DE4200817C1 - Data transmission unit transmitting sonic signals to recorder from hydrophones - arranged on measuring cable towed by ship equipped with sonic pulse generator and identical processor is assigned to each hydrophone with microphone input - Google Patents

Abstract

A data input is transmitted across a data line (D1-Dn), with data received from a preceding processor (P1-Pn), then transmitted to a recorder (4). Current supply lines connect the processors and a common clock line (C), and the data line are connected from the first processor (P1) to the recorder. Each processor has an ADC with a frequency lower than the clock frequency. The ADC converts the sonic signal of the hydrophone (H1-Hn) to supply an evaluator (AW) and produces a transmittable set (PAK) and stores in a signal storage (SS) of the processor. Each processor has an input storage (ES) connected to the data input also a transmission circuit (UB). The output and input stores transmit data strictly synchronised to clock pulse to data output of processors or receive data input. Each processor has an identification transmitter which superimposes an identification for the respective hydrophone on the set (PAK). ADVANTAGE - With simple construction of measuring cable, ensures interference free transmission of large amt. of data.

Description

The invention relates to a data transmission device the type mentioned in the preamble of claim 1.

Such facilities are used for the investigation of Ge water soils, especially seabeds, by means of reflections seismic needed. The ship's sound pulse generator, usually also towed behind the ship is generated, short sound impulses from the water bottom be reflected. The direct sound impulse and all right inflected impulses are given by those in particular preferably equidistant distances on the measuring cable  ordered hydrophones and caught in the recorder, so any suitable data recording device saves. The evaluation of the stored measurement curves enables the creation of geological statements about the Un background of the water floor.

On measuring cables of the type mentioned are usually hydro phone in larger numbers, for example in sizes ordinance 100, provided for statements in the desired resolution to be able to make a solution. This creates problems with the Da transmission from the many hydrophones to the recorder.

Known data transmission devices of the beginning named type work with individual analogue transmission lines for each hydrophone. The disadvantage here is the ge rings signal / signal to noise ratio and the required high lei number in the measuring cable, the high costs, susceptibility to failure and maintenance problems such as replacement of a hydrophone.

DE 36 20 326 A1 describes a data transmission device tion of the type mentioned, in which the Signa le are digitally transmitted after conversion. Here too but one transmission for each connected hydrophone line provided.

DE 24 33 191 B2 discloses one or more To assign geophones to a measuring station, the Da geophones from the last measuring station to the front last measuring station with the addition of the geophone data from the penultimate measuring station and where with this data transfer to the other measuring stations to the main station accordingly. The processors Processing larger amounts of data also means that Construction presents significant problems.  

A state-of-the-art digital solution would have to provide a data transfer bus using of an access management system that the access rights the individual hydrophones when sending them onto the bus Access management known in the prior art systems lead with the high number of Broadcasters do that most of the time with access controls processes is consumed and only a fraction of the available time for data transfer is available. For the present purposes with such a large number of large amounts of data on hydrophones sending on a bus known bus systems are therefore not suitable.

The object of the present invention is therefore to  a data transmission device of the aforementioned To create the type with a simple construction of the measuring cable trouble-free transmission of large amounts of data guaranteed.

This object is achieved with the features of Identification part of claim 1 solved.

In this construction of the data transmission device the sound signals of the hydrophones are digitally transmitted, but not to connect all processors shared bus, but always in cycles from one Processor transferred to the next, the transferring Data packets are cached in each processor and a transmission circuit according to a predetermined priority between the packets to be transferred on your own Interpose package to be sent hydrophone. Because here for the recorder it is unclear which hydrophone a Pa ket comes, each package contains an identifier that makes up can determine the sending hydrophone. Each package contains So at least information about the determined Sound amplitude and the place of the sending hydrophone. With today's common, easy to implement electronically The clock frequencies in the megahertz range can be researched such relatively short packages so quickly through the Processors of the measuring cable push that the time To order of the time of reception with sufficient accuracy speed is possible, so that the important for the evaluation Parameters, namely determined amplitude, location and Determine the reception time from the data stored in the recorder are cash. With this type of transmission, the conventional Niche bus systems required regulation of the access Missing authorization for several transmitters broadcasting simultaneously the. The data lines between the processors are permanent dig free for data transmission. As a result, the number of hydrophones a high data throughput possible where in digital data transmission for high interference immunity worries. Compared to the known measuring cables with one of the An  Number of lines corresponding to hydrophones can be significantly reduce the number of lines to a few Lines, the data line in the case of serial over with bit width 1 as a single-wire line can be. This reduces the cost of the measurement cable reduce and simplify maintenance work.

