Geolux RSS-2-300W User manual

Copyright ©2021 Geolux d.o.o. All rights reserved.
RSS-2-300W
Non-Contact
Surface Velocity Radar
User Manual

Starting Point
Thank you for purchasing Geolux RSS-2-300W non-contact surface velocity radar! We have
put together the experience of our engineers, the domain knowledge of our customers, the
enthusiasm of our team, and the manufacturing excellence to deliver this product to you.
You may freely rely on our eld-proven radar technology. The use of top-quality components
and advanced signal processing algorithms ensures that Geolux surface velocity radar can be
used in various applications and environments.
Although we are certain that you are more than capable of connecting the surface velocity
radar to your system, we have created this User Manual to assist you in setting up and using
Geolux surface velocity radar device.
Should there be any questions left unanswered, please feel free to contact us directly:
Geolux d.o.o.
Ljudevita Gaja 62
10430 Samobor
Croatia
E-mail: [email protected]
Web: www.geolux.hr

Contents
1. Introduction 1
2. Electrical Characteristics 2
3. Connector Pin-Out 3
3.1. Serial RS-232 Interface 4
3.2. Serial RS-485 Interface 4
3.3. Analog 4 – 20 mA Output 5
4. Installing the Surface Velocity Radar 6
4.1. Instrument Mounting and Location Selection 6
4.2. Measurement Quality Indicator 7
4.3. Rain and Wind 7
4.4. Interference and Multiple Radars 8
4.5. Fogging and Evaporation 8
4.6. Reections 8
5. Surface Velocity Radar Settings 10
6. Data Interface 15
6.1. Serial RS-232 Interface 15
6.2. Serial RS-485 Interface 15
7. Data Protocols 16
7.1. NMEA Protocol (RS-232) 16
7.3. Request-Response Protocol (RS-485) 22
7.3.1. Request-Response Protocol (RS-485) 22
7.4. Modbus Protocol (RS-485) 24
8. GeoluxInstrumentCongurator 28
9. Calculating Discharge from Flow Velocity 31
10. Troubleshooting 33
11. Appendix A – Mechanical Assembly 37

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Introduction
Geolux RSS-2-300W surface velocity radar uses radar technology to provide precise
contactless measurement of surface ow velocity. Contactless radar technology enables quick
and simple sensor installation above the water surface, and requires minimum maintenance.
This functionality is achieved by transmitting an electromagnetic wave in 24 GHz frequency
range (K-band), and measuring the frequency shift of the electromagnetic wave reected from
the owing water surface. The frequency shift is caused by the Doppler eect of the moving
surface on the electromagnetic wave. As the relative speed between the radar sensor and the
water surface increases, the detected frequency shift also increases, thus enabling the surface
velocity radar to precisely determine the surface ow velocity.
The surface velocity radar is able to detect water ow traveling at speeds ranging from 0.02 m/s
to 15.0 m/s with precision of 0.01 m/s. Integrated tilt sensor measures inclination angle of the
sensor and the ow velocity measurement is automatically cosine-corrected according to the
measured mounting tilt angle.

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Electrical Characteristics
The electrical characteristics of the Geolux RSS-2-300W surface velocity radar are given in
Table 1.
Table 1. Electrical Characteristics
Parameter MIN TYP MAX Unit
Communication interface
RS-232 interface speed
RS-485 interface speed
1200
1200
115200
115200
bps
bps
Radar sensor
Frequency
Radiated power (EIRP)
Sensitivity
Beam-width (3dB) – Azimuth
Beam-width (3dB) – Elevation
Measurement range
Resolution
Accuracy
Installation height above the water
24.075
-108
0.02
0.01
24.125
-110
12
24
1
24.175
20
-112
15.0
15
GHz
dBm
dBm
°
°
m/s
m/s
%
m
Power supply voltage 9.0 12.0 27.0 V
Power
Operational mode
Sleep mode
950
85
mW
mW
Alarm output maximal current 60 mA
Alarm output maximal voltage 30 VDC
Analog output maximal voltage 30 VDC
Operational temperature range -40 +85 °C
Measurement range 0.02 15.00 m/s
Resolution 0.001 m/s
Accuracy 1 %
Angle compensation 0 30 75 deg
Installation Height Above the Water 0.1 20 m
Sample rate 10 sps
Ingress protection rating IP68
Mechanical 110x90x50 mm

