Metek MRR-2 User manual

2012-03-01 Valid for MRR Service Version 6.0.0.4 / Firmware 6.00
MRR-2
Micro Rain RADAR
User Manual

2012-03-01 Valid for MRR Service Version 6.0.0.4 / Firmware 6.00

2012-03-01 Valid for MRR Service Version 6.0.0.4 / Firmware 6.00
METEK
Meteorologische Messtechnik GmbH
Fritz-Strassmann-Strasse 4
25337 Elmshorn
Germany
Fon [phone]
Fax [phone]
e-mail [e-mail]
internet http://www.metek.de
Copyright: © 2012 METEK GmbH
All Rights reserved. No part of this manual may be reproduced, transmitted,
stored in a retrieval system, nor translated into any human or computer
language, in any form or by any means, electronic, mechanical, optical,
chemical, manual, or otherwise, without the prior written permission of the
copyright owner.

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Table of Contents
1Safety Precautions ...............................................................................6
2How to use this manual .......................................................................7
3Measuring Principle .............................................................................8
4System Description.............................................................................. 9
4.1 Overview ................................................................................................9
4.2 Description of the Components ............................................................10
4.2.1 Parabolic Dish ...................................................................................10
4.2.2 Antenna Heating (Option)..................................................................10
4.2.3 RADAR Control and Processing Device and Transceiver ................11
4.2.4 Junction Box / Power Supply.............................................................12
4.2.5 Control Cable and Serial Cable .........................................................13
4.2.6 MRR-PC ............................................................................................13
5Hardware Installation ......................................................................... 15
5.1 General Provisions ...............................................................................15
5.2 Site Conditions ..................................................................................... 15
5.3 Installation Procedure........................................................................... 16
6Control Program................................................................................. 19
6.1 Installation ............................................................................................ 19
6.2 Limitations using Windows 7 ................................................................ 22
6.3 Using the Control Program ...................................................................23
6.3.1 Main Menu......................................................................................... 24
6.3.2 Control Commands Menu.................................................................. 25
6.3.3 Output Parameters Menu ..................................................................26
6.3.4 Device Parameters Menu ..................................................................28
6.3.5 Parameter Storage ............................................................................30
6.3.6 Status messages ...............................................................................32
6.4 Processed and averaged data..............................................................34
6.4.1 Format description............................................................................. 34
6.4.2 Processed and averaged data example ............................................39

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6.5 Raw Spectra ........................................................................................ 42
6.5.1 Format Description............................................................................ 42
6.5.2 Raw Spectra Example....................................................................... 43
6.6 Removing of the Software.................................................................... 44
7Detailed description of the MRR-2 control program ....................... 45
7.1 MRR-Service........................................................................................ 46
7.1.1 Communication ................................................................................. 46
7.1.2 Data Recording ................................................................................. 46
7.1.3 Error Handling................................................................................... 48
7.2 Control Program................................................................................... 49
8MRR-2 Specifications ........................................................................ 52

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1Safety Precautions
To operate the MRR-2 a mains voltage of 210-240 VAC is needed for the
power supply. An improper handling can be dangerous to you. Only
competent and instructed persons should work with this system or with
parts of it.
The outdoor installation must not be performed in case of an
approaching thunderstorm, to avoid a possibly endangering of
personnel by lightning.
There are not known any health hazards originating from the emitted
electromagnetic radiation of about 50 mW. Nevertheless you should
take care that everybody keeps out of the beam above the antenna
(parabolic dish) when it is in operation.
All connecting cables, plugs and couplings of the MRR-2 are not
interchangeable to prevent any erroneous assembly. This safety
precaution is disabled if other types of plugs are installed by the user.
Therefore any guarantee explicitly expires and METEK accepts no
responsibility for injuries to persons, damage of equipment or other
consequences connected with not authorized changing of connectors,
cables or other parts of the system.
Depending on regional rules for the use of electromagnetic transmitters
frequency permission might be necessary. The operator of the system
will be liable for the achievement of such permission. However METEK
will be of help with providing adequate information. Copies of the
certifications for Germany can be found in chapter 8 of this manual.