The features of claim 2 are advantageously provided. In this way you can use the incoming recorder identifiers identifying the sending processors agree without this needing a fixed own identifier gen. This is e.g. B. advantageous for repair work, because a newly inserted processor does not have an identifier per must be grammed.

The features of claim 3 are also advantageous intended. This allows the data transmission to be simplify direction and make optimal use of it.

The features of claim 4 are also advantageous intended. This ensures that the data transfer can be optimally used without the Danger of data congestion. All processors can be exactly the same send in time. The signals sent at the same time are running then to the recorder, and all the data lines of the measuring cable are empty again before the next packets are sent the.

The features of claim 5 are also advantageous intended. In this way, a separate line can be saved in the measuring cable for the converter cycle. Further can all converters be operated synchronously, which for Data transmission device according to the invention is advantageous is because then all processors can send at the same time NEN, what an optimal use of the Da invention enables transmission device.  

The features of claim 6 are also advantageous intended. This initially results in a considerable amount Data reduction, since only those for the evaluation of the sound interesting maxima and minima as well as their time stands are transferred to each other. Another advantage here is that the sound maxima from the direction of the ship coming along the measuring cable from the first to the last Hy drophon run, but the data packets in the opposite direction towards the ship. Those of the same maximum in the successive processors generated packets thus run at a sufficient interval without data jam in a row to the recorder.

The features of claim 7 are also advantageous intended. In this way, the time interval can be particularly easy and with little circuitry teln.

The features of claim 8 are also advantageous intended. In this way, all processors can be reset to a defined initial state at the same time zen, for example before starting a measurement.

The features of claim 9 are also advantageous intended. Such a data line only needs one Wire, which increases the number of lines of the measuring cable Lich reduced.

The features of claim 10 are also advantageous intended. This prevents data congestion, since in each Processor forwarding packets takes precedence over its own has sent a package. It also results here from the advantage that since the identifier of the sending process sors and the transfer time from this processor to the re corder is known to determine the exact time of transmission leaves.

In the drawings, the invention is for example and shown schematically. Show it:

Fig. 1 is a schematic representation of a reflection seismic measuring operation in the sea,

Fig. 2 is an illustration of signals received at different hydrophones sound signals,

Fig. 3 is a schematic representation of the management and processor arrangement in a measuring cable,

Fig. 4 is a block diagram of a processor and

Fig. 5 illustrates a packet data to be transmitted.

Fig. 1 shows a ship 2 traveling on the sea surface 1 , dragging a measuring cable 3 behind it. On the measuring cable n hydrophones H ₁ to H _n are arranged at predetermined, preferably equidistant intervals. The Meßka bel has a number of electrical lines, Zugübertra transmission facilities, such as steel cables and. Like., On, which are not shown in detail. The measuring cable 3 is connected on the ship to a recorder 4 , which records the sound signals recorded by the hydrophones H ₁ to H _n for later evaluation.

The ship 2 also tows a sound pulse generator 5 , which generates a sound pulse at the start of a measurement process. A generated sound pulse moves in the water at the speed of sound in all directions, including in the direction of the double arrow towards the hydrophones H ₁ to H _n and in the direction of the drawn arrows towards the seabed 6 and after reflection from it towards the hydrophones. The sound also penetrates into the sea floor and is reflected by an underlying boundary layer 7 , which is shown with dashed arrows.

Fig. 2 shows the representation of the sound signals arriving at the hydrophones, namely one on top of the other, each because over the time axis the sound amplitudes in the hy drophones H ₁ to H ₃ .

If one looks at the sound signal on the hydrophone H ₁ in FIG. 2, one first recognizes a larger maximum and minimum which result from the direct sound (double arrow in FIG. 1). Then comes a smaller maximum and minimum from the reflection on the sea floor 6 and then again a smaller maximum and minimum, resulting from the reflection at the boundary layer 7 . With temporal chem offset corresponding to the longer duration of the sound signal in the water there is essentially the same signal for the following hydrophones, as shown in FIG. 2. From looking at the image of FIG. 2, statements can be made about the geology of the sea floor.

It is primarily a question of knowing the exact temporal position of the extreme values, i.e. the maxima or the minima of the sound signal curves, in their amplitude value and in their temporal position on the time axis. In the example of the sound signal of the hydrophone H _3, it is therefore sufficient to know the height of the extreme values in their temporal position, as shown below in the representation R, which shows the correspondingly reduced signal.

