The first truly global ‘Push-To-Talk’ satellite phone for Iridium

The first truly global ‘Push-To-Talk’ mobile communications system

A significant new revenue stream

The Iridium Extreme Push-To-Talk (PTT) system has allowed the low-earth orbit leader to disrupt the satellite communications space, creating a completely new market segment and providing a valuable new revenue stream.

Technology breakthrough: near-instant connection

Iridium Extreme PTT is the world’s first global ‘walkie-talkie’ style service. The novel radio modem functionality and signal processing we developed makes it possible to establish a connection between designated group members in under two seconds, anywhere on the planet.

Iridium Extreme PTT was recognised as the Top Emergency Response Innovation at the Mobile Satellite Users Association (MSUA) 2016 Mobility Satellite Innovation Awards, for its ability to provide rapid and reliable communication between emergency organisations globally.

Intuitive user experience conceals powerful features

We developed a cloud-based Command Center interface that puts the power of the Iridium system at the customer’s fingertips.

The user interface makes it exceptionally easy to undertake complex tasks like configuring users, talkgroups and coverage areas in seconds, actually redeploying satellite resources by simply drawing coverage shapes on a map.

Brand reinforcement through outstanding reliability

We developed robust proprietary radio protocols that continuously track and lock onto the next available satellite, reinforcing Iridium’s reputation for stable, uninterrupted two-way communication.

Superior product performance

To achieve exceptional audio clarity, we developed an enhanced digital error correction system to significantly improve the signal-to-noise ratio, achieving radio sensitivity twice that of a typical mobile phone.

“Cambridge Consultants has a long track record of technically challenging and mission-critical system design, and they have been a trusted core technology partner for more than a decade. That combination of world-class expertise and close collaboration has been crucial in helping us to create the world’s first truly global PTT communication service.”

S. Scott Smith

Chief operating officer, Iridium

Our involvement

Our system architects worked with Iridium to specify and architect the new PTT service in its entirety. Several all-new system components were needed to fulfil the requirements.

After the system design was completed, we developed the necessary handset firmware, carrier-grade telecoms infrastructure and online Command Center to fulfil the system requirements.

During development, static analysis tools and targeted test campaigns using our proprietary regression test system helped ensure quality and minimise development time, whilst the various development partners held regular system-level integration and test events. As well as building confidence in the system, this also provided a further feedback loop into the development teams.

Post-deployment, we continue to support Iridium in addressing any concerns highlighted in operational service, such as understanding system behaviours through to software updates.

The challenge

Ensuring performance through advanced modelling, simulation and testing

The satellite signals received by handsets are only around 10 times more powerful than the natural heat of the Earth. Increasing levels of global noise, Doppler shift and satellites travelling at 17,000mph make radio signal reception extremely challenging. To overcome this, we invested in many hundreds of teraflops of simulation power, test infrastructure and advanced modelling techniques to ensure comprehensive radio design testing.

Pushing the boundaries of handset technology

To achieve a fast and reliable ‘walkie-talkie’ style connection, we redeveloped the radio signal processing in the pre-existing handset to incorporate eight demodulators – all within the constraints of the existing hardware. This significantly increased the hardware’s bandwidth, allowing each handset to be assigned to up to 15 talkgroups simultaneously.

Delivering security without impacting customer experience

To meet Iridium’s security requirements, our engineers developed an advanced key management system with an encrypted overlay. This allows the customer Command Centre to manage synchronisation of encryption keys for thousands of users connecting across hundreds of talkgroups from every corner of the planet.

Iridium Extreme PTT is fully interoperable, allowing different organisations to securely share channels and talkgroups. This enables, for example, police and fire services to co-ordinate their emergency and disaster response efforts.

“Cambridge Consultants is a valuable, long-term partner and provides Iridium flexible access to one of the largest wireless contract development teams in the world. Cambridge Consultants’ expertise minimises our R&D cost, allowing us to quickly bring to market innovative, game-changing products. Our design partnership with Cambridge Consultants is a key component of our successful product innovation.”

Chief technology officer


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