COMPACT RADIO MONITORING DEVICE
FIELD OF THE INVENTION
The invention relates to the field of the monitoring of HF, VHP and UHF transmissions by hertzian path, these transmissions possibly being as well produced by radio broadcasting equipment. It relates more particularly to the field of spectrum measurements and goniometric measurements intended notably to monitor the spectrum of the waves transmitted in a given area and determine, when appropriate, the location of a source that does not, for various reasons, comply with the standards relating to the transmission of a radiofrequency signal in a given area.
CONTEXT OF THE INVENTION - PRIOR ART
Radio monitoring consists very generally in monitoring in a determined area the presence and the position of transmission sources in the area, in monitoring the quality of the spectrum of the transmitted signals and, in the case of transmissions that do not correspond to the standards drawn up by the competent authorities, in determining the location of the corresponding sources. In this context, interest is in particular focused on all the known or unknown transmissions, or on those which, in the event of malfunction, can constitute a pollution for the surrounding transmissions.
To perform the spectrum monitoring tasks on the transmissions made in a given area, the use of separate standalone equipment is known. Such equipment mainly comprises reception means and spectral analysis means. These means process the signals picked up by an antenna perched on a mast, the gain of the antenna and the length of the mast being dependent on the required detection performance characteristics. The spectral analysis is, moreover, generally performed over a narrow band, corresponding, for example, to the bandwidth of the reception means. Because of this, scanning a wide frequency band entails repeating the analysis several times by shifting the bandwidth of the receiver within the frequency band to be analyzed. The spectral analysis means generally consist of a measuring instrument such as

a spectrum analyzer making it possible to determine the amplitude and the width of each spectral component present in the band being analyzed.
Similarly, in the field of locating sources that infringe the regulations, goniometric measurements are implemented making it possible to determine, using known equipment, the direction from which the transmitted wave arrives. The principle of operation of such equipment is conventionally based on phase (or amplitude) interferometric measurements performed on the signals received by an antenna consisting of several dipoles. These goniometric measurements can, moreover, be performed at different points, so as to obtain the location of the source by triangulation.
To fulfill all the radio monitoring related functions, it is therefore essential to have both spectral analysis equipment and goniometry equipment. Now, in the current state of the art, these two types of functions are generally fulfilled by independent equipment items, which themselves consist of separate elements packaged in racks or housed in shelving for example.
This type of configuration presents the advantage of clearly individualizing the functions performed, so that, if the aim is to produce equipment intended only to carry out spectral analysis, it is possible to select and integrate in the equipment only the elements needed to fulfill this function. On the other hand, if, as is generally the case, the aim is to have a comprehensive system making it possible to perform spectral analysis and locate undesirable transmissions, the construction of such a system from independent elements often leads to a relatively bulky and heavy structure, and one that is consequently not very easy to transport.
A radio monitoring installation generally comprises an antenna mounted on a mast, the length of which can, for example, vary from a few meters to a few tens of meters, the reception and spectral analysis means being installed in a technical room, a shelter for example, located at the foot of the mast. Such a structure is complemented, for locating requirements, with the means required for the goniometric measurements which can, depending on the case, be installed in one and the same technical room or in a separate room. Such an installation also requires means making it possible

