Protocab has been designed from the ground up based on fifty years of experience in railway modelling. The design concepts which were laid down in the late 1970s and which are only now technically achievable thanks to advances in batteries and electronics included:
- the ability to drive locomotives using simulations of the controls on the full sized prototype
- fuel carried on the locomotive in prototype practice with the exception that electric powered locomotives or multiple units would draw current from overhead line equipment or third rail
- no current through the rails in order to avoid the need for track insulation and sectioning and subsequent and frequent track cleaning
- no need to insulate the locomotive chassis or wheels (and thus be able to use solid metal wheels and axles)
(this would enable effective track circuiting to be employed)
- a wide variety of scales from 2mm/ft upwards must be catered for and within each scale a wide variety of locomotives and motor types can be controlled
As a design principle, every locomotive is capable of running 'light engine', so that the battery and Locomotive Control Unit (LCU) are installed within the locomotive. The battery has to be recharged within the locomotive, to avoid the need to remove it.
Since the original designs were laid down, a number of further principles have been established:
- all locomotives can be selected to drive from one or more controllers, which must be capable of being hand held
- there must be no ability for an unauthorised controller to take control of a locomotive
- speed, battery charge and other indications on the controller are desirable
- a fully charged battery must provide enough power for the locomotive to run for at least one hour under 'normal' running conditions (in practice, we have found that our locomotives run all day at the exhibitions we attend)
- if radio communications between the controller and locomotive are lost, the Locomotive Control Unit must immediately try to re-establish communications and if, within a short period of time, this is not possible, the LCU must bring the locomotive to a graceful stop
We commenced technical developments in 2009, which included an assessment of existing systems and soon concluded that no system or set of standards would give us the required functions or reliability. A key assessment was that conventional radio control would not provide a satisfactory long term solution to our design requirements. Thus Acc+Ess Protocab is based on international wireless network standards, operating within the 2.45GHz unlicensed wireless band. These standards (IEEE 802.x) are employed on Wi-Fi routers commonly found in the home and office and a derivative standard, IEEE 802.15.4, which provide low data, short range, high rate data transmission was ideal for Protocab. Choosing this standard means that we can employ a variety of control systems, including hand held devices that operate under 802.15.4 and more complex devices such as smartphones, tablet or other computers in the same environment (i.e. IEEE 802.15.4 can integrate seamlessly with e.g. IEEE 802.11 found on Wi-Fi or even 802.3 for full wired integration for complete computer control of a model railway system!)
Following extensive testing, we launched the Pilot Series of products in October 2015. Before launch, all our products underwent independent testing under the EU Directives on Electromagnetic Compatibility (EMC), Radio and Telecommunications Terminal Equipment (R&TTE) and Safety so that we are able to provide a Declaration of Conformity and to be able to place the CE mark legally on all our products.