RF communications system utilizing digital modulation to transmit and receive data

• US 7,154,938 B2
• Filed: 12/31/2002
• Issued: 12/26/2006
• Est. Priority Date: 12/31/2002
• Status: Expired due to Fees

• Current Assignee: Itron, Inc.
• Original Assignee: Itron, Inc.
• Inventors: Cumeralto, Scott, Larson, Gary, Devries, Richard
• Primary Examiner(s): Patel, Jay K.
• Assistant Examiner(s): Odom, Curtis B.
• Application Number:
  US10/335,553
• Publication Number:
  US 20040125889A1
• Time in Patent Office: 1,456 Days
• Field of Search: 375132-138, 375/150, 340/870.02, 340/870.11, 340/870.18
• US Class Current: 375/150
• CPC Class Codes: H04B 1/715 Interference-related aspects
• CPC Class Codes: H04B 2001/71365 using continuous tuning of a single frequency source
• CPC Class Codes: H04L 27/32 Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
• CPC Class Codes: H04L 5/02 Channels characterised by the type of signal
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

The RF communications system of the present invention wirelessly communicates data without encountering undue interference problems with other devices and complies with rules governing unlicensed, spectrum-sharing devices. In an example embodiment, a transmitter device includes a digital subsystem powered by a power supply that processes data from another device and a radio frequency (RF) sub-system that transmits the processed data using a frequency hopping scheme. The RF sub-system includes a microprocessor arrangement that ON-OFF keys a voltage controlled oscillator (VCO) and provides a frequency-hopping scheme. The VCO is coupled to a signal frequency spreading arrangement that spreads the signal to a predetermined transmission bandwidth, wherein the frequency spreading occurs during an ON state of the ON-OFF keying and the transmission bandwidth exceeds a reception bandwidth at which the signal will be decoded.

Claims

1. A method of communicating data comprising the steps of:

preparing a data signal for transmission, including applying a step spreading code to the data signal to spread the data signal frequency within a transmission bandwidth;

placing the data signal onto an RF carrier and ON/OFF keying the RF carrier based on the data signal;

transmitting the data signal on the RF carrier such that the data signal is stepped through a selected number of channels during the ON state of the ON/OFF keying thus spreading the data signal over the transmission bandwidth, thereby reducing interference effects from other RF communication devices and thus facilitating spectrum sharing; and

receiving and decoding the data signal in at least one amplitude modulation (AM) receiver adapted to be synchronized to follow a frequency hopping sequence of the transmitted data signal and to receive the data signal at a reception bandwidth, wherein the transmission bandwidth is greater than a reception bandwidth.

2. The method of claim 1, wherein the step of decoding the transmitted data signal further comprises receiving and decoding the data signal at a plurality of AM receivers, wherein each of the receivers receives the data signal at a bandwidth less than an overall spread bandwidth.

3. The method of claim 1, wherein the data signal is transmitted at a power level below 1 watt.

4. The method of claim 1, while decoding the data signal, further comprising the step of sensing a first step within a bit within the data signal and sweeping the narrowband receiver at the same rate as the steps are occurring across each bit, thereby increasing sensitivity and reducing effects of interference.

5. The method of claim 2, after decoding the data signal, further comprising the steps of:

summing certain outputs of the plurality of narrowband AM receivers; and

rejecting output from any of the narrowband receivers that exhibit interference.

6. The method of claim 1, wherein the step of on/off keying the data signal further comprises the step of amplifying the data signal as its being transmitted.

7. The method of claim 1, after decoding the data signal, further comprising the step of receiving and decoding the data signal at a wideband AM receiver.

8. The method of claim 1, wherein the step of on/off keying the data signal further comprises the step of utilizing a power oscillator to transmit the signal at a higher power level.

9. The method of claim 1, wherein the step of stepping through the selected channels further comprises utilizing a varactor to spread the energy of the data signal and to provide a frequency hopping sequence for transmission of the data signal.

10. The method of claim 1, wherein the step of stepping through the selected channels further comprises utilizing a varactor-transistor arrangement to spread the energy of the data signal and to provide a frequency hopping sequence for transmission of the data signal.

11. The method of claim 1, wherein the step of placing the data signal onto the RF carrier includes frequency modulating the carrier with the prepared data signal.