to control the various equipment items and analyze the results obtained. In certain usage cases, the installation is incorporated in a mobile structure, all of the necessary means, antenna mast included, in this case having to be installed on a vehicle and set up from the vehicle.
Producing a comprehensive radio monitoring system according to the current state of the art thus presents a certain number of drawbacks, of which the bulk must of course be mentioned first. In practice, producing such a system entails using a large number of means consisting of independent subassemblies (reception means, measurement means, switching means, etc.), each subassembly comprising all the elements enabling it to fulfill its function independently.
The current equipment covers this need, but requires several different and independent equipment items, most comprising similar if not identical components. The result is a system which presents redundancies that are functionally unnecessary and which make the whole bulky. This diversity of independent elements means in particular that there is a need to have mechanical structures, subracks or electronic racks for example, making it possible to integrate in a room or in a vehicle all of these elements that make up the radio monitoring system, and the associated antennas. Moreover, it entails setting up interconnecting wiring enabling the various elements to exchange signals, commands and more generally, information. It also requires the installation of power supply means making it possible to supply each element with electrical energy in the anticipated form, from the point of view both of the DC or AC nature, and of the value and the frequency of the power supply voltage required by each element. The duly constructed system therefore generally appears as a bulky assembly, which is relatively heavy and requires complex wiring. All these factors can make its incorporation in a lightweight vehicle of pickup truck type difficult.
Producing such a system according to the state of the art also presents a drawback in terms of management of the various resources that make up the system. In practice, each of the elements performs the task assigned to it in a way that is determined by its own operation, so that the unit dedicated to managing the system does not benefit from total time management freedom to optimize the sequencing of the various tasks, but has to take into account,

to perform each of the functions (spectral analysis, goniometry and locating), the execution times of the various tasks executed independently by each element.
DESCRIPTION OF THE INVENTION
One aim of the invention is to overcome the abovementioned drawbacks and, more particularly, to propose a solution that makes it possible to fulfill all the functions required for the radio monitoring of a wide frequency band extending from a few kHz to a few GHz. Another aim of the invention is to propose a solution that makes it possible to provide integrated management of the various functions implemented to perform the radio monitoring functions. Yet another aim is to propose a solution making it possible to produce a system that is easy to install in a variety of fixed or mobile structures and does not need to be housed in a specific accommodating infrastructure. Yet another aim is to propose a solution making it possible to produce a system that can be carried on a man's back.
To this end, the subject of the invention is a compact reception and processing device for wideband radio monitoring system which comprises at least:
- two receiver modules responsible for receiving V/UHF signals,
- a receiver module responsible for receiving HF signals,
- an LO module responsible for synthesizing the local oscillators
intended for the VHF/UHF receiver modules,
- a digital module comprising:
. a subassembly handling the digitization functions for the signals delivered by the reception modules, at a given sampling frequency Fe, and the spectral analysis of the received signal,
. a subassembly handling the result acquisition tasks and the real time sequencing and management tasks for the resources comprising the other subassemblies,
- a switching module for switching the received signal to a given
receiver module,

- an energy conversion module responsible for producing from a single external voltage source the power supply voltages needed to operate each of the modules.
According to the invention, since the modules of the device are integrated in a single sealed box, they are arranged inside said box so that the heat dissipated by each of the modules is transmitted by conduction to the walls of the box and dissipated by convection towards the outside by the walls of the box, the cooling of the modules being handled only by this means.
According to one embodiment of the invention, the modules are fixed to the internal faces of the walls of the sealed box so as to establish thermal continuity between these modules and the box.
According to a variant of the preceding embodiment, a layer of good thermal conductive material is inserted between the surface of the module and the wall on which it is fixed.
According to the invention, the external walls of the top and bottom lateral faces of the box present a relief structure to increase the dissipation area.
In a preferred embodiment, this relief structure is produced in the form of parallel grooves machined in relief or hollowed out of the thickness of the plate.
Another subject of the invention is a mobile radio monitoring system comprising a compact reception and processing device according to the invention, associated with an extendable antenna, consisting of radiating elements mounted on a telescopic mast, maintained by a system of guy ropes.
Another subject of the invention is a mobile radio monitoring system comprising a compact reception and processing device according to the

