Spectrum Technologies Fieldscout TDR 350 User manual

TDR 350
Soil Moisture Meter
PRODUCT MANUAL
Item # 6435

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Thank you for purchasing the FieldScoutTM TDR 350
soil moisture meter. This manual describes the meter's
general features and operation.
Soil moisture is a critical, and potentially highly varia-
ble, component of the soil environment. Time domain
reflectometry is a proven technology for quickly and
accurately determining volumetric water content
(VWC) in soil. Electrical conductivity (EC) is a func-
tion of the moisture and salt in the soil and can be fac-
tored out to increase the accuracy of VWC measure-
ments. The meter also measures soil surface tempera-
ture. The user can quickly transition between taking
VWC readings in standard, high-clay, and sand soils.
The TDR 350’s shaft-mounted probe allows the user to
take measurements while standing. The meter’s built-in
data logger eliminates the need to record data manually.
The data points can be viewed with the FieldScout Mo-
bile app that maps out soil measurements using logged
location coordinates. Measurements can also be saved
to an external USB flash drive using the built-in USB
port.
Contents
Includes the following components:
- TDR 350 meter (in collapsed position)
- Carrying case
- 4 AA batteries already installed
Note: TDR rods are sold separately
General overview
This manual will familiarize you with the features and operation of
your new Field ScoutTM TDR 350 Soil Moisture Meter. Please read
this manual thoroughly before use

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CONTENTS
General Overview 2
Specifications 4
Product Dimensions 5
Meter Care 6
Button Functions 7
Meter Operation 8
Display Screens 9
GNSS (Location) Features 12
Setting Date/Time 13
Optimizing Geo-Referenced Measurements 14
Maintenance 16
Data Logs 18
Field Scout Mobile App/SpecConnect 20
Pairing TDR350 with FieldScout Mobile App 22
VWC Measurements 24
Electrical Conductivity 25
Optional Accessories 26
Appendix 1: Soil Specific Reading Correlation 27
Appendix 2: Troubleshooting 28
Appendix 3: Updating Device Firmware 29
Appendix 4: Calibration 30
Glossary 31
Warranty and Declaration of Conformity 32

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Measurement
Units
Percent volumetric water content (VWC)
Period (raw sensor reading)
Resolution,
Accuracy and
Range
VWC: 0.1% increment ±3.0% @ < 2 mS/cm
0% to Saturation (Saturation is typically around
50% volumetric water)
EC: 0.01 increment ; ± 0.1 mS/cm; 0 - 5 range
Temperature: 0.2 ˚F (0.1 ˚C) increment ; ± 1.8
˚F (± 1 ˚C); -22 to 140 ˚F (-30 to 60 ˚C)
Thermistor based; Infrared Optional
Connectivity USB Type A, Bluetooth Low Energy
(GNSS)
Accuracy Galileo 1m; GPS 3.5 to 7.5m;
GLONASS 2.8 to 10 m;
QZSS 1 m (where available)
WAAS, SBAS, and EGNOS enabled
Power 4 AA alkaline batteries
Log Capacity 50,000 measurements
Display Backlit, high-contrast, graphic LCD
Weight 4.3 lbs. (1.9 kg)
IP Rating Display: IP53, Probe: IP67
Available
Rod
Dimensions
Turf 1.5” (3.8cm)
Short 3.0” (7.6cm)
Medium 4.8” (12.2cm)
Long 8.0” (20.32cm)
Diameter: 0.2” (0.5cm)
Spacing: 1.2” (3cm)
Specifications

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Product dimensions

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The FieldScout TDR meter will function properly under normal
conditions experienced in field use. The sensor block is sealed
and will not be damaged by immersion in water. The display is
not waterproof so it should not be used during heavy rainfall or
left exposed during irrigation events. If the display does get wet, it
should be dried out immediately.
Follow these tips to prolong the life of the device:
- Store in a cool and dry place when not in use.
- Keep the meter and probe rods clean and dry in between uses.
- Remove the batteries if not used for an extended period of time
(ie: between seasons).
Battery life
If the battery level is low or a
battery is inserted incorrectly,
the low battery icon appears on
the screen briefly then, the dis-
play will power off.
Battery life is affected by the
enabled features, accessories
connected, and the frequency of use. If not needed, the Bluetooth,
GNSS Location and backlight features can be disabled individual-
ly. The backlight can be disabled or set to AUTO mode (p. 10)
which allows enough time to see new measurements and then will
power down the backlight to conserve the battery life.
Meter Care
Total Readings
Bluetooth GPS Backlight Alkaline Lithium
ON ON ON 12,000 24,000
ON ON OFF 24,000 35,000
OFF OFF OFF 150,000 225,000

