Video&power into single ethernet cable with baluns.

[jacko1]

Hi!
I am planning to install camera into divetorch casing. Can i connect rca video and camerapower to same ethernet cable using baluns? Can somebody recommend appropriate baluns, since i am not familiar with these systems? I am planning to use one cable for thrusters and attaching that to image&camerapower wire using cable ties. These are then attatched to rope. Lenght of tether would be 50 meters (aprx.150ft.). Any ideas, suggestions? Thanks in advance

-J

[KR2_Diving]

I have heard mixed reviews and comments about sending power AND video signal down the same Cat5 cable... there tends to be a few issues with noise. I know in industrial applications (which is what i do in my day job) it is a huge No No!

That being said, there are power over ethernet applications and other security system setups that send power and data down the same lines...

As for the balun, this is the part I have had my eyes on since a very early stage.

There are a few other options available on the site if you have a look.

Hope this helps.

[dna1990]

I am coaching a kid team building their first ROV...for this first version we are running power/video in a single CAT5 using passive Baluns at each end. In fact we also power a LED light array on one of the last twisted pairs.

When using a wall wart (AC power supply for 12V DC), the video is fine. I made them test with the cable coiled up, and next to the DC power lines for thrusters, near a drill, you name it. An occasional flicker but a very nice image.

However.

When getting closer to implementation and we switched to powering from battery (a topside 12V DC Deep Cycle AGM), we constantly get some faint but annoying waves in the image. We changed camera, same issue. We temporarily placed monitor on its own power (12V DC headrest monitor designed for auto). I even order and installed a DC regulator and low-pass filter that are used in airplane FOV video setups. No luck. Well, actually the regulator did make a small improvement, but the interference is still there.

A CCTV guy said to watch out for voltage drop, which over that much CAT5 is down to 11.1 volts. But the regulator I bought can step-up the voltage back up to 13.7V with no help. No I did notice the wall wart we used for perfect picture is labelled 12V but puts out a whopping 16.7V.


None of that answers the question very well. But I think for basic runs (100') baluns will do nicely and handle both power and signal. Most will use pair one for + and -, combines with pair two for another + and -, trying to double the size of the 24awg wire. Then a pair for the video and -. And like I said we use the last pair for some lights. If you do not use the last pair, connect all to - on both ends.

But test with whatever power source you plan to use. On board battery may be much cleaner. Or in their version 2 ROV, we plan to send thruster and camera power down separately from the control cable using 12awg wire. Note we do have two topside 12V batteries, one for the monitor/video/lights/and eventually arduino. The other solely for thrusters.

[fluxno]

I am coaching a kid team building their first ROV...for this first version we are running power/video in a single CAT5 using passive Baluns at each end. In fact we also power a LED light array on one of the last twisted pairs.

When using a wall wart (AC power supply for 12V DC), the video is fine. I made them test with the cable coiled up, and next to the DC power lines for thrusters, near a drill, you name it. An occasional flicker but a very nice image.

However.

When getting closer to implementation and we switched to powering from battery (a topside 12V DC Deep Cycle AGM), we constantly get some faint but annoying waves in the image. We changed camera, same issue. We temporarily placed monitor on its own power (12V DC headrest monitor designed for auto). I even order and installed a DC regulator and low-pass filter that are used in airplane FOV video setups. No luck. Well, actually the regulator did make a small improvement, but the interference is still there.

A CCTV guy said to watch out for voltage drop, which over that much CAT5 is down to 11.1 volts. But the regulator I bought can step-up the voltage back up to 13.7V with no help. No I did notice the wall wart we used for perfect picture is labelled 12V but puts out a whopping 16.7V.


None of that answers the question very well. But I think for basic runs (100') baluns will do nicely and handle both power and signal. Most will use pair one for + and -, combines with pair two for another + and -, trying to double the size of the 24awg wire. Then a pair for the video and -. And like I said we use the last pair for some lights. If you do not use the last pair, connect all to - on both ends.

But test with whatever power source you plan to use. On board battery may be much cleaner. Or in their version 2 ROV, we plan to send thruster and camera power down separately from the control cable using 12awg wire. Note we do have two topside 12V batteries, one for the monitor/video/lights/and eventually arduino. The other solely for thrusters.

