DE19909651A1 - Method for distributed wireless video monitoring using several stations with at least one camera unit by transmitting video data set to dependent stations after at least one acknowledgment message to these stations is received - Google Patents

Abstract

A video data set is transmitted to dependent stations after reception of at least one acknowledgment message to these stations and at least one inquiry message to the dependent stations. An inquiry message with at least one free message to the inquiring station is answered as soon as a video data set has been faultlessly transferred to the dependent station with at least one acknowledgment message confirmed. A current distribution unit (17) allocates the electrical energy to video cameras (11), a CPU (16), a reception unit (14) and a transmission unit (15) according to arranged mode of operation. The CPU (16) digitizes the video signals of the cameras (11) to combine video sequences, to undertake data compression where appropriate as well as to coordinate the invented exchange of video data sets. Independent claims are included for: (a) a device for implementing the method; and (b) a device for wirelessly distributed monitoring.

Description

The invention relates to a method and an apparatus for distributed wireless video observation consisting of a A plurality of stations with at least one camera unit, a data receiver and a data transmitter preferably with short range, with the stations simultaneously the Vi make deo observation and wireless data transmission form the supply chain.

It is known that wireless video observation with commercially available radio cameras can be realized, the analog Wirelessly transmit video signals over short distances. The The number of cameras in an observation room is determined by the An number of available radio channels is limited. The Expansion of the observation room is dependent on the development of the Area and determined by the transmission power.

Various methods are also known (e.g. MPEG- Standards) using digitization of analog video signals and a subsequent data reduction a lower Channel bandwidth required than for a transmission of ana lied to video signals. This video data will in particular also wireless in digital radio and television transmitted to the end user (Freyer: DVB - digital television. Verlag Technik, Berlin 1999).

DE 43 07 486 specifies a traffic regulation direction to that by means of an image capture unit and egg ner image radio device a still image to a traffic control unit transmits. The possibility is also given ben, several large crossings using a variety of image to monitor radio devices and this by means of a radio concentrator via a channel with a centrally arranged Connect image recovery unit. It is a matter of  a concept for centrally organized image data transmission. It is suggested that a cellular provider share the data transport takes over. The disadvantage here is that a foreign Infrastructure for data transmission must be used.

The invention has for its object a method and a device for distributed wireless video observation to create so that in a simple and inexpensive manner without the use of external infrastructure for data transmission a video observation along as many locations as possible a stretch of great distance can be reached. The Video scenes preferably of all observation points should be in at least one control center completely and as quickly as possible be available.

According to the invention the object is achieved in that the front direction for distributed wireless video observation from one There are a large number of preferably similar stations, which in turn consists of at least one video camera, one Central unit, a data receiver and a data transmitter preferably assemble with low transmission power. The Stations are within the mutual reach ner wireless data link arranged that they form a data transmission chain. Thus, larger ones Overcome stretches and around radio wave damping obstacles and many video observation points rea at the same time be lized. To ensure the fastest possible availability of the There are video scenes in a central office several stations in transmission mode at the same time.

Several stages form for the implementation of the method a logical data transmission chain in which each station with Exception of the first and last station in the data transfer chain a logical predecessor station and a logical one Has successor station.  

The individual video scenes of the stations should be as possible quickly available in a central office for evaluation. This ge happens through a master station where the video records of the stations.

A video record of a station contains at least one a digital camera recorded by the station's video camera ten video image sequences of an observation period.

The transmission of the video records until they are available in the Master station takes place time and place segment in one Cycle. A cycle is advantageously divided into at least two Sections divided. In the case of a split of the cycle in the first cycle section, the video data records of all in the logical order of the transmission chain even and in the second cycle section the video records of all in the logical order of the transmission chain odd stations one after the other into the master station. In a another embodiment of the method run in the first cycle Klus section the video records of the odd and im second cycle section that of the even-numbered stations in the master station. They are each within a cycle because new video records of all stations in the Mastersta tion before.

Preferably when requested by the master station in the Headquarters send the last station and from there in Abstei gender order of the transmission chain at least each second station after receiving the first prompt message a digitally encoded video record to their predecessor sta tion. The predecessor stations receive the addresses addressed to them th video records via their data receiving units. To the presence of the video data records of the successor stations in the predecessor stations send this via their data transmission at least one acknowledgment message to the respective Successor station and one or more request messages  the respective predecessor station. The predecessor stations answer words this request message with at least one free message if you have successfully completed a Vi have sent the deo data record. It is therefore a determined one Sequence of the video data record transmission to the respective forward gantry station and maximum utilization of the hardwa resources, especially with half-duplex operation poses. The process is repeated analogously until the Video data record of the last station in the transmission chain has entered the master station.

