Low-Power, Noise Insensitive Communication Channel using Logarithmic Detector Amplifier (LDA) Demodulator

• US 20140269972A1
• Filed: 03/14/2014
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: DockOn AG
• Original Assignee: DockOn AG
• Inventors: Rada, Patrick, Brown, Forrest
• Granted Patent: US 9,048,943 B2
• Time in Patent Office: Days
• US Class Current: 375/285
• CPC Class Codes: H03D 2200/0098 by compensating temperature induced variations
• CPC Class Codes: H03D 3/00 Demodulation of angle-, frequency- or phase- modulated oscillations H03D5/00, H03D9/00, H03D11/00 take precedence
• CPC Class Codes: H03D 3/005 wherein the demodulated signal is used for controlling a bandpass filter automatic bandwidth control H03G; automatic frequency control H03J7/02
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/3838 Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04B 3/02 Details
• CPC Class Codes: H04L 27/106 M-ary FSK
• CPC Class Codes: H04L 27/2014 in which the phase changes in a piecewise linear manner during each symbol period, e.g. minimum shift keying, fast frequency shift keying H04L27/201 takes precedence
• CPC Class Codes: H04L 27/2017 in which the phase changes are non-linear, e.g. generalized and Gaussian minimum shift keying, tamed frequency modulation H04L27/201 takes precedence
• CPC Class Codes: H04M 1/0202 Portable telephone sets, e.g. cordless phones, mobile phones or bar type handsets constructional features of telephone transmitters or receivers, e.g. of speakers or microphones H04M1/03

Abstract

A method is provided for communicating signals at a low power level in an electromagnetic interference (EMI) environment. A first device transmits a modulated signal having a first carrier frequency, including the encoded information via a hardwire transmission medium. In one aspect, the power level of the modulated signal can be adjusted to minimize power consumption or reduce the generation of EMI. The modulated signal may be in one of the following formats: frequency modulation (FM) or phase modulation (PM) to name a few examples. A second device including a logarithmic detector amplifier (LDA) demodulator circuit receives the signal, which may be mixed with EMI. The LDA demodulator circuit amplifies the modulated signal, without amplifying the EMI, to supply a demodulated baseband signal, which may be an n-ary digital signal, or an audio signal. A low-power, noise insensitive communication channel is also provided.

Claims

1. A low-power, noise insensitive communication channel comprising:

a first device comprising;

a first modulator having an input to accept a baseband signal with encoded information, and an output to supply a modulated signal having a first carrier frequency, including the encoded information;

a first interface connected to a hardwire transmission medium to supply the modulated signal;

a second device comprising;

a second interface connected to the hardline transmission medium;

a first logarithmic detector amplifier (LDA) demodulator circuit having an input connected to the second interface, and an output to supply the baseband signal with the encoded information.

2. The communication channel of claim 1 wherein the first modulator accepts a baseband signal selected from a group consisting of an n-ary logic digital signal, a digital-to-analog converted signal, an analog signal, and an audio signal.

3. The communication channel of claim 1 wherein the LDA demodulator circuit comprises a frequency-to-voltage converter (FVC) to accept a series of second frequency pulses having a rate of change at least twice that of an encoded information rate, and converts the series of second frequency pulses to a series of voltage levels at the encoded information rate.

4. The communication channel of claim 1 wherein the first modulator is a voltage controlled oscillator (VCO) accepting an n-ary logic digital signal, and supplying an n-frequency shift keying (n-FSK) modulated FM signal;

and,

wherein the first LDA demodulator circuit supplies the n-ary logic digital signal.

5. The communication channel of claim 1 wherein the first device further comprises:

a second LDA demodulator circuit having an input and an output; and

,

a first switch having an input connected to the first interface, a first switch position connected to the input of the second LDA demodulator circuit, a second switch position connected to the first modulator output, and a control input to accept a first control signal selectively connecting the first switch input to a switch position.

6. The communication channel of claim 5 wherein the second device further comprises:

a second modulator having an input and an output; and

,

a second switch having an input connected to the second interface, a first switch position connected to the input of the first LDA demodulator circuit, a second switch position connected to the second modulator output, and a control input to accept a second control signal selectively connecting the second switch input to a switch position.