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Connector Pin-Out
The surface velocity radar uses robust IP68 circular M12 connector with 12 positions and the
mating cable is also delivered with the surface velocity radar. The connector and cable details
are shown in Picture 1 while Table 2 gives a detailed description of each pin.
Picture 1. Surface Velocity Radar Connectors
Table 2. Connector and Cable Pin-out
Pin No. Wire Color Pin Name Pin Description
1 White GND This pin should be connected to the ground
(negative) pole of the power supply
2 Brown +Vin The power supply for the Radar Speed Sensor
is provided on this pin. The Radar Speed Sensor
power supply voltage must be in the range 9
VDC to 27 VDC, and the power supply must be
able to provide at last 0.65W
3 Green RS232 – TxD RS-232 data transmit signal
4 Yellow RS232 – RxD RS-232 data receive signal
5 Grey GND Signal ground
6 Pink CAN – H CAN2.0B high signal (optional)
7 Blue CAN – L CAN2.0B low signal (optional)
8 Red Reserved Reserved
9 Orange RS485 – D- RS-485 data transmitter/receiver low signal
10 Dark Red RS485 – D+ RS-485 data transmitter/receiver high signal
11 Black Alarm SW Alarm - open collector switch signal max.
60mA (optional)
12 Purple 4 – 20 mA Sink for 4 – 20 mA analog interface. Connect
sensing device as pull-up to sink the current

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3.1. Serial RS-232 Interface
Serial RS-232 interface is implemented as standard PC full-duplex serial interface with voltage
levels adequate for direct connection to PC computer or other embedded devices used for
serial RS-232 communication.
In case the RS-232 interface is connected to standard DB-9 PC connector, TxD line (green wire)
is connected to pin 2 and RxD (yellow wire) is connected to pin 3. For proper operation of the
serial interface, additional connection of signal GND (grey wire) is required on pin 5 of the
DB-9 connector.
Picture 2. Serial RS232 DB-9 Cable
3.2. Serial RS-485 Interface
Serial RS-485 interface is implemented as standard industrial half-duplex communication
interface. The communication interface is short-circuit and internally overvoltage protected.
Depending on the receiving device, the interface can be used with only two wires (D+ dark red
wire & D- orange wire) while in some cases the ground connection (signal GND grey wire) is
also required. For more details please consult receiver specication.
Most common communication protocol used with RS-485 interface is Modbus-RTU but other
protocols are also available. Details of communication protocols are described later in this
user manual.
Optionally Geolux can supply a cable with DB-9 connector connected to the cable but this
must be specied as option when ordering the sensors.
Several communication protocols are available, and custom on request. Details of
communication protocols are described later in this user manual.

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3.3. Analog 4 – 20 mA Output
Analog current 4 – 20 mA output is provided for easier compatibility with older logging and
control systems. Output is implemented as current sink architecture with common ground.
Maximal voltage applied to the sink can go up to 30 VDC, providing greater exibility in
connections of the sensor to PLCs, loggers, or data concentrators.
Signal range and function for 4 – 20 mA analog output can be congured in the setup
application so the sensor will be able to signal best suitable value range with available current
range. Current step in the sensor is 0.3 µA, which limits the resolution, so care has to be taken
while setting the minimal value to be represented by 4 mA and the maximal value to be
represented by 20 mA so the resolution is sucient for the system requirements.
Picture 3. Analog 4 – 20 mA Output Internal Architecture
Picture 4. High Side Current Measurement for the 4 – 20 mA Analog Output
Measurement of the current by the client device (logger, PLC, modem etc.) must be
implemented as the high side current measurement as shown on the picture 4. If sensing
resistor is used resistance should be selected from the range 10Ω to 500Ω with recommended
value 100Ω for the sensing resistor.

