SK280398B6 - Method of transmitting measurement data - Google Patents

Abstract

Described is a system for remotely reading out data from a multiplicity of measurement units (10), the system operating by radio transmission at a single frequency. The various measurement units (10) deliver their sets of data within stochastically selected time windows of short duration. In this way, the measurement units (10) can have simply designed circuitry and can be operated over very long periods from long-life batteries (28).

Description

Technical field

The invention relates to a method of transmitting measurement data from a plurality of measurement units to a central evaluation unit, wherein the measurement units are connected at different moments with the data transmission path to the evaluation unit.

BACKGROUND OF THE INVENTION

In practice, such methods of transmitting the measured data are carried out by transmission cables arranged between the central evaluation unit and a plurality of measurement units associated therewith. A multiplexer is provided in the evaluation unit, which connects one of the measurement units to the input-output interface of the evaluation unit at predetermined moments.

For many applications, such data transmission is not applicable, either because the distances between the measuring units and the central processing unit are too large, or because the installation of the different data transmission cables is not acceptable due to the high cost or load involved. One example of this is the remote reading of appliances in existing buildings. In this case, it would be highly desirable that the various meters of water, gas, oil, electricity, heat, etc. appliances that are installed in different residential units of the house at different locations could be read without having access to individual metering points. The reading of the measuring instruments is associated with high personnel costs, especially because in most single-person households no one can be reached during the day.

In these cases, where an additional installation of data transmission lines is excluded, wireless data transmission could be considered. However, there is a problem that the radio frequencies are only available to a very limited extent and, moreover, the modem receiving components required for each transmission channel are too expensive. However, for remote reading of appliances' measuring instruments, one important requirement is that the cost of transmitting the data does not in any way exceed the cost of actually measuring the measured data.

LJS-A-5 056 107, taken into account in formulating the preamble of claim 1, discloses a method of transmitting the measured data from a plurality of units of measurement to an evaluation unit, wherein the units of measurement transmit at the predetermined pseudo-random moments unit. In this case, there are overlaps of records transmitted simultaneously by different measuring units. To overcome this drawback, according to US-A-5,056,107, it is proposed to assign to the central processing unit at least two receiving stations which receive records transmitted from different measuring units on the radio-data transmission path. If the records overlap, the received record with the greater field strength is downloaded, while the received record with the less field strength is discarded.

DE-A-31 19 119 also discloses a method for transmitting measured data, wherein a plurality of units of measurement transmit records at random times. The overlapping of records is known by the fact that the received pulses are longer than for non-overlapping records, or by the fact that the records contain a check password to identify the authenticity of the transmitted data, or by the fact that each record is transmitted several times in succession; the record is only downloaded if at least two unchanged records occur.

It has now been found that a large number of such cases of measurement data transmission, in particular for remote reading of consumer measuring devices, relate to only a relatively small amount of data. The periods of time required to transmit the data of one measuring unit may be of the order of several 10 ms. In this case, it is then possible to have all the measuring units transmitted on one common operating frequency, the individual measuring units being associated with randomly distributed narrow transmission windows. Then, for all units of measurement, a single unit of evaluation can be used, whose receiving part is tuned to a common operating frequency. Since it is possible to carry out a very large number of time intervals per day (several million) for the short individual transmission periods mentioned above, there is a likelihood that two measuring units (out of a total of 100 to 1000 units which are, as usual) residential complexes) broadcast at the same time, very small. A small number of overlaps of data records transmitted from different measurement units simultaneously are recognized in the evaluation unit and the respective signal sequences are discarded.

SUMMARY OF THE INVENTION

The aforementioned drawbacks are eliminated by a method of transmitting the measured data from several measuring units to a central processing unit, in which the measuring units are connected at different moments by a data transmission path operating on a common operating frequency with the processing unit, in the measuring unit the measured data to be transmitted together with an identification signal characterizing the measuring unit is assembled into one record, the measuring units deliver their records to the data transmission path at random predetermined moments, the evaluating unit sorts out the received signal sequence on the operating frequency and corresponds to the overlapping records for further evaluation signals remaining after this sorting, which correspond to a single record, according to the invention, whose essence is that the measuring units store records of measured data at regular intervals and between effect a plurality of stochastically spaced broadcast moments.

Such a method of data transmission can be realized with low technical costs.

