At present, BPSK/DBPSK messages are received using widely known algorithms. Generally, BPSK messages are received coherently, e.g., with the aid of the Costas loop, whereas DBPSK messages are received non-coherently. Usually, BPSK messages are received in the coherent mode using the Costas loop or other circuits that are built using the Costas loop. For non-coherent reception of DBPSK messages, various algorithms based on estimation of the phase difference between adjacent bits may be used. Coherent reception is generally believed to be more efficient, but is known to require significant computational resources, especially when used in a low signal-to-noise ratio environment (for example, when the signal is weak).
U.S. Pat. No. 9,049,732 (Entitled: Method for Using a Shared Frequency Resource, Method for Manufacturing Terminals, Terminals and Telecommunication System, Assignee: SIGFOX™, date of publication: 2015-06-02) discloses that Fourier transforms are carried out with a desired frequency resolution, then, energy peaks are searched for, whereupon all frequencies having such peaks are brought around to a low frequency where the signal is filtered and detected (the process may be both coherent and non-coherent, the algorithms are known in the art).
A disadvantage of this prior art technology appears to be high computational complexity. Part of the computations may be repeated at least twice, when energy peaks are searched for and the signal is filtered.
Currently, various Systems-on-a-Chip (or SoC/SoCs for short) capable of receiving/transmitting RF signals are known and commercially available. Such systems are widely used for applications where a size of a device is limited and low power requirements and cost are of the essence.
Some of the known Systems-on-a-Chip are capable of receiving/transmitting PSK or DPSK messages
One example of such known System-on-a-Chip is a series of the Wireless Gecko systems of Silicon Labs. Some known Systems-on-a-Chip of this series, e.g., EFR32xG13 Wireless Gecko, support data transmission using the DBPSK technique. However, known Systems-on-a-Chip of this series cannot receive DBPSK signals.
Another example of the known Systems-on-a-Chip supporting BPSK is the AT86RF212 system manufactured by Microchip, BPSK is used in direct sequence spread spectrum operation at bit rates of 20 and 40 kbps. The system sensitivity in this mode is up to −100 dBm.
These prior art Systems-on-a-Chip appear to have a number of disadvantages making it challenging to apply such known System-on-a-Chip in telemetry data acquisition networks.
Some such known Systems-on-a-Chip fail to support BPSK message reception. Most known Systems-on-a-Chip support operation at rates of 10 kbps or higher, with the transmission range usually not exceeding several thousand meters. Axsem ax5043 supports BPSK message reception at 100 kbps, whereby a sensitivity of −138 dBm is provided, however, such sensitivity can be provided only if the receive and transmit frequencies coincide.
Also known in the art are: systems using original modulation; CDMA based spread spectrum devices; all of these having a number of specific features known to those persons skilled in the art.