Radio frequency signal multiplexing device, radio frequency signal demultiplexing device and associated digital processing system

Abstract

TITLE Radio Frequency Signal Multiplexing Device, Radio Frequency Signal Demultiplexing Device and Associated Digital Processing System The present invention relates to a radio frequency signal multiplexing device (22) comprising: - a plurality of RF inputs (44); - a plurality of frequency converters (50), each frequency converter (50) being associated with one or more RF inputs (44) and configured to receive RF signals from this or these RF inputs (44) and to convert them into optical signals; - a plurality of optical multiplexers (52), each optical multiplexer (52) being configured to multiplex at least two optical signals of different wavelengths; - a plurality of photoreceptors (54), each photoreceptor (54) being configured to convert a multiplexed optical signal into a multiplexed RF signal; - a plurality of RF outputs (46), each RF output (46) being configured to provide a multiplexed RF signal.Figure for the abbreviation: Figure 2.

Description

Title of the invention: Radio frequency signal multiplexing device, radio frequency signal demultiplexing device and associated digital processing system

[0001] The present invention relates to a radio frequency signal multiplexing system, also called RF signals.

[0002] The present invention also relates to a device for demultiplexing RF signals.

[0003] The present invention ultimately relates to a digital processing system comprising either the RF signal multiplexing device, or the RF signal demultiplexing device, or both.

[0004] The invention is more particularly situated in the field of payloads for telecommunications satellites and in particular payloads comprising a digital processor.

[0005] Such digital processors are increasingly used in telecommunications satellite payloads thanks in particular to the mission flexibility they provide.

[0006] In a manner known per se, these digital processors include analog-to-digital converters at the input and digital-to-analog converters at the output.

[0007] These processors are thus capable of performing a whole series of filtering, switching, equalization, transposition, etc. functions on digitized RF signals. This makes these processors extremely powerful equipment.

[0008] Also known per se, the input and output ports of these processors operate in fixed input and output frequency bands.

[0009] Where possible, the use of RF multiplexing functions makes it possible to aggregate several RF signals and reduce the number of input signals to be processed by the digital processor. By thus reducing the number of processor input ports, it is possible to limit its complexity, i.e., its mass, power consumption, and cost.

[0010] Symmetrically, RF demultiplexing functions at the output of the digital processor make it possible to increase the number of RF channels addressed and to limit the number of output ports of the latter.

[0011] RF multiplexing / demultiplexing functions, however, penalize payloads by the mass and cost of these specific RF filters or multiplexers.

[0012] The current state of the art consists of using RF payloads with multiplexing or demultiplexing functions implemented from filters or RF multiplexers to respectively combine or separate RF signals placed in different sub-bands.

[0013] The major drawback of the prior art is therefore to penalize these RF payloads in mass and cost with the addition of these specific filters and multiplexers.

[0014] The present invention aims to solve this problem of the prior art and therefore to propose means of carrying out multiplexing / demultiplexing functions of RF signals within payloads, in particular telecommunication satellites, without penalizing these payloads in mass and cost.

[0015] To this end, the invention relates to an RF signal multiplexing device comprising:

[0016] - a plurality of RF inputs, each RF input being configured to receive a RF signal;

[0017] - a plurality of frequency converters, each frequency converter being associated with one or more RF inputs and configured to receive RF signals from this or these RF inputs and to convert them into optical signals of wavelength chosen from at least two different wavelengths;

[0018] - a plurality of optical multiplexers, each optical multiplexer being configured to multiplex at least two optical signals of different wavelengths to form a multiplexed optical signal;

[0019] - a plurality of photoreceptors, each photoreceptor being configured to convert a multiplexed optical signal into a multiplexed RF signal;

[0020] - a plurality of RF outputs, each RF output being configured to provide a signal RF multiplexed.

[0021] According to other advantageous aspects of the invention, the multiplexing device comprises one or more of the following features taken individually or in all technically possible combinations:

[0022] - the multiplexing device further comprising a plurality of multiplexers RF, each RF multiplexer being associated with at least two RF inputs and configured to multiplex the RF signals from these RF inputs;

[0023] - each frequency converter is associated with one of the RF multiplexers and configured to receive an RF signal from this RF multiplexer;

[0024] - each frequency converter is an electro-optical Mach- type modulator Zehnder;

[0025] - the number of optical multiplexers is at least twice that of frequency converters;

[0026] - the number of photoreceptors corresponds to that of optical multiplexers;

[0027] - the number of RF outputs is at least half, advantageously four times lower than that of RF inputs;

[0028] - the multiplexing device further comprising a plurality of RF filters optical systems configured to filter optical signals before multiplexing.