invention, associated with an antenna consisting of radiating elements, the assembly being mounted on a platform fitted with a radome, said platform being fixed to the end of a telescopic mast mounted on a vehicle.
Another subject of the invention is a mobile radio monitoring system comprising a compact reception and processing device according to the invention mounted on a carrying structure and equipped with a goniometry antenna.
The device according to the invention presents the advantage of pooling all the basic functionalities used to perform the tasks that make up radio monitoring: it thus avoids the unnecessary redundancies and makes it possible to perform the same operations as the existing equipment with a reduced bulk and weight.
Advantageously, the reception configuration present in the invention is adaptable and configurable according to the requirement. Thus:
- the presence of a V/UHF receiver module and an LO module makes it
possible to access the V/UHF technique interception and listening
function. The addition of a second V/UHF receiver module makes it
possible to also access the V/UHF goniometry function,
- the presence of an HF reception channel makes it possible to access
the HF technical interception and listening function. The addition of a
second HF receiver module makes it possible to also access the HF
goniometry function.
Because of its compactness, the device according to the invention reduces the external interconnection complexity of the system which is advantageously reduced to the coaxial links between the box and the antennas, to the electrical power supply wire and to the link with the management computer. Integrating the equipment in a technical room or in a vehicle is thus simplified. Furthermore, because of its relatively low weight and its seal-tightness, the device according to the invention can be installed with no accommodating infrastructure of the shelter or technical room type. It can thus, for example, be fixed directly to the mast bearing the antenna or

even to the structure of the antenna.
DESCRIPTION OF THE FIGURES
Other characteristics and advantages will become clearly apparent through the following description, based on the indexed figures which represent:
- figure 1, a block diagram of the main modules forming the device,
- figure 2, an illustration of one side of the box showing its dissipating
nature,
- figure 3, a diagrammatic illustration of an exemplary arrangement of
the various subassemblies of the device inside the box;
- figure 4, an illustration of an example of radio monitoring equipment
comprising a device according to the invention mounted directly on the
antenna mast,
- figure 5, an illustration of an example of radio monitoring equipment
onboard a vehicle, this equipment comprising a telescopic mast and
an antenna, the device according to the invention being mounted on
the antenna platform,
- figure 6, an illustration of an example of radio monitoring equipment
that can be carried on a man's back, this equipment comprising a
carrying frame and a specific antenna dedicated to this operational
use.
DETAILED DESCRIPTION
We will firstly study the functional block diagram of figure 1 which clearly illustrates the main advantages of the box equipped in accordance with the invention. As the figure illustrates, this box combines in a single entity all the functional elements needed to perform the operations required to handle spectrum monitoring functions and goniometry functions over a very wide frequency band typically extending from a few kHz to a few GHz. To this end, the device according to the invention mainly comprises the following modules or subassemblies:

- two V/UHF reception modules,
- a local oscillator module (LO)
- an HF reception module,
- a digital module,
The box according to the invention also comprises a power supply module and a switching module.
The two V/UHF reception modules 11 and 12 handle the complex transposition (in phase and in quadrature) of the signal obtained from the antenna (or antennas) used to equip the radio monitoring system and adapt the level of the received signal around a nominal value (automatic gain control). The reception band 8-if represents a fraction of the total frequency band, A-if, covered by the radio monitoring system. The scanning of all of the V/UHF band covered by the system is, moreover, achieved by varying the frequency of the local oscillator supplied to each of the reception modules 11 and 12 by the local oscillator module (LO) 13. The frequency of the LO signal supplied varies according to the fraction of the total bandwidth scanned, so as to enable the reception modules 11 and 12 to perform a transposition of the V/UHF signal received to the fixed intermediate frequency IFi.
The two V/UHF reception modules have a structure and functionalities that are each identical, each of the modules 11 or 12 being able to cover all of the band covered by the radio monitoring system. They can thus be used separately in the context of spectral measurements on the received signals, or even be used jointly for goniometric measurements.
Similarly, the HF reception module, 14, handles the complex transposition of the received HF signals about a fixed intermediate frequency IF2 and the adaptation of the signal level about a nominal value (automatic gain control). The reception band 82f represents a fraction of the total HF frequency band, Aaf, covered by the radio monitoring system. The scanning of all the HF band covered by the system is, moreover, handled by varying the frequency of the local oscillator internal to the HF reception module.
Such a structure has the two-fold advantage of limiting the complexity