The second cycle section follows, in which now - preferably at the request of the master station - the penultimate station and from this in descending order of the transmission chain at least every second station digitally encoded video data set to its predecessor station to transfer. The video records can also by other Da rates are supplemented or replaced.

Since with wireless data transmission with not beforehand tunable delays or the temporary failure of one The master station suitable measure after a specified time has passed initiate error handling. This results in the problem of vagabond messages in the Vorrich tung. This is avoided if all messages have an ent speaking expiry time is given, after its over if they are no longer forwarded. For this he each station averages the length of time the message stays with her and accumulates the value of the total oil that has already expired time of the message. A station puts the headline the message is set according to the set expiry time deleted.

That with video observation systems with a lot of observation score particularly well along long distances  serious problem of an efficient and low effort Data transmission is described through the training of Data transmission chain in which at least every second Station is parallel in transmission mode, in an advantageous Way solved. The data transmission chain enables on set of wireless data transmission means, preferably Radio, with a range that is only a fraction of that too observing distance. This can be done in front geous when using data transmission units with low transmit power objects bypass the spread e.g. B. strongly dampen or prevent radio waves. Because of the usually existing line of sight along Stra ßenzügen can in built-up areas whose course for the Auf construction of the observation and transmission chains can be used.

In one embodiment of the invention, statio NEN are in the data transmission chain that no video own camera. If necessary, these are used for transfer bridging larger distances.

In a further embodiment of the invention, the video data transmission chain to be closed to a ring. This has the advantage that each station from the video records every other station. So everyone can Station also the overall result of the distributed video monitoring tion can be viewed or evaluated. So is a Maximum decentralization achieved.

According to a development of the invention, the Device through the use of solar cells from one to make power supply infrastructure independent and such with in conjunction with the aforementioned design feature advantageously paint a completely self-sufficient, to create decentralized video observation system.  

In a further interpretation of the invention, the Zen supplements traleinheit the message stream for status information about the current energy supply. Can the used elec amount of energy not supplied by the solar cells , all the units of the Station can be switched off for a longer period of time, so that at least the data transmission is ensured can.

The invention thus represents a device with the following advantages:

• - Flexibility and mobility through wireless video data over wear while at the same time being independent of existing infrastructure for data transmission
• - decentralized working method and highest efficiency regarding the channel utilization in connection with a close-knit Video observation by distributed-temporal. parallelism the video data exchange,
• - the shortest possible time for the compilation of the Vi deodata records of all stations
• - Minimal hardware expenditure through half-duplex operation and possible Liche reduction of data storage for a video data sentence

The device and the method are particularly suitable for flexible traffic monitoring along streets.

The invention is intended in the following in exemplary embodiments be explained by the accompanying drawings.

Show it:

Fig. 1 shows a detail of the device for distributed wireless video surveillance;

Fig. 2 shows the structure of a station of the apparatus;

Fig. 3 shows the method according to the exchange of messages between the stations, variant line;

Fig. 4 shows the method according to the exchange of messages between the stations, variant ring;

The section shown in Fig. 1 from the device for distributed wireless video observation allows an example arrangement of individual, preferably similar Statio NEN ( 10 ) along a route ( 1 ) and the data transmission chain, which is formed by individual wireless data transmission paths ( 20 ), detect. In a master station ( 25 ), preferably arranged at the end of the data transmission link ( 20 ), the video data sets of the other stations ( 10 ) are available and can be viewed or evaluated.

Fig. 2 illustrates the structure of a station ( 10 ). The central unit ( 16 ) is connected to the video cameras ( 11 ), to the receiver unit ( 14 ), the transmitter unit ( 15 ) and an interface ( 18 ). The transmitting unit (15) and the receiving unit (14) are connected to an antenna (12) are also each separate antennas for the transmitting unit (15) and the receiving unit (14) possible. The station ( 10 ) has a power supply ( 30 ), which preferably works with solar energy. A power distribution unit ( 17 ) allocates the electrical energy to the video cameras ( 11 ), the central unit ( 16 ), the receiving unit ( 14 ) and the transmitting unit ( 15 ) depending on the agreed operating mode. The task of the central unit ( 16 ) is to read in the video signals from the cameras ( 11 ), if necessary to digitize them, to compile video sequences, to perform a data reduction if necessary and to coordinate the exchange of video data records according to the invention.

