Abstract: A cashless business transaction system (e.g., a vending system, a material tracking system, or a highway toll system) incorporates a method and apparatus for transmitting a digital information signal. A signal generator (311) generates a constant frequency signal. A phase modulator (305) varies the instantaneous phase of the constant frequency signal to represent digital information, thereby producing a phase modulated signal (325). A tuned resonant circuit (307) filters and averages the phase modulated signal to produce a simulated FM signal, and transmits the simulated FM signal via its antenna (309). One such business transaction system (e.g., a vending system) incorporates such a transmitter to facilitate transmission of billing information from a device located within a substantially electrically shielded environment.

Abstract: A transmitter prepares digits for transmission, e.g. as spread spectrum data accompanying commercial radio, using code sequences having exactly zero cross-correlation. The code sequences include phased versions of the maximal length sequence, with an additional "0" bit appended to the end of each phased version. Information signals (which may be analog signals, or digital signals encoded as two or more analog levels) are transmitted by multiplying each information signal by one of the code sequences, and adding the resulting sequences together to form an output sequence for transmission. A receiver that recovers the information signals correlates the received sequence with each of the code sequences, producing results which are directly proportional to the information signals.

Abstract: An electromagnetic induction type hearing aid which comprises (1) an electromagnetic transmitter having an input for receiving a radiated acoustical signal and an output for radiating an alternating electromagnetic signal whose frequency components are determined by the input signal and (2) a wireless magnetostrictive vibrator of bimorph design and of biocompatible material and which is adapted to be surgically implanted on one of the bones of the ossicular chain in a spatial operative relationship to the transmitter output without the need for mechanical anchoring and without any components passing through the boundary of the middle ear of the user. The vibrator is further responsive to the electromagnetic signal radiated from the transmitter and vibrates the ossicular chain in response to such radiated electromagnetic signal to stimulate the inner ear to create the perception of sound to the user.

Abstract: A binary capacitor consists of a piston having a metallized band on its periphery. The piston is movable between first and second positions within a cylinder which carries two spaced metallized bands. One of the positions of the piston defines a position of maximum capacitance, i.e. where the band on the piston overlaps both of the cylinder bands. The second position of the piston defines a position of minimum capacitance; i.e. where the piston band clears at least one of the cylinder bands. The piston is latched in its stable minimum and maximum states by fixed permanent magnets located at the ends of the piston in combination with soft iron slugs at the ends of the cylinder. The piston is moved by appropriately energizing electromagnetic coils wound over the soft iron slugs on the cylinder.