1.Does the camera has common ground between power and signal?
2. does the video monitor have same ground as you power the camera ?
3. Is the screen from the balun connected to anything except from the monitor.

I think you have a nice ground loop(or lack of good ground). the signal from the camera is transformed to a diffrent impendance then transfered back to normal video impendance. this function in addition to convert the impedance, also isolate the signal and ground between the to sides.

when you run the camera trough a wall adapter the ground of the camera(and screen input of balun) is separate to the ground of the output of the balun( and the input of the videoscreen).
when you then connect these to units together on the same powersupply and then getting a common ground on both topside and down at the rov, the ground power go mostly trough the power wires, and is then not related to the balun.
fix? Isolate the power and ground to the camera at the rov. you get small isolating DC/DC converters on ebay. cameras usually dont need that much power, so you can get a small converter for this. (http://www.tracopower.com/category/dc-d ... l-purpose/)

[dna1990]

Ground Loop.

Yes, thank you. I have experienced ground loops in audio setups before with uncommon grounds. And correct, in our setup so far, the 12V topside battery is the only ground. It is connected to the power side of the camera AND the ground side of the balun for the video signal. When using a power supply, obviously it has its own separate ground from the mains.

I have experimented (another way to say accidently) in leaving off the ground connection on the the power to the camera and was surprised to see it all 'was on and working' albeit with more interference than normal. More 'static' than the 'waves' we see now.

At the camera side we are using this regulator:
http://www.dpcav.com/xcart/Adjustable-V ... -Type.html
The regulator helped some, but have also tried this filter to no help (more for wireless I think).
http://www.dpcav.com/xcart/Power-Supply ... -Type.html


I will concentrate on various ground issues and maybe even a ground loop isolator test.



I attached a quick drawing...the purple ground line is the jacket or ground of the BNC connector. I have tried with both the purple connected/unconnected to the black - no real difference.

[rossrov]

2 suggestions, assuming no ground problems:

1. Kind of on the right track with the filter. Leave filter out but put a largish electrolytic capacitor, say 2200uF 16 Volt across the power supply input terminals, soldered directly at the regulator, not at the battery end. This is to stop the regulator putting spikes on the cable, and also help the regulator work properly. Switchmode regulators/power supplies can pull a lot of current and generate lots of noise. They are intended, like most supplies or regulators, to be connected to their source (in this case a battery) via a low-impedance path. The capacitor will help this. If still having trouble, try putting a ceramic capacitor in parallel with the electrolytic

Note: When working with electrolytic capacitors, note that almost all of them need to be connected with the correct polarity. Also note not to exceed the rated voltage. Failure to observe the above results in a ruptured or exploding capacitor. Also, capacitors aside, always put a fuse right at the battery, even when experimenting

2. Depending on your safety requirements, (you may only be allowed 12 Volt down your cable to prevent the potential of electric shock) consider putting the step-up regulator at the battery end, and adjust until you get the desired voltage at the camera, with camera connected of course. If current draw on the camera pair stays constant, then so will the camera volts. Power for other items can be fed down the other pairs.

[dna1990]

Continued thanks.

One big key part of the last post was to use a fuse "even when experimenting". We have the fuses and a main battery cutoff switch. But have YET to install them as we construct a box for the batteries and charger. But you are very correct, the fuse should have been installed as wire #1. At a minimum to save a nice camera, at maximum to prevent fire or injury. Lots of folks here doing 'bench work' with lots of temp connections, jumper wires, exposed contacts. Good reminder to do it smartly.


I did try the regulator both at topside (near battery) and in its current locale on the camera side of the tether. The topside location helped none, the current location helped some. But yes, I wish to keep a ~12V max supply in the tether.

Before the purchased regulator, I tried a simple 7812 with decoupling capacitors around it. But I will try the capacitor you suggested after I ensure I have tried all the grounding ideas. The waves we see in the image do 'look' more like power variation versus 'noise', so the concept of spikes or dips may indeed be what we are facing. I did look at the wall wart to see if it was a 'regulated' supply, it was not - just a cheap 12VDC 500mA.

For another test I also plan to try running the monitor off another separate power supply. I suppose it is possible the camera and signal line thru the tether are not the real source, but mixing power between camera and monitor...?



