869MHz Wide Band FM radio transceiver

The BiM3B radio transceiver module is an enhanced higher power replacement for the European version BiM3A-869-64.
Two frequency variants are available in the European unlicensed band, one with 5mW RF power with no duty cycle restriction other with 25mW RF power with 1% duty cycle restriction.


Figure 1: BiM3B-869-64


  • Complies with European harmonised standards EN 300 220 and EN 301 489
  • 869.85MHz 5mW 100% duty cycle or 868.30MHz 25mW 1% duty cycle
  • RF power output: +14dBm (25mW) on 868.30MHz
  • +7dBm (5mW) on 869.85MHz
  • Data rates up to 64kbps
  • Crystal controlled PLL FM circuitry for both Tx and Rx
  • SAW front end filter and full screening
  • Receiver Sensitivity: -101dBm for 1ppm BER (64kbps)
  • -104dBm for 1ppm BER (10kbps)
  • Supply: 2.9V - 16V @ 35mA Tx (25mW), 17mA TX (5mW), 11mA Rx
  • Usable range up to 300 metres external, 75 metres in building
  • SAW front end filter and full screening
  • RSSI (standard) or carrier detect option
  • Analogue and digital baseband
  • Low profile with small footprint
  • 33 x 23 x 5mm

Evaluation Platform: Universal Evaluation kit or Narrow Band Evaluation Kit


  • PDAs, organisers and laptops
  • Handheld terminals
  • EPOS equipment, barcode scanners, belt clip printers
  • Data loggers
  • Audience response systems
  • In-building environmental monitoring and control
  • Security and fire alarms
  • Restaurant ordering systems
  • Vehicle data up/download

Functional description

The transmit section of the BiM3B consists of a frequency modulated crystal locked PLL feeding a buffer amplifier and RF filter. Operation is controlled by a Tx select line, the transmitter achieving full RF output typically within 1ms of this line being pulled low. Modulation is applied at the TXD input and may be either a serial digital stream toggling between 0V and 3V (digital drive) or a high level analogue waveform with the same peak limits (linear drive). Modulation shaping is performed internally by a 2nd order lowpass filter which minimises spectral spreading. The RF output is filtered to ensure compliance with the appropriate regulations and fed via a Tx/Rx changeover switch to the antenna pin.

The receive section is a single conversion FM superhet with an IF of 10.7MHz. A SAW bandpass filter in the receiver front-end provides image rejection and suppression of other unwanted out-of-band signals. Like the transmitter, the receiver is controlled by its own active low select line. A post-detection lowpass filter establishes the signal bandwidth and ensures clean operation of the subsequent adaptive data slicer. The slicer is optimised for balanced data such as bi-phase code. A received signal strength (RSSI) output with 60dB of range is provided.

User Interface

Figure 2: BiM3B pin-out and dimension

BiM1pin Name Function
1, 3 RF GND RF ground pin; internally connected to the module screen and pin 5, 9, 10, 18 (0 Volt).
2 RF IN/OUT 50W RF input/output from the antenna
17 Vcc 2.9V - 16V DC power supply
16 RX select Pull low to enable Receiver
15 TX select Pull low to enable Transmitter
14 TXD DC coupled input for 3V CMOS logic. Rin = 100kΩ
13 AF 200-400mV pk-pk audio. DC coupled, approx 1V bias
12 RXD Digital output from internal data slicer. Output is "open-collector" format with internal 10kW pullup to Vcc (pin 17)
11 RSSI 0.17-0.33Vdc (no signal), 1.25Vdc (maximum).. 60dB dynamic range
9, 10, 18 0V Supply ground connection

1. RX select and TX select have (10kΩ approx.) pullups to Vcc
2. Pinout is as stanadrd BiM2A and BiM3A. On RF connector end only pins 1, 2, 3, 9 are present.

Limitation of liability

The information furnished by Radiometrix Ltd is believed to be accurate and reliable. Radiometrix Ltd reserves the right to make changes or improvements in the design, specification or manufacture of its subassembly products without notice. Radiometrix Ltd does not assume any liability arising from the application or use of any product or circuit described herein, nor for any infringements of patents or other rights of third parties which may result from the use of its products. This data sheet neither states nor implies warranty of any kind, including fitness for any particular application. These radio devices may be subject to radio interference and may not function as intended if interference is present. We do NOT recommend their use for life critical applications.
The Intrastat commodity code for all our modules is: 8542 6000.

R&TTE Directive

After 7 April 2001 the manufacturer can only place finished product on the market under the provisions of the R&TTE Directive. Equipment within the scope of the R&TTE Directive may demonstrate compliance to the essential requirements specified in Article 3 of the Directive, as appropriate to the particular equipment.
Further details are available on The Office of Communications (Ofcom) web site:
Licensing policy manual