Finding the right bus

SR500 Radio Receivers
Industry / Vertical:


Connexionz is a technology company which develops real-time vehicle tracking systems worldwide. It has implemented systems in the USA, the United Kingdom, Australia, Netherlands, Brazil, China and New Zealand. Connexionz gathers, processes and distributes real-time and historic journey and vehicle information, as well as CCTV information, which can be used by operators and local authorities to manage services, and by their passengers both on and off buses.


Connexionz needed to create a unit to deliver arrival information to passengers at bus stops along routes. The intention was to improve the public perception of bus transport and help raise passenger numbers. The units were to provide accurate real-time information at bus stops, complementing existing variable message signs (VMS) at less frequented locations, which provide limited, scheduled timetable data.

In addition, the units would need to be cost-effective and easy to install, which required them to be small and self-contained. They could then be mounted on existing poles and so avoid the consent process often required for deployment of larger signs. They also needed to present no external switches, and not require mains power, but be able to operate on long-lasting internal batteries.


The key to a successful real-time information (RTI) system is in the delivery - making accurate information available to bus passengers when and where they need it. To help achieve this Connexionz decided to deploy UHF radio to connect the BusFinder™ units, and turned to Wood & Douglas to provide the necessary receiver technology expertise.

The Wood & Douglas SR500 is a UHF synthesized radio receiver which offered Connexionz a cost-effective, high-specification solution and could easily be plugged into the BusFinder™ product. The radio receiver is housed in a compact and resilient screened enclosure with connections for interface, power supply and antenna. The SR500 operates between 433MHz & 458MHz, and within this switching bandwidth up to 128 frequencies, pre-allocated in the factory, can be stored as numbered channels. This provides the flexibility Connexionz required to deliver a variety of relevant information feeds to bus passengers in real time, including route and ‘next bus’ information, displaying the next bus arriving at that stop and countdown to arrival, regardless of the route taken.

Because any schedule changes or service updates - such as day service ended, predicted arrival times or even availability for wheelchair access - are communicated to each BusFinder™ unit via radio, operators do not need to visit each unit to make changes, dramatically reducing operational costs as well as providing a cost-effective solution for city-wide deployment.

Compact, rugged and highly flexible, to meet a wide range of possible applications

High-volume OEM solution

Meets requirements of EN 300 220


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