Abstract: An electronically controlled variable gain amplifier is disclosed which provides an output signal proportional to the value of an input signal multiplied by a gain factor, where the gain factor is in turn logarithmically proportional to the value of a gain control signal in the form of a digital word. The amplifier includes a capacitor, a sampler for periodically sampling the value of the input signal and storing the sampled value as a voltage on the capacitor, and circuits for periodically exponentially charging the capacitor after the input signal has been stored thereon for a duration which is directly proportional to the magnitude of the gain control signal. Also included is a circuit for periodically sampling and holding the voltage stored on the capacitor after each periodic charge, where the sampled and held voltage is the amplifier output signal.

Abstract: A system is provided for processing spot trades in selected commodities among a group of trading stations in a communication network through a series of structured stages. Each trading station is capable of initiating a transaction with any other trading station in the network by transmitting a request for a quotation on a selected commodity. The receiving, or counterparty, trading station responds by transmitting a quotation back to the initiating trader, and the trader transmits a proposal based on this quotation. The counterparty then transmits an acceptance of the proposal and upon receipt of this acceptance by the initiating trader, a confirmation signal is automatically transmitted back to the counterparty and the deal is automatically logged at both sites. Alterations of transmitted quotations and proposals and extensive negotiation are also possible.

Abstract: An improved auto-equalizer technique is disclosed for use in two-way communications systems having terminals which are connected by a communications link having distortion characteristics which are substantially identical for signals traveling in either direction. The technique includes a master modem which is always first to transmit in the system, and one or more remote modems. Each remote modem includes an adaptive filter in the receiver section of the modem which adaptively sets its filter characteristics to be the inverse of the line distortion characteristics. Each remote modem also includes a slave filter in the transmitter section which is also set have filter characteristics which are substantially the same as that of the adaptive filter. The slave filter acts to pre-distort the signals transmitted from the remote modem so that they arrive at the master modem substantially undistorted.