McGeoch’s New Wireless Controlled Signalling System
The McGeoch Group has an extensive history, providing ruggedized lighting and signalling solutions to the military, oil, marine and rail transportation sectors. It is a long-standing supplier of organisations such as the Royal Navy. In recent years it has become heavily involved in the solid state illumination arena,
with the McGeoch LED Technology division (based in Ulverston, Cumbria) serving not only its established high-rel customer base, but also gaining traction in other markets which have similar uncompromising lighting demands. One such market is motorsport.
Having, back in 2007, developed the original LED-based electronic marshalling and safety car flag systems, to improve the signalling visibility for drivers and ensure greater safety in difficult environmental conditions, the company’s technology has been proven in major grand prix venues across the globe. More recently it has looked to apply this to other motor racing applications, by producing a marshal lighting solution specifically for karting.
Designed to be deployed in both club and professional karting circuits, the aim was to create a solution that had far greater light penetration through spray, mist, or smoke than simply using normal flags. With high brightness light emitters being employed, these systems would allow drivers to rapidly be made aware of any problem that occurred on the track, so they had ample time to take any appropriate action. They would mean that race marshals could operate the systems from much safer positions than they would when manually waving a flag, greatly reducing any risk of injury in such high speed settings. Furthermore track owners could cut their overheads; lowering the number of officials needed for corporate racing events, for example, while not in any way compromising the wellbeing of drivers or spectators.
In order to realise this goal, a highly dependable communication mechanism needed to be included in the design. Each of the mounted lighting panels would require a real-time bi-directional wireless interface. The two-way transfer of information would be an important factor as this would mean that, under certain circumstances, if an incident took place the mounted lighting panels could be alerted instantly, and warning signals activated even before the marshals had time to respond, so that valuable seconds could be saved.
According to Phil Logan, Director of Technology at McGeoch LED, “When we started work on this project we looked at a few different radio communications manufacturers. Our main priorities were that firstly the solution we chose was more than capable of doing the job, and secondly that it would be very easy for us to integrate into our system.” After assessing several different options, the decision was made to partner with London based wireless solutions provider Radiometrix.
One of the problems we encountered when embarking on this project was that several of the firms we approached could not offer us the level of technical and application support that we really desired, or looked for heavy upfront payments to do so” Logan explains. “We decided to engage with Radiometrix, as the staff there promptly responded to our queries. Interfacing with the company was straight forward. They swiftly sent out samples and providing strong initial technical back up.”
In addition to the radio solution specified being quick and unproblematic to implement, the McGeoch LED development team were keen to make sure that other key criteria were met. The wireless link would have to cover a long distance (at least 1km), and be secure, though it would not demand anything more that a relatively low data rate. EMI immunity was another important consideration, due to the close proximity to possible interference sources, such as the karts or overhead electricity cabling, etc. The possibility to transmit on multiple channels was also called for. This would not only help deal with issues raised by other radio signals, but also give McGeoch LED provision to put repeaters in place at larger race tracks to extend the scope of the systems.
Keeping power consumption to a minimum was crucial too. The mounted light panels needed to provide 12 hour continuous lighting from a charged battery, so the power for the radio system needed to be minimal. This applied equally to the battery powered handheld controls that each marshal would have on their person. In addition, as the handheld control units needed to be streamlined and light, the radio modules utilised had to be compact in nature.
In light of discussions with the management at McGeoch LED, Radiometrix was able to recommend its LMT2 transmitters and LMR2 receivers. These narrowband, 32 channel UHF modules are capable of supporting 5 kbps data rates, and are therefore more than adequate for requirements here. The particular version opted for transmits at 458 MHz. For this frequency, the transmitters have an output power of 100 mW and can offer a range in excess of 2 km. The modules draw only 90 mA when transmitting at 100 mW and 20 mA for receiving. The transmitter has dimensions of just 33 mm x 23 mm x 9 mm, while the receiver measures 46 mm x 23 mm x 9 mm, meeting the prerequisite for small form factors.
After evaluation of the LMT2/LMR2 in September and October 2009, the development process was carried out through the autumn. Most of the prototyping activity was completed by November. The final product was approved by the relevant industry bodies at end of 2010 and is now in the process of being installed at the first wave of karting courses in the UK.
“The outcome of this collaboration has been the successful production of secure encoded, long range radio systems with up to 32 user-defined flag address codes, that will protect motorsport enthusiasts, at amateur and professional levels, from potential harm” states Sean Clouter, Sales Manager at Radiometrix, who oversaw this project. “We hope to have the opportunity to work with McGeoch LED on the creation of other innovative products in the future.”
Additional boosts to the performance can me made if necessary. As Clouter notes, “McGeoch LED engineers have the option of including Radiometrix AFS2 RF power amplifier modules in their circuit designs should they require even greater operating range. This would take the output power of the LMT transmitter up to 500 mW, and permit the signal to be received from 4 km away.” “Since the Radiometrix LMT2/LMR2 product portfolio addresses the various international frequency band allocations, as we start to roll out this system at sites in other countries” Logan adds “we have access to drop-in replacement modules that will conform with the frequencies relevant to that particular geographic region.” With the prospect of these panels being utilised on race tracks all over the world it also proved important that the specified components could deal with extreme levels of heat or cold. The LMT2/LMR2 transmitter/receiver pair boasts an operating temperature range of -10 °C to +60 °C. The modules’ re-programmability, through their RS232 interfaces means that updates can be made to infrastructure after it has been deployed without any complications.