US 2018/0109403 A1 · Energy efficient highway addressable remote transducer C8PSK modem

Abstract

A method and a Highway Addressable Remote Transducer (HART) soft modem device (SMD) for transmitting a C8PSK signal and receiving and demodulating an Analog signal in either FSK or C8PSK comprising a HART message is provided. A transmitter of HART-SMD improves efficiency by reducing the computation complexity with a novel table lookup technique. A demodulator of the HART-SMD receives the Analog signal, samples and converts the Analog signal into digital data at a predetermined digital sample rate. The demodulator implements a two-step phase estimation technique followed by a single step timing estimate to achieve an optimal operating region for the receiver so that the receiver can be ready to receive state in a very short time as required in C8PSK specifications. A simple method of doing automatic modulation classification by negating the presence of an FSK modulation by the positive assertion of the presence of C8PSK modulation, or by the absence of C8PSK Signal and the presence of Energy detect to assert the presence of FSK signal is also stated.

Claims11

Dependent claims

A method for modulating and transmitting an Analog signal comprising a highway addressable remote transducer message, said method comprising of:

a. Accepting as input said highway addressable remote transducer message and grouping them into 3 bits called symbols;
b. Further grouping sets of these symbols;
c. Implementing C8PSK modulation scheme in an efficient lookup table method to generate C8PSK signals which require only additions and subtractions and thus the requirements of computations are minimized significantly without need for any real time multiplication or other high power signal processing to generate said C8PSK signals;
where such a lookup table is generated ahead of time for a specific sample rate in a non-real time environment by making use of the properties of the C8PSK carrier frequency being in synchronization with the C8PSK baud rate and thus minimizing the size of this lookup table and the final C8PSK signals generated by a lookup table vector comprising of 3n bits representing the n symbols in time and m bits representing the number of C8PSK signals per symbol.

1 more element

Dependencies are inferred from the claim text.

Energy efficient highway addressable remote transducer C8PSK modem

Life of this patent

Energy efficient highway addressable remote transducer C8PSK modem

Life of this patent

Abstract

Claims11