Methods, systems, and apparatus for EM communications. One of the apparatus includes a plurality of receive samplers arranged in parallel and configured to receive an amplitude modulated input signal, each sampler being clocked at a same rate but not a same phase, the rate being in relation with the input signal; a plurality of envelope extractors, wherein each envelop extractor is communicatively coupled to a respective output of one of the plurality of receive samplers, and wherein each envelope extractor is configured to extract the envelope of the input signal after sampling; and a combiner communicatively coupled to the envelope extractors to combine the signal envelopes sampled at their respective phases, creating a combined output that provides an approximate copy of the input signal envelope, providing an output signal for performing symbol synchronization.

A low voltage drive circuit includes a transmit analog to digital circuit that converts transmit digital data into analog outbound data by: generating a DC component; and generating an oscillating component at a first frequency that conveys the transmit digital data, wherein the magnitudes of both the oscillating component and the DC component are limited to a range that is less than a difference between the magnitudes of the power supply rails of the circuit, and wherein the oscillating component and the DC component are combined to produce the analog outbound data. A drive sense circuit drives an analog transmit signal onto a bus, wherein the analog outbound data is represented within the analog transmit signal as variances in loading of the bus at a first frequency and wherein analog inbound data is represented within an analog receive signal as variances in loading of the bus at a second frequency.

A low voltage drive circuit includes a transmit analog to digital circuit that converts transmit digital data into analog outbound data by: generating a DC component; and generating an oscillating component at a first frequency that conveys the transmit digital data, wherein the magnitudes of both the oscillating component and the DC component are limited to a range that is less than a difference between the magnitudes of the power supply rails of the circuit, and wherein the oscillating component and the DC component are combined to produce the analog outbound data. A drive sense circuit drives an analog transmit signal onto a bus, wherein the analog outbound data is represented within the analog transmit signal as variances in loading of the bus at a first frequency and wherein analog inbound data is represented within an analog receive signal as variances in loading of the bus at a second frequency.

Embodiments are disclosed for equalizing input signals for communication systems. An example method includes receiving an input signal. The input signal encodes a plurality of bits in a number of amplitude levels. The example method further includes converting the input signal to an equalized output signal using a plurality of lookup table circuits. The equalized output signal encodes a plurality of symbols in a number of amplitude levels. The example method further includes feeding the equalized output signal to an output driver circuit.

Embodiments are disclosed for equalizing input signals for communication systems. An example method includes receiving an input signal. The input signal encodes a plurality of bits in a number of amplitude levels. The example method further includes converting the input signal to an equalized output signal using a plurality of lookup table circuits. The equalized output signal encodes a plurality of symbols in a number of amplitude levels. The example method further includes feeding the equalized output signal to an output driver circuit.

In a transmission circuit that transmits transmission data using an amplitude shift modulation method (ASK modulation method) for changing an amplitude of carrier waves based on the transmission data or a transmission system that uses the transmission circuit, a phase of the carrier waves is changed based on the transmission data to suppress an irradiation of carrier wave components.

In a transmission circuit that transmits transmission data using an amplitude shift modulation method (ASK modulation method) for changing an amplitude of carrier waves based on the transmission data or a transmission system that uses the transmission circuit, a phase of the carrier waves is changed based on the transmission data to suppress an irradiation of carrier wave components.

In a transmission circuit that transmits transmission data using an amplitude shift modulation method (ASK modulation method) for changing an amplitude of carrier waves based on the transmission data or a transmission system that uses the transmission circuit, a phase of the carrier waves is changed based on the transmission data to suppress an irradiation of carrier wave components.