This article talked about implementing a 3G / Wi-Fi network in a Sydney transit bus to facilitate the Opal “touch-on touch-off” smartcard ticketing system in these buses. But it may also apply to other realities such as Internet access in the car or the car being part of the home network. This is being taken further with the desire for access to online or hard-disk-based infotainment systems that are likely to become the norm for today’s vehicles whether as a factory-supplied option or something installed after the fact.
Moving between different areas
One major issue is that the vehicle will be required to move between its primary network which could be your Wi-Fi network in your home or a marina’s Wi-Fi network to an Internet service provided by a mobile-broadband service. Here, this will require effectively a smooth switchover between these different services in order to provide a smooth Internet connection to network-connected devices such as an online-capable infotainment system and / or a small Wi-Fi network within the vehicle or boat.
The uneven power situation in vehicles
Another challenge is the power issue. Here, if the vehicle’s or boat’s engine isn’t running, the car battery is supplying the power from a finite resource and there also has to be a sufficient amount of current left in the battery to start the vehicle. But when you are starting the vehicle, there is a significant current dip that occurs while the starter motor is in operation. This is something you may notice where your car’s interior light will dim as you are starting the engine and you have one of the vehicle’s doors open. Once the engine has just started to run, there will be a surge of current which is typically limited by various regulator circuits in all of the vehicle’s equipment.
|Ignition key||Expected Power condition for network devices|
|OFF (key can be removed)||Devices are expected to run at bare minimum from the battery to support standby functionality|
|ACCESSORIES (usually used to allow the car radio to be played without the engine running)||Devices are expected to run at full power from the battery|
|ON||Power spike occurs just when the vehicle has been started, but devices run at full power off the engine’s alternator.|
|START||Power dip while the starter motor is being operated|
How was this worked around?
The installation was based around a customised Netcomm router that worked between a particular Wi-Fi network at the depot or Telstra’s 3G mobile broadband when on the road. This router was shoehorned to cope with the abovementioned power issue encountered in vehicles and boats most likely with a significant amount of extra circuitry so that it draws the minimum amount of current when the ignition is off but draws its normal amount while the engine is running. This extra circuitry also is about the provision of a regulator to allow it to cope with the current dip / surge that occurs when the bus driver turns the key to start the engine.
Vehicle builders like BMW, Chrysler, Ford and GM who have worked on the “online vehicle” have developed in-vehicle network equipment from the ground up when developing prototype or production in-vehicle routers for these projects. Typically these would have a mobile broadband setup as the primary setup and have perhaps a WI-Fi LAN for use with tablets and similar devices as well as a specialised Ethernet setup for the online infotainment setups.
In the context of the online personal vehicle or boat, it will mean that if the vehicle is at home, it can connect to the home network and do an update process for maps, AV content and similar material. Then when you are on the road, you could gain access to Internet-hosted content like traffic information, current “open/shut” status reports of nearby businesses, the location of cheapest fuel prices, and audio content from online services like Spotify or Internet radio.
This issue will be faced further as the in-vehicle network becomes as much a must have for vehicle enthusiasts as the souped-up car sound system. It will mean the availability of aftermarket routers that are designed for in-vehicle use along with connection standards for aftermarket infotainment setups that work online whether with a smartphone or their own network / Internet access.