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Button Functions
ON/OFF or BACK button
− Press briefly to power on.
− Press and hold to power on and stay on the logo
screen.
− Press for 2 seconds to power off.
− Press briefly within a menu to return to prior
screen.
MENU or SELECT button
− Press to enter available menus.
− Press to select or confirm a menu selection.
DELETE or UP button
− Press to move up within a menu.
− Delete last measurement from the running aver-
age, counter, and its entry from the internal data
log (see p. 18).
READ or DOWN button
− Press to move down within a menu.
− Press to make a reading from the Reading screen.
− Press and hold to reset the average and count

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Meter Operation
Setting up the meter
1. Pull the battery transport tab out of the display unit.
2. If desired, extend the collapsible shaft by removing the thumb
screw (shown above) from the side, grip and extend the lower
shaft to its new position, re-insert the thumb screw, and hand
tighten.
2. Select a set of probe rods, screw in, and tighten them to the
bottom of the probe block.
3. Set the desired user settings in the settings menu. See the Set-
tings Menu (p. 10).
Taking Readings
1. Grip the TDR handles to the left and right of the display.
2. Push down on the handles maintaining a steady downward
pressure to drive the rods into the soil until the sensor base is in
contact with the soil surface. Refrain from any back and forth or
side to side movement which can introduce air pockets into the
soil medium which will alter the reading accuracy.
Caution: Exercise care not to damage the rods which could lead
to damage. See Meter Care (p. 6).
3. Press the READ button and observe the change in results on
the top display.
Probe base, thumb screw, and probe rods

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Display Screens
The TDR 350 has 3 main display screens;
- Startup (as shown on page 8)
- Reading (shown below)
- Settings Menu (see page 10)
Startup Information screen
Initially displayed after first powered on.
- Displays firmware version information.
- Press and hold ON/OFF|BACK button to remain on this screen.
Reading screen
Measurements from the sensor are displayed on the Reading
screen along with rod type used, soil type, and a reading count
with running average. VWC=0% readings will be displayed but
will not increment the counter or be included in the average.
Press READ to take readings, update Count and the Average.
Indicators:
Battery level icon: upper right corner.
Bluetooth icon: displayed when enabled. A bar appears
through it when not actively communicating.
GNSS location icon: When enabled,
Transitions from clear to dark as a loca-
tion fix is achieved. Crosshatch appears when WAAS/EGNOS in
use.
Sample Reading screen

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Settings Menu screen
Used for changing device features, setting rod length and working
with log files.
Use the arrow buttons to move to the desired option.
Use the MENU|SELECT button to toggle option choices.
Clear Average*: Clears the displayed average and count.
Note: Same as a press and hold of the READ|Down arrow button.
Rod Length: Select the Rod length. See page 4 for options.
Soil Type: Selects the soil type used in measurements:
- Standard: for most mineral soils.
- Hi-Clay: for soils with higher clay content (> 27%).
- Sand: for sand based fields or turf greens.
Clear Logs*: Erases data logs from internal memory.
Save to USB*: Transfers data logs to a USB flash drive if at-
tached.
Backlight: Sets the LCD backlight: ON, OFF, AUTO. In AUTO
mode, the backlight will shut off 5 seconds after a button press
GNSS Location, GNSS Power Save, GNSS Use QZSS: Enable
or disable features related to geo-location capability (see p. 12).
Bluetooth: Enable or disable Bluetooth connectivity to the Field-
Scout™ Mobile app (See p. 20).
Sound: Enable or disable beep for audible feedback.
Temp Source: Changes displayed temperature from the Soil Sen-
sor to the IR Sensor (optional).
Temp Units: Fahrenheit or Celsius scale.

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Moisture Type: Selects displayed moisture mode VWC%, Peri-
od, or TDR 300.
- VWC%: Volumetric Water Content with EC compensation.
- Period: Raw sensor reading in microseconds (us).
- TDR 300: VWC without EC compensation
EC Units: EC value (mS/cm) or Salinity Index (see p. 25).
Auto-Off: Power off delay: 15, 30, 45, 60 minutes.
Current Date, Current Time: Displays or changes current val-
ues. See p. 13 for details.
Timezone: Offset from Greenwich Mean Time. As the offset
changes, the Time and Date will update.
Daylight Savings: ON or OFF.
Calibration*: Overrides factory calibration. See Appendix
Clear User Calibration: Clears the user applied calibration back
to factory settings
Factory Defaults*: Resets menu settings and counter to the fac-
tory default value.
About: General information (Model and serial number, firmware
versions for display and sensor).
* Pressing Select button for these options brings up an additional
screen.
Rod Length None
Soil Type Standard
Backlight, GNSS,
Bluetooth
Disabled
Sound On
Temperature Fahrenheit
Temp Source Soil Sensor
Moisture VWC
EC units mS/cm
Auto-Off 15 minutes
Time Zone GMT