7. The communication channel of claim 1 wherein the first modulator is an LDA-VCO comprising:

an amplifier having an input and an output;

a capacitor connected between the amplifier input and output;

a variable direct current (DC) bias source connected to the amplifier input, responsive to the baseband signal;

a first parallel resonant circuit connected between the amplifier output and a reference voltage, having a resonance at the first frequency; and

,

wherein the amplifier output supplies a signal centered at the first frequency and modulated in response to the variable bias source.

8. The communication channel of claim 1 wherein the modulator is an LDA-VCO further comprising:

an amplifier having an input and an output;

a capacitor connected between the amplifier input and output;

a DC bias source connected to the amplifier input;

a first parallel resonant circuit connected between the amplifier output and a reference voltage, having a resonance at the first frequency;

a varicap connected in parallel with the first parallel resonant circuit, to accept a variable tuning voltage responsive to the baseband signal; and

,

wherein the amplifier output supplies a signal centered at the first frequency and modulated in response to the variable tuning voltage.

9. The communication channel of claim 1 wherein the first modulator supplies the modulated signal in a format selected from a group consisting of frequency modulation (FM), phase modulation (PM), binary frequency shift keying FSK, n-ary frequency shift keying (n-FSK), Gaussian frequency-shift keying (GFSK), n-ary Gaussian frequency-shift keying (n-GFSK), minimum-shift keying (MSK), n-ary minimum-shift keying modulation (n-MSK), Gaussian minimum-shift keying (GMSK), n-ary Gaussian minimum-shift keying (n-GMSK), pulse width modulation (PWM), and amplitude modulation (AM).

10. The communication channel of claim 1 wherein the transmission medium is selected from a group consisting of single-ended and differential signal media, a printer circuit board (PCB) metal trace, conductive ink, conductive semiconductor trace, conductive polymer trace, bad conductor trace, meta-metal conductor, conductive trace, nanotube conductor, wire, wire twisted-pair, wire double twisted pair, wire quadruple twisted pair, DSL line, Ethernet line, connector, wire harness, microstrip, waveguide, fiber optic cable, power line, coaxial cable, and stripline.

11. The communication channel of claim 1 wherein the first modulator has a power control port to receive a variable power level control signal, and wherein the first modulator supplies the modulated signal at a power level responsive to the power level control signal.

12. A method for communicating signals at a low power level in an electromagnetic interference (EMI) environment, the method comprising:

a first device transmitting a modulated signal having a first carrier frequency, including encoded information, via a hardwire transmission medium;

the hardwire transmission medium being exposed to an environment comprising EMI;

the EMI combining with the modulated signal on the hardwire transmission line to create a mixed signal;

a second device including a logarithmic detector amplifier (LDA) demodulator circuit receiving the mixed signal;

the LDA demodulator circuit amplifying the modulated signal, without amplifying the EMI; and

,

the LDA demodulator circuit supplying a demodulated baseband signal.

13. The method of claim 12 wherein the EMI is selected from a group consisting of Gaussian noise, pink noise, thermal noise, shot noise, 1/f noise, flicker noise, burst noise, transit-time noise, avalanche noise, industrial noise, atmospheric noise, solar noise, cosmic noise, quantification noise, cross-talk noise, electromagnetic interference, one or more fast transition logic signal(s) EMI, EMI generated as a result of flickering light a sensitive electronic circuit, and EMI generated by an oscillator clock.

14. The method of claim 12 wherein transmitting the modulated signal includes the modulated signal being in a format selected from a group consisting of frequency modulation (FM), phase modulation (PM), binary frequency shift keying FSK, n-ary frequency shift keying (n-FSK), Gaussian frequency-shift keying (GFSK), n-ary Gaussian frequency-shift keying (n-GFSK), minimum-shift keying (MSK), n-ary minimum-shift keying modulation (n-MSK), Gaussian minimum-shift keying (GMSK), n-ary Gaussian minimum-shift keying (n-GMSK), pulse width modulation (PWM), and amplitude modulation (AM).