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Installing the Surface
Velocity Radar
The surface velocity radar must be installed above the water surface, pointing toward the water
surface at a vertical angle. Recommended minimum height above the water surface is 1 meter,
with maximum height up to 20 meters. Recommended vertical angle is 45 degrees.
Picture 5 shows how the radar should be positioned relative to the water surface.
Picture 5. Installing the Surface Velocity Radar
4.1. Instrument Mounting and
Location Selection
To achieve the specied accuracy, it is important to properly select the measurement site
and to install the sensor with proper horizontal and vertical tilt angle. The tilt angle to
horizontal plane for surface velocity sensor should be between 30° and 60°, and if instrument
is mounted with reasonable tolerances to the pole this should be maintained. For optimal
operation and best results, the instrument should be oriented in parallel with the water ow
direction. Any deviation from parallel water ow direction will introduce oset of the real
measurement value, more precise value will be lower than actual surface velocity of the
water. It is recommended that the instrument is pointed upstream, so that the water ows
towards the instrument.
The height of the instrument above the water surface and the inclination determine area
on the surface that is covered by the radar beam. This measurement area should be clear
of any obstacles. The structure holding the instrument (pole, bridge fence, etc.) must be
solid and without vibrations. There should be no vegetation between the radar and the
measurement area because it could aect measurement accuracy.

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Water surface directly below the sensor should be clean of vegetation, rocks, sand deposition
or other obstacles that could aect measurement.
Surface velocity radar beam will cover an elliptical area on the water surface. The radar
reports average surface velocity of the covered area and instrument uses complex Kalman
lters with physical modelling of the water ow to give stable measurements even under
turbulent conditions. However even the moderate waviness of the water surface will improve
the measurement, if the water ow is strongly turbulent, uctuations in measured data could
be expected as well as somewhat reduced measurement accuracy. If strongly turbulent ow
can be expected at monitoring site, then the lter length of the radar should be congured to
120 or more.
4.2. Measurement Quality Indicator
Geolux RSS-2-300W instrument is constantly calculating various parameters of the signal in
the signal processing algorithms and will continuously, along with measurement data, report
the measurement quality. Quality indicator value is in range from 0 (the best quality) to 3
(the worst quality) and can be used to interpret data in the analysis software with better
understanding and condence.
For example, when the radar is mounted on the railway bridge, one of common applications,
measurements will be very good quality most of the time except when train is passing the
bridge due to the extensive vibrations. In this case radar will still report measurements but
values could be quite wrong, but also the measurement quality indicator value will go up
to the higher value. It is up to every user to interpret the quality indicator value for their
application, but general recommendation is that measurements with quality indicator 3
cannot be trusted, value 2 could be questionable, and values 1 and 0 are very good and
accurate.
4.3. Rain and Wind
Geolux RSS-2-300W instrument has integrated internal software lters to lter out eects
of rain, fog or wind both for surface velocity. These lters however have some limitations.
Majority of measurement inaccuracies caused by environmental factors can be solved by
proper sensor installation.
For rain and snow suppression, the most eective solution is to mount the radar so that it
points upstream and the water ows towards the radar. As rain falls down and the radar is
tilted downwards, rain droplets will move away from the radar, while the water ows towards
the radar. The radar can then easily distinguish the water movement from rain movement. To
further improve rain ltering, the radar should be congured to report only incoming direction
of water ow. In this case, the radar will completely ignore all movement with direction going
away from the sensor.
Inuence of the wind on the accuracy of measured data is, in most cases small and can be
neglected. The only exception is strong wind as it will create surface waves that are traveling
in dierent direction from the water ow. This can aect surface measurement accuracy.

