Disclosure of Invention
It is therefore an object of the present invention to provide a transmitter-receiver comprising an electronic chip which allows sharing the same processing means of the chip to process signals originating from different transmission media while providing the possibility of full duplex communication in such different transmission media.
To this end, the invention relates to a transmitter-receiver comprising an electronic chip, which comprises the features specified in independent claim 1.
Particular embodiments of the transmitter-receiver are defined in the dependent claims 2 to 13.
One advantage of the invention is that with the arrangement proposed in the transmitter-receiver according to the invention, it is possible to use the same radio frequency reception channel as used in conventional radio frequency signal transmitter-receivers for demodulating signals coming from another optical or acoustic transmission medium.
Furthermore, since there is a second frequency synthesizer in the transmitter-receiver, which is configured to synthesize a low-frequency modulated signal to be provided by the auxiliary output terminal, full-duplex communication can be performed in different transmission media. The second frequency synthesizer is typically a low frequency synthesizer. The center frequency of the modulated signal provided by the second frequency synthesizer is equal to the value of the intermediate frequency.
Another advantage of the transmitter-receiver according to the invention is that in case the radio frequency medium is interrupted, a secure, confidential and efficient communication can still be performed on a medium different from the radio frequency medium. Such a break in the radio frequency medium may be the result of saturation of a domestic radio frequency network of the WiFi or bluetooth type, for example.
Another advantage of the transmitter-receiver according to the invention is that it is possible to accurately locate its carrier, whether it be a user or an object. In particular, this is a result of the properties of certain given transmission media (e.g., infrared and ultrasonic media). This may be advantageously used in applications of the type such as locating people in rooms of a building, public and/or urban lighting systems or even underwater or surface communication beacons.
Another advantage of the transmitter-receiver according to the invention is that it allows to easily add additional functionalities in existing radio frequency transmitter-receivers, providing them with advantageous characteristics, typically directional characteristics such as ensuring confidentiality of the transmission. Such added functionality includes, for example, adding two infrared diodes, one for receiving infrared signals and the other for emitting infrared signals.
A further advantage of the arrangement proposed in the transmitter-receiver according to the invention is that it limits the power consumption of the transmitter-receiver, while in particular the radio frequency function is only woken up when a signal from another transmission medium is detected. Such detection may comprise, for example, the detection of low-power infrared signals, or the detection of signals originating from RFID (radio frequency identification) sensors in a network of sensors arranged in the vicinity of the transmitter-receiver.
Advantageously, the first frequency synthesizer comprises for example an internal sigma-delta modulator, and the second frequency synthesizer may be formed by a part of the sigma-delta modulator and thus reconfigured as a low frequency synthesizer. This allows a greater sharing of resources already present in the electronic chip in order to process the radio frequency signals. This saves space and reduces the number of components that make up the chip, thereby reducing cost.
Detailed Description
In the following description, all components of the frequency synthesizer, in particular in the transmitter-receiver of radio frequency signals and signals from a frequency domain different from the radio frequency domain, which are well known to the person skilled in the art, are described only in a simplified manner.
Fig. 1 shows an overall view of a transmitter-receiver 1. The transmitter-receiver 1 comprises an electronic chip 2. In the normal operation mode, the transmitter-receiver 1 further includes: an antenna 4 for transmitting and receiving radio frequency signals having a carrier frequency of about 2.4 GHz; means 6 for receiving optical, infrared, sound or ultrasonic signals, and means 8 for emitting optical, infrared, sound or ultrasonic signals. In the exemplary embodiment shown in fig. 1, the receiving means 6 are constituted by an infrared diode for receiving infrared signals and the transmitting means 8 are constituted by an infrared diode for transmitting infrared signals.
The electronic chip 2 comprises a radio frequency input and output terminal 10 connected to the antenna 4, an auxiliary input terminal 12 connected to the receiving means 6 and an auxiliary output terminal 14 connected to the transmitting means 8. The radio frequency input and output terminal 10 is used for receiving and transmitting high frequency signals. Auxiliary input terminal 12 and auxiliary output terminal 14 are used for receiving and transmitting, respectively, low frequency signals, typically periodic signals having a frequency substantially equal to 400 kHz. The electronic chip 2 preferably also includes a receive Low Noise Amplifier (LNA)18 that receives the signal from the antenna 4, a modulated signal output Power Amplifier (PA)20, a receive low frequency amplifier 22 that receives the signal from the auxiliary input terminal 12, and a programmable supply component 24 that provides the modulated output signal to the auxiliary output terminal 14. This modulated output signal is used by the device 8 to emit an optical, infrared, acoustic or ultrasonic signal. The programmable supply component 24 is, for example, a programmable low frequency amplifier, as shown in fig. 1. Alternatively, the programmable supply assembly 24 may be a programmable current source or voltage source. The electronic chip 2 preferably also comprises an impedance matching transformer 26 connected between the radio frequency input and output terminals 10 on the one hand and the receiving low noise amplifier 18 and the power amplifier 20 on the other hand.
