EP2178229A1 - Überwachungssystem für ein synchrones Übertragungsnetz - Google Patents

Überwachungssystem für ein synchrones Übertragungsnetz Download PDF

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Publication number
EP2178229A1
EP2178229A1 EP09172933A EP09172933A EP2178229A1 EP 2178229 A1 EP2178229 A1 EP 2178229A1 EP 09172933 A EP09172933 A EP 09172933A EP 09172933 A EP09172933 A EP 09172933A EP 2178229 A1 EP2178229 A1 EP 2178229A1
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EP
European Patent Office
Prior art keywords
pulse
transmitter
received
transmitters
point
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP09172933A
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English (en)
French (fr)
Inventor
Pierre Boutou
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telediffusion de France ets Public de Diffusion
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Telediffusion de France ets Public de Diffusion
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Publication date
Application filed by Telediffusion de France ets Public de Diffusion filed Critical Telediffusion de France ets Public de Diffusion
Publication of EP2178229A1 publication Critical patent/EP2178229A1/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H60/00—Arrangements for broadcast applications with a direct linking to broadcast information or broadcast space-time; Broadcast-related systems
    • H04H60/56—Arrangements characterised by components specially adapted for monitoring, identification or recognition covered by groups H04H60/29-H04H60/54
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/12—Arrangements for observation, testing or troubleshooting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/28—Arrangements for simultaneous broadcast of plural pieces of information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/65—Arrangements characterised by transmission systems for broadcast
    • H04H20/67—Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency