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4.4. Interference and Multiple Radars
Surface velocity radar operates in K band, in frequency range around 24.125 GHz. Frequency
stability and phase noise of the internal oscillator is very good and always trimmed in factory
to precise central frequency but even with the best possible trimming and most stable
oscillators it is very unlikely that two devices will be working on the exact same frequency to
cause interference. Doppler frequency shift caused by water in speed range up to 15 m/s is
measured in kHz frequency shift. As this frequency shift is relatively small in comparison to
the central frequency, in most cases below 0.00005%, it will be required to keep dierence
between central frequencies of two radars in the same range to get interference.
Similarly, as interference from two or more surface velocity radars on the same location it is
very unlikely that other radiation sources in K band will also aect radar measurements. It is
possible that some wideband radiation sources can introduce small and impulse interference
for the short period of time, but this should not, or is very unlikely to aect measurements
reported by radar sensor continuously.
4.5. Fogging and Evaporation
Generally, radar sensors are not aected by fog or evaporation of water unless very heavy
evaporation is present and water density in the air is very high. Very high amount of
evaporation can introduce reections and can aect measurement on surface velocity sensor.
In the case of evaporation, the best solution for surface velocity sensor problem solving is to
use outbound ow direction and to congure sensor with only downstream directional lter.
As evaporation is traveling upwards from the water surface, inbound or approaching to the
radar, directional lter will solve the problem in most of the cases.
4.6.Reections
Water is very reective medium for the radar waves and most of the power transmitted from
radar transmitter will be reected from the water surface. Reections of the radar transmitted
power beam follow the same physical laws as in optics and every time radar beam hits the
surface part of the power is reected away from the radar, part of the power is reected
towards the radar and only a small part of power is absorbed by the water. Depending on
the surface roughness and incident angle ratio between power reected in the direction away
from the radar and direction back towards the radar can signicantly vary.
Ratio between reections is determined by water surface roughness and rule of thumb
can be applied where more rough water surface will lead to stronger reection inbound
the radar thus easier detection and greater SNR (signal to noise) ration on the radar which
enables more accurate measurement. Geolux surface velocity radar is designed with special
techniques to achieve accurate measurements even in the very small SNR environments so the
required surface roughness of 1 mm is usually enough for the precise measurements.

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When selecting location for surface velocity sensor additional care must be taken to avoid
reected power away from the radar (red arrow) to hit moving objects (gray cloud) on the
side of water channel as this can cause additional reection to inbound the radar and can
signicantly aect measurement accuracy. Installations where pedestrians, cars or other
objects are moving in front of the sensor closer than 75 m should be avoided as it is proven in
practice that it can cause problems.
Indoor applications are generally not recommended as it could lead to wrong readings due to
the reection of the radar beam and hitting any moving or rotating object which could cause
false readings.

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Surface Velocity Radar Settings
Communication Interfaces
Baud rate
1
0
010010 1 1 01
N bits per second
Band Rate
1 bit
Baud rate - Congures the baud rate (bits per second) for serial communication on both RS-232
and RS-485 data lines. This setting controls how many bits are sent on the communication line
in one second. The available values are standardized. Using higher baud rate over longer lines
may introduce errors in transferred data. The default instrument baud rate is 9600 bps.
RS-232 and RS-485 Protocol
1 0 0 1 0 $ABCD...
Protocol RS232 and RS485
RS-232 protocol - Selects the communication protocol to be used for data communication on
RS-232 interface. The NMEA protocol is a GPS-like human readable messaging protocol where
each data packet contains a checksum for data integrity verication. SDI-12 protocol is used for
interfacing older type of Geolux SDI-12 adapters. Unless the instrument is connected to an older
Geolux SDI-12 adapter, NMEA protocol must be selected.
RS-485 protocol - Selects the communication protocol to be used on RS-485 half-duplex
interface. HS protocol is a simple request-response protocol for the simplest applications.
Modbus RTU protocol is a standardized protocol which is commonly used in automation and
instrumentation as it provides all measurements with detailed diagnostics of device operation
and the possibility to change the instrument’s operating parameters.

