|
Science Forum Index » Electronics - Design Forum » add video to dc power and then later recover video
Page 1 of 1
|
| Author |
Message |
| Guest |
 Posted: Thu Feb 15, 2007 5:24 pm |
|
|
|
|
Hi I'm hoping that someone out there can help me out and point me in
the right direction.
I have an application where I have a dc powered video camera. I'd
like to add the video (composite) to the wire feeding the camera with
power and then elsewhere in the system recover the video and feed it
to a monitor.
Is that possible ?
How ?
Is it easy ?
What do I need to be aware of ?
Any hint's or tips of what might be OK and what problems/issues to be
aware would be greatly appreciated.
Thanks in advance.
Anbeyon. |
|
|
| Back to top |
|
| Paul Hovnanian P.E. |
| Posted: Thu Feb 15, 2007 5:42 pm |
|
|
|
Guest
|
anbeyon@btinternet.com wrote:
Quote:
Hi I'm hoping that someone out there can help me out and point me in
the right direction.
I have an application where I have a dc powered video camera. I'd
like to add the video (composite) to the wire feeding the camera with
power and then elsewhere in the system recover the video and feed it
to a monitor.
Is that possible ?
How ?
Is it easy ?
What do I need to be aware of ?
Modulate the video and return it on the coax carrying the power. A
simple filter should be able to seperate the signal from the DC at
either end. I have a 'Channel 3' modulator used for feeding video into a
TV set.
--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
The Three Laws of Thermodynamics:
1) You can't win.
2) You can't break even.
3) You can't quit the game. |
|
|
| Back to top |
|
| Guest |
| Posted: Thu Feb 15, 2007 5:45 pm |
|
|
|
|
Hi Paul
Thanks for the reply.
I Should have told you a little more.
The application is on an articulated truck/lorry. I have to use the
existing wiring of the lorry. There will not be any co-ax - well at
very small bit at either end.
Thanks
Anbeyon |
|
|
| Back to top |
|
| martin griffith |
| Posted: Thu Feb 15, 2007 6:01 pm |
|
|
|
Guest
|
On 15 Feb 2007 13:24:05 -0800, in sci.electronics.design
anbeyon@btinternet.com wrote:
Quote: Hi I'm hoping that someone out there can help me out and point me in
the right direction.
I have an application where I have a dc powered video camera. I'd
like to add the video (composite) to the wire feeding the camera with
power and then elsewhere in the system recover the video and feed it
to a monitor.
Is that possible ?
How ?
Is it easy ?
What do I need to be aware of ?
Any hint's or tips of what might be OK and what problems/issues to be
aware would be greatly appreciated.
Thanks in advance.
Anbeyon.
The other option to Pauls suggestion is to use cat5 cable, and a
suitable interface, which if you google for CCTV cat5 will probably
eventually give some almost useful hits
http://www.eql.com.au/baluncctv.htm
http://www.eql.com.au/cctvbalun.htm
is typical
martin |
|
|
| Back to top |
|
| Ancient_Hacker |
| Posted: Thu Feb 15, 2007 6:04 pm |
|
|
|
Guest
|
On Feb 15, 3:24 pm, anbe...@btinternet.com wrote:
Quote: Hi I'm hoping that someone out there can help me out and point me in
the right direction.
I have an application where I have a dc powered video camera. I'd
like to add the video (composite) to the wire feeding the camera with
power and then elsewhere in the system recover the video and feed it
to a monitor.
Video doesn't travel very well over plain old wires. You could try--
put a 10mH choke at each end of the DC wire, couple the video to the
wire in between with a pair of 1uF capacitors.
You'll get *something* out, but it will be rather smeary, fuzzy, and
noisy video.
If you don't need a immediate real-time picture, you could use a
webcam, and send the data using PPP over the wire, and get pretty good
data. But I suspect you need the image right away, not three seconds
later. Hard to back up a truck with a 3-second delay! |
|
|
| Back to top |
|
| Rich Grise |
| Posted: Thu Feb 15, 2007 6:05 pm |
|
|
|
Guest
|
On Thu, 15 Feb 2007 13:24:05 -0800, anbeyon wrote:
Quote: Hi I'm hoping that someone out there can help me out and point me in the
right direction.