The electronic chip 2 further comprises a mixer 28, a switch 30 having two inputs, a filter and gain stage 32, a modulator-demodulator 34, a first frequency synthesizer 36 and a second frequency synthesizer 38.
A first input of mixer 28 is coupled to the output of receive low noise amplifier 18. A second input of mixer 28 is coupled to an output of a first frequency synthesizer 36. Thus, the mixer 28 is operative to mix the frequency of the amplified radio frequency signal received from the receive low noise amplifier 18 with the frequency of the oscillator signal provided by the first frequency synthesizer 36 to provide an intermediate periodic signal of intermediate frequency. The value of the frequency of the oscillating signal is for example substantially equal to 2.4 GHz. The intermediate periodic signal provided at the output of mixer 28 is a single or quadrature intermediate signal. The intermediate frequency of the intermediate signal is for example substantially equal to 400 kHz.
A first input of the switch 30 is connected to the output of the receiving low frequency amplifier 22. A second input of switch 30 is connected to the output of mixer 28. Switch 30 is configured such that it selects one of the two signals present at its inputs and provides the selected signal at the output to filter and gain stage 32. Thus, by using the switch 30, the intermediate frequency part of the radio frequency circuit can be used and a low frequency signal from the auxiliary input terminal 12 can be injected therein. In addition, the arrangement proposed in the transmitter-receiver 1 according to the invention allows to demodulate signals coming from another transmission medium using the same radio frequency reception channel, while maintaining a standard chip size.
A filter and gain stage 32 is connected between the output of switch 30 and the input of a modulator-demodulator 34. As shown in fig. 1, filter and gain stage 32 includes a low pass or band pass filter 40 and at least one amplifier 42, which amplifier 42 amplifies the filtered intermediate signal.
The modulator-demodulator 34 allows to demodulate the received data signal and is itself connected to a processing unit not shown in the figure. It should be noted that in general the filtered, amplified and demodulated intermediate signal is digitally converted, i.e. sampled, in the processing unit while being clocked by a clock signal from a reference oscillator.
A first frequency synthesizer 36 is connected between the output of the modulator-demodulator 34 and the power amplifier 20. As mentioned above, the other output of the first frequency synthesizer 36 is connected to the input of the mixer 28. The first frequency synthesizer 36 is configured such that it provides a modulated signal, for example a frequency modulated signal, to the radio frequency input and output terminal 10 via the power amplifier 20. The carrier frequency of such frequency modulated signals is for example equal to about 2.4 GHz. The first frequency synthesizer 36 typically comprises, for example, an internal sigma-delta modulator (sigma-delta modulator) not shown in fig. 1. The first frequency synthesizer 36 may be, for example, an FSK (frequency shift keying) or GFSK (gaussian frequency shift keying) two-point frequency modulation synthesizer.
A second frequency synthesizer 38 is connected between the output of the modulator-demodulator 34 and the programmable supply assembly 24. Second frequency synthesizer 38 is configured to provide a modulated signal, such as a frequency modulated signal, to programmable supply assembly 24. The center frequency of the signal synthesized by the second frequency synthesizer 38 is equal to the intermediate frequency. Thus, the frequency (synthesized by the second frequency synthesizer 38) is, for example, substantially equal to 400 kHz. The modulation signal provided by the second frequency synthesizer 38 to the programmable supply assembly 24 is frequency modulated at a deviation of ± 50kHz, for example around 400 kHz.
In an advantageous example embodiment of the present invention, the second frequency synthesizer 38 forms part of the first frequency synthesizer 36 and is configured such that it synthesizes a modulated signal using a sigma-delta modulator internal thereto.
The second frequency synthesizer 38 is typically a low frequency synthesizer. The auxiliary output terminal 14 is a low-frequency signal output terminal that supplies a low-frequency modulation signal to the transmission device 8. The emitting means 8 emit an optical, infrared, acoustic or ultrasonic signal upon receiving the low frequency modulated signal.
It will thus be appreciated that, thanks to the transmitter-receiver according to the invention, full duplex communication can be carried out in different transmission media, to enable additional transmission of other signals in case the radio frequency medium is interrupted.