Tuesday, November 6, 2018

rear view camera for brunnhilde - revision 2.0

With the 8045 Trailex trailer in tow Brunnhilde becomes a 40-foot road train. Additionally backing up to the trailer tongue requires precision driving which is impossible without a spotter. For backing up even with a spotter the task is far from easy as most people do not have the skills of how to negotiate the tow vehicle to steer the trailer into a tight spot.
I installed a rear view camera by the third brake light in Brunnhilde immediately after taking delivery. This camera no longer is sufficient due to the big span it needs to cover. Actually I installed 2 cameras in Brunnhilde. In addition to the one by the third brake light I also have a backup (as in dual redundant) camera by the rear license plate.

With the trailer a dedicated camera is needed to aim at the trailer hitch solely for negotiating the motorhome up to the trailer tongue accurately. The license plate location does not serve this function well as it is too off center. With a lot of thinking I decided that adding a camera by the third brake light is the best solution. However feeding another video cable through the already tight wiring grommet would require enlarging the hole and replacing the grommet with a larger one, which will in turn require re-feeding the cable of the original camera.

Fortunately I came up with a solution with the right camera choice.

the rear camera system has an external multiplexer that supports up to 3 cameras

this is the new camera that I'd chosen because of its small size (no illumination LEDs); it has been jury rigged onto a piece of scrap aluminum for test mounting

test mounted for view covering checking

the camera aimed at the trailer hitch ball - I placed a cardboard box to aid visibility

this is the existing wiring at the wiring grommet which is already full

Once I was somewhat sure that the two side by side cameras would work I need to splice in the cable of the new camera to the existing license camera's cable. This avoid the time consuming work of running a new cable from the back all the way to the multiplexer in the cockpit (under the vehicle in the cable chase that I installed a few years ago.

I mildly surprised to find the video signal is not carried in a shielded coax cable; there are three unshielded wires (red = +12V, yellow = video, black = ground)

I spliced in this RCA female pigtail so the video cable of the new camera can be plugged into

the new miniature camera I chose for its small diameter cylindrical barrel connector

I did not use the long video cable that came with it as it would involve the arduous task of running it end to end under the chassis

the new camera that I chose has a very small diameter connector at the last few feet which makes it suitable for the constraints; even then feeding this cable with the tiny interconnect from the third brake light down to the underside of the Sprinter took some perseverance and dogged determination

this is the new camera - sole function is to allow one to see the trailer hitch ball is aligned with the trailer tongue

Sometimes a well laid plan may not materialize, and requires design on the fly. This is one of those situation.  I realize immediately that as the new miniature camera does not have illumination LEDs it is better suited for being tasked as a rear view camera for keeping tap of the traffic behind. Instead I would re-purpose the large exiting camera for the task of providing view of the trailer hitch ball.

A picture is worth a thousand words. Here is a photo depiction of the hybrid camera system, one camera for near field and the other for far field.

the two cameras are arranged in cross fire configuration (vertically) - like the WWII German machine gun bunkers along the Western coast; the little camera is secured to the belly of the big camera with pressure sensitive adhesive

the crossfire arrangement of the two cameras

near field coverage by the big camera

far field coverage by the new miniature camera

this is what the end result - looks just like the old single camera until you look closely

Upon wrapping up the installation, I spent some time to align the aims of the cameras to optimize their intended functions. With the dedicated camera aims at the trailer hitch ball backing up the 4 ton motorhome up to the trailer with precision is not as easy as cakewalk. The total cost of the version 2.0 revision - $14.99.

Here are the actual image from a recent trip to central Oregon.

view with three vehicle in various distance

It is not immediately apparent that able to see the idiot that is following too close the trailer with a rear view camera requires a camera that is mounted very high, and thankfully I have a Westfalia James cook. The following photo you can see the angle of the camera in order to clear the open trailer carrying the Porsche. With the Mini the visibility would be reduced slightly due to the higher roof.

I plan to modify the power provisions to the LCD display and the multiplex box so the cameras may be used while camping. It would serve as security cameras as well.

Update: I am shock to see the misspelling on the original title: "review camera...". It is fixed.

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