Abstract: A cable television system provides conditional access to services. The cable television system includes a headend from which service “instances”, or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.

Abstract: A cable television system (100) includes forward and reverse paths. Reverse path circuitry within an optical node (400) of the system (100) receives reverse analog electrical signals from subscriber equipment (140) and generates therefrom a multiplexed reverse digital optical signal. The reverse digital optical signal is transmitted over a fiber optic cable 420 to a cable television hub (430), the reverse path portion of which includes no active circuitry. The hub (430) multiplexes the reverse digital optical signal with other reverse digital optical signals from other nodes to generate one or more forwarded digital optical signals at a hub output, wherein generation of the one or more forwarded digital optical signals requires only passive devices in the reverse path of the hub (430).

Abstract: A cable television system (100) having forward and reverse paths includes, in the reverse path, a digital optical transmitter (200) for receiving an RF signal, converting it to a digital signal, and adding a digital pilot tone thereto. A laser is driven in accordance with the summed digital signal to generate a digital optical signal representative of the pilot tone and the RF signal. The cable television system (100) also includes an optical receiver (305)for receiving the digital optical signal and recovering therefrom the RF signal and the pilot tone. The optical transmitter (200) and receiver (305) are coupled by fiber optic communication media (110).

Abstract: A cable television system provides conditional access to services. The cable television system includes a headend from which service “instances”, or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.

Abstract: A cable television system provides conditional access to services. The cable television system includes a headend from which service “instances”, or programs, are broadcast and a plurality of step top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.

Abstract: The method, apparatus, and system for controlling audio anomalies by using a mute switch 51 to prevent output of an auxiliary audio signal 21 in a television signal 20 with an auxiliary audio signal 21, such as a NICAM audio signal or dual language audio signal, adjacent to a first audio signal 22. The mute switch 51 operation is a function of the type of receiver 19 receiving television signal 20 and a function of verifying the presence of an auxiliary audio signal 21 in television signal 20. The present invention controls audio anomalies such as audio whistle and audio pop.

Abstract: A bypass switch (155) for use in an electronic device (125) includes a substrate (205) on which first, second, and third terminals (215, 220, 235) are mounted and an electrically conductive primary element (250), having first and second opposing ends, mounted to a bottom surface of the substrate (205) and electrically coupled to the first terminal (215) at its first end and to the second terminal (220) at its second end. The switch (155) also includes an electrically conductive bypass element (255), having first and second opposing ends, mounted to the bottom surface of the substrate (205) and electrically coupled to the third terminal (235) at its first end and vertically aligned, at its second end, with the second end of the primary element (250). A switch actuator (225) is mechanically coupled to the bypass element (255), extends through the substrate (205), and has an actuating surface (290) accessible at a top surface, opposite the bottom surface, of the substrate (205).

Abstract: The disclosed invention relates to a pick list generator which displays selectable terms for inclusion in a selection field. One embodiment of the pick list generator is in assisting an Internet user in the user's population of search fields without the use of a keyboard containing all 26 letters and 10 digits. Accordingly, through application of the present invention, browsing and searching of the Internet is enhanced for the keyboardless user.

Abstract: A cable television system (100) having forward and reverse paths includes, in the reverse path, a digital optical transmitter (200) for receiving an RF signal, converting it to a digital signal, and adding a digital pilot tone thereto. A laser is driven in accordance with the summed digital signal to generate a digital optical signal representative of the pilot tone and the RF signal. The cable television system (100) also includes an optical receiver (305)for receiving the digital optical signal and recovering therefrom the RF signal and the pilot tone. The optical transmitter (200) and receiver (305) are coupled by fiber optic communication media (110).

Abstract: A surface mount, tunable inductor (200) includes a core (205) that is substantially toroidal in shape. The core (205) has a first flattened surface (206) and a second flattened surface (207) opposite the first flattened surface (206), and a hole (208) is formed through the core (205). A wire (210) is wound about the core (205) and terminates in first and second leads (215). The inductor (200) also includes a substrate (220) on which first and second conductive pads (225) are formed. Each of the wire leads (215) is electrically coupled to one of the conductive pads (225), and an adhesive (240) secures the first flattened surface (207) of the core (205) to the substrate (220).

Abstract: A communication system (300) includes amplifiers (325) having an improved thermal response. The amplifiers (325) include a Bode circuit (208) for attenuating the signals and a thermal compensation circuit (320) for adjusting the gain in response to changes in temperature. The thermal compensation unit (320) provides a non-linear impedance to offset for the non-linear performance of the amplifiers gain versus control current. The thermal compensation unit (320) has circuit paths that are selectively turned on to provide the non-linear relationship of impedance versus input control voltage.

