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The RFD900u is a high performance 900MHz, ISM band radio modem covering the 902 – 928 MHz frequency band. It is designed to be the smallest, lightest and most sensitive diversity switched modem on the market.

Key Features:

  • The smallest, lightest and most sensitive diversity switched modem on the market.
  • Long range >10km depending on antennas and GCS setup
  • 2 x u.FL RF connectors, diversity switched.
  • 2 x user controllable I/O pins.
  • 100 mW (+20dBm) transmit power.
  • Integrated transmit low pass filter to reduce interference to other co-located radio links.
  • Latest technology pHemt, high gain > 24dB, high linearity Low Noise Amplifier (LNA).
  • Receive SAW filter for blocking out of band interference.
  • Open source firmware SiK / tools, field upgradeable, easy to configure.
  • Multipoint software capability with MP SiK (V2.x)
  • 128kB flash, 8kB RAM – more space for customisation.
  • Compatible with 3DR / Hope-RF radio modules.
  • License free use in Australia, Canada, USA, NZ

Compliance:

The RFD900 is designed to be compliant with the following standards:

  • FCC Part 15.247 (Frequency hopping and digitally modulated intentional radiators)
  • AS/NZS 4268:2012 (Radio equipment and systems – short range devices)

Specifications:

  • Frequency Range:  902 – 928 MHz (USA) / 915 – 928 MHz (Australia)
  • Output Power: 1W (+30dBm), controllable in 1dB steps ( +/- 1dB @ <20dBm, +/- 0.5dB >=20dBm typical )
  • Air Data transfer rates: 4, 8, 16, 19, 24, 32, 48, 64, 96, 128, 192 and 250 kbit/sec ( 64k/128k default )
  • UART data transfer rates: 2400, 4800, 9600, 19200, 38400, 57600, 115200 baud  ( 57600 default )
  • Receive Sensitivity: <-111dBm at 9.6kpbs, <-107 dBm at 64kbps, <-105dBm at 129kbps (air serial speed)
  • Size: 19.0 mm (wide) x 30.4 mm (long) x 4.5 mm (thick) – Including RF Shield and maximum connector extremities
  • Weight: 2.7g
  • Mounting: 2 x M1.5 screws
  • Power Supply: +5 V nominal, (+3.5 V min, +5.5 V max), ~190mA avg TX +20dBm, ~230mA peak TX +20dBm, ~77mA RX
  • Temp. Range: -40 to +85 deg C

Interfaces:

  • RF : 2 x u.FL/IPX connectors
  • Serial: Logic level RS232 (+3.3v nominal, +5v tolerant)
  • Power: +5v, ~300mA max peak (at maximum transmit power)
  • GPIO: 2 General purpose IO (Digital, ADC, PWM capable).
  • Connector: DF13, 8 way connector (interface cables available from RFDesign)

Pin Signals and Layout

Pin # SiK Mapping Name Colour Direction Description Max Voltage
8 GND Black Ground 0V
7 CTS White Either Clear to send 5V
6 VCC Red Power supply 5V
5 Rx White Input UART Data In 5V
4 TX Blue Output UART Data Out 5V
3 RTS White Either Request to send 5V
2 0 P1.0 Blue Either Digital I/O 5V
1 1 P1.1 Black Either Digital I/O 5V

In case there is need to force the modem into boot mode, short circuit Pins 1 and 2 or Pads labelled CTS and GND on the back of the modem (BIG Pads on edge of board)