15. The method of claim 12 wherein transmitting the modulated signal includes transmitting a signal modulated to carry a baseband n-ary logic digital signal;

and,

wherein supplying the baseband signal includes supplying the baseband n-ary logic digital signal.

16. The method of claim 12 wherein the transmitting the modulated signal includes transmitting an n-frequency shift keying (n-FSK) modulated FM signal;

and,

wherein supplying the baseband signal includes supplying log₂(n) streams of baseband binary logic digital signals.

17. The method of claim 12 wherein transmitting the modulated signal via the hardwire transmission medium includes transmitting via a hardwire transmission medium selected from a group consisting of single-ended and differential signal media, a printer circuit board (PCB) metal trace, wire, wire twisted-pair, conductive ink, conductive semiconductor trace, conductive polymer trace, bad conductor trace, meta-metal conductor, conductive trace, nanotube conductor, wire double twisted pair, wire quadruple twisted pair, DSL line, Ethernet line, connector, wire harness, microstrip, waveguide, fiber optic cable, power line, coaxial cable, and stripline.

18. The method of claim 12 wherein supplying the demodulated baseband signal includes:

converting the modulated signal to a series of second frequency pulses having a rate of change at least twice that of an encoded information rate; and

,

converting the series of second frequency pulses to a series of voltage levels at the encoded information rate.

19. The method of claim 12 wherein supplying the baseband signal includes supplying a baseband signal selected from a group consisting of an n-ary logic digital signal, an analog signal, and an audio signal.

20. The method of claim 12 further comprising:

the first device receiving a power control signal; and

,

wherein the first device transmitting the modulated signal includes the first device transmitting the modulated signal at a power level responsive to the control signal.

21. A method for communicating signals at low power levels, the method comprising:

at a first time, a first device transmitting a baseband signal with encoded information via a first hardwire transmission medium;

at the first time, a second device successfully receiving the baseband signal when it is transmitted at a minimally sufficient first power level, or greater;

at a second time, the first device modulating the baseband signal, creating a modulated signal having a first carrier frequency, including the encoded information;

at the second time, the first device transmitting the modulated signal, via the hardwire first transmission medium, to the second device at a second power level, less that the first power level; and

,

at the second time, the second device using a logarithmic detector amplifier (LDA) demodulator circuit to successfully convert the modulated signal to the baseband signal.

22. The method of claim 21 wherein the first device transmitting the baseband signal at the first time includes transmitting baseband binary logic digital signals via log₂(n) hardwire transmission media, where n is an even integer greater than 1;

wherein the first device modulating the baseband signal at the second time includes modulating an n-ary logic digital signal, creating an n-ary modulated signal;

wherein transmitting the modulated signal at the second time includes transmitting the n-ary modulated signal via only the first hardline transmission medium; and

,

wherein the second device successfully converting the modulated signal to the baseband signal at the second time includes converting the n-ary modulated signal to the n-ary logic digital signal.

23. The method of claim 21 wherein the first device modulating the baseband signal at the second time includes the first device modulating a baseband signal selected from a group consisting of an n-ary logic digital signal, a digital-to-analog converted signal, an analog signal, and an audio signal.

24. The method of claim 21 wherein transmitting the modulated signal via the first hardwire transmission medium at the second time includes transmitting via a hardwire transmission medium selected from a group consisting of single-ended and differential signal media, a printer circuit board (PCB) metal trace, conductive ink, conductive semiconductor trace, conductive polymer trace, bad conductor trace, meta-metal conductor, conductive trace, nanotube conductor, wire, wire twisted-pair, wire double twisted pair, wire quadruple twisted pair, DSL line, Ethernet line, connector, wire harness, microstrip, waveguide, fiber optic cable, power line, coaxial cable, and stripline.

25. The method of claim 21 further comprising:

subsequent to the second time, the first device receiving a power control signal;

at a third time, the first device transmitting the modulated signal at a third power level less that the second power level in response to receiving the power control signal; and

,

at the third time, the second device successfully converting the modulated signal to the baseband signal.