Video over Twisted Pair cable (cat5)

[Iceskater]

video over twisted pair

Hi ,

I want to build a video over CAT5 circuit for transmitting 1280x1080 VGA signal up to 200 feet.

Which parts can i use ?



in CAT5 we have 4 pairs of twisted pair cable:

first pair : i can transmit +Vred and -Vred
second pair : i can transmit +Vgreen and -Vgreen
third pair: i can transmit +V blue and -Vblue
forth pair : i can transmit supply volatage and ground.

how can i encode horizontal and veritical sync (Vsync, Hsync) signals onto the twisted pairs , transmitting this additional information without requiring additional driver and receiver op-amps since i am using all pairs?

Can anyone explain or point me to a circuit ? How can i do that ?

I appreciate your help.

Iceskater

 

[anok]

vga cable cat5e circuit

read this:

**broken link removed**


Andrzej

 

[echo47]

cat5 twisted pair for video

200 feet of CAT5 is will significantly attenuate the high frequencies of your VGA signal. You will want some sort of compensation circuit.

What is that "supply voltage"? You won't be able to transmit much power because 200 feet of CAT5 has about 5 ohms of resistance in each wire.

Some VGA monitors support "sync on green". I don't know how many VGA boards do that, but maybe explore it as a way to eliminate the extra sync wires.

 

[IanP]

what are cat 5 transmit pairs

Here you will find info on how to produce composite sync signal:
**broken link removed**
So, you will have RED, GREEN, BLUE and Comp. Sync = 4 twisted pairs.
At the other end you may need to separate the Comp. Sync back to V and H.
Regards,
IanP

 

[Iceskater]

vga sync on video cat5e

Hi All,

Thank you for all of your answers. Here are my replies and still could not figure out how to solve my problem, I have made further research on net and found followings:

echo47 : supply voltage is 12V and i am planning to supply only the "Video over CAT5 driver" circuit and i want "video over CAT5 receiver " to get its supply volatage over one pair of twisted pair wires.

anok: Thank you for pointing me Analog devices AD8133 triple differantial driver , i have checked the datasheet and i could not find any information on solving my problem with Vsync and Hsync (my first post).

IanP: Thank you for the link , that was usuful at least i have some solution now i can use 4th twisted pair on CAT5 cable to transmit +Composite Sync -Composite Sync , but do not i need a reference ground signal for all these signals on CAT5 cable since now all wires are occupied with differencial signals ?

I have decided to read some installation manuals of commorcial products and i have found this :

one of the companies is giving details of signals carried on each wire at CAT5 cable :

wires connected to RJ45 connector:

Pin Color Wire
1 White-green Red/V. sync+
2 Green Red/V. sync-
3 White-orange Power
4 Blue Green+
5 White-blue Green-
6 Orange Power
7 White-brown Blue/H. sync+
8 Brown Blue/H. sync-

it seems like they are converting and transmitting Hsync and Vsync on Red and Blue as separate and imposed differantial signals ?

What is the logic behind this ? Any idea?

How that is possible to send both red and blue signals and sync signals on the same wires ???
I am curious about the Vsync and Hsync circuit on both receiver and transmitter side of the video over CAT5 .

i have looked to some IC manufactures and found that Intersil has this IC, EL4543 Triple Differential Twisted-Pair Driver with Embedded Sync Encoding.
This manufactured this year, a new one.

How they are doing that ? what is the logic behind not using 4th twisted pair but embedding syncs on other twisted pairs ?

thank you for your help,
I appreciate your help

Iceskater

 

[echo47]

cat-5 video drivers ic

Video pixels and sync pulses are transmitted at different times, so it's possible to combine them and separate them later (similar to television). In RGB systems, the green signal is commonly chosen to carry the sync.

Here's the ancient Sync on Green FAQ. Maybe helpful to you. Or search Google for more info and products.
**broken link removed**