Download RF401-to

900 MHz radio link between two
remotely located Weather Stations
:Sanjaya Gurung
Base Station
Remote Station
1
Required Equipments
Local Station:
• RF401: 900 MHz radio modem
• Appropriate antenna and connecting cables
• Compatible Datalogger or PC
• Power Supply
Remote Station:
• CR206: Datalogger having built-in 915 MHz radio
• Appropriate antenna and connecting cables
• Power Supply
• Datalogger support Software
RF401
900 MHz radio modem
Operating frequency range: 910 - 918 MHz
Supports point-to-point and point-tomultipoint datalogger communications
RF401
Antenna can be replaced with any other
frequency compatible antenna according to
the transmission range need
CR206
CR206 is a datalogger to measure a few sensors
and transmit data using built-in 915 MHz spread
spectrum radio
6 Kbyte program storage
Powered by 12 V battery
CR206
Connection Set-Up
Yagi
(directional antenna)
Omni-directional
antenna
Power Supply:
Powered by CR1000
CR206
Sensors
Power Supply:
12 V battery, charged
with solar panel
Remote Weather Station
CS I/O
RF401
Weather Station
Datalogger
(CR1000)
Local Weather Station
(Base Station)
5
Technical Specifications
RF401
Operating frequency:
Type:
I/O Data rate:
Tx power:
Tx range:
Rx sensitivity:
Power requirement:
Avg.Current Drain:
900 MHz
Frequency hopping spread spectrum TRx
Point-to-Point/Point-to-multipoint
9600 bps
100 mW
0.25 – 5 miles (omni-directional antenna)
10 – 20 miles (9 dB directional antenna)
-110 dBm
9-16 V…12 Vdc (nominal)
<1 mA..standby
24 mA while receiving
<75 mA while transmitting
Communication Port:
Default protocol setting:
Dataloggers:
9-pin serial CS I/O – connection to CR206
9-pin serial DCE RS-232 – connection to PC
Transparent protocol
CR200-series, CR10X, CR1000 etc.
6
Technical Specifications (contd..)
CR206
Operating frequency:
Communication port:
Power requirements:
915 MHz
9-pin serial RS-232: Connection to PC
7-16 Vdc (12 V nominal)
Avg.current drain:
0.2 mA (quiescent period..radio turned off)
20 mA (radio always on)
Single Ended Channel:
5 (SE1-SE5)
Excitation Channels:
2 (Ex1 and Ex2)
Control Ports:
2 (C1, C2)…SDI 12- C1
Antenna port:
1 antenna port
Pulse Channels:
2 (P_LL and P_SW)
Operating system:
PakBus
Software Support:
ShortCut, PC400 or Loggernet
Analog voltage range:
0 to +2500 mV
On-board 12 V dc lead acid battery charger
7
900 MHz signal propagation
MW frequency range: 300 MHz – 300 GHz
MW freq. range
(UHF) (0.3–3 GHz), (SHF) (3–30 GHz), and (EHF) (30–300 GHz) signals
UHF signals travel over LOS (Line Of Sight) distances
UHF: widely used in 2-way radio systems
8
Friis Radio wave transmission
formula
At = Transmission line loss between transmitter and transmitting antenna
Ar = Transmission line loss between receiver and receiving antenna
FSL, At and Ar are the one which constitutes the attenuation of microwave signal.
FSL (dB) = 32.4+20log(f)+20log(d)
MHz
km
Problems in LOS propagation
Obstacles between Tx and Rx antenna
Obstacles such as trees, buildings, high hills etc. lying between Tx and Rx antenna
blocks or reflect/absorb/diffract the direct signal
Line of Sight between Tx and Rx should be clear for best reception of the
transmitted signal at Rx (i.e. for best RSL)
Antennas
Omni directional antenna
(14203) 3 dB with cable clamp mounts
N female connector attaches to an antenna cable
Requires COAXRPSMA-L or COAXNTN-L
Omni-directional:14203
Directional antenna
Yagi antenna (14201): 9 dB
Yagi:14201
Transmission Range of RF401
Depends upon the selection of antenna
Ideally,
With 3 dB Omni-directional antenna (14203): 0.25 – 5 miles
With Yagi 9 dB directional antenna (14201): 10 – 20 miles
Antenna Gain
Transmission range