Abstract: A cable television system provides conditional access to services. The cable television system includes a headend from which service “instances”, or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.

Abstract: A reprogrammable subscriber terminal of a subscription television service which can have the control program code of its control processor modified by downloading new program code from the headend. The control processor stores a boot program in an internal read only memory. Upon start up and resets, the boot program determines whether the control program should be changed from a command sent from the headend. The command, termed a parameters transactions, includes the number of expected download program code transactions required to complete the control code modification, the memory space areas where the code is to be loaded, and the channel over which the download program code transactions are to be transmitted. The channel is tuned and when the boot program receives all the download program code transactions accurately and stores them, the boot program will cause the control program to be restarted at a selected address of the new or modified control program code which has been downloaded.

Abstract: An optical transmitter (405) includes a distributed feedback semiconductor laser (100) operated in a linear regime below a threshold associated with stimulated Brillouin scattering to generate an optical signal. A resistor (125) or other heater is physically coupled to the semiconductor laser (100), and a modulated current source (120) drives the resistor (125) with a triangle waveform (300), thereby varying an optical wavelength of the optical signal such that the optical signal and a double Rayleigh backscattered signal are characterized, at the optical receiver (410), by different optical frequencies. As a result, interference generated by Rayleigh backscattering is minimized at the optical receiver (410).

Abstract: The problem of wasting IP addresses by statically assigning them to hosts is solved as follows: when a cable router or RF modem becomes active, it sends a message requesting a set of IP addresses from the head end, which dynamically assigns the set of IP addresses and sends a message comprising the set of IP addresses to the cable router or RF modem. The cable router or RF modem then responds to requests by the hosts for IP addresses by assigning them IP addresses from the set. Furthermore, the set of IP addresses is released when the session terminates with the cable router or RF modem.

Abstract: A distribution amplifier (210) for a cable television system (100) includes an output gain stage section (215) for receiving an input signal from a cable head end section (105). The output gain stage section (215) includes multiple active amplifier circuits (225, 230) for amplifying the input signal to generate main and auxiliary outputs that are processed by a radio frequency (RF) detector (255) having at least a first detector circuit (300) for processing the main output to generate a first voltage and a second detector circuit (305) for processing the auxiliary output to generate a second voltage. Further included in the distribution amplifier (210) is a status monitor (260) coupled to the RF detector (255) for converting the first and second outputs to first and second digital values and transmitting the first and second digital values. In this manner, an indication of a system or amplifier malfunction can be provided.

Abstract: A dual-frequency antenna (100) includes a transmit element (110) that is substantially planar and that is formed from a conductive material, such as aluminum, having a loaded slot (140) formed therethrough for transmission of first radio frequencies. The antenna (100) also includes a receive element (115) that is substantially planar and that is also formed from a conductive material having a loaded slot (155) formed therethrough for reception of second radio frequencies. The transmit and receive elements (110, 115) are mounted in a single plane adjacent to a ground plane (105) that is held only a small distance from the transmit and receive elements (110, 115). Preferably, the height of the antenna (100), i.e., the distance between the transmit and receive elements (110, 115), and the ground plane (105) is equal to or less than about 1.4 centimeters for low-profile mounting on truck-drawn trailers.

Abstract: A top-loaded, vertically polarized antenna (10) comprised of two ring radiators (108, 110) formed into loops to provide a dual resonant frequency antenna less than 8 inches on a side for use in the 130 to 150 MHz frequency band. By using separate transmit and receive elements, separate resonant frequencies can be provided without the use of lossy duplexers. The antenna can be concealed inside a housing also containing the radio equipment.

Abstract: A method for transporting digital data from a sender to a receiver in a system where the digital data is broken into data packets for transmission over radio frequency channels, each data packet including forward error-correcting code, the method comprising the steps of receiving the data packets at the receiver; reconstructing the data packets to the digital data, the forward error-correcting code for fixing corrupted data packets; and halting the data packet reconstructing step if a data packet is uncorrectable.

Abstract: A node (100) for a communications system includes a forward distribution amplifier within a housing (600). Plug-in modules (200,400) can be removably attached to the forward distribution amplifier within the same housing (600) to change the functionality of the node (100). For example, the plug-in module can be a reverse amplifier module (200) for adding reverse signal processing function or an optical module (400) for adding optical capabilities.