[0029] The present invention also relates to an RF signal demultiplexing device comprising:

[0030] - a plurality of RF inputs, each RF input being configured to receive a RF signal;

[0031] - a plurality of frequency converters, each frequency converter being associated with one of the RF inputs and configured to receive RF signals from that RF input and to convert them into optical signals comprising two modulated wavelengths;

[0032] - a plurality of optical demultiplexers, each optical demultiplexer being configured to demultiplex each optical signal to form at least two demultiplexed optical signals of different wavelengths;

[0033] - a plurality of photoreceptors, each photoreceptor being configured to convert a demultiplexed optical signal into a demultiplexed RF signal;

[0034] - a plurality of RF outputs, each RF output being configured to provide a signal RF demultiplexed.

[0035] According to other advantageous aspects of the invention, the demultiplexing device comprises one or more of the following features taken individually or in all technically possible combinations:

[0036] - the demultiplexing device further comprising a plurality of RF filters optics configured to filter optical signals after demultiplexing;

[0037] - the multiplexing device further comprising a plurality of demultiplexers RF, each RF demultiplexer being associated with one of the photoreceptors and allows to form from the RF signal supplied by this photoreceptor at least two demultiplexed RF signals;

[0038] - each RF output is associated with one of the RF demultiplexers and configured for receive a demultiplexed RF signal from this RF demultiplexer;

[0039] - the number of optical demultiplexers is at least twice that of photoreceptors;

[0040] - the number of RF outputs is at least twice as high, advantageously four times lower than that of RF inputs;

[0041] The invention finally relates to a digital processing system comprising a processor comprising a plurality of analog input ports and / or a plurality of analog output ports;

[0042] the processing system further comprising:

[0043] - a multiplexing device as defined above, connected to the inputs analog outputs of the processor via its RF outputs; and / or

[0044] - a demultiplexing device as defined above, connected to the outputs analog inputs to the processor via its RF inputs.

[0045] These features and advantages of the invention will be better understood upon reading the following description, given solely by way of non-limiting example and with reference to the drawings in which: - [Fig.1] The [Fig.1] is a schematic view of a digital processing system according to the invention; - [Fig.2] Fig.2 is a schematic view of a multiplexing device of the digital processing system of the [Fig.1]; - [Fig.3] Fig.3 is a schematic view of the multiplexing device according to an embodiment other than that of [Fig.2]; - [Fig. 4] Fig. 4 is a schematic view of a demultiplexing device of the digital processing system of [Fig. 1]; and - [Fig. 5] [Fig. 5] is a schematic view of a demultiplexing device according to an embodiment other than that of [Fig.4].

[0046] A digital processing system 10 according to the invention has indeed been illustrated in [Fig.1].

[0047] The digital processing system 10 presents, for example, a payload from a satellite, in particular a telecommunications satellite.

[0048] According to other embodiments, the digital processing system 10 is part of any other system enabling the digital processing of digitized RF signals.

[0049] In the example of [Fig.1], the digital processing system 10 is connected at the input to a plurality of RF signal receivers 12 and at the output to a plurality of RF signal transmitters 14. According to different embodiment examples, such a connection can be made directly or through other elements known per se, such as different types of amplifiers, noise reducers, etc.

[0050] Advantageously, each RF signal receiver 12 has a radiating element, such as an element of a network antenna, for example, which is capable of receiving RF signals in a predetermined reception band. Alternatively, each RF signal receiver 12 has a passive antenna.

[0051] Similarly, each RF signal emitter 14 has an element, for example a radiating element of a network antenna, which is capable of emitting RF signals over a predetermined frequency band. Alternatively, each RF signal emitter 14 has a passive antenna.

[0052] The processing system 10 thus makes it possible to digitally process RF signals received by the RF signal receivers 12 and to generate RF signals to be emitted by the RF signal transmitters 14.

[0053] In some embodiments, the digital processing system 10 only processes received RF signals or only generates RF signals to be transmitted. In the first case, the digital processing system 10 can be connected only to the RF signal receivers 12, and in the second case, only to the RF signal transmitters 14.

[0054] To implement RF signal processing, the digital processing system 10 includes a processor 20. In addition, depending on different embodiments, the processing system 10 includes a multiplexing device 22 and / or a demultiplexing device 24.

