JPH0224348B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data recording device for a magnetometer that detects and records geomagnetic fluctuations and the like.

In general, when measuring and recording a physical quantity with a relatively low fluctuation frequency that changes gradually, such as geomagnetic fluctuations, if the measured value is A/D converted and recorded as is, it is not necessary when high resolution is required. As the number of bits increased, the recording capacity became larger.

This poses a problem in that the device itself becomes large and inconvenient to handle, and conversely, when the device is downsized, it becomes insufficient in capacity, making it impossible to carry out long-term continuous measurements. In particular, in the case of a data recording device for a magnetometer that is sunk to the ocean floor to measure geomagnetism, it is desirable that the device itself be small and convenient to handle, since it requires work such as lowering to the ocean floor and pulling it up. Therefore, it is necessary that the power supply and recording device be as small as possible.

Therefore, there is a call for the emergence of a new data recording device that satisfies these demands.

The present invention has been made in view of the above points, and the detection signal of a magnetic sensor is sampled, and the amount of change between each sample value after compensation and the sample value before it is temporarily stored in a primary memory. Data recording of a magnetometer that records a large amount of measured values with a small storage capacity by intermittently recording data on a recording means, and that is compact and convenient to handle by supplying power intermittently. It provides equipment.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

As shown in FIGS. 1 and 2, reference numeral 1 is a magnetometer data recording device that is sunk in the ocean floor to detect and record geomagnetism and the like. This data recording device 1 is composed of a magnetic detection means 2, a recording means 3, and a power supply means 4.

This magnetic detection means 2 is equipped with a magnetic sensor 5 that detects a magnetic field, and this magnetic sensor 5 is provided with a detection coil 5a, a compensation coil 5b, and an excitation coil 5c, and the magnetic flux generated by the excitation coil 5c is detected. Changes due to magnetism are detected by a detection coil 5a. A signal conversion circuit 6, an A/D conversion circuit 7, a measurement control circuit 8, and a primary memory 9 are connected to the detection coil 5a in this order.

The signal conversion circuit 6 converts the output of the detection coil 5a into an electrical signal, and the A/D conversion circuit 7 converts the detection signal from the signal conversion circuit 6 into a digital quantity.

The measurement control circuit 8 is composed of, for example, a microcomputer, and is configured to sample the detection signal from the A/D conversion circuit 7. Further, this measurement control circuit 8 outputs a compensation signal for the constant magnetic field value B, and sets an arbitrary value to the constant magnetic field value B. For example, the first detected total magnetic field value M is set to the constant magnetic field value B.
It is becoming more and more like this. The measurement control circuit 8 is connected to the compensation coil 5b via the D/A conversion circuit 10 and the constant magnetic field compensation circuit 11 in order, and the compensation signal is converted into an analog quantity by the D/A conversion circuit 10, and the constant magnetic field The compensation circuit 11 is configured to cause a compensation current to flow through the compensation coil 5b. Due to the operation of the compensation coil 5b, the constant magnetic field value B is canceled out from the total magnetic field value M, and the detection coil 5a detects a varying magnetic field value D with the constant magnetic field value B as a reference.

Further, the measurement control circuit 8 compares each sample value after compensation, that is, the fluctuating magnetic field value Di+1, with the previous fluctuating magnetic field value Di sampled, and outputs the amount of change Si+1 as a signal to the primary memory 9. It's summery.

The primary memory 9 is composed of, for example, a RAM, and is configured to store the change amount signal of the measurement control circuit 8 for a certain period of time (for example, 24 hours).
Further, the primary memory 9 is configured to store the fluctuating magnetic field value D that the measurement control circuit 8 compares, and temporarily stores a new fluctuating magnetic field value D each time the comparison is made.

The recording means 3 includes a data recording control circuit 12 and a data recording section 13 (for example, a magnetic bubble memory), and is linked to a primary memory 9. The data recording control circuit 12 controls the transfer of data in the primary memory 9 to the data recording section 13 at predetermined time intervals, and the data recording section 13 records this data.

The power supply means 4 is composed of a power supply 14 and a power supply control circuit 15, and supplies power to the magnetic detection means 2 and the recording means 3 intermittently. This power supply control circuit 15 performs on/off control of the power supply 14, and is operated by a control signal from the measurement control circuit 8.
It operates for 3 seconds at sampling intervals of seconds, and an operating voltage is supplied to the recording means 3 only when recording data.

Note that 16 is an excitation circuit connected to the excitation coil 5c, and supplies alternating current to the excitation coil 5c.