The process of exchanging messages for distributed wireless video monitoring for a line topology will be explained in more detail below. This is shown in Fig. 3, the Zei tachsen of the individual stations (M) and (S1) to (S6), wherein (M) is the master station. The individual video data records (D1) to (D6) of the stations should be available in succession at the master station (M) for observation and evaluation in the shortest possible time.

For this purpose, the central units ( Fig. 2: 16 ) of the stations from the analog or digital video signals of the cameras ( Fig. 2: 11 ) continuously digitally coded video data sets (D1) to (D6) of an observation period.

The transmission of the video records until they are available in the Master station (M) takes place in time and location sections one cycle (Z). A cycle (Z) consists of two sections (ZA1) and (ZA2), in each of which the video data sets (D1) to (D6) of the stations with even and odd numbers Identification addresses (S1) to (S6) successively the Sta through (S1) to (S6) until they are in the master station (M) are present.

Preferably after a request message (AG), which starts from the master (M) and runs through all stations (S1) to (S6), in the cycle section (ZA1) all stations with an even identification address (S2), (S4), ( S6) their video data set (D2), (D4), (D6) via the data transmission unit ( Fig. 2: 15 ) to the respective predecessor station (D2), (D3), (D5). The predecessor stations (S1), (S3), (S5) receive the video data sets (D2), (D4), (D6) addressed to them via their data reception units ( FIG. 2: 14 ). After the respective complete video data sets (D2), (D4), (D6) of the successor stations (S2), (S4), (S6) in the predecessor stations (S1), (S3), (S5) send them via their Data transmission units ( Fig. 2: 15 ) at least one acknowledgment message (Q) to the respective successor station (S2), (S4), (S6) and one or more request messages (AF) to the respective previous station (M), (S2) , (S4). The predecessor stations only respond to this request message (AF) with a free message (F) if they have successfully passed on a complete video data record, which is confirmed by the receipt (Q). This blocking mechanism is necessary because the transmission time can be extended due to interference, particularly in the case of wireless communication. This situation is shown in FIG. 3 for the video data record (D2) outgoing from the station (S2). The station (S3) only receives a free message (F) from its predecessor station (S2) after several request messages (AF). Subsequently, the passing on of the video data sets (D2), (D4), (D6) is repeated analogously until the video data set (D6) of the last station (S6) in the transmission chain has entered the master station (M).

This is followed by the second cycle section (ZA2), in which now - preferably after receiving the from the master station (M) transmitted and through the stations (S1) to (S5) submitted request message (AU) - all stations with un even-numbered identification address (S1), (S3), (S5) their Video data record (D1), (D3), (D5) to the respective predecessor Send station (M), (S2), (S4). Then repeats itself the passing on of the video data sets (D1), (D3), (D5) finally the above Blocking mechanism analog, so long until the video data record (D5) before in the transmission chain last station has entered the master station (M). A cycle (Z) can also start with the send activity of the stations with an odd identification address (S1), (S3), (S5) can be opened, then the second Zy Class section (ZA2) with the time-parallel transmission activities the stations with an even-numbered identification address (S2), (S4), (S6) is started.

Fig. 4 shows a section of the message exchange in a ring topology.

Claims (11)

1. A method for distributed wireless video observation before preferably using the device according to claim 7, characterized in that

• a) several stations form a logical data transmission chain, in which each station, with the exception of the first and last station in the data transmission chain, has a logical predecessor station and a logical successor station, and
• b) create at least two stations from video image sequences of an observation period of digitally coded video data sets,
• c) a station, preferably at the beginning of the data transmission chain, initiates a cycle by sending a first request message to its successor station, and
• d) the first request message is passed on from one station to the next station in the data transmission chain until it has reached the last station in the data transmission chain, and
• e) the last station and from this in descending order of the transmission chain at least every second station after receiving the first request message transmit a digitally coded video data set to its predecessor station, and
• f) after receiving a video data record, these predecessor stations transmit at least one acknowledgment message to their successor stations and at least one request message to their predecessor stations, and
• g) a station answers a request message with at least one release message to the requesting station as soon as a video data set is sent to the previous station and error-free reception has been confirmed by this previous station with at least one confirmation message, and
• (h) a station transmits the video data set which it has received from the successor station after the arrival of at least one release message from its predecessor station to its predecessor station, and
• i) the procedure described by the features f), g) and h) is repeated until the video data record of the last station of the data transmission chain has arrived in the station which initiated the cycle, and
• j) the station which initiated the cycle sends a second request message to its successor station after the arrival of the video data record of the last station in the data transmission chain, and
• k) the second request message is passed on from one station to the next station of the data transmission chain until it has reached at least the previous station of the data transmission chain, and
• l) the penultimate station and from this in descending order of the transmission chain at least every second station after receiving the second request message transmit a digitally coded video data record to its predecessor station, and
• m) the procedure described by the features f), g) and h) is repeated until the video data record of the penultimate station of the data transmission chain has arrived in the station which initiated the cycle.

