TDR 150 Soil Moisture Meter PRODUCT MANUAL Item # 6445
CONTENTS Meter Dimensions 4 Batteries 5 Button Functions 7 Display Screens 9 Meter Calibration 13 Updating Firmware 14 Adding GPS/Bluetooth Capability 15 Electrical Conductivity 17 Meter Operation 19 Replacing or Re-attaching the Probe Block 22 VWC Measurements 23 GPS Status 24 Field Scout Mobile App/SpecConnect 25 Data Logs 27 Specifications 29 Optional Accessories 30 Appendix 1: Soil-Specific Calibration 31 Appendix 2: Checking VWC Readings 33 Appendix 3: FAQ 34 This
General overview Thank you for purchasing the Field ScoutTM TDR 150 soil moisture, electrical conductivity and soil surface temperature meter. This manual describes the meter's general features and operation. Soil moisture is a critical, and potentially highly variable, component of the soil environment. Time domain reflectometry is a proven technology for quickly and accurately determining volumetric water content (VWC) in soil.
Meter dimensions 3.00 in 3.00 in 11.5 in 23.0 in 5.15 in 3.30 in 4 1.
Batteries Changing the batteries The TDR 150 requires 4 AA batteries. The battery holder is on the underside of the display unit. Remove the screws and take off the base plate. Install batteries and ensure correct polarity by referencing the (+) positive and (-) negative labels at either end of each slot. Replace the base plate. Be sure the sensor is still plugged into the socket (see fig. 1). Do not permanently remove the foam plug (fig. 2). It ensures the plug does not come detached. cable Fig.
Battery life The battery level is checked every time the display unit is turned on. If the battery level is low, or if a battery is inserted incorrectly, this low battery image shows on the full screen for about 10 seconds and the display will automatically turn off. In addition to frequency of use, battery life is impacted by use of the backlight and GPS receiver (for upgraded units). If not needed, the GPS feature should be disabled. The backlight can be set to AUTO mode (p. 11).
Button Functions Basic Button Operations ON/OFF or BACK button Press this button briefly to turn on the display. The meter will then display the Data screen (p. 10). To turn the meter off, press and hold this button for about 2 seconds. When in the Settings Menu screen (p. 11), press this button to return to the Data screen.
DELETE or UP button When on the Data screen (p. 10), press this button to delete the last measured data point from the both the log file and the computed Average. The Delete button also decrements the Count. When on the Settings Menu screen (p. 11), press this button to scroll up to the previous menu item. READ or DOWN button When on the Data screen, press and release this button to take a sensor reading. Press and hold to clear the average and reset the sample count to 0.
Display Screens The TDR 150 has 3 main display screens; - Startup Information screen - Data screen - Settings Menu screen Startup Information screen The Startup Information screen is displayed for about 2 seconds after the display is turned on. If desired, the startup screen can be kept on for a longer duration. While powering up the meter, press and hold the On/Off/Back button to continue displaying the Startup Device Information screen. Release the button to proceed to the Data screen.
Data screen Readings from the sensor are displayed on the Data screen. The battery level indicator appears in the upper right corner. The running average and number of readings included in that average are shown in the lower right corner. Pressing and holding the READ button will clear the average and re-set the counter to 0. If the meter has been upgraded to add GPS and Bluetooth capability (see p. 15), these icons will appear next to the battery indicator.
Settings Menu screen The contents of the Settings Menu are shown on the following figure. Use the arrow buttons to scroll to the desired option. The options are described below. For most options, pressing the Select button simply toggles you through the different choices for that option. Some options require an additional step or steps. Note: GPS and Bluetooth will only be available for upgraded units (see p. 15). Clear Average*: Clears the current average and resets the counter to zero.
Temp Source: Choose Soil Sensor or IR Sensor Temp Units: Choose Fahrenheit or Celsius. Moisture Type: Choose volumetric water content (VWC%), raw sensor reading (Period), or TDR 300 mode. The latter will report a VWC that matches the output of the TDR 300 meter (no EC optimization). EC Units: Choose simple EC value (mS/cm) or the Salinity Index (see p. 18). Auto-Off: Choose how long the meter will stay on before automatically powering off. Current Date, Current Time: These are reported values.
Meter Calibration The meter has internal calibrations for standard and high-clay soil types. It also has the option of outputting a value that matches its predecessor, the TDR 100. These calibrations will work for a large number of soils. However, each meter will have a small difference in how it responds to identical soil conditions. This is due to sensor drift or variability in the electronic components used during manufacturing.
