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ThomasScherrer

NOISE from cameras, be warned

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the noise the KX151 cams send back on the GND and +12V line

and on the Video line is alarming high.

ok it is understandable it contain huge amounts of noise in the 0-5MHz range,

due to coubling from the video line into the powerlines.

but check all those other spurs I found:

KX151 NTSC KPC-S700C

19.08MHz -62dBm

29.08MHz -76dBm

38.14MHz -55dBm

47.16MHz -80dBm

57.21MHz -62dBm

76.28MHz -63dBm

KX151 PAL KPC-S700CH hires

24.93MHz -70dBm

28.38MHz -47dBm

32.81MHz -70dBm

35.47MHz -80dBm

42.57Mhz -70dBm

56.75Mhz -46dBm

63.8MHz -81dBm

70.94MHz -60dBm

at all frequencies I have double checked the spur goes away when power to the CAM is taken off,

the signal power is simply measured directly over the cams power supply,

I used 20 cm wires to a lab DC supply.

no OSD and no other stuff near the cams while testing,

Spectrum Analyzer HP E4402B is calibrated.

remember the receivers we use are not always double super converting,

so they are open (wide) so this is a potential cause of bad range when not isolated and not power supplied right,

be very carefull with the GND and power connections.

Good RC receivers have -110dB sensitivity

Bad RC receivers have -100 dB

if they are broken and have only -90dB you can only fly 200-300m away,

I have tested that !!

I have opened both of the above mentioned cameras and found:

the PAL version crystal oscilator is 28.3 Mhz

and its gnd caps share the same GND area as the video output driver

and the crystal is bended directly in over the video output amp,

and the crystal case is just left un grounded,

there is room for a tiny condenser mic, the onboard mic amp is mounted and connected, the 4th pis is the audio out.

The NTSC version is a bit better designed, the crystal osc does not share directly gnd with th video amp, and the crystal is bended in the other direction.

I suggest to the designers of the cams: add a low pass filter to the video output,

and better power supply filterings and case grounding,

yes the case is so much alive, so keep them cams away from your RX

and be care full with range checking before flying.

Edited by ThomasScherrer

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Hi,

Also have a Sharp 1/4" CCD cam,

and it also make some noise i found out.

Tryed powered the cam from the RX receiver batttery - know is not so good to do so - and servos flipped alot only at short distance, so guess it make some noise!

How much db sensitivity is the Dynam R6P on?

Will try to check out crystal in cam etc.

LoopForEver

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