[0055] The processor 20 is for example implemented according to VHTS technology (from the English "Very High Throughput Satellite").

[0056] Furthermore, the processor 20 allows for the conversion of analog signals into digital signals and vice versa. The processor 20 also allows for the digital processing of digitized RF signals and the generation of other signals for transmission, according to techniques known per se.

[0057] To do this, the processor 20 includes an analog / digital converter 32 for converting RF signals into digital signals and a digital / analog converter 34 for converting digital signals into RF signals.

[0058] The analog-to-digital converter 32 comprises a plurality of analog input ports. The number of these analog input ports is, for example, equal to NI.

[0059] The digital / analog converter 34 comprises a plurality of analog output ports. The number of these analog output ports is, for example, equal to N2.

[0060] The number N1 can be equal to the number N2.

[0061] This number NI or N2 is for example between 30 and 80 and advantageously equal to 50.

[0062] Moreover, the number NI is strictly less than the number of RF signal receivers 12 and the number N2 is strictly less than the number of RF signal emitters 14.

[0063] The multiplexing device 22 allows the RF signal receivers 12 to be connected to the NI analog input ports of the processor 20 and the demultiplexing device 24 allows the N2 analog output ports of the processor 20 to be connected to the RF signal emitters 14. In some embodiments, at least one RF signal receiver 12 is connected directly to an input port of the processor 20 (i.e. without going through the multiplexing device 22) and / or at least one RF signal emitter 14 is connected directly to an output port of the processor 20 (i.e. without going through the demultiplexing device 24).

[0064] The multiplexing device 22 will now be explained in more detail with reference to [Fig.2].

[0065] Thus, with reference to this [Fig.2], the multiplexing device 22 comprises a plurality of RF inputs 44. The number of these RF inputs 44 is equal to the number N3 which corresponds for example to the total number of RF signal receivers 12.

[0066] The number N3 is for example twice, advantageously four times, greater than the number NI of analog input ports of the processor 20. Thus, this number N3 is for example between 150 and 250 and for example advantageously equal to 200.

[0067] Each RF input 44 is thus connected to a corresponding RF signal receiver 12 and allows to receive each RF signal from this RF signal receiver 12.

[0068] The multiplexing device 22 further includes a plurality of RF outputs 46. Each RF output 46 is connected to one of the analog input ports of the processor 20. The number of these RF outputs 46 is then equal to the number NI.

[0069] Thus, the number of RF outputs 46 of the multiplexing device 22 is at least twice, advantageously four times less than the number of RF inputs 44.

[0070] Optionally, the multiplexing device 22 includes a plurality of RF multiplexers 48 allowing at least two RF signals from different RF inputs 44 to be multiplexed.

[0071] In particular, each RF multiplexer 48 is connected to at least two RF inputs 44, for example by RF harnesses, and allows the RF signals from these RF inputs 44 to be received and multiplexed.

[0072] Thus, the number of RF 48 multiplexers is advantageously equal to N3 / 2.

[0073] The multiplexing device 22 further comprises a plurality of frequency converters 50.

[0074] Each frequency converter 50 is connected to one of the RF multiplexers 48 and configured to receive an RF signal from that RF multiplexer 48 and convert it into an optical signal. The wavelength of this optical signal is chosen from at least two different wavelengths, namely Xi and X2.

[0075] In particular, in the embodiment of [Fig. 2], the frequency converters 50 are divided into two groups. Preferably, each group has the same number of frequency converters as the other group.

[0076] The first group of frequency converters 50 is powered by the optical signal at wavelength Xi and which carries the frequency OL1. At the output of each converter 50, the optical signal at wavelength Xi carries the mixture of the frequency OL1 with the input RF signal A at the frequency RFin of that converter 50.

[0077] The second group of frequency converters 50 is powered by the optical signal at wavelength X2 and which carries the frequency OL2. At the output of each converter 50, the optical signal at wavelength X2 carries the mixture of the frequency OL2 with the input RF signal B at the frequency RFin of that converter 50.

[0078] Thus, the total number of frequency converters 50 is advantageously equal to the number of RF multiplexers 48, i.e. N3 / 2.

[0079] Advantageously, each frequency converter 50 features an electro-optical Mach-Zehnder type modulator.

[0080] According to the invention, the multiplexing device 22 further comprises a plurality of optical multiplexers 52 and a plurality of photoreceptors 54.

