1.1 Connection of sensors to the recorder
M-K5-SM25 set consists of the recorder, two symmetric electric lines and two or three magnetic antennae. The sensors should be connected to five channels of the recorder. Channels order is fixed. Channels numbers 1, 2, 3, 4, 5 (in the "Arrangement settings" menu, and on the top covers of the recorder and preamplifier they mark as H1, E1, E2, H2 and H3 correspondingly) should be connected to sensors which measure following field components Hх, Ey, Ex, Hу and Hz.
During the measurements along one profile, the orientation (bearing) of sensors must be the same at each measurement station. In this case the radio transmitter’s azimuths will be determined more exact and the data processing will be easier. To make this process easy the electric lines can be labeled by some marks. Magnetic antennae are also mark and fix one relative to another using special holder. In this case they always will be placed orthogonally one to another and it’s easy to put them horizontally relative to ground. Marks should be putted on some side of the coils and their orientation relative to parts of the world and their orientation during field works should be invariable.
1.2 Installation of the M-K5-SM25 set
M-K5-SM25 installation at a station
The special attention should be paid to the connection of electric lines to the preliminary amplifier. It is important to connect lines according to selected orientation (not to confuse E1 and E2 channels). Usually connection wires of ungrounded electric lines have two types of color correspond to two different electric channels.
The selection of Gain factor occurs directly at the work site, time series should not be higher than ¾ of the dynamic range.
It is better to make measurements without the host PC, because it produces significant electromagnetic noises, but it can be used for preliminary setting of measurement schedule and other adjustments. The recorder, magnetic sensors and electric preamplifier should be protected from water, shocks and blows. The equipment should be kept clean, especially output connectors of the recorder, magnetic sensors and preamplifier.
Before the device installation is necessary to mark the center of the measurement point. All sensor bearings are counted relatively to this point. It is better to remove the recorder from the sensors at the distance that provides by length of connection cables.
Order of the installation:
- put electric lines in the directions of interest (along or across the profile); in each station electric line putted along the profile usually should be connected to E1-connector of the preamplifier, the other line should be putted across the profile (orthogonally to E1) and connected to E2-output.
- holder with 2 or 3 magnetic coils (magnetic sensors) should be placed near the center (usually about 1 m) of the electric lines.
- Magnetic sensor H1 ( connected to the first magnetic channel of the recorder) should be directed orthogonally to the electric line E1 (first electrical channel of the preamplifier) Coil H2 in this case will be directed along the profile (and across the E2 direction). Antenna H3 (if any) should be installed at the holder vertically.
- connect the preamplifier cable and magnetic antennae cables to the recorder. The connection scheme is on the preamlifier’s cover.
- The duration of measurement (time series length) is determined by the conditions of measurements and it is selected by the operator. It is usually about: 8 seconds in D1; 2 seconds in D2; 1 second in D3 frequency bands. The collection time in D4 frequency band is usually ¼ of time series length in D2.
1.3 Switching on the recorder
Switching on the recorder occurs by single long pressing of the button POWER (about 5 seconds). During the transition from one station to another it is not necessary to switch it off. Full battery charge is enough for two days of measurements. The night time is enough for the battery charging by power supply unit. Switching off the recorder is desirable in case of using of 12V external battery.
Switching on of the recorder’s display occurs after the pressing of any key of its keypad. After the switching on it is necessary to pay attention on the status bar information about free space of memory, charge of battery e.t.c in the bottom of the screen.
For the switching off the recorder is necessary to make three short pressing of the POWER button (during 5 seconds). Single pressing of this button during the measurement stops the data acquisition.
1.4 Setting of magnetic antennae, preamplifier and recorder serial numbers, and antennae azimuths
Pressing of button 1 two times in the main menu opens menu. Then the operator has to set serial numbers, according with the recommendations. Azimuths of sensor’s orientation (bearings) should be measured using the compass. Azimuth of electric line is usually measured clockwise from the north direction to the direction of line connected to red output E1 of electric preamplifier. Magnetic sensor’s azimuth is usually measured clockwise from the north direction to the direction of safe cover of sensor. The output wire of antenna should be directed to operator during azimuth determination. The error of orthogonal orientation of electric lines and magnetic sensors must not exceed 2 degrees.
1.5 Creation of the data file name
Forming of the measurement point parameters and data file name:
- button ← of the main menu – transfer to the menu of setting of measurement site parameters;
- using buttons 5, 6, 7 it is possible to change these values manually.
First three digits of the file name correspond to the number of profile, digits from forth to six are for the station number, last two digits are specified for the number of repeat (see items 5.5).
File name corresponding to these settings will be shown in the down part of this window.
1.6 Preparation of schedule
RMT-F measurements
Measurements at the work site are usually made using only one schedule in the memory, where start type is specified as COMAND and cyclic collection is switched off. Cyclic collection usually uses during mobile measurements.
RMT-M measurements
It is necessary to activate the periodic (cyclic) collection mode during the mobile measurements by pressing of button “3” (value YES Periodic collect) of the keypad. Periodicity (button “4”) usually is zero (i.e. there is no gap between measurements). The GPS settings in this case are following:
- GPS work mode – AUTO
- GPS power mode – ON
1.7 Data acquisition
Recorder’s start is carried out using the ENT button (data logging) from the menu shown in Fig. 5.5. If the recorder is ready to the data acquisition and it does not need more settings, measurements start from the main menu using the button combination ←-ENT or from any other menus using the button combination F - ← - ENT.
If the recorder stops data acquisition before the specified measurement time it is necessary to look for a reason of interruption in LOG file.
Confirmation of data collection marks by switching off the display and switching on the LED Mode.
Data acquisition should be stopped manually by the operator In case of mobile measurements (single pressing of button "Power").
1.8 Data viewing
The part of H1 time series appears after the measurement by default. Operator can change the channels according to 5.15 and use this information in order to estimate the signal level changing and noise situation in field (but usually a host-PC is used).
2. MANAGEMENT OF THE RECORDEr using the host-PC
Management of the recorder can be realized on-line by PC through Ethernet cable ("Laptop" PC is used in field conditions). Management software (SM25m) is delivered with the recorder and allows an installation of data acquisition parameters, initial check-up and control of recorder operations, data communication with host PC, and permit operator to check data acquisition and data processing results in graphic form.
Computer requirements:
- CPU frequency – 400 MHz or higher;
- RAM – 128 Мb or more;
- OS Microsoft Windows 2000 or higher;
- Metwork board with Ethernet output;
- parallel cable ("Ethernet" connector);
- display resolution not less than 1024 x 768 pixels.
Connection of the recorder to the host PC makes through the Ethernet cable. Connection status is marked by Ethernet LED of the recorder according to the table.
For checking of network settings it is necessary to set the network address as 192.168.0.XXX, where XXX – any number from 1 up to 200. Subnet mask is 255.255.255.0.
Sequence of network settings for Windows XP: Start-up - Settings - Control panel - Network connections - Connection on the local network - Properties - TCP/IP settings - In the window "IP address" one must set the network address 192.168.0.XXX - In the window "Subnet mask" one must set 255.255.255.0.
