Various embodiments provide for data transmission using alert signals to carry data, which can be used in such applications as data network communications between sensors (e.g., cameras, motion, radar, etc.) and computing equipment within vehicles (e.g., smart and autonomous cars).

A cascadable AGC amplifier in a signal distribution system includes a low noise cascadable amplifier having a through path and a cascadable output. The cascadable amplifier is also configured to provide AGC over a predetermined input power range. The cascadable AGC amplifier can be configured to provide gain or attenuation. When the cascadable AGC amplifier is implemented in a signal distribution system, typically as part of a signal distribution device, an input signal can be gain controlled and supplied to multiple signal paths without distortion due to degradation of signal to noise ratio or distortion due to higher order amplifier products. The distributed signal is not significantly degraded by distortion regardless of the number of cascadable AGC amplifiers connected in series or the position of the cascadable AGC amplifier in the signal distribution system.

An echo cancellation method includes steps of (a) extracting phase-distortion estimates, (b) reconstructing an echo signal, (c) generating a clean signal, and (d) producing a primary signal. Step (a) includes extracting, from a first phase signal, a plurality of phase-distortion estimates, the first phase signal having been estimated from an echo-corrupted signal received at a first coherent transceiver of a coherent optical network. Step (b) includes reconstructing an echo signal from the plurality of phase-distortion estimates and a transmitted signal transmitted by the first coherent transceiver. Step (c) includes generating a clean signal as a difference between the reconstructed echo signal and the first phase signal. Step (d) includes producing a primary signal by mapping each of a plurality of clean-phase estimates of the clean signal to one of a plurality of constellation symbols associated with a modulation scheme of the primary signal.

An echo cancellation method includes steps of (a) extracting phase-distortion estimates, (b) reconstructing an echo signal, (c) generating a clean signal, and (d) producing a primary signal. Step (a) includes extracting, from a first phase signal, a plurality of phase-distortion estimates, the first phase signal having been estimated from an echo-corrupted signal received at a first coherent transceiver of a coherent optical network. Step (b) includes reconstructing an echo signal from the plurality of phase-distortion estimates and a transmitted signal transmitted by the first coherent transceiver. Step (c) includes generating a clean signal as a difference between the reconstructed echo signal and the first phase signal. Step (d) includes producing a primary signal by mapping each of a plurality of clean-phase estimates of the clean signal to one of a plurality of constellation symbols associated with a modulation scheme of the primary signal.

An echo cancellation method includes steps of (a) extracting phase-distortion estimates, (b) reconstructing an echo signal, (c) generating a clean signal, and (d) producing a primary signal. Step (a) includes extracting, from a first phase signal, a plurality of phase-distortion estimates, the first phase signal having been estimated from an echo-corrupted signal received at a first coherent transceiver of a coherent optical network. Step (b) includes reconstructing an echo signal from the plurality of phase-distortion estimates and a transmitted signal transmitted by the first coherent transceiver. Step (c) includes generating a clean signal as a difference between the reconstructed echo signal and the first phase signal. Step (d) includes producing a primary signal by mapping each of a plurality of clean-phase estimates of the clean signal to one of a plurality of constellation symbols associated with a modulation scheme of the primary signal.

Examples described herein include devices and systems utilizing backscatter communication to directly generate transmissions in accordance with wireless communication protocols that can be decoded existing devices. Examples include devices that generate 802.11b transmissions using backscatter communication. Examples of network stacks are described which may facilitate backscatter devices to coexist with other devices (e.g. in the ISM band), without incurring, or reducing a need for, the power consumption or carrier sense and medium access control operations.

Examples described herein include devices and systems utilizing backscatter communication to directly generate transmissions in accordance with wireless communication protocols that can be decoded existing devices. Examples include devices that generate 802.11b transmissions using backscatter communication. Examples of network stacks are described which may facilitate backscatter devices to coexist with other devices (e.g. in the ISM band), without incurring, or reducing a need for, the power consumption or carrier sense and medium access control operations.

An echo cancellation method includes steps of (a) extracting phase-distortion estimates, (b) reconstructing an echo signal, (c) generating a clean signal, and (d) producing a primary signal. Step (a) includes extracting, from a first phase signal, a plurality of phase-distortion estimates, the first phase signal having been estimated from an echo-corrupted signal received at a first coherent transceiver of a coherent optical network. Step (b) includes reconstructing an echo signal from the plurality of phase-distortion estimates and a transmitted signal transmitted by the first coherent transceiver. Step (c) includes generating a clean signal as a difference between the reconstructed echo signal and the first phase signal. Step (d) includes producing a primary signal by mapping each of a plurality of clean-phase estimates of the clean signal to one of a plurality of constellation symbols associated with a modulation scheme of the primary signal.

Apparatus and methods relating to synchronization of communication equipment are disclosed. Synchronization information received from a bonded communication link can be used to synchronize local and/or remote communication equipment, such as femtocell sites coupled to nodes in a ring network. This may involve isolating a frequency reference signal from a DSL (Digital Subscriber Line) communication link which is a constituent link of a bonded communication link, for example. In a ring network, received synchronization information could be used in synchronizing a locally connected installation of communication equipment, and passed for transmission in the ring network for synchronizing other communication equipment. Such dropping and passing of an analog frequency reference signal could be applied in networks having other topologies as well. At least some embodiments of the invention are applicable to optical links. One or more dedicated wavelengths of an optical link could be used to transfer a frequency reference signal, for example. Other functions, such as quality monitoring, quality reporting, and/or predictive traffic forwarding may be provided in some embodiments.