The FIELD SCOUT CM1000TM Chlorophyll Meter senses light at wavelengths of 700 nm and 840 nm to estimate the quantity of chlorophyll in leaves. The ambient and reflected light at each wavelength is measured. Chlorophyll a absorbs 700 nm light and, as a result, the reflection of that wavelength from the leaf is reduced compared to the reflected 840 nm light. Light having a wavelength of 840 nm is unaffected by leaf chlorophyll content and serves as an indication of how much light is reflected due to leaf physical characteristics such as the presence of a waxy or hairy leaf surface.
♦ Lasers define the target as the trigger is pressed. At a distance of 11.2 inches (28.4 cm), the field of view is 0.434 inches (1.10 cm) in diameter. At a distance of 72 inches (183 cm), the field of view increases to 7.4 inches (18.8 cm) in diameter.
♦ A chlorophyll index value (0 - 999) is calculated from the measured ambient and reflected light data.
♦ The number of samples taken and a running average of chlorophyll index values is displayed.
♦ Ambient light level is displayed on a scale of 0 to 9.
♦ The optional data-logging system records the latitude and longitude (if GPS is used), the sample number, the individual chlorophyll index reading, and the value assigned to the ambient light level.
♦ The recorded data is downloaded to your PC using the optional Field ScoutTM software.
♦ The data-logged files are comma-delimited text files and can be opened and worked with in any spreadsheet, graphing, statistical, or word processing program.
1.Initial Startup
Allow the temperature of the CM1000 to equilibrate with the plant environment prior to sampling. For example, storing the meter overnight in a freezing tool shed and then immediately taking readings upon entry into a warm greenhouse will result in invalid data. When the CM1000 is first turned on, battery strength (Battery at __% ) will appear on the LCD. The available battery power percentage assumes alkaline batteries are being used. If rechargeable NiCd batteries are installed, the available battery power will be less than displayed. If the data logging option has not been enabled, the unit will then proceed to the normal reading mode. In order to record data and global positioning system (GPS) coordinates, the data logger must first be enabled through the software (See p. 14). If the data logger has been enabled, battery strength and the amount of remaining memory (Memory __ % FULL) will be displayed. If GPS data is being recorded as well, the meter will display the status of the GPS signal. The meter will then proceed to the normal reading mode. IMPORTANT: When connecting the meter to an external GPS receiver, the receiver must be powered up, have located the satellites and been connected to the meter before turning the meter on (see Connecting to GPS Unit p. 6).
a.GPS Setting
-Your GPS unit must be set for NMEA 0183 input/output messages. If the meter has trouble receiving the GPS signal, check that the GPS unit has the following settings: Data bits: 8 Stop bits: 1 Baud rate: 4800 bps Parity: None Timing: 1 second GGA data string
b.Cable Connections
-A GPS/DGPS cable (item # 2950CV5) is required to connect the CM 1000 meter to a GPS unit. This cable has a 9-pin male connection and a stereo pin that connects to the meter’s data port. You will also need a cable that allows the GPS unit to connect to a 9-pin male serial port. If this cable doesn’t come standard with your GPS unit, it should be available from the manufacturer. This cable is generally used to upload information from a computer to the GPS unit. These components should be connected as shown in the figure below.
2.Keypad Operation
-The ON/OFF button turns the meter on and off. When the meter is turned on, it will display the battery status for 3 seconds. The screen will then display the amount of memory available and the status of the GPS connection. The meter then goes into normal reading mode. CAUTION: If the meter is inactive for 20 minutes, it will automatically turn off to conserve power. When the meter is powered off, either with the ON/OFF button or due to inactivity, the AVG and N values are reset to zero (see Normal Reading Mode)
-As chlorophyll measurements are taken, up to 99 readings are stored in the meter’s short-term memory. These will be the readings taken since meter was turned on or the Delete/Clear Avg button was pressed This is separate from the internal data logger. The readings in short-term memory can be reviewed by hitting the Data Recall button. With each press of the button, the LCD will display the preceding data point (INDEX and BRT values). The next time the trigger is pressed, the LCD will revert to normal reading mode and the current N-value will be displayed along with an updated Average.
