The aim of the last meeting was to attach the cam of the RasbPi on the car and to adjust the angle of view to get useable pictures. After different approaches the resolution was to let the cam stick out of the hood of the car. So it is necessary to glue the cam on a frame, and glue this frame on the frame (in the inside) of the car.
To work economical some leftovers of plasiccasts were used to build the frame for the cam. After cutting on, the board with mounted-cam was glued on this frame first. Later this frame was glued on the frame of the car. A hole to stick the frame of the cam through it was built in the hood of the car.
To adjust the cam, the RasbPi was connected to a laptop via LAN to tranfer the pictures of the cam to a screen. The glue wasn’t dry yet, so the frame of the cam could be pressed in the right angle very well.
At this time the broadcasting (video stream) was fluent and without any interferences. But after turning on the remote controller and the motor of the car, the broadcasting was very haltingly.
After some tests the remote could be set as the source of distrubance. It sends with a frequency of 2,4 GHz. This band of frequency is used very often for remote controllers of RC-cars, because you can use this band without licences. Such a high frequency is not necessary for the data rate which we want to transmit. The frequency is, from a technical view, a unfavorable choice. If we want to connect the RasbPi via WLAN to a computer, some problems can arise, because WLAN works at the same band of frequency (2,Ghz) as the remote. Apart from this the use of higher frequencies takes higher Doppler frequencies with it too. That will be another source of interferences. It would be advantageous to use lower frequencies (lower than one kHz).
So the high frequency of the remote controller interferes the frequency generator on the RasbPi which is responsable for the picture frequency to display the video. The super position of this two frequencies (sending and picture frequency) results a delayed picture-frequency. This is the reason why the video isn’t fluent anymore if the remote controller is turned on.
To fix this interference we have to build a shielding around all affected parts (circuit board of RasbPi and broadband cable to the cam). The first idea is to realize a shielding with aluminum foil around this parts. If necessary it can be connected to the minus pole of the battery in the car, too.
Further information will follow after testing the shielding.