I have an application where I have a dc powered video camera. I'd like to
add the video (composite) to the wire feeding the camera with power and
then elsewhere in the system recover the video and feed it to a monitor.
Is that possible ?
How ?
Is it easy ?
What do I need to be aware of ?
Any hint's or tips of what might be OK and what problems/issues to be
aware would be greatly appreciated.
Thanks in advance.
Must be mid-terms.
Cheers!
RIch |
|
|
| Back to top |
|
| martin griffith |
| Posted: Thu Feb 15, 2007 6:07 pm |
|
|
|
Guest
|
On 15 Feb 2007 13:45:52 -0800, in sci.electronics.design
anbeyon@btinternet.com wrote:
Quote: Hi Paul
Thanks for the reply.
I Should have told you a little more.
The application is on an articulated truck/lorry. I have to use the
existing wiring of the lorry. There will not be any co-ax - well at
very small bit at either end.
Thanks
Anbeyon
then get a 2.4GHz video sender, check out campervan accesories for old
gits who can't reverse properly
martin |
|
|
| Back to top |
|
| Rich Grise |
| Posted: Thu Feb 15, 2007 6:08 pm |
|
|
|
Guest
|
On Thu, 15 Feb 2007 13:45:52 -0800, anbeyon wrote:
Quote: Thanks for the reply.
I Should have told you a little more.
The application is on an articulated truck/lorry. I have to use the
existing wiring of the lorry. There will not be any co-ax - well at very
small bit at either end.
Then give up, or rewire the truck - you'll never get reliable video to go
through ordinary truck wiring.
Good Luck!
Rich |
|
|
| Back to top |
|
| Guest |
| Posted: Thu Feb 15, 2007 6:44 pm |
|
|
|
|
On 15 Feb, 21:24, anbe...@btinternet.com wrote:
Quote: Hi I'm hoping that someone out there can help me out and point me in
the right direction.
I have an application where I have a dc powered video camera. I'd
like to add the video (composite) to the wire feeding the camera with
power and then elsewhere in the system recover the video and feed it
to a monitor.
Is that possible ?
How ?
Is it easy ?
What do I need to be aware of ?
Any hint's or tips of what might be OK and what problems/issues to be
aware would be greatly appreciated.
Thanks in advance.
Anbeyon.
The lorry chassis is a bit of a hotbed of electrical noise as it acts
like a substantial steel aerial. Also, the chassis loom wiring
(electrically) looks like a mass of unterminated, high quality, open
transmission lines/resonators that spend their lives singing gentle
medium wave tunes to themselves in response to every single transient/
change on the battery/alternator.
Sending -clean- 1V video down unshielded wire from say the rear light
cluster up through the Suzi connector and into the cab for inductively
splitting off, looks a problem.
Myself, I'd be looking at a seperate coax feed.
john |
|
|
| Back to top |
|
| Homer J Simpson |
| Posted: Thu Feb 15, 2007 6:49 pm |
|
|
|
Guest
|
<anbeyon@btinternet.com> wrote in message
news:1171574645.717983.190490@j27g2000cwj.googlegroups.com...
Quote: I have an application where I have a dc powered video camera. I'd
like to add the video (composite) to the wire feeding the camera with
power and then elsewhere in the system recover the video and feed it
to a monitor.
Is that possible ?
Probably
Filter the DC out with an inductor.
Try it and see if it works. Ideally you want a piece of coax cable. |
|
|
| Back to top |
|
| Paul Hovnanian P.E. |
| Posted: Thu Feb 15, 2007 9:07 pm |
|
|
|
Guest
|
Homer J Simpson wrote:
Quote:
anbeyon@btinternet.com> wrote in message
news:1171574645.717983.190490@j27g2000cwj.googlegroups.com...
I have an application where I have a dc powered video camera. I'd
like to add the video (composite) to the wire feeding the camera with
power and then elsewhere in the system recover the video and feed it
to a monitor.
Is that possible ?