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2How to use this manual
The delivered hardware items are described in chapter 4. Make sure that the
delivery is complete and free of damage. Consult chapter 5 for setting up the
hardware. In chapter 6 the installation and use of the control software is
described. The technical specifications are listed in chapter 8.
Chapter 7 contains more detailed information which is not needed for
standard operation.
All auxiliary information marked by a grey vertical line on the left margin may
be skipped at first reading as it is not needed for standard setting up and
operation.

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3Measuring Principle
The Micro Rain Radar MRR-2 retrieves quantitative rain rates, drop size
distributions, radar reflectivity, fall velocity of hydro meteors and other rain
parameters simultaneously on vertical profiles up to several kilometers above
the radar.
It operates with electromagnetic radiation at a frequency of 24,230 GHz with
a modulation of 0.5 15 MHz according to the height resolution (e.g. 300 m 
10 m). The radiation is transmitted vertically into the atmosphere where a
small portion is scattered back to the antenna from rain drops or other forms
of precipitation.
Due to the falling velocity of the rain drops on the antenna there is a
frequency deviation between the transmitted and the received signal
(Doppler frequency). This frequency is a measure for the falling velocity of
the rain drops. Since drops with different diameters have different falling
velocities the backscattered signal consists of a distribution of different
Doppler frequencies. The spectral analysis of the received signal yields a
power spectrum which is spread over a range of frequency lines
corresponding to the Doppler frequencies of the signal.
The RADAR Control and Processing Device (RCPD) determines this power
spectrum with a high time resolution (10 per second) and sends mean power
spectra every 10 s to the connected MRR-PC where the reflectivity spectrum
is calculated considering the calibration parameters of the RADAR module.
Using known relations between fall velocity, rain drop size and scattering
cross section the drop spectrum (or drop size distribution) is derived. The
integration over the entire drop size distribution, considering further
correction terms, followed by further averaging over 10 to 3600 seconds,
results in rain rate and liquid water content.
The output signal of the RADAR is transmitted continuously (CW mode), a
linearly decreasing saw tooth modulation of the transmit signal (FM mode)
makes it possible to perform profile measurements with selectable range
resolution.
The RADAR antenna is an offset parabolic dish with vertical beam
orientation. This antenna design allows rainwater to drain without building
ponds. In order to avoid disturbances from snow which could cover the
antenna dish, optional antenna heating is offered.

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4System Description
4.1 Overview
Figure 1: Components of the System
The MRR-PC, a commercial PC, (not part of delivery) must be ordered
separately. The operating system should be Windows® 2000 or XP.
(Windows® Vista and Windows 7 are supported with some limitations).
1- Parabolic Dish
2- Transceiver
3- Antenna Arm
4- Bubble Level
5- RCPD
6- Pivot
7- Tube Socket
8- Junction Box
9- Control Cable
10- Serial Cable
11- Power Cable

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4.2 Description of the Components
4.2.1 Parabolic Dish
The antenna is used for the transmission of the RADAR signals and the
receiving of backscattered signals. It is designed as an offset parabolic dish
(see Figure 1). Its largest diameter is 70 cm, the beam width is 2°. Due to the
offset-design of the parabolic dish rainwater can drain off.
For antenna mounting the tube socket (see Figure 1) (inner Ø = 49.4 mm) is to
be plugged onto a pole with an outer diameter of max. 49 mm. The socket is
fastened with an M10 screw.
Connect a ground wire to this screw which serves as a surge protector.
Check the vertical alignment of the antenna with the built in bubble level.
The transmitting and receiving properties of the antenna affect the radar
calibration. Therefore the reflector surface should be clean (e.g. free from
leaves or wet snow). For the same reason any mechanical deformation of the
parabolic dish must be avoided. If nevertheless obvious deformation occurred,
the reflector must be replaced.
4.2.2 Antenna Heating (Option)
Figure 2: Antenna Heating
1- Parabolic Dish with Heater
2- Heater Connection Box
3- Heater Power Cable