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Device ID
Device ID - Congures the device (slave) ID to be used on RS-485 interface protocols (Modbus
RTU or HS). Both protocols use request/response format and allow multiple instruments to
be connected on the same bus. When a remote master transmits the request message, it will
use the device ID as a device address. All instruments will receive the request, but only the
instrument with matching device ID will answer to the received request.
Modbus Settings
Modbus settings - Congures the parity and number of stop bits used in communication.
Parity is used in serial communication for basic error detection. When parity is set to none, no
parity is used, and no error detection is possible on bit level. When parity is set to odd parity,
an additional bit is added to the communication that will be set to 1 when there is odd number
of bits with value 1 in the 8-bit payload byte. Similarly, when parity is set to even parity, an
additional bit is added to the communication that will be set to 1 when there is even number of
bits with value 1 in the 8-bit payload byte. In general, all bytes on the receiver side where the
parity bit is not matching the message will be discarded. Default setting on most devices that
use Modbus is even parity. Stop bits are added to the end of each data byte transferred over
serial communication, to allow pause between two bytes. The default setting is even parity and
one stop bit.
Warm Up Time
Warm up time - The time after sensor power-up, during which all measurements are ignored.
This time is used to settle auto-gain parameters, Kalman lter values, averaging lter, and all
other operational parameters. It is recommended to set this value to a minimum of 5 seconds. In
extreme cases where a quick response after unit power-up is required, 3 seconds can be used, with
a possibility of losing measurement accuracy.
ID ID+1
ID
Device ID
WARM UP TIME
POWER ON
Dead time

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4-20 mA Output
4-20 mA output - this parameter is used to select the value that will be presented on the 4 - 20
mA output. When velocity is selected the output current will be proportional to the measured
velocity. When none is selected 4 - 20 mA output will be disabled.
4-20 mA min. and 4-20 mA max.
Output value 4-20 mA
20 mA
4 mA
Min. Value Max. Value
4-20 mA min. – To congure the 4-20 mA output range, the minimum measured value which will
correspond to 4 mA analog output needs to be set. The value is set in the currently congured
measurement unit. Example: if values measured by the instrument are expected to be within
the range of 700 mm/s to 1500 mm/s, it is recommended to congure the minimum value to
slightly below 700 mm/s (for example 500 mm/s). Alternatively, if the resolution is not critical, then
minimum value for 4-20 mA output can be left to the instrument minimum of 0 mm/s.
4-20 mA max. – To congure the 4-20 mA output range, the maximum measured value which will
correspond to 20 mA analog output needs to be set. The value is set in the currently congured
measurement unit. Example: if values measured by the instrument are expected to be within the
range of 700 mm/s to 1500 mm/s, it is recommended to congure the maximum value to slightly
above 1500 mm/s (for example 2000 mm/s). Alternatively, if the resolution is not critical, then
minimum value for 4-20 mA output can be left to the instrument maximum of 15000 mm/s.
Processing Parameters
Sensitivity Level
Sensitivity level – Congures the radar sensitivity level. The sensitivity level threshold is used by the
radar to determine whether the reected signal is too low to detect any ow. If the instrument is
incorrectly reporting ow when there is no water in the channel, it’s necessary to increase the value
of this parameter.

