Device for the digital radio transmission of data comprising video information

Translation of description of equivalent WO 2004062290 A1

RADIO TRANSMISSION DEVICE DIGITAL DATA

INCLUDING INFORMATION VIDEO

Technical Field The invention relates to the field of digital transmission systems.

It is more particularly transmission devices that can be networked in order to transmit by radio video signal type.

The invention finds particular application in the realization of remote surveillance camera networks, in a variety of configurations including places difficult equippable with traditional wired devices.

pRIOR ART

To date, existing solutions in the field of video monitoring are limited for various reasons related to the technology used. Thus, systems have been proposed in which a camera is equipped with a radio transmitter transmitting to a single receiver associated with a video processing system. Such systems are in particular marketed by the Company MICROWAVE RADIO COMMUNICATION. This type of system is used in particular in the field of television report, but it can not be transposed to the field of remote monitoring, which requires multiple images can be analyzed simultaneously.

Other solutions have already been proposed in which several cameras each have a transmitter and transmit their information to a single receiver associated with the video information processing chain.

This type of solution has the disadvantage of requiring and position the receiver to a location where it is accessible to all issuers. This limits the extent of the coverage of the system to a power level given emission. In addition, complex configurations, with multiple canyons can not be equipped with such systems.

Furthermore, technologies, including communication protocols do not allow the transmission of a large amount of video information, so that this type of system is not adapted to provide remote monitoring.

Have also been described in document US 2002/009154 a domestic system, for connecting to a local network of very small dimensions different electronic and computer devices. This type of system works with an IEEE 1394 interface that requires very high bandwidth to carry video streams, so it is in no way transferable to a radio monitoring system, including a large number of camera.

A first objective of the invention is to allow to connect a large number of video cameras with a central facility capable of providing analysis, backup or other operation on the set of video data acquired by each camera.

An object of the invention is also to enable to deploy this type of very simple installation, thus without requiring costly wired infrastructure.

Another objective is to enable the implementation of this type of installation without limitation as to the configuration of the area to cover.

Disclosure of Invention

The invention therefore relates to a digital radio data transmission device including video information. According to the invention, this device is characterized in that it comprises: ^at a video capture camera,

"A compression stage, adapted to generate a digital signal from the signal from the video capture camera, with a compression ratio at least greater than 1: 300,

"A shaper stage, suitable for inserting the compressed video signal in a frame,

"A stage of digital modulation, adapted to generate a digital radio signal," a transmission / reception stage, adapted to transmit the digital radio signal in a predetermined frequency band, similar to transmission devices and to receive signals including frames of same structures issued by similar devices.

In other words, the invention consists in providing a network connecting each of the unit devices. A stream of data is thus provided between each of the devices, which integrate to this feed the video signal of his own camera and in real time. Each device therefore receives all the video signals of all devices connected to the network, and thus ensures the transmission screw to screw devices which are in its field of transmission and reception.

The network of these devices unit thus providing a mesh that can be deployed on a network coverage area can be extensive, without comparison with that of existing devices. In addition, each of the devices of the network providing the spread of all the video signals, it is possible to deploy the network in bumpy configuration areas, since it is sufficient that a single device is connected with another device network for its video signal can be routed to the monitoring system.

In practice this means that a camera can be placed in a confined area, since it is within reception range and emission of another device in a more open area. In addition, this mesh ensures a certain redundancy in case one of the devices fails.

The integration of a large number of video signals to allow particular ensure remote monitoring tasks is achieved through the use of a compression rate particularly high and greater than 300. This type of compression can be achieved in particular using compression algorithms in MPEG-4 format, with the option of rate adaptation.

In practice, the video capture camera can generate either an analog signal or a digital signal. This is compared to the bandwidth of the digitized equivalent analog signal that is determined compression rate.

In a particular embodiment, the compression stage can be directly integrated with the video capture camera. However, it can be separated from the latter and form a specific electronic circuit.

Advantageously in practice, each device may include means for remotely change the viewing angle of the camera, that is to say that each camera can provide zoom, or even can be rotated or moved to sweep a wider area.

In the latter case, it may be provided to physically separate the mobile camera of the transmission / reception floor to avoid Doppler phenomena can disrupt the transmission and radio reception.

In the case where the device form a unitary mechanical assembly, these phenomena are taken into account in the characterization of the transmission and reception performance. To facilitate the implementation of these devices in inaccessible places, notably in terms of electrical infrastructure can advantageously include autonomous power supply means, for example through solar panels or equivalent. The type of camera used can allow a night surveillance, or more generally can be adapted to specific conditions of visibility.