Fig. 3 shows a highly schematic structure of the measurement line 3. The hydrophones H ₁ to H _n and the recorder 4 are shown . A processor P ₁ to P _{n is assigned} to each hydrophone. Supply lines (+) and (-) to which all processors are connected run continuously from the ship in the measuring cable. Furthermore, a reset line and a clock line C run continuously, to which all processors are also connected. Recorder 4 is also connected to clock line C.

Data lines D ₁ to D _n each run from one processor to the next and to the recorder 4 . A data line D ₁ therefore runs from the first processor P ₁ to the recorder 4 , a data line D _{2 runs} from P ₂ to P ₁ . . . and a data line D _n from processor P _n to processor P _ni .

The structure of the processors is explained in the block diagram using the processor P _x in FIG. 4.

As can be seen in Fig. 4, the associated hydrophone H _{x is} connected to an input. The processor is connected to the continuous lines C, R, (+) and (-). It receives data from the data line D _{x + 1} and sends on the data line D _x .

In the illustration of FIG. 4, the interior of the Pro zessors P _x, which is identical to all other processors, illustrates in schematic block representation of the major functional components, as necessary for understanding of the electronics art and sufficient.

There is an output memory AS connected to the output line D _x and an input memory ES connected to the data input line D _{x + 1} . Data that come from the preceding processor P _{x + 1} and are to be sent to the processor P _x-1 lying next to the ship first arrive in the input memory ES, must be transferred from there to the output memory AS and are sent from there . The transmission is regulated by a transmission circuit ÜB, whose input is connected to the output of the input memory ES and whose output can transmit data to the output memory AS.

In the block diagram of FIG. 4, all data-transmission lines are shown as solid lines with an arrow within the processor P _x , the arrow indicating the direction of the data transmission. Dashed lines represent clock lines on which clock signals for clocking the connected circuits are transmitted. It can be seen from FIG. 4 that AS, ES and ÜB are connected to the clock line C of the measuring cable 3 , that is to say all are clocked at the same frequency as the clock line C.

The sound signal from the hydrophone H _x first arrives at an A / D converter A / D, where it is converted into a digital signal and transmitted to an evaluation circuit AW, which uses it to produce a data packet that is written to a signal memory SS, the output of which is sent to another input of the transmission circuit ÜB is connected.

The transmission circuit B monitors its two inputs lines from the storage ES and SS to each there lying, not yet read data and provides according to the given Priority that one or the other of the Storage ES or SS the data in the output storage AS be transmitted.

In the advantageous exemplary embodiment, the priority was regulated in such a way that ES is always overwritten first. Only if there is no data that has not yet been written there will be transmission from SS. It is therefore priority to pass on data before sending your own data. Since data congestion is prevented, and it loads from the arrival time of a data packet on the recorder 4, exactly determine the send time from a specific processor.

The transmission circuit also includes a not shown set up a Ken to send the package to impress. In the preferred embodiment, ge this happens because in an identifier part of the packet the identifier by a certain amount in one direction  is changed, for example increased by 1, namely every time a packet from the input memory ES is transferred to the output memory AS. In one out the packet transmitted to the signal memory SS becomes the identifier when transferring to a fixed standard value, e.g. B. 1, set. In this way there are clear, the Identifiers identifying the place of dispatch.

A packet that comes from the processor P ₁ has the originally set identifier 1. A packet from the processor P ₂ had the identifier 1 when it was sent. This was increased by 1 when the processor P ₁ was run through, ie set to 2 . A packet from the processor P _n originally had a 1 and was increased n-1 times, that is, after it has run through all the processors of the measuring cable, it finally has the identifier n. In the data recorder, the identifier can therefore be used to clearly identify where the packet comes from.

The A / D converter A / D of each processor is supplied with a clock frequency from a coaster UN, which is connected to the clock frequency on line C. The converter frequency is generated from the clock frequency in a fixed reduction ratio. With this type of generation of the converter frequency, all the A / D converters of the processors run synchronously with the same converter frequency. Sound signals can thus be converted simultaneously in each processor and converted into packets to be transmitted. All processors can send packets at the same time, which are then pushed in a row through the measuring cable 3 to the recorder 4 ge.

