Amtel Communications, Inc.

Bahr Technologies, Inc.

Cas Medical Systems, Inc.

General Railway Signal Corporation

Kendall E Post

Dennis E Bahr

Paul N Henning

Thomas P Blandino

William J Curtin, Iv

Mark Brian Monson

Erich T Ziemann

Kenneth R Clark

Neil K Fortney

Michael Skroch

A communication system for submitting RF signals responsive to the currents of defects or hazards in a railway system wherein a reserve cell ampule containing an electrolyte is disposed in one compartment of a housing and the electronic apparatus transmitting desired signals is disposed in a second compartment such that when the reserve cell is heated the pressure rises within the ampule to rupture it, whereby the electrolyte contained is dispersed in the first compartment and causes energization of electronic apparatus including an antenna connected to such apparatus, whereby the antenna is ejected from the housing and is able to broadcast suitable RF signals.

Communication system for transmitting RF signals representative of

A preamplifier system adapted for a Loran receiver includes a buffer amplifier receiving the signal from the antenna at its input and a tuned circuit connected between the input of the buffer amplifier and ground. The tuned circuit includes a parallel combination of a resistance, capacitance and inductance with values selected such that a resonant frequency is provided substantially at or near the carrier frequency of the Loran signal to pass it while higher and lower frequencies, constituting extraneous noise signals, are substantially attenuated. In particular, low frequency, e.g. 60 Hz signals and DC from sources such as precipitation static, are shunted to ground through the parallel inductor in the tuned circuit so that these low frequency components do not affect the performance of the receiver. A secondary filter section is connected to the output of the buffer amplifier and has components that may be selected in value such that the overall transfer function of the preamplifier, including the tuned input circuit, has a desired bandpass characteristic. Thermal noise contributed by the parallel resistor in the tuned circuit may be reduced by feeding back the output of the buffer amplifier through the resistor to effectively reduce its noise contribution while leaving the effective input resistance the same. Notch filters may be incorporated with the input tuned circuit to reject strong extraneous signals within the passband.

Receiver preamplifier with tuned circuit adapted for Loran reception

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

The device measures blood pressure automatically using the oscillometric technique. The device includes a pressure cuff which is automatically inflated to an initial pressure which is calculated to be above the subject's systolic pressure. The cuff is then deflated stepwise in preset pressure increments while cuff pressure oscillations are sensed at each cuff pressure level and stored in a computer incorporated into the device. Cuff deflation is continued until the cuff pressure is below the subject's diastolic pressure whereupon the cuff is automatically deflated. The computer then fits a calculated parabolic curve onto the greatest cuff pressure oscillation and onto a lesser oscillation on each side of the greatest oscillation. From the thusly derived curve, the computer determines the mean blood pressure, and the systolic and diastolic blood pressures.

Automatic blood pressure measuring device and method

An automatic line supervisor is disclosed for a telephone system having a line concentrator which converges a plurality of subscriber lines into a single output line to a telephone answering service (TAS) which is coupled to the concentrator by a telephone line with automatic ring down (ringing tie line). In order for the line to properly operate after the TAS has answered a subscriber call, and gone back on hook, the telephone concentrator must be disconnected from the ringing tie line and from the caller. In a first embodiment, the automatic line supervisor is an integral part of the concentrator and operates to make the requisite disconnection of the concentrator from the ringing tie line and the caller on a subscriber line by monitoring the tie line for appropriate audio tones, generating a control signal either in response to the presence of a dial tone for a particular time interval or in response to the absence of DTMF tones (dual tone multifrequency) for a particular time interval. The control signal is used to open appropriate relays to disconnect the line concentrator from the caller and the ringing tie line to prepare the ringing tie line for ringing the TAS that another call is present. In the second embodiment, the automatic line supervisor is a separate device which is located at the TAS. The second embodiment monitors the current flow in the ringing tie line coupling the telephone concentrator with the TAS to sense the discontinuance of current flow which is indicative of the operator going on hook. When the discontinuance of current flow is sensed, a control signal is produced which is coupled to the telephone concentrator via the tie line. The control signal is sensed at the concentrator and initiates the opening of the requisite switches to disconnect the concentrator from the ringing tie line and the subscriber line.

Automatic line supervisor for use with a call concentrator

A control system for enabling direct inward dialed telephone calls received on a single access line from a telephone central office to be answered with identity. The single access line is coupled at the telephone central office to a block of telephone numbers, and incoming calls to any of these numbers are connected to the access line and to an operator at a telephone answering location through the control system, and the number called is decoded by the control system. A DID line ('DID' stands for direct inward dial) on the interface is arranged in the input section of the control system and is coupled to the single access line that receives the telephone calls from the telephone central office. At least the last digit of the telephone number is decoded within the control system and a visual display of the decoded number is then provided for identifying the incoming call. The control system includes an operator interface for enabling an operator at the site of the telephone answering system to be plugged into the control system for being coupled to the incoming calls being transferred along the single access line. A microprocessor controls the operation of the control system.

Growing community of inventors

Madison, WI, United States of America

Kendall E Post