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The location reference will be stored with the measurement in the
data log. The TDR350 has 3 settings related to the geo-location
feature. These settings can be enabled or disabled in the Settings
Menu (p. 10). Select the desired option and press the Menu/
Select button to toggle between the ENABLE and DISABLE op-
tions.
GNSS Location
Enable to log Geo-Referenced locations of a soil measurement or
disabled to make soil measurements without location referencing.
If the GNSS Location is disabled, the date and time information
will still be transmitted to the meter.
GNSS Power Save
Disable for expedited geo-referencing and speed of measure-
ments. Enable to reduce power consumption in between distant
soil measurements. Note: Enabling will delay the response time of
a measurement.
GNSS Use QZSS
QZSS (Quasi-Zenith Satellite System) is a regional system for use
in the immediate surrounding areas of Japan, Australia, Guam,
Hawaii, Singapore and Bangalore. Enable to add QZSS geo-
referenced locations to soil measurements.
GNSS accuracy is improved if the meter remains active for 6
minutes or more during a data collection session.
GNSS (location) Features

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By default, the TDR350 gets the date and time from the satellite
signal. These values are displayed in the Settings Menu (p. 11).
The date and time can also be set manually. When the time and
date are set manually, they will over-ride the default value.
Note: When the batteries are removed, the date/time are reset
and the meter resumes getting this information from the satel-
lites.
Updating the Date and Time
1. Press the MENU|SELECT button to get to the Settings Menu.
2. Press the UP or DOWN arrows to navigate to either the Cur-
rent Date or Current Time option.
3. Press the MENU|SELECT button to access the Time/Date up-
date screen. There are 3 options.
A. Press the READ|DOWN button to download an update from
the GNSS satellites. Proceed to an area with a good view of the
sky and press the Menu/Select button to initiate the process.
B. Press the DELETE|UP button to set the date and time manual-
ly. The current settings will be displayed. Use the UP and DOWN
arrows to adjust the highlighted selection. Press the
MENU|SELECT button to confirm and proceed to the next pa-
rameter. After pressing the MENU|SELECT button to set the
minutes, the display will return to the Reading screen.
C. Press the ON/OFF|BACK button to return to the Settings
Menu without making any change.
Setting Date/Time

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Optimizing Geo-Referenced
Measurements
Achieving optimal results of the geo-referencing feature depends
on several factors including how long the meter has remained ac-
tive, atmospheric conditions for the day, which satellite systems
are in range and obstacles that may block the reception of the sat-
ellite signals. The meter accesses 3 - 4 satellite systems, each with
different levels of accuracy available to the general public.
Galileo: within 1 meter of target
GLONASS: within 2.8 - 10 meters of target
GPS: within 3.5 - 7.5 meters of target
QZSS (where available): within 1 meter of target
Additionally, systems such as SBAS, MSAS and others are used
along with the meter’s own internal satellite mapping data to im-
prove the accuracy further.
Creating the internal satellite maps
The meter relies on internal satellite maps to improve accuracy.
These maps are built by the meter during the first three days of
consistent use. The meter will track available satellites and hone
in on the location of use by referencing the internal maps along
with satellites in view. Typically, after the first use, the position
accuracy may appear low as the satellite maps are synchronized
with the area in which the meter is being used. After the third use,
the TDR will have a complete satellite map of the use area and the
speed and accuracy of the location referencing will be at its best.
Internal maps will re-synchronize if the meter has been out of use
for a season or taken out of its usual use areas. This process may
result in lower accuracy until the synchronization has completed.

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Preparing for a data collection session
Upon initially powering on or enabling the GNSS location fea-
ture, expect the first geo-referenced location to take place within a
minute or so of operation on a clear day. The GNSS location ar-
row icon (page.7) will transition from clear to a shaded color as
more satellites or higher level of precision are reached. The GNSS
location icon gives an indication of the quality of the satellite fix.
A minimum of 5 received satellites are necessary for a location
fix. Achieving 10 or more satellites will yield high quality posi-
tion data.
For Best Results
Geo-Location referencing will show the best accuracy when the
meter is kept active for 6 minutes or more. The positioning data
will be most accurate when the sky is clear, there are few, if any,
reflective surfaces, and there is an unobstructed view of the sky.
Optimally, the meter should have a clear view of the sky above a
15 degree elevation. When possible, keep clear of buildings, bod-
ies of water, and other reflective surfaces that may distort the sig-
nal triangulation. Solid objects, such as trees, buildings, aircraft
and even the user themselves can block satellite signals.