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The back side of the reflector is optionally equipped with a heater coil. It is
covered and sealed with a molded lid which provides also extra stability for the
reflector. The energy consumption increases with decreasing temperatures
and amounts to maximum 500 W. The heating is activated when the
temperature falls below a threshold which can be adjusted in the heater-
connection box. The heater coil works with 230 VAC voltage supply and needs
an extra power cable which is connected to the heater connection box
(see Figure 2).
4.2.3 RADAR Control and Processing Device and Transceiver
Figure 3: RCPD and Transceiver
The RADAR Control and Processing Device RCPD (see Figure 3) generates
the RADAR transmit modulation signal and passes it to the transceiver (see
Figure 3). It analyses the backscattered receiver signal, calculates Doppler
spectra and transfers average power spectra to
the MRR-PC where these spectra are interpreted. The RCPD has a water
protected IP65 housing which is fixed to the antenna arm (see Figure 3). At
the bottom side of the RCPD is the socket (see Figure 3) for the control cable
(see Figure 5)
service. As far as possible the RCPD should not be opened by the user.
1- Transceiver
2- RCPD
3- Antenna Arm
4- Connector (Control Cable)

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4.2.4 Junction Box / Power Supply
Figure 4: Junction Box
The junction box is used to pass through the communication between the PC
and the RCPD. For this purpose it has a 9-pin D-sub-miniature socket for the
serial cable (see Figure 5) to the MRR-PC and a flanged socket for the control
cable (see Figure 5) to the RCPD.
The power supply for the RCPD and Transceiver is also integrated in the
junction box. An IEC connector for the mains supply of 230 VAC is on the front
side of the case. The power supply (24 VDC) for the RCPD and Transceiver is
also passed through the control cable (see Figure 5).
All MRR systems produced in 2011 ff. are equipped with an RS422 Interface:
The communication between RCPD and Junction Box is on RS422 level. In
the Junction Box the signals are converted to RS232 level.
The communication between junction box and PC is on RS232 level.
MRR systems prior to 2011 use only RS232 level for communication, there is
no RS422/RS232 converter in the junction box.
Note: The junction box is not appropriate for outdoor operation.

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4.2.5 Control Cable and Serial Cable
Figure 5: Control Cable (left) and Serial Cable (right)
The control cable connects the RCPD with the junction box.
The control cable has a length of 25 m, on both ends are screwed plugs (male
and female respectively). They must be screwed onto the matching plugs at
the junction box (cable has pins) and at the RCPD (cable has sockets).
The serial cable (RS232) connects the Junction Box with the PC.
The maximum length of the serial cable is 2 m, a serial cable with a 9-pin
(female) and a 9-pin (male) plug and a length of 1.8 m is delivered. This cable
is not appropriate for outdoor applications.
4.2.6 MRR-PC
A personal computer (PC) with the operating system Windows® 2000 or XP
serves for setting the operation parameters and data evaluation of the MRR.
(Windows® Vista and Windows® 7 are supported with some limitations). The
PC must have at least one serial port which will be configured by the control
program as follows:
57600 baud,
8 data bits, no parity,
Software Handshake (XON/XOFF)
Pinning (D-Sub-9-socket at the junction box) :
Pin 1 CD carrier detect
Pin 2 RD receive data
Pin 3 TD transmit data
Pin 4 DTR data terminal ready
Pin 5 GND ground
Pin 6 DSR data set ready
Pin 7 RTS request to send
Pin 8 CTS clear to send
Pin 9 RI ring indicator

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The control program which is needed to operate the MRR-2 is part of delivery.
Its installation and operation is described in section 6 Control Program page 19.
Figure 6: MRR block diagram

