1. 2nd Floor, Wing-4, West Block – 1, R.K. Puram, New Delhi-1100605. Telephone 011-26100285,
Fax 011-26181267, E-mail rdcdte-cwc@nic.in and nswdc_delhi@Yahoo.com
30.001 AUTOMATIC WEATHER STATION
Approval Date: 10.05.2010 Version: 3
Purpose
The Automatic Weather Station (AWS) will be used to automatically make standard
meteorological observations and record the collected values in memory. The following
parameters will be monitored:
• wind speed
• wind direction
• air temperature
• relative humidity
• rainfall
• solar radiation
• air pressure
Conditions and requirements
• The AWS equipment should incorporate the state-of-the-art technology and provide
capability for unattended operation for at least one year using a 12V/65 AH single
sealed maintenance-free battery, rechargeable through a solar panel. The battery
shall be capable to run the system for minimum of 30 days during total cloudy
conditions.
• All equipment should be qualified for MIL STD – 454K specifications and suitable for
outdoor applications.
• The AWS must be housed in weather-proof enclosure and shall meet all specified
environmental specifications of international standards.
• Data logger must have certification from authorized agency for functional operation.
• AWS system should have in-built memory of storing data for at least 12 months
period.
• PCMCIA memory card slot, USB or any other commercially available latest
technology memory device for data retrieval and transfer of set up of the system
shall be provided. All set up and configuration files should be transferable through
the solid state memory device to the data logger and vice versa.
• If specified in the Schedule of Requirements, the data logger should support
GPRS/GSM-based and satellite-based technology for transmitting the data.
• Facility for standard positioning system (SPS) with GPS (location and time) receiver.
(L1 frequency) shall be provided
• The number of analogue / digital / SDI channels provided in the data logger shall be
compatible to the sensors being supplied. There should have facility to interface at
least 2 additional digital & 2 additional analogue channels.
• RS 232 ports / RS 485 ports being provided shall be compatible to requirement of
interfacing GSM/GPRS modem, radio modem for the remote display unit. At least 3
RS232 ports in the form of standard DB9 connector, 1 RS 485 and 1 SDI-12 port or 2
USB 2.0 or better port shall be provided in the data logger.

2. 2nd Floor, Wing-4, West Block – 1, R.K. Puram, New Delhi-1100605. Telephone 011-26100285,
Fax 011-26181267, E-mail rdcdte-cwc@nic.in and nswdc_delhi@Yahoo.com
• Facility to log and store data locally into a flash EPROM, retrieve them later by
placing a data call so as to obtain detailed logs with sampling intervals as accurate
as 2 minutes.
• Facility to display data, export to Excel, Matlab or similar applications for graphical
representation of weather data.
• Provide information on sudden developments like gust, squall, threshold of rainfall,
etc.
• The data logger shall have in-built lightning protection.
• The vendor shall retain sufficient stock of spares and consumables at their nearest
maintenance centre in India for replacement at field sites on priority basis during the
free warranty period of 5 years.
Specifications
1. Sensors
• The meteorological sensors with accuracy specifications as per WMO norms
applicable shall be provided. All the sensors should have certification of NIST or
accredited lab of IMD.
• The sensors along with the accessories shall be fully compatible with the data logger
and transmission system specified below.
• Optional features available with the sensors may also be clearly specified by the
bidder.
• Range of operating temperatures : -10°C to +55°C
Individual Sensor Specifications
Air temperature
Range : -10°C to +55°C
Accuracy : + 0.2 °C or better (with radiation shield)
Resolution : 0.1°C
Sensor Type : Solid state
Response Time : 10 sec or better
Wind Speed
Range (Operation) : 0 to 60m/s or better
Accuracy : + 0.5 m/s or better
Resolution : 0.1 m/s
Sensor Type : Ultrasonic
Threshold : 0.5 m/s or less
Response time : immediate (being ultrasonic)
Wind Direction
Range : 0 to 359 Degrees
Accuracy : + 5 degrees or better
Resolution : 1 deg.
Sensor Type : Ultrasonic
Threshold : 0.5 m/s or better
Response time : Immediate