Probably
How ?
Filter the DC out with an inductor.
Try it and see if it works. Ideally you want a piece of coax cable.
The problem with adding DC to the raw video is that video is DC coupled.
The filter at the other end will take out the reference to the black
level. One could build a circuit to recover it, but that would probably
be more involved than RF modulation.
BTW, Martin's idea for a 2.4 GHz wireless link would seem to be the best
if one cannot modify or add to the truck wiring. 100% off the shelf
solution.
--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Opinions stated herein are the sole property of the author. Standard
disclaimers apply. All rights reserved. No user serviceable components
inside. Contents under pressure; do not incinerate. Always wear adequate
eye protection. Do not mold, findle or sputilate. |
|
|
| Back to top |
|
| Homer J Simpson |
| Posted: Fri Feb 16, 2007 12:03 am |
|
|
|
Guest
|
"Paul Hovnanian P.E." <paul@hovnanian.com> wrote in message
news:45D503E0.FD122800@hovnanian.com...
Quote: The problem with adding DC to the raw video is that video is DC coupled.
The filter at the other end will take out the reference to the black
level. One could build a circuit to recover it, but that would probably
be more involved than RF modulation.
It's a monitor - black level is not such a big deal.
--
..
..
..
..
..
..
..
.. |
|
|
| Back to top |
|
| Guest |
| Posted: Fri Feb 16, 2007 6:09 am |
|
|
|
|
On Feb 16, 4:03 am, "Homer J Simpson" <nob...@nowhere.com> wrote:
Quote: "Paul Hovnanian P.E." <p...@hovnanian.com> wrote in messagenews:45D503E0.FD122800@hovnanian.com...
The problem with adding DC to the raw video is that video is DC coupled.
The filter at the other end will take out the reference to the black
level. One could build a circuit to recover it, but that would probably
be more involved than RF modulation.
It's a monitor - black level is not such a big deal.
--
.
.
.
.
.
.
.
.
Thanks for all of your suggestions/thought and comments
Anbeyon |
|
|
| Back to top |
|
| Jan Panteltje |
| Posted: Fri Feb 16, 2007 10:28 am |
|
|
|
Guest
|
On a sunny day (15 Feb 2007 13:24:05 -0800) it happened anbeyon@btinternet.com
wrote in <1171574645.717983.190490@j27g2000cwj.googlegroups.com>:
Quote: Hi I'm hoping that someone out there can help me out and point me in
the right direction.
I have an application where I have a dc powered video camera. I'd
like to add the video (composite) to the wire feeding the camera with
power and then elsewhere in the system recover the video and feed it
to a monitor.
Is that possible ?
How ?
Is it easy ?
What do I need to be aware of ?
Any hint's or tips of what might be OK and what problems/issues to be
aware would be greatly appreciated.
Thanks in advance.
Anbeyon.
One thing you could try is use a 74HC4046, set it to oscillate at about 20MHz,
or higher if you can, connect the video the the VCO input, this will give you good
linear FM.
Add a small inductor on both sides of the supply line, and superimpose the 20MHz.
On the receiving side use the same chip in PLL mode with the XOR phase
comparator, and grab the video from the source follower output.
Watch cable impedance, likely around 100 Ohm.....
Actually in the olden days (1968) I used 2 x 74121 ones hots, byting their tail,
with a video modulated current source at about 12 MHz, not the resistor.
If you use a low frequency making a low pass will become more difficult.
The FM method keeps DC component, but it will likely be H clamped anyways in the monitor.
Works great for audio too. |
|
|
| Back to top |
|
| Ancient_Hacker |
| Posted: Fri Feb 16, 2007 2:18 pm |
|
|
|
Guest
|
On Feb 16, 8:28 am, Jan Panteltje <pNaonStpealm...@yahoo.com> wrote:
[ very clever idea]
Quote: The FM method keeps DC component,
Well, you'll get a DC component, but it's very likely to wander a bit.
Quote: but it will likely be H clamped anyways in the monitor.
True. Or you can restore the DC level with a diode and two
resistors. |
|
|
| Back to top |
|
| |
