal is within the peak-to-peak value. The ratio of the times the LEDs are activated is a linear representation of the battery voltage between predetermined 'warning' and 'discharge' voltages. When the frequency of the triangular wave is thirty Hertz or greater, any flashes produced by the diode set switching between activated LEDs are not discernable by the human eye, resulting in a mixing of colors when the battery signal is within the peak-to-peak value of the triangle wave form.

Battery status indicator

A radio signal containing Loran C pulses from stations of interest is received and periodically sampled to convert the input signal to sample data. The data is assigned to memory locations within an acquisition memory at positions in the memory which correspond to specific times within the group repetition interval (GRI) of the Loran chain of interest. A GRI counter assigns the locations in the memory to which the data are written and cycles the memory after the completion of each GRI so that new data corresponding to a new set of pulses from the master and secondary stations of the Loran C chain will be assigned to essentially the same memory locations as data acquired during a previous GRI. The new data is ensemble averaged with the old data contained in the memory locations and the averaged data stored back in the memory. As data is collected and averaged over a sufficient number of GRI's, any signals present in the received radio signal which are not synchronous with the GRI will tend to be averaged out, improving the signal to noise ratio of the Loran C pulses in the memory. Averaging of the sampled input signal over several GRI's in this manner minimizes the effect of sporadic noise, continuous wave interference and cross rate interference. After completion of the averaging process, the data in the acquisition memory may be searched to determine the time differences between the master and secondary pulses in a manner normally carried out in Loran C receivers.

Apparatus and method for receiving and proessing Loran signals

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Madison, WI, United States of America

Neil K Fortney