In practice, each device includes a compressed video signal in a predetermined manner organized frame, according to the techniques known under the name of "transport stream". The shaper stage therefore provides multiplexing for inserting data in the general frame.

Thereafter, the frame is forwarded to the digital modulation stage which can operate according to different techniques, so as to generate radio frequency signals. The modulations may be of multi-access type division broadband code, coding more known as COFDM for "Coded orthogonal Frequency Division Multiplexed."

Other types of coding, including encoding by division multiple access in broadband code, also known as WCDMA name for "Wide Band Code Division Multiple Acc Bachelor" can be used.

Other coding systems, for example mixing the two types shown may also be used.

The radio signal thus generated can be sent or received in different modes of transmission, especially in SFN mode to "Single Frequency Network" or even in MFN mode "Multiple Frequency Network".

In practice, the floor emission reception may have either a local directional antenna, or even a distributed antenna, which can take the form of a radiating cable, for example of coaxial type. Brief description of figures

The manner of implementing the invention and the advantages thereof will appear from the description of the embodiment which follows, given by way of example, and in support of the appended figures in which: Figure 1 is a plan view General of an area equipped with a device according to the invention.

Figure 2 is a block diagram illustrating the operation of a single device.

Embodiment of the invention

As already stated, the invention relates to a digital radio transmission device including video information, which finds particular application in the field of remote monitoring.

In this case, and as illustrated in Figure 1, several unit devices (1,

2, 3, 4) can be installed on different buildings at particular locations, so as to monitor the zones Zl, Z2, Z3, Z4 specific.

These transmission devices (1-4) are connected by digital radio link between them so as to form a network. It is observed that this network can be meshed between devices (1, 2, 3). The device (4) is itself disposed in an area wherein it is within the reach of one device (2), which however allows to connect to the network.

This network is also connected to a particular device (5) to ensure the collection of information and analysis, for example in a monitoring center.

Of course, the central station can be connected to the device (5) either directly or via a computer link high speed, for example by optical fiber. Schematically and as illustrated in Figure 2, a unitary device (10) comprises a video capture camera (11). The camera (11) is developing a video signal, which can be decorated eg an audio signal, and data specific to the camera, which may for example include the date and time of 5 shots, different identifiers, and the positioning parameters and camera orientation.

This camera is connected to a compression stage (15) for compressing the various data, whether it is video, audio or other,

10 according to predetermined formats. This format may preferably be the format

MPEG-4 or DivX-5 in terms of video data, or alternatively the format

MPEG-1 audio signals.

The camera can incorporate into its internal electronic operations 15 compression so that it delivers an already compressed signal.

This signal is then passed to a shaping stage (16). This signal provides the basic framing (TSN) of the various signals produced by the camera (11) and compressed. Each of the subframes (TSN) is then integrated by multiplexing 20 in a general frame (18).

The compression ratio is greater than 300, so as to limit the bandwidth used. In practice, it is preferred that this bandwidth is lower for each of the unit devices 500 kbit per second. 25

Thereafter, the overall frame (18) thus produced is transmitted to a modulation stage (19), to ensure the channel coding. Different types of coding can be used, including those already mentioned and known by the abbreviations COFDM or WCDMA, depending mainly on the standard ETS 300

30,744. This digital modulation stage (19) generates a signal which is then transmitted to a radio modulation stage (20) to generate the wireless signal to be transmitted by the antenna (21).

This signal is typically in the frequency bands of 2.4 gigahertz or 5 gigahertz, but not whether a key point for the embodiment of the present invention.

The device (10) is also capable of receiving information from similar devices, the receiving stage (22) which provides the demodulation of the radio signal received by the antenna (23).

The signal is then passed to a demodulator providing the channel decoding (24). This floor (24) thus decodes the received signal to transmit the global frame to the shaping stage (16). It is in this overall decoded frame that the device (16) incorporates, as already mentioned data on the new acquisition by the camera (11).

It follows from the above that the device according to the invention has many advantages, including that of allowing the realization of camera networks and more generally systems for transit of video or data derived, with the option to retain a particularly high flow rate (typically of the order of 512 kbit / s) and for a sufficient number of high cameras (typically several tens).

industrial applications

This device is particularly suitable for the realization of remote monitoring tasks, either in group housing, in particular areas such as car parks, shopping malls and other public places where security requirements are important. -s "

In particular forms, the devices can be mounted on moving vehicles such as buses, subways, trains and other armored vehicles.

The device according to the invention can also be installed very quickly to cover public or private places as part of event organization or event.