12. A method of communicating data comprising the steps of:

preparing a data signal for transmission, including applying a step spreading code to the data signal to spread the data signal frequency within a transmission bandwidth;

placing the data signal onto an RF carrier and ON/OFF keying the RF carrier based on the data signal;

transmitting the data signal on the RF carrier such that the data signal is stepped through a selected number of channels during the ON state of the ON/OFF keying thus spreading the data signal over the transmission bandwidth, thereby reducing interference effects from other RF communication devices and thus facilitating spectrum sharing; and

receiving and decoding the data signal in at least one wideband amplitude modulation (AM) receiver.

13. The method of claim 12, after decoding the data signal, further comprising the step of receiving and decoding the data signal at a plurality of AM receivers, wherein each of the receivers receives the data signal at a bandwidth less than an overall spread bandwidth.

14. The method of claim 13, while decoding the data signal at the narrowband receivers, further comprising the step of sensing a first step within a bit within the data signal and sweeping the narrowband receiver at the same rate as the steps are occurring across each bit, thereby increasing sensitivity and reducing interference.

15. The method of claim 13, after decoding the data signal, further comprising the steps of:

summing certain outputs of the plurality of narrowband AM receivers; and

rejecting output from any of the narrowband receivers that exhibit interference.

16. The method of claim 12, wherein the step of on/off keying the data signal further comprises the step of amplifying the data signal as its being transmitted.

17. The method of claim 12, wherein the step of on/off keying the data signal further comprises the step of utilizing a power oscillator to transmit the signal at a higher power level.

18. The method of claim 12, after decoding the data signal, further comprising receiving and decoding the data signal in, at least one, single AM receiver adapted to be synchronized to follow a frequency hopping sequence of the transmitted data signal.

19. The method of claim 12, wherein the step of placing the data signal onto the RF carrier includes frequency modulating the carrier wit the prepared data signal.

20. A transmitter device comprising:

a digital subsystem powered by a power supply adapted to process data from another device; and

a radio frequency (RF) sub-system adapted to transmit the processed data using a frequency hopping spread spectrum signal, the RF sub-system comprising a microprocessor arrangement adapted to ON-OFF key a voltage controlled oscillator (VCO) and to provide a frequency hopping scheme, the VCO coupled to a signal frequency spreading arrangement adapted to spread the signal to a predetermined transmission bandwidth, wherein the frequency hopping occurs on an ON state of the ON-OFF keying and wherein the transmission bandwidth exceeds a reception bandwidth at which the signal will be decoded.

21. The transmitter device of claim 20, wherein the frequency spreading arrangement includes a varactor-transistor circuit arrangement adapted to spread the signal to exceed a predetermined bandwidth.

22. The transmitter device of claim 21, wherein the varactor is adapted to be multiplexed to provide frequency hopping and to spread the transmitted signal'"'"'s energy over a frequency that exceeds a predetermined bandwidth.

23. The transmitter device of claim 20, wherein the frequency spreading arrangement includes a pin diode circuit arrangement adapted to be multiplexed to provide frequency hopping and to spread the transmitted signal'"'"'s energy over a frequency that exceeds a predetermined bandwidth.

24. The transmitter device of claim 20, wherein the voltage-controlled oscillator is a power oscillator adapted to transmit the signal at a higher power level.

25. The transmitter device of claim 21, wherein the varactor-transistor arrangement includes two varactors and two transistors, a first varactor adapted to provide frequency hopping and a second varactor adapted to spread the transmitted signal'"'"'s energy over a frequency that exceeds a predetermined bandwidth.

26. The transmitter device of claim 20, further comprising a power amplifier adapted to boost the transmitted signal.

27. A meter end point encoder transmitter device, wherein the device is operably coupled to a utility meter that forms part of a utility meter reading system, the device comprising:

a digital subsystem powered by a power supply adapted to process consumption data from the utility meter; and

a radio frequency (RF) sub-system adapted to transmit consumption data from the utility meter using a frequency hopping spread spectrum signal, the RF sub-system comprising a microprocessor arrangement adapted to ON-OFF key a voltage controlled oscillator (VCO) and to provide a frequency hopping scheme, the VCO coupled to a varactor-transistor arrangement adapted to spread the signal to a predetermined transmission bandwidth, wherein the frequency hopping occurs on an ON state of the ON-OFF keying and wherein the transmission bandwidth exceeds a reception bandwidth at which the signal will be decoded.