Definitions

  • the invention relates to a transmission network comprising N transmitters distributed in a geographical area, each transmitter being capable of transmitting a synchronous data signal with respect to a reference signal.
  • the invention also relates to a method for monitoring such a transmission network.
  • the invention is particularly interesting for all synchronous radio networks (also called iso-frequency or single frequency networks or SFN for single frequency network in English) may include a large number of transmitters.
  • the invention is applicable to synchronous data broadcast networks, in which data transmitters and data receivers are distinct; for example, Digital Terrestrial Television (DVT) networks, implemented according to the DVB-T standard for example, or Terrestrial Personal Mobile TV (TMP) networks, implemented according to the DVB-H standard by example.
  • DVD Digital Terrestrial Television
  • TMP Terrestrial Personal Mobile TV
  • the invention can also be applied to communication networks in which all or some of the data transmitters are also receivers.
  • the signals transmitted simultaneously by all the transmitters are identical: they contain in particular the same data (in the broad sense: data, images, speech, etc.) and the same instructions, modulated and interleaved according to known techniques. .
  • the transmitted power the output power of the transmitter, and power receives the power of the same signal when it is received at a point in the network.
  • the power received from a signal varies in particular as a function of the power emitted and the distance between the transmitter and the receiver of said signal.
  • the received signals are superimposed and their power is added to form a resulting signal.
  • the simultaneously transmitted signals arrive at said receiving point at different times.
  • a receiver receives a signal resulting from the combination of the signals of several transmitters arriving at the reception point.
  • the receiver In order for the receiver to be able to synchronize with the resulting signal and to demodulate said resulting signal, it is necessary for the signals to arrive from each transmitter at said receiving point at the same frequency and on a same predefined time interval called the guard interval. If a signal arrives from a transmitter outside the guard interval and the received power of said signal is below a disturbance threshold, then said signal is ignored from the receiver.
  • the guard interval can be defined by [TR, TR + ⁇ GM] or by TR +/- ⁇ GM, where TR is the moment of reception of the signal whose received power is the strongest, and ⁇ GM is a maximum acceptable relative delay.
  • each transmitter must imperatively transmit a synchronized signal in frequency and time on a reference signal.
  • the reference signal may be provided by an external system, such as a satellite positioning system (Global Positioning System GPS, Galileo, etc.) or a broadcast network.
  • the reference signal can also be constructed from a time reference included in the data stream received by the transmitter. Any other reference signal can be used.
  • the known surveillance devices comprise a receiver able to synchronize on the resulting signal it receives, to extract the component of each signal that composes it and to determine parameters (power level, frequency, etc.) of each component. the resulting signal.
  • the known tools can only be used if the reception is correct; they are inoperative in the presence of an interfering signal and therefore do not identify a defective transmitter.
  • the subject of the invention is a monitoring system that does not have the disadvantages previous systems.
  • a system according to the invention is adapted to control the transmission simultaneously by all transmitters of a pulse, to discriminate any interfering signal in a signal received at a point of the network, and to study a pulse response detected at a point to monitor the network.
  • a system according to the invention thus makes it possible, in a resultant signal received at a point, to reject an interfering signal, to separate all the received signals, and to identify the contribution of each transmitter.
  • the list of pulses obtained is then used for the identification of a transmitter.
  • the system and method can thus determine the individual coverage of each transmitter. For this, the total power received is measured at the monitored point of the network. Then, the power contribution of each transmitter from which at least one signal is received at said monitored point is determined from the impulse response. The measurement of the total power and the Determination of the contribution of each transmitter is repeated for various points of the network.
  • the monitoring system for example in a motor vehicle, to be easily moved to various points of the network. Measurements are made for example a first time during the commissioning of the transmitter to determine its coverage, then at regular intervals, for example every 3 to 6 months for verification.
  • the system and the method according to the invention can thus make it possible to continuously monitor the network by performing at regular intervals, for example of the order of a few hundred milliseconds to a few tens of minutes, impulse response measurements at a few points. relevant network. A possible failure of a transmitter is thus identified and taken into account very quickly.
  • the said parameter is a reception delay of a pulse, and the step of transmitting the warning signal is carried out if the said reception delay is greater than a maximum value.
  • the said parameter is a frequency of the said pulse, and the step of transmitting the warning signal is performed if the said frequency is outside a predefined interval around a frequency of the signal. reference.
  • said parameter is the delay of reception of the pulse, and the step of transmitting the warning signal is carried out if said reception delay leaves a predefined interval including an initial value of said delay in reception.
  • said parameter said parameter is a power received from the pulse, and the step of transmitting the warning signal is performed if said power comes out of a predefined interval including an initial value of the said received power.
  • several parameters are monitored simultaneously, as will be seen later.
  • the identification means may also comprise means for detecting a delay of each pulse and identifying the transmitter from the indication of the delay of reception of said received pulse.
  • the system and the method according to the invention can thus make it possible to verify the identity of a transmitter by comparing the delay of each pulse with that expected for each transmitter of the network.