of the reception modules 11,12 and 14 and of procuring a high degree of usage flexibility either to scan all of the bands Aif and A2f piece by piece, or even to perform an analysis of certain parts of these frequency bands.
As the figure illustrates, the digital module 15 comprises several functional subassemblies:
- a subassembly 16 handling the digitization functions for the complex
signals delivered by the reception modules, at a given sampling
frequency Fe, and the spectral analysis of the received signal. For this,
it comprises means, an FPGA-type microprogrammed circuit for
example, enabling it in particular to perform signal processing (SP)
operations such as spectral acquisition, filtering/decimation and
decomposition.
- a subassembly 17 handling the result and data acquisition tasks and
the real-time sequencing and management tasks for the resources
consisting of the other subassemblies, these tasks making it possible
to use these resources to handle the operational functions of the radio
monitoring system such as, for example, interception,
characterization, goniometry, or even data storage functions. This
subassembly 17 can, for example, consist of an onboard computer
with its software.
The digital module 15 finally comprises a so-called "carrier card" (not represented in the figure) intended to serve as a physical support for the two cards mentioned previously, and able to provide the interface with all the peripheral devices that can be linked to the onboard computer (hard disk, keyboard/mouse, Ethernet, USB, serial link), and other ancillary functions.
The device according to the invention also comprises a switching subassembly, or module, 18 which can be controlled by the onboard computer so as to connect to the receiver subassemblies 11,12 and 14, the antenna or the radiating elements with which the requirement is to pick up a signal. Thus, for example, if the task to be carried out consists of an analysis

of the HF band, the switching subassembly 18 is configured to connect the input of the HF receiver module to the appropriate radiating element. The switching subassembly thus makes it possible to switch the received signal to a given receiver module.
The device according to the invention finally comprises an energy conversion module 19 responsible for producing from a single external voltage source, the power supply voltages needed to operate each of the modules.
From its breakdown into functional subassemblies and the centralized management of the resources made up of these subassemblies, the unit according to the invention compares advantageously with the existing hardware in that it can perform all the functions handled by a complete radio monitoring system with a minimum of resources that are pooled and deployed by an intelligent unit 15. It also presents the advantage, thanks to its centralized pooled resource management, of offering a more flexible realtime management making it possible in particular to optimally sequence the various tasks in the context of complex radio monitoring missions. This particular structure also makes it possible to produce a device with a bulk and a weight that are significantly less than those of the existing equipment.
All of the elements that make up the device according to the invention are integrated in a mechanical structure or box, which houses the various subassemblies and the mechanical and connector interface with the antenna on the one hand and with external equipment on the other hand. The box also encloses all the wiring elements that enable the signal interchanges between the various subassemblies. The block diagram of figure 1 uses arrowed lines to represent the information and signals exchanged.
Thus, the radiofrequency signals originating from the antenna or antennas of the system are directed by the switching module to the receiver modules (subassemblies) which also receive their local oscillator from the LO module. The demodulated signals are then transmitted via appropriate links to the module responsible for digitization and processing which delivers the digitized and processed signals to the computer module. As for the computer