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Sensitivity level
SNR
SNR Threshold
SNR Threshold
SNR threshold – The minimal Signal to Noise Ratio that is required to detect the water ow. If the
actual measured SNR is lower than the threshold, the instrument will not report any ow. Setting
SNR threshold to a higher value will result with more robust measurements but may also result with
no measurements when the water is very smooth. As a general rule of thumb, the measurements
with SNR below 10 dB may be inaccurate, and measurements with SNR below 6 dB should not be
trusted. The SNR threshold should be set accordingly.
Filter Length
Input Value
Filtered Value Filter length = 50
Filter length = 10
Filter length – The length of the averaging lter, in number of readings, to smoothen the measured
values. The instrument performs 10 readings per second, so a lter length value of 50 will result
in 5 second integration time. When using longer lter lengths, more measured values are used for
ltering, and the resulting data will be smoother. However, when the surface velocity changes, it will
take more time for the new measurement to be reported. Typically, this parameter should be set to
a value between 50 and 200. For highly turbulent water, larger lter length is recommended.

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Direction Filter
Directionlter– Direction lter is used to choose whether the instrument will detect ow in
both directions, or if it should detect only incoming or only outgoing ow. If the direction lter
is set to both directions, the instrument will measure the ow velocity in any direction and will
also report the actual direction of the ow. If the direction lter is set to incoming direction, then
the instrument will reject all radar returns that correspond to outgoing ow, and vice versa.
On monitoring sites where it is expected that the ow will always be in only one direction, it is
recommended to properly congure this parameter to either incoming or outgoing, as that will
improve the consistency of measurements.
PGA sensitivity – This parameter limits the maximum gain (amplication level) of the internal
programable gain amplier. It is strongly recommended to use the default value 9, which allows
the internal signal amplier to use the maximum gain when the reected radar signal is very low.
Setting this value to a lower value is used only when the instrument is mounted very close to the
water surface, typically less than 1 meter, and in that case this parameter should be set to a value
4 or 5.
Velocity min. and Velocity max.
Velocity min. - This parameter is used for setting up the minimum velocity value of interest.
Velocity max. - This parameter is used for setting up the maximum velocity value of interest.
Direction Filter
PGA
Grain
PGA Sensitivity
Measurement Parameters
Velocity Unit
Velocity unit – The measurement unit used to report the measured velocity value. For NMEA
protocol which is used over RS-232 connection, the velocity is reported as an integer value. To
preserve higher precision with integer numbers, the measured velocity will be multiplied by 10 for
m/s, km/h, mph, fps and fpm when being transferred over RS-232. When mm/s and cm/s units
are used, the measured values will not be multiplied by 10. This application internally handles the
multiplication factor which is used over RS-232 protocol, and it displays the correct values to the
user.
PGA sensitivity

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6
Data Interface
Geolux RSS-2-300W surface velocity radar oers multiple data interfaces, in order to make the
integration of the device with existing SCADA/telemetry systems easy.
6.1. Serial RS-232 Interface
Serial RS-232 interface is used for direct connection of a single surface velocity radar unit with
the computer. The serial interface is used both for retrieving live ow measurements and for
conguration of the surface velocity radar device. Geolux provides a PC application for unit
conguration and ow monitoring free of charge.
Default communication parameters are:
Bitrate: 9600 bps
Data bits: 8
Stop bits: 1
Parity: None.
A NMEA-like communication protocol is used to deliver ow measurements over RS-232 interface.
Detailed description of the protocol is given in the Chapter 7 of this user manual.
6.2. Serial RS-485 Interface
Serial RS-485 interface is used for connecting multiple surface velocity radars to a single data
logger. RS-485 interface uses a dierent protocol then the protocol used over RS-232 interface,
in order to allow multiple surface velocity radars connected on a single RS-485 bus. The main
dierence from the protocol used over RS-232 interface is that the ow measurements are not
reported automatically, but are instead reported only after being requested by the master device
(data logger unit). Detailed description of the protocol is given in the Chapter 7 of this user manual.
Default communication parameters are:
Bitrate: 9600 bps
Data bits: 8
Stop bits: 1
Parity: None.