  • the invention also provides a computer program including at least one set of program code instructions for performing at least one of the steps included in a monitoring method as described above, when said program is executed by a microprocessor.
  • FIG. 1 is represented part of a synchronous transmission network, comprising three transmitters E1, E2, E3 among a plurality of N transmitters.
  • the transmitters simultaneously transmit the same synchronized signal on a reference signal; here the reference signal is a signal provided by a satellite navigation system. All the transmitters simultaneously transmit the same signal containing data (in the broad sense: data, images, lyrics, etc.), the same parameters (in particular an identifier of the transmitters) and the same instructions (instructions intended for a receiver for the display of data for example), modulated and interleaved according to known techniques.
  • the network is deployed in a geographical area comprising in the example shown three obstacles 01, 02, 03, in this case buildings, capable of reflecting the signals emitted by the three transmitters E1, E2, E3.
  • the signals received at point A are shifted in time with respect to the instant T0 of their simultaneous transmission by the transmitters. This is of course due to the distance that each signal must travel between the transmitter and point A.
  • a consumer receiver (mobile phone, television set, etc.) placed at point A will thus receive a combination of the signals S10, S20, S30, S11, S22, S31 and S33, if the signals arrive synchronously at point A and during a period of time. time called guard interval, or will pick up only a scrambled signal if one of the signals S10, S20, S30, S11, S22, S31 or S33 is interfering, that is, if one of the signals is shifted too strongly in time (beyond the guard interval) or in frequency (beyond a variation ⁇ f0 of allowable frequency) relative to the reference signal.
  • the invention relates to a monitoring system.
  • the monitoring system includes receiving means such as a reception antenna RA placed at point A of the network and monitoring means grouped together in an RS box remote, possibly with respect to the antenna RA.
  • the antenna is for example placed at a point A located in a street, at the top of a signpost for example, or placed on the roof of a building, and the RS box is placed at a distance from the point A, in a technical room of a building for example.
  • the antenna RA and the monitoring means are grouped together in the same fixed housing, on the roof of a building for example, or in a mobile manner, in a vehicle used for monitoring the vehicle. network for example.
  • control means are adapted to remotely control the transmitters of the network according to an appropriate protocol. They are adapted to individually control each transmitter to, for example, turn on or off a transmitter, set an output power level of a transmitter, change the identifier and other parameters of a transmitter, etc. They are also adapted to control at one or more transmitters the momentary interruption (for a few milliseconds for example) of a signal being transmitted and to control transmitting, at a predefined time T0, a pulse signal of power and of predefined duration.
  • the receiving means are adapted to receive a signal resulting from the combination of the signals received from each transmitter.
  • the reception means are adapted to receive a resultant impulse response of the pulses emitted by the plurality of transmitters.
  • the discrimination means are adapted to, in a resulting impulse response received on the antenna, separate the different pulses received and reject a received pulse scrambling the resulting impulse response.
  • the identification means are themselves adapted to identify each pulse of the resulting impulse response from the identifier of the transmitter in each pulse received.
  • the control means control a modification of the identifier of each transmitter and control the emission of a pulse simultaneously by all transmitters.
  • the identification means extract the identifier of the transmitter of said pulse and the distance traveled by the signal.
  • This embodiment goes against the usual use of synchronous networks. Indeed, in such networks such as DBV-T or DVB-H networks, in normal operation, there must be a unique identifier common to all the transmitters so that the signals they emit are perfectly identical (the identifier of a transmitter is integrated with the signals that it emits). As said before, a consumer receiver can not synchronize on the signals it receives if one of these signals is different from the others.
  • this change of identifier will preferably be limited to short periods (of the order of a few milliseconds) so that this change, which will necessarily lead to a stealthy desynchronization of the consumer receivers, has no impact for a user.
  • the identification means may also comprise means for measuring the delay of reception of a pulse with respect to a reference time.
  • the reference time is for example the signal receiving time TR whose power level is the strongest.
  • the identification is done for example by comparison with a list of pulses associating, with each reception delay, an identifier of a pulse and a transmitter of said pulse.
  • the list may also comprise, for each reception delay, a length of a path traveled by a pulse between said transmitter and the point to be monitored and / or an indication of a received power level of an associated pulse.
  • the monitoring means may also include initialization means for establishing the list of pulses associating, at each reception delay, an identifier of a pulse and a transmitter of said pulse.
  • the list associates at least, with each reception delay, an identifier of a pulse and a transmitter of said pulse.
  • the list can take various forms: multi-column lists and / or two-dimensional or three-dimensional map on which are positioned the issuers, obstacles, the paths followed by the emitted signals and their length and / or a representation of an initial resultant impulse response in the form of a timing diagram, etc.
  • the list of pulses can be established manually from a simple diagram in two or three dimensions of the network representing in particular the transmitters, the obstacles reflecting the transmitted signals, by measuring the lengths of the paths of the different signals.
  • the list may also be established by the initialization means, from the initial command of the emission of a pulse, by each transmitter at successive times, and the identification of each pulse of the impulse response associated with each transmitter.