3. 2nd Floor, Wing-4, West Block – 1, R.K. Puram, New Delhi-1100605. Telephone 011-26100285,
Fax 011-26181267, E-mail rdcdte-cwc@nic.in and nswdc_delhi@Yahoo.com
Pressure sensor
Range (with single sensor) : 600 to 1100 hPa
Accuracy : + 0.2 hPa or better
Resolution : 0.1 hPa
Sensor Type : Solid state
Response Time : 10 sec. or better
Relative Humidity Sensor
Range : 0 to 100% RH
Accuracy : +3% or better
Resolution : 1% or less
Sensor Type : Capacitive / Solid-state
Response Time : 10 sec. or better
Rainfall Sensor
Range : unlimited
Accuracy : ±2% of rainfall for non-monsoon
conditions; ±5% of rainfall or better under
monsoon conditions
Resolution : 0.5 mm
Sensor Type : Tipping bucket rain gauge or any other
suitable sensor.
Global Radiation Sensor
Range : 0 to 1500 W/m2
Operating temperature range : -10°C to +60°C
Calibration traceability : World Radiometric Reference
Temperature dependence : <± 1%
Note: Wind Speed and Wind Direction measurements are to be made at a height of 2
metres above ground level at all the AWS stations. The mast should be rugged and
rust proof and should be able to withstand wind speed > 60m/s.
2. Data logger
a. Data logger shall automatically collect the observations from attached sensors,
process the same and store them into its memory as per the pre-programmed
procedure at every 1 hour interval or any other user-defined interval which the user
must be able to set.
b. Data logger shall be provided with a LCD colour screen for efficient control of the
AWS. The screen shall be easily readable under field conditions, with a keypad
option and a minimum 2-line backlit LCD display in the front panel with facility to
display at least 16 characters per line.
c. The number of analog/digital/ SDI channels in the data logger must be compatible to
the sensors being supplied.
d. At least ten built-in high performance analog channels, eight built-in digital channels,
three RS-232 ports in the form of standard DB9 connector, one RS-485 and one SDI
-12 channels must be available to interface different types of sensors. It should have
at least one USB 2.0 or better port. It should have standard ethernet port.
e. The sensor's signal conditioning unit should be an integral part of the data logger.

4. 2nd Floor, Wing-4, West Block – 1, R.K. Puram, New Delhi-1100605. Telephone 011-26100285,
Fax 011-26181267, E-mail rdcdte-cwc@nic.in and nswdc_delhi@Yahoo.com
f. Data including the setup and program files shall be transferable from the system via
a serial port/USB 2.0 or better port to PC and PCMCIA card or other suitable
memory device and vice versa. It should be possible to upload or upgrade the
software of the data logger using USB or RS-232 port
g. If specified in the Schedule of Requirements, the data logger should support
GSM/GPRS-based and satellite-based technology for transmitting the data, with the
following features:
• The AWS shall also send the data with the help of GSM/GPRS modem
interfaced to the data logger in a format compatible for decoding at the
GSM/GPRS server.
• In addition, as and when the remote AWS is queried by the GSM/GPRS Server
at any time to take samples of meteorological parameters, the same shall also be
done and information be provided to the server for onward availability to the
forecaster.
• The system shall also send the values of meteorological parameters (user
selectable) to a remote display unit located at a distance between 50 meters to 2
km depending on the location of each of the AWS site. It should be possible to
interface any other commercially available standard scrolling display unit.
• The data logger should also have provision for satellite transmission.
h. The system shall have provision to easily include and change the following
information as mandatory requirements:
• Unique station identification code
• Sensor identification.
• Time of observation
i. Providing necessary electrical power to the sensors and conversion of electrical
output signals from the sensors into engineering values based on calibration
equations stored in the memory shall be mandatory. Full compatibility with all types
of sensors provided in the packages shall be mandatory.
j. Storage of observed data along with time for all the parameters in the memory shall
be mandatory.
k. Memory capacity to retain at least one year’s data is required. Data shall be available
even if the power supply to the system has failed (RAM Backup battery) for one year.
l. The stored data shall be retrievable via serial port/USB 2.0 or better port to a
PC/laptop and a PCMCIA card or any other compact and commercially available
solid state memory device.
m. The system should be stand-alone and all programming functions/set-ups to be
carried out through system keypad and display independent of a PC/Laptop.
n. Setup shall be organized in a tree of menus and sub-menus. Protection of setup
parameters and data through password should be supported by the system.
o. The system should be capable of continuous updating of the values of sensed
weather parameters and post processing the instantaneous values into average or
total values over a specified period of time for transmission to the AWS data
receiving station.
p. Data logger should have a real time operating system. The data logger should have
32 bit or better microprocessor.
q. The data logger should have in-built library or C/Basic language compiler which shall
allow the user to create, compile and execute customized programs in the data
logger. The library or compiler should support structured and modular programming.
The library/compiler shall have in-built functions to take measurement of desired