[0081] Each optical multiplexer 52 is connected to at least two frequency converters 50 from different groups and thus allows the optical signals of different wavelengths from these frequency converters 50 to be grouped together.

[0082] Each optical multiplexer 52 thus allows the optical signals of different wavelengths received to be multiplexed to form a multiplexed optical signal.

[0083] Each optical multiplexer 52 is advantageously connected to the corresponding frequency converter 50 by an optical fiber.

[0084] Thus, the number of optical multiplexers 52 is at least twice less than the number of frequency converters 50.

[0085] In the example of [Fig.2], the number of these optical multiplexers 52 is then equal to N3 / 4.

[0086] Advantageously, each optical multiplexer 52 is implemented according to WDM technology (from the English "Wavelength Division Multiplexing").

[0087] Each photoreceptor 54 is advantageously connected to one of the optical multiplexers 52 by an optical fiber and configured to receive the multiplexed optical signal from this optical multiplexer and convert it into a multiplexed RF signal. This RF signal contains the two components A and B, converted in frequency to the RFin-f0L1 frequency for signal A and to the RFin-f0L2 frequency for signal B.

[0088] The number of these photoreceptors 54 is therefore equal to that of the optical multiplexers 52.

[0089] Finally, each photoreceptor 54 is advantageously connected by a coaxial cable or an RF harness to one of the RF outputs 46 and thus allows each converted multiplexed RF signal to be transmitted to this RF output 46.

[0090] Advantageously, the frequency band of multiplexed RF signals generated by the photoreceptors 54 is included in the bandwidth of the RF signals that the analog input ports of the processor 20 are capable of receiving.

[0091] The multiplexing device 22 may further include other elements, in particular connection elements for connecting the different components explained above.

[0092] For example, the multiplexing device 22 further includes a connecting ring 59 arranged between the RF multiplexers 48 and the first group of frequency converters 50 and another connecting ring 59 arranged between the RF multiplexers and the second group of frequency converters 50.

[0093] The multiplexing device 22 may further include a connecting ring 59 arranged between the photoreceptors 54 and the RF outputs 46.

[0094] This connecting ring 59 can be redundant with another connecting ring arranged on the side of the processor 20.

[0095] In an alternative embodiment shown in [Fig.3], the multiplexing device 22 further comprises a plurality of optical RF filters 56 configured to filter the optical signals before multiplexing them.

[0096] In particular, each optical RF filter 56 is connected between one of the frequency converters 55 and the corresponding optical multiplexer 52.

[0097] The number of these optical RF filters 56 then corresponds to that of the frequency converters 55.

[0098] Each optical RF filter 56 filters the corresponding optical signal, thus complementing the rejection provided by the processor 20 and preserving the signal-to-noise ratio after multiplexing. In particular, such a filter has a bandpass filter around the optical carrier with a bandwidth sufficient to avoid filtering the mixing of the corresponding LO frequency with the input RF signal corresponding to the RFin frequency of the RF converter.

[0099] The demultiplexing device 24 will henceforth be explained with reference to [Fig.4].

[0100] This demultiplexing device 24 has a structure substantially symmetric to that of the multiplexing device 22. The different components of this demultiplexing device 24 described below are therefore analogous to the corresponding components of the multiplexing device 22 but some of them operate in the opposite direction.

[0101] In particular, the demultiplexing device 24 comprises a plurality of RF inputs 64 connected to the analog output ports of the processor 20.

[0102] Each RF input 64 is therefore connected to one of the analog output ports of the processor 20 and allows receiving an RF signal from that port.

[0103] The number of these RF 64 inputs then corresponds to the number N2, that is to say, to the number of analog output ports of the processor 20.

[0104] The demultiplexing device 24 further includes for each RF input 64, a frequency converter 70.

[0105] Each frequency converter 70 is configured to receive an RF signal from the corresponding RF input 64 and to convert this RF signal into an optical signal.

[0106] Each frequency converter 70 is powered by a multiplexed optical signal consisting of a wavelength Xi which carries the frequency OL1 and a wavelength X2 which carries the frequency OL2.

[0107] At the output of each frequency converter 70, the corresponding optical signal carries the mixture of the frequency OL1 with the input RF signal A+B at the frequency RFin of this converter and the mixture of the frequency OL2 with the input RF signal A+B at the frequency RFin of this converter.

[0108] The demultiplexing device 24 further comprises, for each frequency converter 70, an optical demultiplexer 72 connected to one of the frequency converters 70 by an optical fiber.