To prevent data congestion, the converter frequency must be essential Lich lower than the clock frequency. In the preferred Embodiment the converter frequency is so low that if all processors are sending at the same time, they are singing packages first all through the measuring cable to the recorder are pushed before the next Pa  kete are generated. For this, the converter frequency must be one Factor lower than the clock frequency that the Pro product corresponds to the required transmission time ei package from one processor to the next and the number of processors.

As mentioned in the discussion of FIG. 2, it is sufficient for evaluating the sound signals received from the hydrophones to determine the amplitudes of the extreme values of the sound signal and their time interval. The evaluation circuit between the A / D converter and the transmit memory is designed for this purpose so that it evaluates the sound signal digitized by the A / D converter accordingly and each forms a data packet only when reaching a relative maximum. The data packet therefore contains the amplitude value of the maximum determined and its time interval from the previous maximum. The time interval to the previous maximum is determined in the preferred embodiment in a simple manner by counting the converter clocks and by specifying their number.

This results in a significant reduction in data. Data packets to be transmitted are no longer formed with each converter cycle, but only at larger intervals whenever the sound signal has an extreme value that must be transmitted. This considerably reduces the data load on the data transmission device. In addition, data congestion is further reduced in this way in that a certain extreme value, which is received by the hydrophones, usually runs past the hydrophones from the direction of the sound pulse generator 5 , i.e. from the direction from the beginning of the measuring cable, and successively in chronological order of this must be received and then sent by the assigned processors. The correspondingly formed data packets run on the measuring cable 3 in the opposite direction, ie towards the ship. The result of this is that in any case the packets to be transmitted always find a free data line.

In the preferred embodiment of the invention, data packets are used, the format of which is shown in FIG. 5. The packet PAK shown is transmitted serially in the direction of the arrow. It consists of several parts, namely a header (K) with two bits, an identifier part (Kenn) of 8 bits in length, a part (Amp1) of 8 bits in length containing the amplitude value, a part containing the time interval to the previous maximum ( Abst) of also 8 bits in length and an end part (E) of 1 bits in length. The entire packet PAK therefore has a length of 27 bits. With serial transmission on a 1-bit single wire line, which is used in the preferred embodiment, requires 27 clock pulses. With a length of the measuring cable 3 of 100 hydrophones at least 2700 clock pulses are required to transmit a packet from the last processor P _n to the recorder 4 . The converter frequency of the A / D converter should then be at least 2700 times smaller than the clock frequency. If this is common with today's technology such. B. is 2.7 MHz, the A / D converter can be clocked at 1000 Hz, which is sufficient for the evaluation of the sound signals.

Compared to the described preferred embodiment can be varied widely within the scope of the invention.

For example, to increase the transmission speed, the number of wires in the data lines D ₁ to D _{n can be} increased. In the case of the 27-bit data packet shown in FIG. 5, a 27-bit data line can be used, for example, which therefore has 27 parallel wires. A packet can then be transmitted in one clock cycle, i.e. at 27 times the transmission speed. Accordingly, the converter frequency can be increased by a factor of 27, which improves the temporal resolution when determining the signal.

In the preferred exemplary embodiment, it was shown that the transmission circuit ÜB of a processor P _x always gives priority to the transmission from the input memory ES over the transmission from the signal memory SS. This is to ensure that data congestion in the measuring cable 3 is avoided. However, it may be advantageous to give priority to the sending of a processor's own packet from the signal memory SS, since then time shifts between the conversion of a sound signal and its sending are avoided, that is to say the time assignment is precisely preserved. With a suitably high clock frequency and correspondingly low converter frequency, there is always such a low load on the data transmission device even with a larger number of hydrophones that data congestion is avoided even with this priority selection.

The converter frequency for the A / D converter A / D is derived in the preferred embodiment with the coasters UN from the clock frequency in a fixed ratio. The converter frequency can also be generated on board the ship 2 and separately supplied to all processors via an additional continuous line in the measuring cable 3 . This has the advantage that the converter frequency can easily be individually adapted to the given conditions.

In the preferred embodiment shown, the Identification of a packet in the sending processor on a fe most initial value, e.g. B. 1, and then each Transfer in the subsequent processors by one fe Most amount changed, for example increased by 1. But it can also be worked in other ways. At for example, each processor can have a fixed identifier, which he writes in the identifier part of the package. When over carry by the processors is then the identifier part transfer unchanged.  

The package can also contain other pieces of information ten that contain, for example, the exact time which is the data content of the package by conversion in the A / D wall of the respective processor was determined. Hereby improves the accuracy of timing the signals will.

