FIELD OF THE INVENTION
To provide unbalanced dual power supply interface to video interface ICs for switching of
high frequency component video signal in airborne system.
BACKGROUND OF THE INVENTION
The high frequency component video signal is also called RGB video signal. The RGB
component Video signals come from the video source to video switch through High Speed
Triple Differential Video receiver. Then after processing through video switch, single ended
Outputs of the switch are fed to triple differential Driver. The driver IC converts the single
ended video signal to differential signal compatible for the display unit. There are various
control logic and selection logic required for the video switching of the video signal is
governed by CPLD/Microcontroller and shift register.
The subject IC is a triple, low cost, differential-to-single-ended receiver specifically designed
for receiving red-green-blue (RGB) signals from video source. It works on power supply
range +5 VDC, ± 5VDC and ± 12 VDC. It is a triple, low cost differential or single-ended input
to differential output driver. It also works on the power supply range of +5 VDC & ± 5VDC.
High performance video switch works on ±3V, ±5V, or +5V Supplies.
The invention is that, for the switching of the RGB component video signal, specific
electrical interface has been used. But the power supply interface for these ICs are dual
unbalanced (+5 VDC, - 3.3 V DC) in place of ± 5VDC dual balanced power supply.
SUMMARY OF PRESENT INVENTION
In accordance with one aspect of present invention is to provide a unbalanced dual power
supply interface to a VIDEO DRIVER for video signal processing in place of balanced power
supply interface.
In accordance with second aspect of present invention is by providing unbalanced dual
power supply interface to VIDEO DRIVER and video switch, Component video signal can
also be switched to display as in case of balanced dual power supply interface.
In accordance with another aspect of present invention is, The MIL PRF PCB comprising of
the video switching section VIDEO DRIVER and video switch with unbalanced dual power
supply, can withstand the random vibration up to 8g.
In accordance with another aspect of present invention is, The MIL PRF PCB comprising of
the video switching section and MAX 4355 with unbalanced dual power supply interface,
can withstand the temperature range -40°C to +55°C in operating condition without any
distortion of the video signal.
In accordance with another aspect of present invention is that STANAG 3350 B CLASS B
RGB Video can be processed and switched by VIDEO DRIVER and video switch with
unbalanced dual power supply interface.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1: It shows Power supply interface layout for video switching.
Figure 2: It shows Component video switching with unbalanced dual power supply interface
DETAILED DESCRIPTION
The RGB component video signals come from the video source in the form of differential
signals to VIDEO DRIVER video interface IC of Analog Devices. The component video
signal is as per STANAG 3350 B CLASS B RGB Video. RGB stands for Red, Green and
Blue signal named component video. The VIDEO DRIVER is a triple, low cost, differentialto-
single-ended receiver specifically designed for receiving red-green-blue (RGB) signals in
the form of Red (R+, R-), Green(G+, G-) and Blue (B+, B-) differential signals. The
characteristic Impedance of the each signal is 120 ohm which matches to the characteristic
impedance of the video signal input so that the each video signal can be received with no
reflection/ loss to the receiver IC VIDEO DRIVER. For the functioning of VIDEO DRIVER,
the unbalanced dual (+5 VDC, - 3.3 V DC) power supply interface is provided in place of
balanced dual power supply interface of ± 5VDC. VIDEO DRIVER converts the differential
video signal to single ended video signal named OUT_R, OUT_G and OUT_R. These single
ended video signals are electrically interfaced to high performance video switch with
input/output buffers. The video switch also works on unbalanced dual (+5 VDC, - 3.3 V DC)
power supply in place of ± 5VDC balanced dual power supply. The logical input to the video
switch and also switching logic comes from the CPLD and 16 bit Serial/Parallel In Serial Out
shift register with processing device (Microcontroller). Shift register and Microcontroller work
on single +5V power supply interface. After receiving the single ended video signal from the
receiver IC VIDEO DRIVER, the high performance video switch ,switches these signals as
per the switching logic received by it. The out put of the video switch goes to video driver.
This driver IC also works on unbalanced dual (+5 VDC, -3.3 V DC) power supply interface is
provided in place of balanced power supply interface of ± 5VDC. Video driver IC converts
the single ended output from the video switch in the form of Red (R+, R-), Green (G+, G-)
and Blue (B+, B-) differential signals. The characteristic impedance of 120 ohm is provided
to every differential output from driver, so that the maximum output video signal can be
received at display end with no reflection/losses.
As per fig: 1: It shows the power supply section required for the video switching of the
component video signal. 28 V power supply is received by the airborne system from the
aircraft/helicopter. This power signal is interface to the power supply module through
physical interfaced airborne system connector followed by backend motherboard. Power
supply module converts 28V DC power supply to ripple free ± 15VDC, +5VDC, +3.3VDC and
-3.3V DC.
As per fig: 2: It shows the video switching of the component video signal by using VIDEO
DRIVER a triple, low cost, differential-to-single-ended receiver, high performance video
switch and a triple, low cost differential or single-ended input to differential output driver with
unbalanced dual (+5 VDC, -3.3 VDC) power supply input in place of balanced dual power
supply ± 5VDC for each IC.

WE CLAIMS:-
Accordingly, the description of the present invention is to be considered as illustrative only and is for the purpose of teaching those skilled in the art of the best mode of carrying out the invention. The details may be varied substantially without departing from the spirit of the invention, and exclusive use of all modifications which are within the scope of the appended claims is reserved. We Claim

1. STANAG 3350 B CLASS B RGB Video can also be processed into compatible display format by a triple video receiver & a triple video driver by applying unbalanced dual power supply in place of balanced dual power supply.

2. STANAG 3350 B CLASS B RGB Video can also be switched to compatible format for display unit by triple video receiver, video switch & a triple video driver by applying unbalanced dual power supply.

3. MIL PRF based PCB containing component video switching interface circuit with triple video receiver, video switch and a triple video driver is capable of giving sustained performance over the temperature range of -40°C to +55°C.

4. This video switching interface with dual unbalance power supply for STANAG 3350 B CLASS B RGB Video is easy to implement, requires less space of 60x40 mm2 PCB and is reliable. ,TagSPECI:As per Annexure-II