-When the DELETE/CLR AVG button is pressed and immediately released, the last data point will be removed from the short-term memory and the running average. Pressing and holding this button will reset the running average (AVG) and N-value to zero.
3.Normal Reading Mode
a.Taking Readings
-When the meter is on, pressing the trigger on the front of the handle will activate the targeting lasers and will cause the measuring and calculating mechanism to become “Live”. That is, while pulling the trigger, the user can see the INDEX (see below) being constantly updated as the targeting lasers are moved around the leaf surface. Releasing the trigger locks in the INDEX reading and incorporates that reading into the running average and the logger’s memory. NOTE: Readings should be taken only on individual leaves. Canopy-level measurements are encouraged by Spectrum Technologies only for fine-textured turf grass. (See Light Management, p. 18) When in normal reading mode, the LCD of the CM1000 will display the chlorophyll index value, the brightness reading from the ambient light sensor, a running average and indicate whether the data logger is functioning. The contents of the LCD are explained below.
b.INDEX The CM 1000 chlorophyll index reading is reported on a scale of 0 to 999. The INDEX value is a measure of the relative greenness of the leaf. This value remains in the meter’s short-term memory until it is deleted or the meter is shut off (see Keypad Operation, p. 8). If the data logger is enabled the INDEX value is also recorded in the logger’s memory.
c.BRT
-The response of the ambient light sensor is displayed as a brightness index value (BRT) from 0 - 9. A BRT value of one or greater indicates that there are at least 250 to 300 µmol·m-2·s-1 of PAR (photosynthetically active radiation) light available. This is the minimum light level at which the meter is useful. At low levels of ambient light, the index reading may be suspect Full sun should return a BRT value of seven to eight. Because of the way the CM1000 estimates chlorophyll content, higher light levels enable greater resolution in the chlorophyll content INDEX. (Also see Light Management, p. 18) NOTE: Excessively bright ambient or reflected light will saturate the light sensors and thereby cause invalid readings. When the light sensors near the saturation point, an LCD message of ERROR, EXCESSIVE LIGHT will appear.
d.AVG and N
- As each reading is taken, i.e. each time the trigger is released, the chlorophyll INDEX reading is incorporated into the running average (AVG) and the sample number (N) is incremented. The current AVG and N are both displayed on the bottom line of the LCD. Although N can increment up to 250, only a maximum of 64 INDEX readings (N064) can be used to generate the running AVG. If more than 64 readings are taken before the short-term memory is cleared, the screen will display AVG=- - -. However, deleting an INDEX reading from short-term memory (thus causing a new AVG to be calculated) does not free up memory space for storing an additional reading. In other words, the average is not calculated if the trigger has been pressed more than 64 times without clearing the average (see Keypad Operation, p. 8).Valid INDEX readings can be taken beyond the maximum N value of 250. But N will not continue to increment unless the entire current data series is cleared, resetting N to zero.
e. LOG
- The data logger must be enabled in order to download data to a PC (See Meter Settings, p. 14). The LOG symbol will be displayed in the lower right corner when this feature is enabled.
4.CONNECTING TO A COMPUTER
- The data port on the underside of the CM 1000 meter can be accessed by removing the plastic screw. It is through this port that the meter is connected to either a PC or to a GPS unit. Connecting to a PC The CM 1000 software comes with a black PC interface cable. This cable connects to the USB port of your computer and to the meter’s computer port. The meter’s configuration can be modified by clicking on the Meter Settings button (see Meter Settings, p. 14). The Com Port, Meter Type, Download, Clear Memory and Meter Settings buttons are explained in the Main Toolbar section (p. 14). Note: Prior to 2014, the meter was shipped with a gray cable that connected to a 9-pin serial port. This cable will still work but may require a USB-to-serial adapter.
.jpg)
.png){kind=small}