28. A system for communicating data via RF comprising the steps of:

means for preparing a data signal for transmission, including applying a step spreading code to the data signal to spread the data signal frequency within a transmission bandwidth;

means for placing the data signal received from the means for preparing the data signal for transmission onto an RF carrier and ON/OFF keying the RF carrier based on the data signal;

means for transmitting the data signal on the RF carrier such that the data signal is stepped through a selected number of channels during the ON state of the ON/OFF keying thus spreading the data signal over the transmission bandwidth, thereby reducing interference effects from other RF communication devices and thus facilitating spectrum sharing; and

at least one amplitude modulation (AM) receiver adapted to receive and decode the data signal, wherein the AM receiver is adapted to be synchronized to follow a frequency hopping sequence of the transmitted data signal and to receive the data signal at a reception bandwidth such that the transmission bandwidth is greater than a reception bandwidth.

29. A system for communicating data via RF comprising the steps of:

means for preparing a data signal for transmission, including applying a step spreading code to the data signal to spread the data signal frequency within a transmission bandwidth;

means for placing the data signal received from the means for preparing the data signal for transmission onto an RF carrier and ON/OFF keying the RF carrier based on the data signal;

means for transmitting the data signal on the RF carrier such that the data signal is stepped through a selected number of channels during the ON state of the ON/OFF keying thus spreading the data signal over the transmission bandwidth, thereby reducing interference effects from other RF communication devices and thus facilitating spectrum sharing; and

at least one wideband amplitude modulation (AM) receiver adapted to receive and decode the data signal in.

30. A method of communicating data in a message sent via RF comprising the steps of:

a) preparing a data signal incorporating the message for transmission, including applying a step spreading code to the data signal to spread the data signal frequency within a transmission bandwidth;

b) placing the data signal onto an RF carder and ON/OFF keying the RF carrier based on the data signal;

c) transmitting the data signal in a single frequency per bit schemc, including, selecting a frequency of transmission prior to an ON state of the ON/OFF keying and holding at the selected frequency during the ON state such that each subsequent bit in the overall message corresponding to an ON state is transmitted at a different frequency than the previous bit corresponding to the previous ON state, thus spreading the energy of the data signal message over the transmission bandwidth, thereby reducing interference effects from other RF communication devices and thus facilitating spectrum sharing;

d) receiving and decoding the data signal in at least one receiver, the receiver being adapted to decode a data signal encoding scheme for each message, the signal encoding scheme being selected from the group consisting of frequency changes that occur in each message and all the frequencies used in transmitting the message, the receiver being synchronized to follow a frequency selection sequence of the transmitted data signal and to receive the data signal at a reception bandwidth, wherein the transmission bandwidth is greater than a reception bandwidth.

31. The method of claim 30, further comprising the step of adding a special preamble code to the message that provides a synchronization pattern of frequencies that allow the at least one receiver to utilize any one of the pattern frequencies to monitor those used in the synchronization pattern thereby providing interference protection.

32. The method of claim 30, after decoding the data signal, further comprising the steps of:

implementing an adaptive error correction algorithm for correcting a predefined number of errors, the error correction algorithm being is implemented upon detecting a high bit error rate on any combination of frequencies; and

selecting a correction algorithm for the high bit error rate, the correction algorithm selected from the group consisting of a new set of frequencies and additional overhead bits that utilize the existing frequencies, wherein providing the additional bits on the message would correct for the bits lost on corrupted frequencies.

33. The method of claim 30, wherein the step of placing the data signal onto the RF carrier includes frequency modulating the carrier with the prepared data signal.

34. A meter end point encoder transmitter device, wherein the device is operably coupled to a utility meter that forms part of a utility meter reading system, the device comprising:

a digital subsystem powered by a power supply adapted to process consumption data from the utility meter; and

a radio frequency (RF) sub-system adapted to transmit consumption data from the utility meter using a spread spectrum signal, the RF sub-system comprising a microprocessor arrangement adapted to ON-OFF key a voltage controlled oscillator (VCO) and to select an new frequency of transmission for every bit of the consumption data, the VCO coupled to a varactor-transistor arrangement adapted to spread the signal to a predetermined transmission bandwidth, wherein the transmission bandwidth exceeds a reception bandwidth at which the signal will be decoded.

35. The transmitter device of claim 34, further comprising a resistive ladder coupled between the microprocessor arrangement and a varactor tuning diode coupled to the VCO, wherein the resistive ladder functions to change the transmission frequency.

36. The transmitter device of claim 34, further comprising a digital to analog converter coupled between the microprocessor arrangement and a varactor tuning diode coupled to the VCO, wherein the digital to analog converter functions to change the transmission frequency.