Starting from the installation typical of remote reading of appliances data in a residential block, a 20 mW high-frequency transmit power is sufficient, which corresponds to an operational wattage of about 200 mW. The short transmission times, which are of the order of 10 ms, therefore result in such a low overall power consumption that it is possible to use long-life batteries for the operation of the measuring units, usually for 10 years. Therefore, the capability of the radio data transmission capability is comparable to the calibration periods of the units of measurement, so that it is quite sufficient to replace these units entirely in time periods after about 10 years.

Further advantageous solutions according to the invention are set out in the dependent claims.

According to claim 2, the measured data from the measuring point are transmitted only if it has to some extent changed from the last transmitted measured data. Thus, it is possible, for example, for measuring units of heat consumers in summer

2806 for a period in which it does not heat up, completely waive the transmission of the measured data for weeks. This extends the usable time of the batteries supplying the metering unit.

When transmitting data, it is known that, in addition to a predetermined algorithm, a control number, i.e., one control bit, which is routed along the data path, can be calculated from the data to be transmitted. At the end of the reception, the control number can then be calculated from its own data and compared with the transmitted control number. If both control numbers match, the data transfer was correct. In the method according to claim 3, this checking method is simply used to determine the overlap of records, since when overlapping records transmitted independently from different measurement units, a total sequence of signals is generated with a completely different bit structure which corresponds to a substantially logical sum of the two individual structures. If the time offset between the two sub bit structures is large, the check number detected by the evaluation unit at the end of the entire sequence belonging to the time later bit structure does not correspond to all previously received data. With only a small time offset, there will be no control number at all at the end of the entire sequence, or a check number that does not belong to a previously transmitted data sequence.

According to a further preferred embodiment according to claim 4, it is possible first to observe the time generation of the measured data, and secondly, it can be inferred from the fact that for a certain measuring unit that the last received measured data record was made long ago to malfunction.

In the method according to claim 5, it is also guaranteed for a long time that the timing of the measurement data to be loaded is correct in time.

In the embodiment according to claim 6, there is an additional possibility of fault detection. For example, for measuring units of appliances, the control criterion may be that the measured data transmitted increases monotonically. Transmitting measured data that is smaller than the last correctly measured data indicates a fault. However, a record received from one measuring point can be compared not only with previously transmitted records from the same measuring point, but also with records from other measuring points if there is a factual link. If, for example, in a building complex, the transferred records of other units indicate that heat consumption is stagnating overall (eg due to heating off) and in a single unit according to the transmitted records, the heat consumption nevertheless increases significantly, it means that either or that its installation is faulty.

According to claim 7, the resulting faults in the evaluation unit can be stored and stored for later evaluation for fault elimination.

A further embodiment according to claim 8 is advantageous in view of increasing the security of data transmission.

By means of a further preferred embodiment according to claim 9, a random distribution of the transmission times of the different measuring units is obtained in a simple manner using identical random number generators.

According to claim 10, it is ensured that the eventual matching option is completely eliminated as a result of the identical design of the random number generators or their algorithms used. The last or last two decimal places of the measured values may be used as an uncontrollably changing physical variable in a measuring instrument with maximum resolution.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to the accompanying drawings, in which: FIG. 1 shows a block diagram of a heat consumption measuring device in a building complex, FIG. 2 is a flow chart of a control program used in the computer of the evaluation unit of the device of FIG. 1, and FIG. 3 and 4 each show a block diagram similar to FIG. 1, of a varied embodiment of a device for measuring heat consumption in a building complex.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, one heat consumption measuring unit 10 is shown which transmits, at irregular intervals, a broadcast antenna 12 having the following composition: block initial, measured data (heat sink counter status at this time), identification data (number and, optionally, type) unit), the end marker of the block. This data can be converted into a high frequency signal packet with a duration of about 10 ms in a typical heat consumption measuring unit 10.

The RF signal packet is captured by the receiving antenna 14, which belongs to the evaluation unit 16 arranged in the building complex at a location accessible for reading. The evaluation unit 16 demodulates the RF signal packet, checks it, and stores the heat consumption data for the measurement unit in the assigned memory area, as will be described in more detail below.

The metering unit 10 is a self-contained unit which is not dependent on the mains electricity and which is located on the heating element of the dwelling unit of a building complex or is assigned to a meter of hot water consumption for this dwelling unit.