[0109] This optical demultiplexer 72 is configured to receive each optical signal from the corresponding frequency converter 70 and to generate demultiplexed optical signals of different wavelengths, namely Xi and X2.

[0110] The demultiplexing device 24 further includes a photoreceptor 74 for each optical signal demultiplexed by the corresponding optical demultiplexer 72.

[0111] Each photoreceptor 74 is configured to convert the corresponding demultiplexed optical signal into a demultiplexed RF signal. This demultiplexed RF signal contains the two components A and B, converted to a frequency RFout = OL + RFin. For the photoreceptors in the first group (receiving Xi), component A is centered at the RFout frequency. For the photoreceptors in the second group (receiving X2), component B is centered at the RFout frequency.

[0112] An RF filter 75 after each photoreceptor 74 allows the component that we do not want to keep to be filtered (B for the first group and A for the second group).

[0113] The number of photoreceptors 74 is at least twice that of the optical multiplexers 72.

[0114] The set of photoreceptors 74 form two groups: a first group capable of receiving demultiplexed optical signals of wavelength Xi and a second group capable of receiving demultiplexed optical signals of wavelength X2.

[0115] Optionally, the demultiplexing device 24 further includes for each photoreceptor 74 an RF demultiplexer 78 enabling the formation of at least two demultiplexed RF signals from the RF signal supplied by this photoreceptor 74.

[0116] Finally, the demultiplexing device 24 further comprises a plurality of outputs 84 for supplying the demultiplexed RF signals to the transmitters of the corresponding RF signals 14. In particular, the number of these outputs 84 is equal to N4, which advantageously corresponds to the number of RF signal transmitters 14.

[0117] Thus, advantageously, the number N4 is four times greater than the number N2 of analog output ports of the processor 20.

[0118] The demultiplexing device 24 may further include other elements ensuring in particular the various connection functions within the demultiplexing device 24.

[0119] Thus, with reference to [Fig.4], the demultiplexing device 24 further includes a connecting ring 89 allowing the frequency converters 70 to be connected to a corresponding connecting ring on the processor side 20.

[0120] In addition, the demultiplexing device 24 includes a connecting ring arranged between each group of photoreceptors 74 and the corresponding RF signal demultiplexers 78.

[0121] The demultiplexing device 24 may further include an RF amplification unit 90 connected between the photoreceptors 74 and the RF demultiplexers 78. This amplification unit 90 may, for example, be of the LCTWTA type (Linearized Channelized Traveling-Wave Tube Amplifier).

[0122] Fig. 5 illustrates another example of an embodiment of the demultiplexing device 24.

[0123] According to this embodiment, the demultiplexing device 24 comprises a plurality of optical RF filters 86.

[0124] Each of these filters 86 is analogous to the optical RF filters 56 explained in relation to the multiplexing device 22.

[0125] In the example of [Fig. 5], each optical RF filter 86 is connected between one of the photoreceptors 74 and the corresponding optical demultiplexer 72.

[0126] The operation of the digital processing system 10 will now be explained.

[0127] It is initially assumed that the receivers of the RF signals 12 receive RF signals in a corresponding frequency band.

[0128] Each RF signal is then transmitted to the RF input 44 of the multiplexing device 22 to be subsequently multiplexed by the corresponding RF multiplexer 48 with another RF signal received by another RF signal receiver 12.

[0129] Next, each signal multiplexed by the RF multiplexer 48 is transmitted to one of the groups of frequency converters 50. The RF signals received by the first group of frequency converters are converted into optical signals of wavelength Xi and the RF signals transmitted to the second group of frequency converters 50 are converted into optical signals of wavelength X2.

[0130] Next, the signals of different wavelengths are multiplexed within the same optical multiplexer 52 to obtain a multiplexed optical signal which is then converted into a multiplexed RF signal by the corresponding photoreceptor 54.

[0131] Next, each multiplexed RF signal is transmitted to the processor 20 via the corresponding output 46.

[0132] The processor 20 then converts these RF signals into digital signals for their digital processing.

[0133] Then, depending on these processed signals, the processor 20 can for example generate other digital signals which will be transmitted by the transmitters of the RF signals 14.

[0134] In such a case, the processor 20 converts these digital signals into analog signals which are then transmitted via the inputs 64 to the demultiplexing device 24.

[0135] Next, each signal received by the demultiplexing device 24 is first processed by the corresponding frequency converter 70 before being transmitted to the optical demultiplexer 72.