When trying to accurately measure the constant magnetic field compensation value,
Since an A/D conversion circuit with a large number of bits or a measurement range switching circuit is required, in this device, the setting value of the D/A conversion circuit 10 is determined and set using an appropriate algorithm in the measurement control circuit 8. ,
The set value of the D/A converter circuit 10 when the output of the A/D converter circuit 7 becomes 0 or within a certain range is used as a constant magnetic field compensation value in the temporary memory 9 and the data recording section 1.
Remember it in 3. This is because the output of the A/D conversion circuit 7 often overflows while the constant magnetic field compensation value is not set.

The compensation signal thus obtained is converted into an analog quantity by the D/A conversion circuit 10, and the constant magnetic field compensation circuit 11 supplies a compensation current to the compensation coil 5b. By supplying current to the compensation coil 5b, the detection value detected by the detection coil 5a thereafter becomes a variable magnetic field value D, which is the total magnetic field value M canceled by the constant magnetic field value B.

The detection signal of this fluctuating magnetic field value D is sent to the measurement control circuit 8.
, the measurement control circuit 8 receives the previously sampled fluctuating magnetic field value Di from the primary memory 9, compares it with the currently sampled fluctuating magnetic field value Di+1, and outputs the amount of change Si+1.

Subsequently, the primary memory 9 sequentially stores the amount of change S, and stores the current changing magnetic field value Di+1 in place of the previous changing magnetic field value Di.

The above operations are sequentially and intermittently repeated, and power is supplied from the power supply control circuit 15 only during this operation.

Next, after a predetermined period of time has passed since the data is stored in the primary memory 9, the data is recorded in the data recording section 13 of the primary memory 9 based on a control signal from the data recording control circuit 12. At this time, power is supplied from the power supply control circuit 15 only when the recording means 3 operates.

Note that although a lithium battery is used as the power source 14, the present invention is not limited to lithium batteries.

Furthermore, the magnetic sensor 5 is not limited to that of the embodiment.

As described above, according to the present invention, the detection signal of the magnetic field detected by the magnetic sensor is sampled by the measurement control circuit, each sample value after compensation is compared with the previous sample value, and the amount of change is stored in the primary memory. Since the data in the primary memory is intermittently recorded in the recording means, a large amount of measured values can be recorded even with a small recording capacity. In other words, since only the amount of change is recorded, a large amount of data can be recorded.
The entire device can be downsized and measurement can be carried out over a long period of time. This is particularly effective for signals with relatively long fluctuation periods, such as geomagnetic fluctuations.

In addition, since power is supplied intermittently, power consumption can be reduced, and the power supply can be made smaller, which in conjunction with the reduction in storage capacity, allows the entire device to be further downsized. ,
Handling can also be made extremely easy.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a block diagram of a data recording device for a geodynamic force meter, and FIG. 2 is a diagram illustrating recorded data based on geomagnetic fluctuations. 1: Data recording device, 2: Magnetic detection means, 3:
Recording means, 4: Power supply means, 5: Magnetic sensor,
5a: detection coil, 5b: compensation coil, 5c: excitation coil, 6: signal conversion circuit, 7: A/D conversion circuit, 8: measurement control circuit, 9: primary memory, 10:
D/A conversion circuit, 11: Constant magnetic field compensation circuit, 12:
Data recording control circuit, 13: Data recording section, 1
4: power supply, 15: power supply control circuit, 16: excitation circuit, M: total magnetic field value, B: constant magnetic field limit, D: variable magnetic field value, S: amount of change.

Claims (1)

[Claims] 1. A magnetic sensor 5 consisting of a detection coil 5a, a compensation coil 5b, and an excitation coil 5c, an excitation circuit 16 that drives the excitation coil 5c, and an A/D converter that converts the detection signal of the detection coil 5a into a digital signal.
A D conversion circuit 7, a constant magnetic field compensation circuit 11 that provides a constant magnetic field compensation signal to the compensation coil 5b, and the A/
It samples and captures the detection signal from the D conversion circuit 7, and outputs a constant magnetic field value compensation signal, and also compares each sample value after compensation with the previous sample value and outputs the amount of change as a signal. a measurement control circuit 8, and a D/A that converts a constant magnetic field value compensation signal outputted from the measurement control circuit 8 into an analog value and applies it to the constant magnetic field compensation circuit.
A conversion circuit 10, a primary memory 9 for updating and storing the sample value of the current detection signal output from the measurement control circuit 8, and a primary memory 9 for temporarily storing the change amount signal output from the measurement control circuit 8; A recording means 3 for intermittently recording the data stored in the memory 9 at predetermined time intervals, a power source 14, and power from the power source 14 is intermittently connected to each of the circuit sections according to a control signal from the measurement control circuit 8. A data recording device for a magnetometer, characterized in that it is equipped with a power supply control circuit 15 that supplies power to the magnetometer.