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Body Worn Radio Module

The Zimiti ZWM Body-Worn Radio Module is a low power, symmetrical, bidirectional wireless monitoring and control system for portable applications that require information to be exchanged between two or more small battery powered devices (often coin cell batteries). It has a ranging capability which can provide estimates of the distances between devices. A proprietary “multi-path fading” mitigation technique is employed for improving repeatability of distance estimates. The radio and antenna are designed to optimise performance when worn on the body as a pendant or watch for example. It operates in licence-exempt bands for short-range devices (e.g. 868MHz, 915MHz, 2.4GHz) using a proprietary peer to-peer protocol that allows devices at both ends to be extremely small, inexpensive and battery powered. The protocol supports secure authentication between peered devices and also one-to-many groups. It employs frequency hopping and smart power control to maximise battery life.

BB Monitor

The signalling update rate and payload are variable. It has an operational range of 200m in open areas where there is “line-of-sight”. The antenna is a robust magnetic loop which is very resistant to de-tuning effects caused by the body.

A number of analogue and digital inputs and outputs are provided and they can be configured to monitor various signals and provide different kinds of outputs including visual, audible and vibration alerts. Battery monitoring provides early warning of a battery low condition and bi-directional radio link monitoring provides a reliable out-of-range alert. The user interface can be tailored to meet the needs of the application.

Applications

A range of applications are possible including:

  • Baby and toddler monitoring, including tamper, microphone, temperature and out-of-range indicators.

  • Asset monitoring of both human and physical assets with alarm alerts for exceptional status conditions.

  • Healthcare and sports applications requiring continuous monitoring

Each device can be customised with different inputs outputs and features and either end of the link can be fitted with a variety of of I/O options.

The first product developed using this platform was the Boardbug baby and toddler monitor. 

Availability 

The product is normally customised to the target application by tailoring the functions implemented. For example not all applications require an LCD display or vibration alert. Customisation may take from a few weeks to several months depending on the scale of the work required.

Zimiti can arrange manufacture through manufacturing partners in the Far East, or the design can be licensed to the customer for manufacture in their facility.

Specifications (Electronics Module)

Size:                       approx. 35mm x 35mm x 10mm
Weight:                  10g
Battery:                  typically a 3V coin cell
Battery life:            application dependent but typically several months to one year
Frequency:             868MHz, 915MHz and 2.4GHz variants available
Temperature:        -20 ºC to +60 ºC
Range:                   up to 200m outdoors
Data rate:              up to 100kbits/s
Update rate:          variable
Usable payload:     variable
Protocol:                 proprietary, peer to peer
Authentication:       28-bit unique device ID
Inputs:                   digital (e.g. Tamper, push buttons) and analogue (e.g. microphone, temp.)
Outputs:                 LCD display, LEDs, vibration alert, audible alert.
Ranging:                 RSSI-based with proprietary multi-path fading mitigation techniques