Further, a plurality of other measuring units 10-i are disposed at other locations of the building complex, of which in FIG. 1 only one. Typically, the number of these measuring units 10-i cooperating with the evaluation unit 16 may range from 20 to 1000 pieces.

The measuring unit 10 is provided with a temperature sensor 18 which is thermally connected to the associated appliance. The non-volatile memory 20 stores the identification signal of the unit 10, for example in the form of a number assigned to the unit 10.

The computing circuit 22 integrates the output signal of the temperature sensor 18 or evaluates it in a predetermined manner, and composes the thus measured consumption value signal with the identification signal from the non-volatile memory 20 and the block start and end blocks in one record.

The recording prepared by the computing circuit 22 is further sold to a memory 24, which in the considered embodiment is activated to store data around midnight.

For this purpose, the clock module 26 of the measuring unit 10 is connected to a first clock circuit 28 programmed at 24.00, whose output terminal is connected to the memory control terminal 24.

The output signal of the first clock circuit 28 further activates the random number generator 30. The random number generator 30 receives three input signals, namely the contents of the non-volatile memory 20, the output signal of the temperature sensor 18 reduced by the rounding circuit 32 to the last digit after the decimal point, and finally is its own output signal. From these three signals, a random number generator 30 calculates a set of transmission times randomly distributed throughout the day according to a predetermined algorithm. In the exemplary embodiment contemplated herein, it is assumed that 6 transmit times per day are required, the mean distance is therefore 4 hours.

Six transmission times are provided at the output for the second clock circuit 34, which in addition receives the time of day prepared by the clock module 26.

If the current time of day matches the transmit times calculated by the random number generator 30, the second clock circuit 34 activates the transmit circuit 36.

On the one hand, the transmitter circuit 36 is connected to the memory 24 and, upon activation, always receives one complete record with the composition "block start tag, measured data, identification data, block end tag", and converts it into a serial representation and modulates it. using the serial bit structure of the output signal of the RF generator belonging to the transmitter circuit 36, and in FIG. 1, which has a transmit power of about 20 mW and operates in the higher MHz range or in the lower GHz range.

Power to the transmitter circuit 36 is provided by a long-life battery 38, which can provide about 200 mW of power to operate the transmitter circuit 36 for the short transmission periods for approximately 10 years.

The electrical logic clock circuit 28, 34 of the metering unit 10, on the other hand, is supplied with energy by the long-life battery shown in FIG. 1 is shown only schematically, without showing its connection to the individual clock switching circuits 28, 34.

In order to provide the consumer with information about which data is transferred from the measuring unit 10 to the evaluation unit 16, a display unit 42 is also connected to the output of the memory 24.

The evaluation unit 16 has a receiving circuit 44 which demodulates and forms the signals received by the receiving antenna 14. The current generated from these signals is applied to the input of a computer 46 which performs evaluation and storage of the received measurement data according to the flowchart shown in FIG. Second

The computer 46 checks in step 71 the current generated from the signals first for the presence of the initial block marker. If such a block start marker is detected in step 72, the following signals are scanned in step 73 until a block end marker is detected in step 74.

The block markings are separated from the received record in step 75 and the check bit is separated. A check number is then calculated from the measured data, which is then compared to the transmitted check number in step 76. If the two control numbers do not match, the program returns to the starting point of the program.

If these two check numbers match, in step 77, the computer fetches from the read / write memory 48 associated therewith, which may be a sufficiently large RAM or a hard disk or diskette, one or more of the previously transmitted recordings of the measured data stored therein, which, according to the identification signal, belong to the received measurement data record.

In a next step 78, the new measurement data record is now subjected to a sense check, which for measuring heat consumption can simply consist in checking, for example, whether the new heat consumption value is greater than the last stored value. For complicated use, a sense check may also be to test whether the just received record of the measured values constitutes a constant and meaningful further development of a larger number of previously received records.

In checking the sense, it is possible to add records received from other units of measurement 10-i when their signals are materially related.

If the record just received satisfies the sense check, this record is compiled with the time prepared by the clock module 50 of the computer 46 and stored in step 79 in a read / write memory array 48 adapted for the measurement unit 10 under consideration.

In practice, this field may consist of only a few memory cells, but preferably at least as many memory cells that are sufficient for the records to be transmitted by one measuring unit 10 per day.