And I thought the camera would be the easy part...

[fluxno]

Ground Loop.

Yes, thank you. I have experienced ground loops in audio setups before with uncommon grounds. And correct, in our setup so far, the 12V topside battery is the only ground. It is connected to the power side of the camera AND the ground side of the balun for the video signal. When using a power supply, obviously it has its own separate ground from the mains.

I have experimented (another way to say accidently) in leaving off the ground connection on the the power to the camera and was surprised to see it all 'was on and working' albeit with more interference than normal. More 'static' than the 'waves' we see now.

At the camera side we are using this regulator:
http://www.dpcav.com/xcart/Adjustable-V ... -Type.html
The regulator helped some, but have also tried this filter to no help (more for wireless I think).
http://www.dpcav.com/xcart/Power-Supply ... -Type.html


I will concentrate on various ground issues and maybe even a ground loop isolator test.



I attached a quick drawing...the purple ground line is the jacket or ground of the BNC connector. I have tried with both the purple connected/unconnected to the black - no real difference.

So to confirm: if you leave the system as now, but power the camera from a wall outlet, the picture is "perfect"?
the dc-dc regulator and filter you got, is not isolating the ground between the camera and the video monitor.
you need a isolating dc-dc converter to fix this most likely. or you skip the baluns and try the camera directly over cat5 (probaly worse, but worth a try)

if you measure resistance between power-ground and the coax-screen on both the camera and monitor you will see that this is the same common point. but you will not get any resistance measurement if you would measure on just the balun connected with a cat5 cable inbetween. the baluns isolate the signal.

because of the signal is going trough the baluns, this signal will be dampened- about 6db usually. Since you have a perfect copper cable without any obstructions between the camera and the video monitor, the balance between the battery ground, and the ground coming out of the balun will be diffrent - thus disturbances.

i've tried to illustrate this with a really bad drawing attached.

the reason everything works with the wall adapter is because you separate the ground on the camera from the rest of the system.

[jacko1]

Hello everyone!
Nice conversation about things that are involved! Thanks!

It seems.. pretty complicated

Would it be "dumb proof" to:
-Use one cable from thusters to battery A
-2 separate cables (picture & power) from camera.
-Camera power is conneced to battery B.

Have a nice day everyone!

-J

[dna1990]

Well I had moved my camera testing so the kids could get back to work on the frame and motors.

I set it up again inside last night to try the various topics discussed above. I am perplexed if not embarrassed to say the problem went away. I went over connections many times when I first set it up to test, assuming a loose connection or slight short somewhere, amisdt all the jumpers and temp wiring...but I think now somewhere in that mess - was the culplrit. I was able to remove both the filter and regulator and still got a clean image.

Now back to the issue of separate grounds for a minute. My camera has but three wires. Power, Signal, Ground. So as I look at keeping the ground going to the balun separate from the ground coming from the battery, it always tied together at the camera anyway. ?



Now what started my contribution to this thread was to say that yes we have power/signal over a single CAT5, but also power some LED light bars. The team wanted to mount both white LED bars that we have, but also be able to switch to some IRs as well. So I took the last pair in the CAT5 and made both of those a power line to each LED set, but only one powered at a time. Then used the other existing wires there already ground. The lights work fine. And the IR set works fine with no video interference. But I now find the white LED bars (a little more current draw) do cause some static type noise on the video. If I keep just the white bars and use the 'twisted' pair for a power/ground combo - it works fine without interference. So I think they will need to make a choice to have one or the other, but not be able to switch between both.

In version two (if we get that far), it will be a more traditional power tether and control cable to an arduino setup. At that point we can send any series of commands to switch relays for various light options.




To why the video image is clean now, I can only think of two possibilities. One the most obvious is that I had a bad connection somewhere in all the temp wiring, or something sitting too close to something else. Two, I just thought of. In the garage workbench is a a series of flourescent light fixtures. In the house where it tested fine - is plain incadesent bulbs. Could the ballasts been putting out a interference that was picked up by the long CAT5 cable? If so, I may still have an issue once they lay this CAT5 alongside the three thruster power cables and begin to pickup noise that way. Next meeting tomorrow night, hopefully we can test all that together.