T24 Telemetry Basic Principles; Transmitters & Receivers; Transmitters; Receivers - Mantracourt T24 User Manual

T24 Telemetry Basic Principles

There are some basic radio settings and concepts that should be understood to effectively configure, deploy,
optimise and troubleshoot T24 telemetry systems.
Transmitters & Receivers
Although all of the T24 modules are in fact transceivers and transmit as well as receive, they tend to mainly
operate as either a transmitter or receiver so we will choose to describe them as Transmitters and Receivers.
The T24 system was designed so that Transmitters are configured to send out messages at a user defined rate.
Receivers can then use this data to analyse, display or perform other actions depending on their function.
A PC and base station are only required to configure the modules although they may be part of a data collection
system. Once configured the T24 modules operate autonomously and only minimal control over the Transmitter
modules is usually required, by Receiver modules, such as sleeping or waking.

Transmitters

These are the sensor modules that measure strain, voltage, temperature etc. and send messages containing the
sensor value and status information at regular intervals for use by Receiver modules or for delivering to a PC via a
base station.
Because these modules need to be very power efficient to operate on batteries they operate in three distinct
modes. See Transmitter Module Modes of Operation

Receivers

These modules use messages provided by Transmitters and have functionality such as handheld displays, large
displays, analogue outputs and relay modules. These modules may also offer control over Transmitter modules
such as sleeping or waking.

Radio Channel and Group Key

To be able to communicate, two radio modules must share some basic settings. There are ways to learn these and
to recover unknown settings and these are discussed later in the pairing section.

Radio Channel

This is the frequency that the radio operates on. T24 radio bandwidth is divided into 15 channels. Modules must
be on the same channel to be able to transfer messages.

Group Key

Group keys are a way of isolating groups of modules even if they are operating on the same radio channel. This
can improve efficiency and also offer security because no radio module can affect another or see their messages
unless they share the same group key.
A group key is defined by the user and is up to 15 alphanumeric characters.
Group keys were introduced in v3.0 radio firmware in March 2015. New radio modules will work with older radio
modules but group keys cannot be used.
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T24 Telemetry User Manual