OUR ’CAM CAR’
The 'Cam Car' is an ongoing experimental project so this page will be updated as the work and our understanding of it progress.
The objective of this project, which is on-going and managed by 'Pirate' Peter Shelton, is to build a First Person View (FPV) live video streaming system for our HO scale exhibition layout. FPV delivers an "up-front" view from the engineer's seat while driving a locomotive through a fully scenicked layout. A whole new level of participation is created since model railways normally only present a bird's eye view.
The challenges:
- Model railways revolve around scale and realism. Any video technology needs to be hidden as much as possible and/or blended into the layout without intruding into the realism. HO scale is 1:87 (1:87.1 to be precise) so video equipment needs to be small enough to fit into tiny spaces in very small trains.
- FPV uses wireless technology. At model railway exhibitions there is a lot of other radio clutter around just about every operating model; wireless locomotive throttles, DCC control functions, scenery tower lighting, turnout machines, cell phones, smart phones and tablets and so on. The motors in the locomotives themselves emit constantly changing magnetic fields, which can also affect wireless transmission and reception.
- Unlike aerial FPV (e.g. quad-copters, a.k.a. drones) which has a lot of free space, our trains move in, around and through many hard objects such as other trains, scenery, tunnels, bench work, walls and people, all of which can cause interference or signal bounce (multi-path).
- The video quality must be clear and realistic enough to enhance the up front and personal nature of the scene detail. A lot of time and skill goes into the creation of good scenery. A blurry, white or unclear image would not enhance the experience.
- Our exhibition layout is portable and operates in many different locales, each with a unique radio frequency environment. The FPV video system must also be portable, easy to setup and tear down, and be adaptable to the various surroundings.
Much of the technology for FPV is available currently in the radio controlled quad-copters and model aircraft hobbies. The basic components required are a camera, transmitter, receiver, antennas, power supplies and a TV monitor. We chose a 5.8Ghz frequency since the components are small enough to build into our HO scale rolling stock. Other lower frequencies require a larger antenna system, especially for the transmitter, and the 2.4Ghz spectrum is very congested.
The camera must be high quality, i.e. 600 TV lines or better, use very little power and be small enough to fit into the cab of an HO scale locomotive or freight or passenger car. A 5.8ghz transmitter must also be small enough to fit in to the same space, be durable, powerful enough to overcome hard objects and use little power. The receiver and antennas must be able to cope with multi-path issues and deliver a quality image to the monitor.
Prototype Platform (Cam Car):
Our first prototype platform or 'Cam Car' was built to prove the concept and test the quality of streaming wireless video from the layout. Disguise was not the primary objective. Realism and disguise would be the prime objectives of a second platform. The prototype was built into a snow-blower shell that provided sufficient space for the 5.8ghz transmitter, an 11.1v 3-cell battery and a 6" whip (straight) polarized antenna. A camera with a 3.2m lens was mounted in a protective housing and partially disguised into the hub of the blower mechanism. This 'snowblower' Cam Car, which started off as just a shell with 2-two axle trucks, is pushed around the layout by a powered locomotive. The receiver is located alongside a 32" television some distance away.
The initial results were very good - a high quality colour image as if looking out the engineer's window. Very small objects can be seen as close as 2 inches away and objects up to 10 feet away are clearly visible. There were no fuzzy or white images and no hesitation in refreshing the image.
Issues Encountered with the Prototype:
- as the train moved around the layout there was quite a lot of image flickering and drop outs. Not consistent but enough to interfere with the experience.
- there was no capability to record the video stream.
- the battery had to provide 5-11 volts over a long period of time.
To improve the overall signal performance both antennas (receiver and transmitter) were changed over to polarized circular (cloverleaf). The cloverleaf in the locomotive significantly improved the overall quality of the video with fewer drops outs and far less flicker. However, it did introduce some clarity problems and a fuzzier image. Changing the receiver antenna back to a whip cleaned up the image and also helped reduce the flicker.
A USB video capture device and software were obtained to record the video stream on to the hard drive of a laptop.
The FPV system is now regularly used on our exhibition layout. Video flicker remains an issue and the severity varies with the location of the layout. It's worse in large metal clad buildings, such as arenas but better in basements. We suspect the signals are bouncing off the exposed steel work in the larger buildings. We will continue experimenting with different combinations of antennas to, if not eliminate this as much as possible. There are larger and more directional 5.8Ghz antennas which could be semi-permanently mounted above the layout and hardwired to the receiver with shielded cables.
Summing up:
The FPV system prototype works well and has added an entirely new dimension to our presentation at exhibitions. The club has been running the FPV Cam Car system with a 19" LED TV at all shows since Bracebridge in August 2015 and we'll continue to do so in the future. See our 'Events' page for all of the shows we attend. It's generated great interest with adults and children alike. When we give a child a throttle, sit them in front of the TV and let them drive the train around the layout for as long as they like, they're doing the three things they like best - watching TV, playing with a computer and driving a train! Anyone running a switch list has to keep out of the way of this Class 1 train because kids, a) like to drive the trains fast and, b) don't really understand what 'can't stop on a dime' means.
The three pictures below show the snowblower cam car. The lens is in the hub of the blower blades and the cloverleaf antenna can be seen at the back in the first photograph.
The next six photographs show the second prototype platform, which was mounted in an F1-A unit. The camera is in the nose with the 'works' behind. The problem with this locomotive is the lack of weight over the trucks, the space being taken up by the camera at the front and the hidden antenna at the back. This is an issue we think we can overcome by trial and error with weights and different wheel sets. The B unit is the driver.