module, it supplies each subassembly with the commands and synchronization signals needed to operate the various resources in such a way as to perform a determined radio monitoring task.
The structure of the box enclosing the various elements of the device conventionally consists of six faces, a front face, a rear face, a top face, a bottom face and two lateral faces. One characteristic of the box is that the six faces are assembled, either directly to each other or via a framework, so as to form a compact and sealed box. Duly packaged in this way, the device according to the invention can advantageously be used in an uncontrolled atmospheric environment, any room or in a vehicle for example, and can even be set up in the open air, placed on the ground or fixed to a mast supporting an antenna for example.
To ensure the various elements of the device operate correctly and in particular to enable the heat dissipated by these various elements to be dispelled, the structure of the box is defined so that the box itself behaves as a dissipator. To this end, as figures 2 and 3 illustrate, its sides advantageously serve as support and dissipator for the various elements of the device.
For this, each face 21 of the box, side, top or bottom, comprises a plate 22 made of a heat-conducting material, a metal plate for example, the external wall 23 of which has a relief structure to increase the dissipation area. This relief structure can, for example, be produced as illustrated by cross section AA in figure 2, in the form of parallel grooves 24 machined in relief or hollowed out of the thickness of the plate. This set of grooves advantageously increases the thermal convection capabilities of each of the plates forming the faces of the box and thus transforms it into a heat sink.
The plates forming the faces of the box also have smooth internal walls 25, with the various elements of the device positioned and secured in contact with them. Ideally, the various elements are fixed to the plates so that the heat that they release is transferred as completely as possible to the plate that serves as their support. This contact can also advantageously be reinforced if, on fitting an element of the device on one of the plates, a layer of paste or foam of a good thermal conductive material is inserted between the surface of the element and the plate. This way, the heat dissipation is

entirely handled by convection and it is advantageously possible to have a sealed box while ensuring a satisfactory operating temperature for the component elements of the device.
Figure 3 is a transverse cross-sectional view showing one possible exemplary arrangement of the elements of the device inside the box. In this arrangement taken as an example, the receiver subassemblies 11,12 and 14, and the local oscillator (LO) subassernbly 13, are fixed to the top 32 and bottom 33 faces, by clamps for example, so as to ensure that they are secure and in thermal contact with the plates. The subassemblies 16 and 17 that form the digital module are fitted on a support card (not represented) so as to be in contact with one of the lateral faces 34. For simplicity, the layers of conductive elements inserted between the elements and the corresponding plates are not represented in the figure.
The duly constructed device 31 presents a structure that is advantageously sealed, lightweight and compact, and can be fitted on any supporting structure or even placed on the ground via feet or studs (not represented in the figure) directly fitted on the box.
We will now look at figures 4, 5 and 6 which present three characteristic examples of use of the device according to the invention to form mobile radio monitoring systems.
The illustration of figure 4 diagrammatically represents a mobile radio monitoring system comprising an extendable antenna, consisting of radiating elements 41, 42 mounted on a mast 43, of telescopic type for example, secured temporarily, for the duration of the monitoring mission, by a system of guy ropes 44. In this example, the mast is a conventional antenna-support mast on which the device 31 according to the invention is fixed via appropriate fixing means. The device is connected to the radiating elements via the switching subassernbly and to an operator console via a remote digital link of Ethernet type for example. Depending on the operational constraints, the operator console can amount to a simple PC-type laptop computer for example. The assembly then requires no infrastructure, shelter or otherwise, for its implementation and can therefore be transported and

deployed in relatively inaccessible areas. The electrical power supply for the device can also be supplied by a voltage source located on the ground, a generator set for example, or even by a battery coupled to the device. A complete monitoring system, easy to move, is thus advantageously obtained thanks to the compactness and the lightness of the device according to the invention.
This advantage does, moreover, also apply in the case of a fixed (or infrastructure) configuration for which the use of a device according to the invention thus significantly reduces the installation constraints.
The illustration of figure 5 also presents a radio monitoring system, comprising a device according to the invention, mounted on a vehicle 51. In this example, the vehicle is equipped with a conventional telescopic mast 52 supporting a platform 54 in a radome. On this platform, an antenna 53 consisting of radiating elements is installed. The radiating elements are connected to the device 31 according to the invention, which is fixed directly under the platform 54 and linked by a remote digital link 55 to a control console 56 installed inside the vehicle.
As can be seen through this second exemplary embodiment, the device according to the invention makes it possible, thanks to its compactness and its light weight, to create a complete monitoring system whose installation on board a vehicle requires very little rearrangement and is therefore because of this inexpensive. Furthermore, in as much as, because of its structure, the device consumes relatively little energy and requires only one power source, the electrical power supply of the device can, for example, be provided by a simple battery installed in the vehicle.
The illustration of figure 6 presents a portable radio monitoring system 65, comprising a device according to the invention mounted on a carrying support structure 61 and equipped with a dedicated antenna. This antenna can, for example, be a goniometry antenna 62 or a specific directional antenna. Equipped with a battery 63 to supply it with the necessary energy, the radio monitoring system thus provides an operator with complete independence, and handles all the missions covered by a fixed or mobile station. In such conditions of use, the operator console can, for example, be