In the illustrated embodiment, a continuous reset line R is included in the measuring cable 3 , with which all processors are reset to a defined initial state, who can. If necessary, this line can be omitted and the processors can be reset in another way if necessary, for example by interrupting the supply voltage (+).

It can be reduced to data by transferring only the Am plititude values (Amp1) and the time interval values (Abst) ver to be waived. The part included in the PAK package (abst) is in the preferred embodiment by counting the Converter cycles determined, but this time interval also specify in another way, for example by counting len of the clock clocks.

To standardize the data transmission, the packets to be transmitted are of fixed length in the preferred embodiment, as shown in FIG. 5 with the example 27 bits. Other formats can also be used, for example with a variable length as required, the structure of the packets being different from that shown in FIG. 5. The packets can be shortened, for example, by data compression.

Claims (10)

1. Data transmission device for transmitting sound signals to a recorder of several hydrophones, which are arranged on a measuring cable, which is towed by a ship, which is equipped with a sound pulse generator, characterized in :
that on the measuring cable ( 3 ) each hydrophone (H ₁ -H _n ) is assigned an identical processor (P ₁ -P _n ), each of which with a microphone input to the hydrophone, with a data output via a data line (D ₁ - D _n ) is connected to a data input of the processor preceding the recorder ( 4 ), with a clock input to a common clock line (C) and at least to common power supply lines (+), (-), the clock line (C) and the Da tenleitung (D ₁ -D _n ) from the first processor (P ₁ ) lying to the recorder ( 4 ) are connected to the recorder,
that each processor (P ₁ -P _n ) with a converter frequency that is lower than the clock frequency, ge clocked A / D converter (A / D), the sound signal of the hydrophone (H ₁ -H _n ) converts into a digital signal and feeds it to an evaluation circuit (AW), which creates a transferable packet (PAK) and places it in a signal memory (SS) of the processor (P ₁ -P _n ),
that each processor (P ₁ -P _n ) has an input memory (ES) connected to the data input, an output memory (AS) connected to the data output, and a transmission circuit (ÜB) which has its output to the output memory (AS) and two inputs are connected to the input memory (ES) and the signal memory (SS), are designed in such a way that they monitor the presence of unread packets (PAK) at their inputs and transmit them to the output memory (AS) according to a predetermined priority,
that with each processor (P ₁ -P _n ) all three memories (AS, ES, SS) and the transmission circuit (ÜB) are connected to the clock line (C), with the output memory (AS) and input memory (ES) being so formed are that they send or receive data from the data output of the processor (P ₁ -P _n ) in strict synchronization with the clock clock, and
that each processor (P ₁ -P _n ) has an identifier (ÜB), which imprints the packet with an identifier (Kenn) for the respective hydrophone (H ₁ -H _n ). 2. Data transmission device according to claim 1, characterized in that the identifiers (ÜB) of the processors (P ₁ -P _n ) are designed such that they transmit the packet (PAK) for each of the input memory (ES) to the output memory (AS) Change the identifier by the same amount in the same direction. 3. Data transmission device according to one of the preceding existing claims, characterized in that the Pa kete (PAK) are of a given length. 4. Data transmission device according to one of the preceding claims, characterized in that the converter frequency of the A / D converter (A / D) is a factor lower than the clock frequency, which is greater than the bit length of the packets (PAK) divided by the Bit width of the data line (D ₁ -D _n ) multiplied by the number of hydrophones (H ₁ -H _n ). 5. Data transmission device according to one of the preceding claims, characterized in that each processor (P ₁ -P _n ) has a coaster (UN) which leads from the clock frequency to the converter frequency. 6. Data transmission device according to one of the preceding the claims, characterized in that the Aus value circuit (AW) the digital signal of the converter (A / D) monitored for extreme values and from their Am plitude (Amp1) and their time interval (Abst) to the previous extreme values the package (PAK) creates. 7. Data transmission device according to claim 6, characterized characterized in that the time interval (abst.) as a number the converter cycle is determined.   8. Data transmission device according to one of the preceding claims, characterized in that all processors (P ₁ -P _n ) are connected to a common reset line (R). 9. Data transmission device according to one of the preceding claims, characterized in that the data line (D ₁ -D _n ) has the bit width (1). 10. Data transmission device according to one of the preceding existing claims, characterized in that the Transmission circuit (ÜB) is designed such that it during the transfer to the output memory (AS) Input memory (ES) priority over the signal memory (SS) there.