As a rule, the read / write memory 48 is read out once a day from a master main terminal (not shown) via modem 52. For example, the modem 52 may be a TEMEX unit.

Unless otherwise the correct record fails the sense check, in step 80, this record is also stored, together with the time of day, in a fault memory 56, which is also constructed as a read / write memory, and read with the read / write memory 48 via modem 52 from the central main terminal, which then draws conclusions from the faults on the appropriate repair or installation improvements. In practice, the read / write memory 48 and the fault memory 54 may be sub-portions of a single large memory.

For local inspection and maintenance of the computer 46, a keyboard 56 and a monitor 58 may be attached to the computer 46, for example in the form of a laptop computer.

From the description of the device of FIG. 1, it is clear that this device is quite sufficient without data transmission in the direction from the evaluation unit 16 to the various measuring units 10-i. In practice, it is only necessary to arrange the expensive receiving circuit 44 once. In doing so, accurate measurement of the measured data is guaranteed, although the clock modules 26 of the individual measuring units 10-i also differ from time to time due to manufacturing inaccuracies. However, setting the local time in the individual measuring units 10-i is not necessary in the described method of transmitting the measured data to the evaluation unit 16.

In the embodiment of FIG. 3, the electronics of the measuring units 10, 10-i are further simplified. First, it is always based on the current transmission time, from which the only subsequent transmission time is calculated according to the principle of randomness, at which time the next transmission time, which in the contemplated embodiment at any time lies within four hours of the current transmission time. The transmitter circuit 36 is also directly connected to the output of the computing circuit 22.

In another modified device of FIG. 4, an additional memory 60 is connected to the output of the memory 24, which always receives the last transmitted measurement data record (C = clock terminal, I = data input, O = data output). The outputs of memories 24 and 60 are coupled to inputs of comparator 62, which prepares the output signal when both input signals differ by more than one predetermined value, which can be set, for example, at potentiometer 64. Between the output of the second clock circuit 34 and the control a transceiver 36 is inserted into the terminal of the transmit circuit 36, the second input of which is coupled to the output of the comparator 62. In this way, the activation of the transmit circuit 36 will cease until the measured data is substantially altered.

Claims (9)

PATENT CLAIMS A method of transmitting measurement data from a plurality of measuring units (10) to a central processing unit (16), wherein the measuring units (10) at different moments connect a data path working on a common operating frequency to an evaluation unit (16) at the measuring unit (10), the measured data to be transmitted together with the identification signal characterizing the measuring unit (10) is assembled into one record, the measuring units (10) issue their records to the data transmission path at random predetermined times, from the received signal sequence at the operating frequency, those signals which correspond to the overlapping records and, for further evaluation, assume the signal sequences remaining after this sorting, which correspond to a single record, characterized in that the measuring units (10) store the measured data records in at regular intervals and always between defi several stochastically distributed transmission moments. Method according to claim 1, characterized in that the measuring units (10) store the last transmitted measurement data and the random determination of the future transmission time is performed or activated only if the current measurement data differs by more than the last measurement data transmitted as a predetermined value. Method according to claim 1 or 2, characterized in that the measuring units (10) calculate a control number from the measured data to be transmitted according to a predetermined algorithm and supply a corresponding control signal to the measured data, thus forming an extended record that the evaluation unit (10). 16) separates the control signal from the extended records, calculates the control number from the measured data according to the same predetermined algorithm, and stores the downloaded record only if the control number corresponding to the transmitted control signal and the calculated control number match. Method according to one of Claims 1 to 3, characterized in that the evaluation unit (16), together with the record found to be correct, stores the time of day at which the record was received. Method according to claim 4, characterized in that the clock module (50) of the evaluation unit '(16) is set at intervals of time to a normal time. Method according to one of Claims 1 to 5, characterized in that the evaluation unit (16) compares the correctly transmitted record with at least one of the previously received records according to predetermined criteria and saves it only when the new record meets these criteria. Method according to claim 6, characterized in that the evaluation unit (16) maintains a record of records not meeting these criteria and stores these records, in particular together with the time of their receipt and the type of failure to meet these criteria. Method according to one of Claims 1 to 7, characterized in that the determination of the random transmission times is carried out by a random number generator (30), based on the number of outputs characteristic of each measuring unit (10). The method according to claim 8, characterized in that the determination of random transmit times is performed in addition to the uncontrolled changing physical variables.