The meter will then show that the calibration is complete for that specific rod length. If more than one rod size is being used, a calibration operation must be done for each one. Note: This procedure is different than a soilspecific calibration (Appendix 1, p. 31) where a unique calibration curve is generated. Updating Firmware The firmware of the TDR 150 can be updated using a USB flash drive. Firmware update files can be found at the Spectrum website.
Adding GPS/Bluetooth Capability The standard version of the TDR 150 meter comes with the GPS and Bluetooth capability locked. These features can be unlocked by purchasing item 6445GBU (TDR 150 GPS/Bluetooth Upgrade). After purchasing the upgrade, the unlock file is downloaded from the following website: www.specconnect.net/activate This will bring up the Get Product Activation Key screen. Select the "TDR 150 GPS/Bluetooth Upgrade" option from the dropdown menu.
The procedure for loading this file onto the TDR 150 is as follows. 1. 2. 3. 4. Copy the unlock file to a USB flash drive. Power off the meter. Insert the flash drive into the meter's USB port. Power up the meter. If the upgrade is successful, the Startup screen (p. 9) will display the text "GPS/BT Upgrade OK". After this, the GPS and Bluetooth options will be available in the Settings Menu screen (p. 11).
Electrical Conductivity Electrical Conductivity Knowledge of the salinity level of your soil is an important component of irrigation and nutrient management. The source of the salts in the soil ranges from the original parent material to additions from natural sources and management activity. Often, having salt in the soil has a negative connotation. This is because when the soil solution has a high salt concentration, plant roots cannot bring in sufficient soil moisture.
Salinity Index The TDR 150 measures the bulk EC of soil that may or may not be saturated. There are two competing mechanisms at place. As the soil dries, the remaining solution in the pore space becomes more concentrated which increases its EC. However, reduced water in the pores leads to a longer and more tortuous path between the sensor electrodes, which decreases EC. The second mechanism dominates. This means that bulk EC will decrease as soil moisture decreases.
Meter Operation Configuring the meter Meter configuration is done in the Settings Menu (pp. 1112). The TDR 150 can be set to one of three Soil Type modes, Standard, High Clay, or Sand. The Standard mode will be appropriate for most mineral soils. The High Clay mode will be more accurate for soils with higher clay contents (> 27%). Sand is applicable for sand based sports fields or golf greens. There are 3 Moisture Type options.
reading and number of readings included in the average are visible in the lower right corner. The current Rod Length and Soil Type are shown in the lower left corner. Taking Readings Push the rods into the soil. When taking a measurement, it is important that the rods be fully inserted into the soil. If not, part of the sampling volume will be composed of air and the reading will be inaccurately low. For the same reason, the probe should be inserted with a steady, downward pressure.
Occasional rod bending is normal, and can be expected during the course of sampling. Longer rods will be more susceptible to bending than shorter rods. If bending occurs, rods should simply be bent back to parallel position, perpendicular to the TDR block. Measurements will continue to be accurate provided that rods are reasonably close to parallel. If care is not taken to reposition rods to a parallel position, subsequent pressure on the rods will accentuate the bending and may cause the rods to break.
Replacing or Re-attaching the Probe Block The TDR 150 sensor block is a user-replaceable component (item 6445S). Turn the TDR 150 display upside down and remove the 4 screws. Open the bottom and remove the base plate (fig. 1). The sensor connects to the meter via the jack located between the two battery holders. After attaching the cables, re-insert the foam plug. When replacing the base plate, take care to feed the sensor through the slot on the base plate (fig. 2). cable Figure 1.
VWC Measurements Volumetric Water Content (VWC) The soil can be thought of as being composed of soil, water and air. The volumetric water content (VWC) is the ratio of the volume of water in a given volume of soil to the total soil volume. This can be expressed as either a decimal or a percent. Three soil moisture levels of importance can be defined as follows: Saturation: All soil pores are filled with water. The VWC will equal the percent pore space of the soil.
Electronics in the TDR 150 generate and sense the return of a high energy signal that travels down and back, through the soil, along the waveguide composed of the two replaceable, stainless steel rods. The sampling volume is an elliptical cylinder that extends approximately 3 cm out from the rods. The high frequency signal information is then converted to volumetric water content.
Field Scout Mobile App/ SpecConnect In addition to transferring data to a flash drive, upgraded units (see p. 15) can use the FieldScout Mobile App to send data directly to the SpecConnect web utility. Data can be viewed on a Smartphone in two formats. In grid mode, the site is divided into a customizable 2-dimensional grid of 3 to 5 rows and 3 to 5 columns. Measurements are taken in each grid cell. Average, color-coded data are displayed on the app (Fig. 1).