5. 2nd Floor, Wing-4, West Block – 1, R.K. Puram, New Delhi-1100605. Telephone 011-26100285,
Fax 011-26181267, E-mail rdcdte-cwc@nic.in and nswdc_delhi@Yahoo.com
sensors connected to any channel of the data logger at user defined intervals. The
library or compiler should have in-built functions to change the properties of all COM
ports (RS232 port in the form of standard DB9 connector) such as baud rate, data
bits, parity, stop bits, flow control, CTS, DSR, DTR, RTS etc and thus enable the end
user to flush required data in desired format to the COM port. All standard baud rates
between 300 baud to 115.2 K baud shall be supported. The data logger should also
support recursive execution of a customized program at user defined interval.
r. The data logger should have capability to sample and log the data for specified
parameter at user defined intervals in multiple log files.
s. It should have open architecture system to configure any standard commercially
available sensor. The system must also support the future up gradation of hardware
and software without removing the system from the site.
t. Data including the set-up and configuration files shall be transferable from the logger
via a serial port/USB 2.0 or better port to both PC and any commercially available
memory device (preferable USB pen drive) and vice versa.
Data Logger Specifications
• ADC Resolution 32 bit or better
• Conversion Accuracy ± 1 LSB
System clock:
• Stability Long-term 1 ppm/year or better
• Stability (Temperature) 3 ppm or better from -10°C to 55°C
• Operating Temperature
range
-10°C to + 55°C
• Internal Memory 1 MB RAM minimum
• Battery Backup (internal) Lithium Battery, storage: 1 years
• Real-Time Clock GPS synchronized
• Watchdog Timer System Reset upon microprocessor failure
• Sample Intervals 1 sec. to 24 hr. in 1 second increments (user selectable)
• Visual Display 16 Character or more, alphanumeric LED/LCD to
operate in temp. range -10°C to +55°C
• Power consumption Average over an hour shall be less than 0.5 A at 12V
D.C. including that of sensors.
Power Supply:
a) Battery Single 12V/65 AH rechargeable Sealed maintenance-
free battery which shall be capable to run the system for
minimum of 30 days during total cloudy conditions.
b) Charge controller Internal or External
c) Solar panel Rated capacity 30W, Open circuit voltage: 21V, Short
circuit current 2.4 A
3. Details of weather parameters
The following weather parameters are required from the sensors interfaced with the data
logger.
(i) Instantaneous sampled value of air temperature in deg 0
C at every 10 minute
interval and at every full hour UTC.

6. 2nd Floor, Wing-4, West Block – 1, R.K. Puram, New Delhi-1100605. Telephone 011-26100285,
Fax 011-26181267, E-mail rdcdte-cwc@nic.in and nswdc_delhi@Yahoo.com
(ii) Maximum air temperature of the hour (samples taken every minute).
(iii) Minimum air temperature of the hour (samples taken every minute).
(iv) Daily maximum temperature
(v) Daily minimum temperature
(vi) Wind speed in knots at every 10 minute interval with 2 minute vector averaging.
(vii) Wind direction in degrees at every 10 minute interval with 2 minute vector
averaging.
(viii) Wind speed in knots (3 minute vector averaging prior to full hour UTC).
(ix) Wind direction in degrees (3 minute vector averaging prior to full hour UTC).
(x) Daily minimum and maximum wind speed
(xi) Daily maximum wind gust.
(xii) Station level pressure (sampled at the end of every 10 minutes and full hour
UTC).
(xiii) Instantaneous value of RH at the end of every 10 minutes and at full hour UTC.
(xiv) Daily maximum and minimum value of Relative Humidity.
(xv) Global solar radiation at an interval of 10 minutes and full hour UTC.
(xvi) Dew Point temperature at every 10 minute interval and at full hour UTC
(xvii) Cumulative rainfall since last reset (reset at 03 UTC everyday)
(xviii) Hourly rainfall (reset every full hour UTC)
(xix) Battery voltage (hourly)
(xx) Graphical representation of logs and statistics.
4. Data retrieval software (DRS)
The DRS software shall support functions for conversion of the collected data into
ASCII (text) tables, and for efficient visualisation of the time series in tabular and
graphical form.
• Graphical axes shall be generated automatically and be manually adjustable.
Units along the axes shall not be awkward but intuitive and easily understandable.
• All axes shall have sufficient graduation.
• The labels along the time axis shall be in sensible time intervals, i.e. hh:mm for
relatively short periods and dates, e.g.: DD/MM/YYYY, for long periods. The same
applies for the level axis.
• The unit-labels shall not cover each other.
• To enhance readability, adequate gridlines, both along time and level axes, shall
be generated automatically by the graphics functions, approximately 5 gridlines per
axis.
• The gridlines shall also be user adjustable.
• The user interface shall support efficient functions to select and visualise subsets of
the time series, e.g. a single day or several days somewhere out of many weeks of
data.
• Efficient window functions shall be available to visualise the data in the
required resolution, i.e. the level scale shall be user adjustable.
• Software that can only display sample counts or total duration or does not support
axis and grid adjustment is not permitted.
• The DRS software shall support error free transfer of the retrieved data to a PC.
• Note that in particular, the graphics capabilities are a major reason to apply a
palmtop or Laptop computer as DRS.

7. 2nd Floor, Wing-4, West Block – 1, R.K. Puram, New Delhi-1100605. Telephone 011-26100285,
Fax 011-26181267, E-mail rdcdte-cwc@nic.in and nswdc_delhi@Yahoo.com
5. PC Software
• PC software shall be part of the delivery and will be used in the office, e.g. on a
desktop PC.
• The PC software shall efficiently and reliably transfer the collected data from the
DRS to a PC environment.
• The PC software shall have functions for conversion of the collected data into
ASCII (text) tables.
• The tabular data will be imported by other software packages, e.g. for analysis
and presentation in a spreadsheet and for storage in a database.
• The PC software shall support the same and more tabular and graphical
presentation functions as specified under DRS software.