a PDA, 64, for a very summary display or a PC-type laptop computer to access more advanced functions. Such a device can be used, for example, in the case of radiofrequency monitoring, for an operator moving around on foot, to search for a transmitter in the final approach or when a vehicle can be used.
The exemplary embodiments illustrated by figures 4, 5 and 6 also reveal that the device according to the invention presents the characteristic of being able to set up short links between the radiating elements of the antenna and the receiver subassemblies, the advantageous consequence of which is to reduce the losses on the received signal and therefore increase the sensitivity of the system.
These examples also show the multipurpose nature of the device according to the invention, which can handle all of its functions in multiple configurations of use: fixed, transportable, mobile or portable.

CLAIMS
1. A compact reception and processing device for wideband radio
monitoring system, comprising at least:
- one or two receiver modules (12) able to receive UHFA/HF
signals,
- a receiver module (14) able to receive HF signals,
- an LO module (13) responsible for synthesizing the local
oscillators intended for the receiver modules,
- a digital module (15) comprising:
- a subassembly (16) handling the digitization functions for the
complex signals delivered by the reception modules, at a given
sampling frequency Fe, and the spectral analysis of the received
signal,
- a subassembly (17) handling the result acquisition tasks and
the real time sequencing and management tasks for the resources
comprising the other subassemblies, so as to perform the requested
surveillance radio task,

- a switching module (18) for switching the received signal to a
given receiver module,
- an energy conversion module (19) responsible for producing
from a single external voltage source the power supply voltages
needed to operate each of the modules,
characterized in that, since the modules of the device are integrated in a single sealed box (31), they are arranged inside said box so that the heat dissipated by each of the modules is transmitted by conduction to the walls of the box and dissipated by convection towards the outside by the walls of the box, the cooling of the modules being handled only by this means.
2. The device as claimed in claim 1, in which the modules are fixed
to the internal faces of the walls (32, 33, 34) so as to establish
thermal continuity between these modules and the box.
3. The device as claimed in claim 2, in which a layer of good thermal
conductive material is inserted between the surface of the module
and the wall on which it is fixed.

4. The device as claimed in one of claims 1 to 3, in which the
external walls of the top (32) and bottom (33) lateral faces of the box
present a relief structure to increase the dissipation area.
5. The device as claimed in claim 3, in which the relief structure is
produced in the form of parallel grooves (24) machined in relief or
hollowed out of the thickness of the wall.
6. A mobile radio monitoring system comprising a compact reception
and processing device as claimed in any one of the preceding claims,
associated with an extendable antenna, consisting of radiating
elements (41, 42) mounted on a telescopic mast (43), maintained by
a system of guy ropes (44).
7. A mobile radio monitoring system comprising a compact reception
and processing device as claimed in any one of claims 1 to 5,
associated with an antenna (53) consisting of radiating elements, the
assembly being mounted on a platform (54) fitted with a radome, said
platform being fixed to the end of a telescopic mast (52) mounted on
a vehicle (51).
8. A portable radio monitoring system, comprising a compact
reception and processing device as claimed in any one of claims 1 to
5, mounted on a carrying structure (61) and equipped with a
goniometry antenna (62).