The data from the Pro version of the app is sent instantaneously to SpecConnect. Data can be viewed in map form (fig. 3), exported to an Excel spreadsheet, or viewed as a Trend Report (fig. 4). More details are available in the user's guide for the app. Fig. 3. 2-D Contour Plot in SpecConnect Fig. 4.
Data Logs Figure 1: Sample TDR 150 data file Downloading Data Data stored in the meter's internal memory can be transferred to your PC with a USB flash drive. Connect the flash drive to the USB port on the front of the meter. Press the Menu/Select button (p. 7) to open the Settings Menu. Scroll to the Save to USB option and, again, press the Menu/ Select button. The data will be saved to the flash drive as a file with a .csv extension.
meter. These files can be opened with text-editing software or spreadsheet software (fig. 1). The data is separated into 11 fields. Column 1 Description Date and time a b 2-6 Sensor readings (VWC, Period, EC, Soil Temperature, IR Temperature) 7-8 GPS coordinates (longitude, latitude) c 9 Number of satellites visible during reading 10 Satellite fix status 11 Rod length 12 Soil type d e ef a Time is based on the GMT offset selected in the Timezone option (p.
Specifications Measurement Units Percent volumetric water content (VWC) Period (raw sensor reading) Resolution VWC: 0.1% VWC units EC: 0.01 mS/cm Temperature: 0.2 ˚F (0.1 ˚C) Accuracy VWC: ±3.0% volumetric water content with electrical conductivity < 2 mS/cm EC: ± 0.1 mS/cm Temperature: ± 1.
Optional Accessories There are two optional items that can be used to expand the capabilities of the TDR350. They are described briefly below. See the website for the product's specific user information and installation instructions. Infrared Temperature Sensor (item 6435TS) The Infrared Temperature Sensor is an alternate to the surface temperature sensor. The sensor detects the infrared signature from the surface just ahead of the sensor block.
Appendix 1 Soil-Specific Calibration For maximum accuracy, you may choose to perform a soil-specific calibration rather than use either of the internal (Standard, High Clay, or Sand) soil calibrations coded into the TDR 150’s firmware. In these cases, an independent soil moisture content measurement is required. A relation can then be developed that relates the meter’s period reading (see Moisture Type option, p. 12) to actual volumetric water content (VWC).
VWC = 100*(Mwet - Mdry)/w*Vtot) Where: Mwet, Mdry = Vtot = w = mass (g) of wet and dry soil respectively total soil volume (ml) density of water (1g/ml) An alternate, but equivalent, calculation can be obtained from the gravimetric water content and soil bulk density.
Appendix 2 Checking VWC Readings There are two tests that can be performed to check if the meter is operating properly. Test 1 (No rods): Disconnect the rods from the probe block. Select the Period option for Moisture Type (p. 12). With no rods connected, the meter should read 1930 ± 30 µs. Test 2 (Rods attached): Readings can be taken in three standard environments; air, distilled water, and playground sand saturated with distilled water.
Appendix 3 FAQ 1. What are the factory default settings? Rod Length Turf Temp Source Soil Sensor Soil Type Standard Moisture VWC GPS, Bluetooth* Disabled EC units Salinity Index Auto-Off 15 minutes Time Zone GMT Backlight Disabled Sound On Temperature Fahrenheit 2. What type of sensor is used to measure surface temperature? The sensor on the underside of the probe block is a thermistor. 3.
Warranty This product is warranted to be free from defects in material or workmanship for one year from the date of purchase. During the warranty period Spectrum will, at its option, either repair or replace products that prove to be defective. This warranty does not cover damage due to improper installation or use, lightning, negligence, accident, or unauthorized modifications, or to incidental or consequential damages beyond the Spectrum product.
DECLARATION OF CONFORMITY Spectrum Technologies, Inc. 3600 Thayer Ct. Aurora, IL 60504 USA Model Numbers: Description: Type: Directive: Standards: 6435 Portable Soil Moisture\Conductivity\Temperature Probe Electrical Equipment for Measurement, Control, and Laboratory Use 2004/30/EU EN 61326-2:2012 EN 61000-6-1:2007 EN 61000-6-3:2007+A1:2010 ICES-003:2016; ITE Emissions for Canada (ANSI C63.4:2014) FCC Part 15:2016: Emissions for Unintentional Radiators for USA (ANSI C63.