[0136] This optical demultiplexer 72 then generates demultiplexed optical signals which are transmitted to the corresponding photoreceptors 74 and are converted by these photoreceptors 74 into radio frequency signals.

[0137] Next, the demultiplexed signals are demultiplexed again by the demultiplexers 78 before being transmitted to the signal emitters 14 via the outputs 84.

[0138] Thus, the radio frequency signals are received by the RF signal transmitters 14 which can then transmit them in a corresponding frequency band.

[0139] It is therefore understood that the present invention has a number of advantages.

[0140] First, the invention makes it possible to implement the multiplexing / demultiplexing function using an optical multiplexer / demultiplexer, respectively. The latter can be mass-produced and has a cost and mass much lower than those traditionally used in the prior art, namely radio frequency demultiplexers or multiplexers.

[0141] Thus, the mass and cost of the multiplexing and demultiplexing device can be reduced.

[0142] In addition, the invention allows for greater use of fiber optic cable connections.

[0143] This is particularly advantageous because optical fiber has a weight that is less than that of harnesses or coaxial cables.

[0144] Thus, it is possible to replace most of the harnesses or coaxial cables currently used in digital processing systems with optical fiber cables, thereby further reducing the cost and mass of this system.

[0145] Of course, other embodiments are also possible.

Claims

Demands

1. RF signal multiplexing device (22) comprising: - a plurality of RF inputs (44), each RF input (44) being configured to receive an RF signal; - a plurality of frequency converters (50), each frequency converter (50) being associated with one or more RF inputs (44) and configured to receive the RF signals from this or these RF inputs (44) and to convert them into optical signals of a wavelength selected from at least two different wavelengths; - a plurality of optical multiplexers (52), each optical multiplexer (52) being configured to multiplex at least two optical signals of different wavelengths to form a multiplexed optical signal; - a plurality of photoreceptors (54), each photoreceptor (54) being configured to convert a multiplexed optical signal into a multiplexed RF signal;- a plurality of RF outputs (46), each RF output (46) being configured to provide a multiplexed RF signal.;

2. Multiplexing device (22) according to claim 1, further comprising a plurality of RF multiplexers (48), each RF multiplexer (48) being associated with at least two RF inputs (44) and configured to multiplex the RF signals from these RF inputs (44).

3. Multiplexing device (22) according to claim 2, wherein each frequency converter (50) is associated with one of the RF multiplexers (48) and configured to receive an RF signal from that RF multiplexer (48).

4. Multiplexing device (22) according to any one of the preceding claims, wherein each frequency converter (50) is an electro-optical Mach-Zehnder type modulator.

5. Multiplexing device (22) according to any one of the preceding claims, wherein the number of optical multiplexers (52) is at least twice less than the number of frequency converters (50).

6. Multiplexing device (22) according to any one of the preceding claims, wherein the number of photoreceptors (54) corresponds to that of optical multiplexers (52).

7. Multiplexing device (22) according to any one of the preceding claims, wherein the number of RF outputs (46) is at least twice, advantageously four times, less than the number of RF inputs (44).

8. Multiplexing device (22) according to any one of the preceding claims, further comprising a plurality of optical RF filters (56) configured to filter optical signals before multiplexing.

9. RF signal demultiplexing device (24) comprising: - a plurality of RF inputs (64), each RF input (64) being configured to receive an RF signal; - a plurality of frequency converters (70), each frequency converter (70) being associated with one of the RF inputs (64) and configured to receive the RF signals from that RF input (64) and to convert them into optical signals comprising two modulated wavelengths; - a plurality of optical demultiplexers (72), each optical demultiplexer (72) being configured to demultiplex each optical signal to form at least two demultiplexed optical signals of different wavelengths; - a plurality of photoreceptors (74), each photoreceptor (74) being configured to convert a demultiplexed optical signal into a demultiplexed RF signal; - a plurality of RF outputs (84), each RF output (84) being configured to provide a demultiplexed RF signal.

10. Demultiplexing device (24) according to any one of the preceding claims, further comprising a plurality of optical RF filters (86) configured to filter optical signals after their demultiplexing.

11. A digital processing system (10) comprising a processor (20) comprising a plurality of analog input ports and / or a plurality of analog output ports; the processing system (10) further comprising: - a multiplexing device (22) according to any one of claims 1 to 8, connected to the analog inputs of the processor (22) by its RF outputs (46); and / or - a demultiplexing device (24) according to any one of claims 9 to 10, connected to the analog outputs of the processor (22) by its RF inputs (64).

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