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7
Data Protocols
Geolux GLX-RSS-2-300W surface velocity radar supports the following data protocols:
• NMEA-like protocol on RS-232 interface that constantly outputs the detected speed and
reected signal power, and also the current measured tilt angle
• Servicing protocol on RS-232 interface for conguring the unit
• Request-response protocol on RS-485 interface that allows multiple units to be used on a
single RS-485 bus
• Modbus-RTU protocol on RS-485 interface which is supported by variety of third-party data
loggers
Support for additional protocols is available upon customer request.
7.1. NMEA Protocol (RS-232)
NMEA protocol is based on the standard protocol family widely used by the navigation equipment.
NMEA protocol is sentence oriented, and is capable of sending multiple sentences with dierent
information. The sentence content is designated by the starting keyword which is dierent for each
sentence type. NMEA sentences are terminated with the checksum which makes this protocol
extremely reliable. NMEA protocol is singe-direction protocol: data is only transmitted from the
surface velocity radar.
At RS-232 interface the device periodically outputs following data sentences:
 Directowmeasurementreport
$RDTGT,D1,S1,L1*CSUM<CR><LF>
$RDTGT: The keyword sent on the beginning of each detection report. This sentence
is sent whenever there is detected ow.
D1: The direction of the ow, as detected by the instrument (1 incoming, -1
outgoing). Geolux Instrument Congurator displays this value as “In” for
incoming and “Out” for outgoing direction.
S1: The measured surface velocity, without applying additional averaging lter
(velocity is reported as velocity*10 for m/s, km/h, mph, fps and fpm and as
velocity*1 for mm/s and cm/s). Geolux Instrument Congurator internally
handles the multiplication factor and displays the correct values to the user.
L1: The relative level strength of the returned radar signal. This value is used
internally by the auto-gain algorithm which adjusts the gain levels of the
internal signal ampliers.
CSUM: The check sum of the characters in the report from $ to * excluding these
characters.

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RSS-2-300W Non-Contact Surface Velocity Radar
Averageowmeasurementreport
$RDAVG,S1*CSUM<CR><LF>
$RDAVG: The keyword sent on the beginning of the report. This sentence reports
smoothed ow measurement. This is the preferred reading, since it lters
out minor uctuations in ow speed reading due to waves.
S1: The measured surface velocity with additional average lter applied
(velocity is reported as velocity*10 for m/s, km/h, mph, fps and fpm and as
velocity*1 for mm/s and cm/s). Geolux Instrument Congurator internally
handles the multiplication factor and displays the correct values to the user
CSUM: The check sum of the characters in the report from $ to * excluding these
characters.
Tilt angle report
$RDANG,A*CSUM<CR><LF>
$RDANG: The keyword sent on the beginning of each angle report.
A: Device tilt angle in degrees, as measured by the internal tilt angle sensor.
The angle is relative to the horizontal plane.
CSUM: The check sum of the characters in the report from $ to * excluding these
characters.
Signal to noise ratio (SNR) report
$RDSNR,S1,S2*CSUM<CR><LF>
$RDSNR: The keyword sent on the beginning of each SNR report.
S1: Signal to Noise Ratio of the detected signal in dB. SNR is the dierence
between signal level corresponding to measured velocity and the noise
oor level. Low SNR levels indicate that the measured value may be
inaccurate.
S2: The average Signal to Noise Ratio of the detected signal. SNR is the
dierence between signal level corresponding to measured velocity and the
noise oor level. Low SNR levels indicate that the measured value may be
inaccurate.
CSUM: The check sum of the characters in the report from $ to * excluding these
characters.
Quality of signal report
$QOS,Q1,Q2*CSUM<CR><LF>
$QOS: The keyword sent on the beginning of each quality of signal report.
Q1: This is an indicator of the Quality of the Service (measurements) related to
the instrument vibrations. If the instrument is vibrating, the
measurements may be incorrect, and the amount of vibrations is measured