Abstract: The present invention is directed towards a frequency modulated burst mode optical transmitter and systems and methods related thereto. Reverse electrical signals are used to frequency modulate a carrier signal. A carrier detect circuit checks for the presence of a subcarrier signal in received reverse electrical signals. When a subcarrier signal is detected, a laser is turned on and the frequency modulated carrier signal is used to intensity modulate the laser to provide an optical signal. In the absence of a subcarrier signal, the laser is turned off and no optical signals are transmitted. By operating in a burst mode, resources are conserved as optical signals are transmitted only when content-carrying reverse electrical signals are received.

Abstract: Voltage-induced hum modulation in an amplifier can be caused when shunt capacitors begin to saturate and enter their non-linear region of operation. Bypass coils within the amplifier are magnetically coupled to the shunt capacitors and exacerbate hum modulation by coupling additional energy to the shunt capacitors. By introducing a resistance (R) in series with the shunt capacitors (C), energy that would normally be stored in the shunt capacitors (C) is dissipated. As a result, the shunt capacitors (C) remain in their linear region of operation more often and present a more stable impedance. The resistor (R) is especially beneficial at reducing hum modulation at the resonant frequency of the shunt capacitors (C), when the transfer of energy from the bypass coils (L) is at a maximum.

Abstract: An amplifier (125) having automatic gain control (AGC) includes a gain stage (220), having a variable amplifier (215), for amplifying a signal received by the amplifier (125). The amplifier (125) also includes an AGC circuit (228) that adjusts amplification of the gain stage (220) and that includes a manual switch (246) having first and second switch settings. Sequential operation from the first switch setting to the second switch setting causes the AGC circuit (228) to automatically and correctly set the gain of the amplifier (125) without further human intervention.

Abstract: A bidirectional communications system is provided for sending signals along a cable in a forward path from a central location to a plurality of remote receiver locations and for sending return signals along the same cable in a reverse path from the remote receiver locations to the central location. The communications system includes a plurality of taps placed along the cable for splitting the signals to be sent to the remote receiver locations, and a radio frequency sensed switch placed at each of the plurality of taps for sensing the return signals so as to turn on the reverse path when the return signals are present and to turn off the reverse path when no return signals are present.