2. A method for distributed wireless video observation before preferably using the device according to claim 7, characterized in that

• a) several stations form a logical data transmission chain, in which each station, with the exception of the first and last station in the data transmission chain, has a logical predecessor station and a logical successor station, and
• b) create at least two stations from video image sequences of an observation period of digitally coded video data sets,
• c) a station, preferably at the beginning of the data transmission chain, initiates a cycle by sending a first request message to its successor station, and
• d) the first request message is passed on from one station to the next station of the data transmission chain until it has reached at least the last station of the data transmission chain, and
• e) the penultimate station and from it in descending order of. Transmission chain at least every second station after receiving the second request message transmit a digitally encoded video data record to its predecessor station, and
• f) after receiving a video data record, these predecessor stations transmit at least one acknowledgment message to their successor stations and at least one request message to their predecessor stations, and
• g) a station answers a request message with at least one release message to the requesting station as soon as a video data set has been sent to the previous station and error-free reception has been confirmed by this previous station with at least one confirmation message, and
• (h) a station transmits the video data set which it has received from the successor station after the arrival of at least one release message from its predecessor station to its predecessor station, and
• i) the procedure described by the features f), g) and h) is repeated until the video data record of the penultimate station of the data transmission chain has arrived in the station which initiated the cycle, and
• j) the station which initiated the cycle sends a second request message to its successor station after the video data record of the penultimate station of the data transmission chain has arrived, and
• k) the second request message is passed on from one station to the next station in the data transmission chain until it has reached the last station in the data transmission chain, and
• l) the last station and, in descending order of the transmission chain, transmit at least every second station a digitally coded video data record to its predecessor station after receiving the second request message, and
• m) the procedure described by the features f), g) and h) is repeated until the video data record of the last station of the data transmission chain has arrived in the station which initiated the cycle.

3. A method for distributed wireless video observation according to claim 1 and 2, characterized in that

• 1. the logical data transmission chain is closed to a ring ge, in which the video data sets are circulating and
  • - The video data records are updated as they go through their own station.

4. Procedure for distributed wireless video observation after Claims 1 and 2, characterized in that the video records can be supplemented with additional data.   5. Procedure for distributed wireless video observation after Claims 1 and 2, characterized in that the video records can be replaced by other data. 6. Procedure for distributed wireless video observation after Claims 1 and 2, characterized in that messages include an expiration time after which it is exceeded they are no longer forwarded. 7. Device for performing the method according to claim 1 and 2 with a plurality of stations, which in turn from

• 1. at least one video camera and
  • - A data receiving unit for receiving data at least one other station and
  • - A data transmission unit with preferably small transmission power for transmitting data to at least one further station and
  • - there is a central unit,

characterized in that

• 1. the stations are arranged within the at least pair-wise mutual range of wireless data transmission paths that they form a data transmission chain of greater length than a single range of a wireless data transmission path, and
  • - in at least one station
• 2. at least one video camera takes video image sequences and the video signal in analog or digital form to the central unit, and
• 3. the data receiving unit receives at least one video data set from the transmitting unit and at least one further station and forwards it to the central unit, and
• 4. The central unit digitizes the analog video signals supplied by the video camera, which compiles digital video data into video data sets and coordinates the message exchange according to claims 1 and 2.

8. Distributed wireless video observation device according to claim 7, characterized in that it in the Data transmission chain also stations without a video camera can give that at least one video data set of min received at least one station and this at least transmit another station. 9. Device for distributed wireless video observation according to claim 7, characterized in that at least at least one station over the available video data sets an interface can be viewed. 10. Device for distributed wireless video observation according to claim 7, characterized in that the current the stations are supplied via solar cells. 11. Device for distributed wireless video observation according to claim 7, characterized in that the current saving operation of the stations a power distribution unit the video cameras, the central unit, the emp capture unit and the transmitter unit the electrical energy allocated depending on the agreed operating mode.