  • control means control the extinction of all transmitters, then the emission of a pulse by a transmitter, one by one, successively at predefined times.
  • the pulse series received at the monitored point corresponds to the contribution (direct or reflected on an obstacle) of said single transmitter.
  • All the pulses of all received pulse series are listed with an indication of the relative time of reception, and then ordered according to the indication of the relative time of reception.
  • the relative moment of reception of a pulse is the difference between the instant of reception and the instant of reference.
  • the moment of receipt of a pulse is the signal propagation time between the transmitter and the antenna of the surveillance system.
  • the reference time is for example the moment of reception of the strongest pulse.
  • pulses P1, P2, P3, P4 are taken into account because their received power level is greater than a threshold of taking into account (here of the order of -30dB). Below this threshold, the energy of the received signal is not sufficient to be detected by a standard receiver and / or is negligible compared to the predominant signals.
  • the pulses P1, P2, P3 are for example received directly from the emitters E1, E2, E3.
  • the pulse P4 is for example a reflection on the obstacle 01 of the pulse emitted by the transmitter E1.
  • the monitoring system is used to determine the actual coverage of a network and in particular to determine in various points to monitor the power received from each transmitter, the total power received, so to check the compliance of the network with a set of specifications.
  • the actual coverage of a network is determined by measuring, at a point to be monitored A of the network, the power of the signals received from each transmitter, directly or by reflection, the other transmitters being extinguished.
  • the time required to determine the actual coverage is proportional to the number of issuers and the number of points to monitor and can be particularly long.
  • the first measuring means are, for example, a power meter adapted to measure the total power of the resulting signal received from the transmitters.
  • the calculation means determine in the impulse response the proportion of power provided by each signal in the total power of the resulting signal, then determine the power provided by each signal by multiplying the proportion of power provided by each signal by the total power measured. Finally, the calculation means determine the power received from each transmitter by adding the powers provided by all the signals of the same transmitter. So, in the example of the figure 2 , the power provided by the emitter E1 and the sum of the power provided by the signal P1 and the power supplied by the signal P4.
  • the monitoring system is used to continuously monitor a network during normal operation. Small variations in the network parameters (frequency, reception power of signals at a point, time offset, etc.) over time are normal. But too large variations are likely to cause a break in service and desynchronization of the receivers at certain points of the network. Continuous monitoring of the network at certain points makes it possible to detect as soon as possible an excessive drift of a transmitter.
  • a template is defined, that is to say, according to the parameter, a minimum value, a maximum value, and / or an interval of acceptable values.
  • the said parameter is a reception delay of a pulse
  • the warning means are adapted to emit the warning signal if the said reception delay is greater than a maximum value.
  • the said parameter is a frequency of the said pulse
  • the warning means are adapted to emit the warning signal if the said frequency is outside a predefined interval around a signal frequency. reference.
  • the said parameter is the delay of receipt of the pulse
  • the warning means are adapted to emit the warning signal if said receiving delay exits a predefined interval including an initial value of said reception delay.
  • said parameter is a power received from the pulse
  • the warning means are adapted to emit the warning signal if said power comes out of a predefined interval including an initial value of said power. received.
  • the alert signal indicates an identifier of the pulse P3, provided by the identification means.
  • a pulse of the impulse response is identified from a list of expected pulses, and an indication of the delay of reception of pulses of the impulse response.
  • an alert signal is issued, it is also possible, for security reasons, to verify the identity of a failed transmitter for which an alert has been triggered. This verification can be done by changing the identifier of the transmitters, at least the defaulting transmitter, as described previously in the context of the establishment of the list of pulses.
  • the figure 4 shows this check: the column cell_id indicates the identifier of the transmitter of each pulse P1 to P4.
  • the monitoring system is used to confirm the identification of a transmitter of a signal received by a receiver.
  • This particular application can be used for example to establish the list of pulses described above, or to confirm the identity of a failed transmitter detected during a network monitoring as described above.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)
EP09172933A 2008-10-15 2009-10-13 Überwachungssystem für ein synchrones Übertragungsnetz Withdrawn EP2178229A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR0857008A FR2937202B1 (fr) 2008-10-15 2008-10-15 Systeme de surveillance d'un reseau de transmission synchrone

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EP2178229A1 true EP2178229A1 (de) 2010-04-21

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19642633A1 (de) * 1996-10-16 1998-04-23 Bosch Gmbh Robert Verfahren zur Bestimmung von Empfängerstandorten in einem Gleichwellennetz
EP1063799A1 (de) * 1999-06-22 2000-12-27 Swisscom AG Messverfahren für Einfrequenznetze und dafür geeignete Vorrichtungen
US20070274423A1 (en) * 2003-09-11 2007-11-29 Christoph Balz Method for Monitoring the Synchronism of Transmitters in a Common Wave Network

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19642633A1 (de) * 1996-10-16 1998-04-23 Bosch Gmbh Robert Verfahren zur Bestimmung von Empfängerstandorten in einem Gleichwellennetz
EP1063799A1 (de) * 1999-06-22 2000-12-27 Swisscom AG Messverfahren für Einfrequenznetze und dafür geeignete Vorrichtungen
US20070274423A1 (en) * 2003-09-11 2007-11-29 Christoph Balz Method for Monitoring the Synchronism of Transmitters in a Common Wave Network

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FR2937202A1 (fr) 2010-04-16
FR2937202B1 (fr) 2011-04-08

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