900 MHz radio link between two remotely located Weather Stations :Sanjaya Gurung 900 MHz Base Station Remote Station

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-to-multipoint 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 Weather Station Datalogger (CR1000) Omni-directional antenna Yagi (directional antenna) RF401 RF401 900 MHz link Power Supply: Powered by CR1000 CS I/O CR206 Weather Station Datalogger (CR1000) Power Supply: 12 V battery, charged with solar panel Sensors Remote Weather Station Local Weather Station (Base Station)

Technical Specifications RF401 Operating frequency: 900 MHz Type: Frequency hopping spread spectrum TRx Point-to-Point/Point-to-multipoint I/O Data rate: 9600 bps Tx power: 100 mW Tx range: 0.25 – 5 miles (omni-directional antenna) 10 – 20 miles (9 dB directional antenna) Rx sensitivity: -110 dBm Power requirement: 9-16 V…12 Vdc (nominal) Avg.Current Drain: <1 mA..standby 24 mA while receiving <75 mA while transmitting Communication Port: 9-pin serial CS I/O – connection to CR206 9-pin serial DCE RS-232 – connection to PC Default protocol setting: Transparent protocol Dataloggers: CR200-series, CR10X, CR1000 etc.

Technical Specifications (contd..) CR206 Operating frequency: 915 MHz Communication port: 9-pin serial RS-232: Connection to PC Power requirements: 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

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

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