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Maintenance
Separating the Display and Sensor:
1. Remove the probe rods from the sensor base.
2. Flip the display so the backing plate is facing up.
3. Remove the 4 screws on the base using a Philips screwdriver.
4. Gently separate the display from the base plate. Note: The
sensor cable connected in the center has limited cable length.
Battery Replacement:
1. Follow the steps in Display and Sensor Removal to access
the batteries.
2. Install four new AA batteries observing correct polarity by
referencing the (+) positive and (-) negative labels.
3. Follow the procedure on the next page to reinstall the display.
Display Removal:
1. Follow steps for Display and Sensor Removal to access the
display and cable connections.
2. Remove the foam spacer and unplug the sensor cable
connector from the jack (fig. 1). If an IR temperature sensor is
connected, disconnect this plug as well. Do not discard the
foam spacer.
cable
plug
Figure 1. Sensor connection to the display.

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Display Installation:
1. Follow the procedures for Display Removal to access the
display and cable connections.
2. Re-connect the sensor cable to the 3.5mm connector on the
back of the display module.
3. Insert the foam spacer back into place behind the sensor cable.
The split end fits around the sensor cable molding.
4. If equipped with the IR temperature sensor option, attach it to
the smaller diameter connector.
5. Guide the excess cable length back down through the base
plate.
6. Align the arrows on the base and display in the same
direction. The USB port should face the same side as the
serial number label.
7. Tighten the four mounting screws.
Sensor Block Removal / Replacement:
1. Follow steps for Display Removal to
access the cable connections.
2. Remove the thumb screw lock bolt
that joins the lower probe base to the
upper shaft.
3. Separate the probe base from the shaft
(fig. 2).
4. Feed the cable from the replacement probe base through the
upper shaft. Attaching a string fed down from the top can aide
in the process of cable reconnection.
5. Follow the procedure for Display Installation to complete the
replacement.
Figure 2. Shaft interface

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Downloading Data Logs to a USB Flash Drive
1. Connect the flash drive to the meter’s USB port.
2. Press the MENU|SELECT button to open the Settings Menu.
3. Press the READ|Down arrow button to reach the Save to USB op-
tion.
4. Press the MENU|SELECT button to select the option.
The data will be saved to the flash drive as a comma-separated text file
(.csv) named with the serial number as the filename. These files can be
opened with common text-editing or spreadsheet software. If a previous
data file exists on the flash drive with the same filename, it will be over-
written. Be sure to save any existing data logs on the flash drive prior to
saving a new file.
Erasing the internal Data log
1. Press the MENU|SELECT button (p. 7) to open the Settings Menu.
2. Press the READ|Down arrow button to reach the Clear Logs option
3. Press the MENU|SELECT button to select the option.
4. Press MENU|SELECT button again to start the process or the ON/
OFF|BACK button to return back to the menu.
Data Collected
The following information is logged with each reading:
Time, VWC%, Period, EC, Temp_Soil, Temp_Soil(F), Temp_IR,
Temp_IR(F), Latitude, Longitude, Satellites, Fix, Rod Length, Soil
Type, VWC Mode
Sample TDR 350 data file
Data Logs

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Time: MM/DD/YYYY HH:MM:SS based on the GMT offset selected in
the Timezone option (p. 11)
VWC%: Volumetric Water Content based on the Moisture Type setting
- EC Compensated or “TDR 300” (without EC compensation)
Period: Raw Period result (after any applied user calibration)
EC: Electrical Conductivity in milliSiemens per centimeter
Temp_Soil: Soil temperature sensor reading in degrees Celsius
Temp_Soil(F): Soil temperature sensor reading in degrees Fahrenheit
Temp_IR: InfraRed soil temperature sensor reading in degrees Celsius
(if equipped)
Temp_IR(F): InfraRed soil temperature sensor reading in degrees Fahr-
enheit (if equipped)
Latitude, Longitude: Geo-referenced coordinate acquired in decimal
degrees format. Note: A negative sign may appear indicating South or
West coordinates.
Fix: GNSS location fix level; 0 - unreferenced, 1 - fixed reference, 2 - fix
with additional accuracy correction (SBAS, WAAS, EGNOS)
Rod Length: character is depicted as L: Long (8"), M: Med (4.8"), S:
Short (3"), and T: Turf (1.5")
Soil Type: character depicted as S: Standard, H: Hi-Clay, and D: sand.
VWC Mode: depicted as V for EC compensated or 3 for non-
compensated (TDR-300).

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The FieldScout Mobile App can be used to send data directly to
the SpecConnect web interface. 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 col-
umns. Measurements are taken in each grid cell. Average, color-
coded data are displayed on the app (Fig. 1). In freeform mode, a
color-coded pushpin icon is placed at every sampling point. If the
TDR has a good GNSS location fix (p. 9), the app will use the
coordinates from the meter. If not, or if the meter's GNSS location
is disabled, it will use the internal location of the smartphone.
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 a spreadsheet, or viewed as a Trend Report (fig. 4).
More details are available in the user's guide for the app.
Field Scout
Mobile App/
SpecConnect
Figure 1. Grid Mode Figure 2. Freeform Mode