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5Hardware Installation
5.1 General Provisions
Before you start the system, all cable connections must be set up.
Only the antenna unit including RCPD, transceiver and control cable
(see Figure 1) are designed for outdoor operation. All other
components, e.g. the junction box and PC, must be installed in a
weather protected environment with temperatures within 5 - 40°C.
The electronics cases may be opened only in dry environment.
Especially in outdoor area you risk damage by moisture.
If cables are laid on free field, a cable conduit is recommended.
All cable connections should be protected by strain-reliefs.
Use only the original connectors. Guarantee is void if other connectors
are installed.
5.2 Site Conditions
Before actual installation the site must be checked for its suitability for rain
measurements.
There must be free view of at least 10° zenith angle over the radar.
Nearby transmitters (base stations of mobile phones, broadcast towers,
radars) can cause interference although they operate nominally at different
frequency bands. If such neighborhood is necessary, a simple metallic screen
or larger object (container) obscuring the direct line of sight to the interfering
source can help.
The vicinity of electric machines (e.g. drive of elevators) should be avoided,
since they can create interfering signals which are difficult to screen.
If measurements at very low heights are planned, (with appropriate settings
the MRR-2 allows measurements from a minimum height of 20 m above
ground) take care that the wind field in this level is not disturbed by nearby
buildings, trees, masts etc. because strong turbulence could falsify the data.
In contrast with in-situ rain sensors the exposure of the antenna to the free
wind field is not detrimental but favorable.
Figure 7 shows various examples of MRR installations: On ground, on top of
containers and on top of buildings.

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Figure 7: Examples of MRR installations
5.3 Installation Procedure
Preparations:
A fixed vertical pole (Ø max. 49 mm, length min. 30 cm) is required for
attaching the antenna. Operating of the MRR-2 requires a 230 VAC mains
supply, with a fuse protection of 8 A (slow) minimum. To prevent disturbance
of the device by variations or breaks of the power supply we recommend the
use of a no-break power supply (UPS).
Required Tools:
17 mm wrench
5 mm hexagon socket screw key

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Installation Steps:
1. Install the MRR-PC according to the documents of the manufacturer.
2. Plug the tube socket (see Figure 1) of the RADAR antenna over the
attachment pole and clamp it with the M10 fixing bolt.
3. Check the vertical alignment of the antenna with the built in bubble level
(Figure 8).
Figure 8: Vertical alignment of the radar beam
4. Attach a ground wire to the fixing bolt for lightning protection after
mounting of the antenna (Figure 8).
5. Connect the control cable between RCPD and Junction Box. Ensure that
the nut cap is tightly screwed, If the black o-ring is visible the connection
will not be waterproof (see Figure 9).
Figure 9: Control cable connector
6. Connect serial cable (Figure 5) to the serial interface of the MRR-PC
which was selected in the operating system for the connection of the
MRR-2. If this serial port is unknown, it can be looked up in the
administration of the "services" in the operating system of the computer
and it can be changed accordingly there. See also installation of the
control program chapter 6.
Ground wire
o-ring

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7. Connect power cable of the Junction Box to the mains voltage of
230 VAC.
8. Check the power supply of the Transceiver: If the cabling is Ok a green
LED in the Transceiver indicates the correct supply.
Figure 10: Transceiver with LED
9. Establish the communication between the control program MRR-2
and the RCPD-firmware.
10. Check the correct data transmission and recording.
LED

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6Control Program
If you use your own PC for controlling the MRR-2 the MRR program is
delivered on a CD-ROM and must be installed according chapter 6.1.
If the PC was configured and delivered by METEK (optional) chapter 6.1 may
be skipped.
6.1 Installation
The software can be installed on a PC with Windows® 2000 or Windows® XP
(Windows® Vista and Windows® 7 are supported with some limitations).
For installing the Control Program:
Insert the CD-ROM.
Login as administrator.
Open the program group my computer (icon on the desktop).
Open the folder for the CD-ROM device.
Change to the folder METEK.
Start the program MRRSetup␣V6002.exe
The setup program will start with the welcome screen; click the next button to
proceed with the installation. The next screen is the destination folder
selection (default: C:\Program Files\METEK Software\MRR), normally no
changes are needed, please 
Figure 11: Welcome Screen

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Figure 12: Destination Folder
The next screen is the selection of the data folder (Figure 13), the default
value for the data folder is
D:\Documents and Settings\All Users\Documents\MRR Data
The default value depends on the windows version, please change this value
according to your preferences and confirm with ext.
In a next step the communication port (Figure 14) is selected: the list of the
serial ports shows all available serial ports on your PC, please change this
value to your preferences .
Figure 13: Data Folder