Post subject: See TV in a CRT monitor without using CPU
!! Posted: Sun Feb 19, 2006 12:35 pm
Sun Feb 19, 2006 12:26 pm
Actually this is related
to a more complex project(like what i done in the Van eck phreaking
project). Please help to solve my problem. I am going to present
it in a nice way. You may think this as weird. Please dont give
a complete alternate suggestion. Yes this is weird.
I am going to use my old CRT monitor as a CRT tube only. The rest
of TV circuits are going to be added to it.(Like tuner, demodulation
etc..). Ok now scenario clear .....
After the received signal
from the antenna I will tune it amplify it and demodulate it to
get the video data.
Now I have the monitor ON with power
supplied to it. The Data input to the monitor(15 pin VGA cable)
is lying there hungry for input.
Now I am going to give the
demodulated data to vga cable of monitor. Yes... I have impedence
matched it to get it in to the corresponding voltage level of monitor.
Then I fed it to the Blue input of VGA cable. Red and Green are
left blank. So the display will be Blue and Black instead of Black
and white.... Suppose I have grounded the signals well.... Now what
is still required is sync signals. H-sync and V-sync to be fed to
the corresponding pins of VGA cable.
You may think of a sync
seperator from the input signal. No . I dont want that . Leave that
option. I want to genearate the syncs externally. And I want a good
range. 50-100 Hz for Vertical sync and 30-95KHz for H-sync. These
signals will be supplied to their respective pins. Then I can see
the display on the monitor. I can tune the Syncs to get perfect
So what I need is
1)To know whether this will
work.(If this wont work, please tell how to teak this. Dont provide
a complete alternative solution like RGB to VGA converter. I know
that. What I need is a good range for sync tuning)
circuits with option for fine tuning in the specified range and
volatage levels according to monitor.
3)I have a monochrome TV
circuit set at hand(with option for V-Hold and H-Hold). Please tell
how to tweak it to get the sync signals from it.
"There ain't no rules around here. We're trying to accomplish
something." -- Thomas Alva Edison
Those who desire peace should prepare for war " - anonymous
Post subject: CRT issuePosted: Wed
Feb 22, 2006 4:12 pm
Joined: Wed Feb
22, 2006 3:51 pm
Broadcast and consumer
video is interlaced - only alternating lines are sent each field;
two fields (one with the odd-numbered lines, one with the even-numbered
lines) make up one frame of 525 linesw. This interlacing allows
running the horizontal scanning frequency at 1/2 the rate that would
be required with non-interlaced (called "progressive") scanning.
So the resolution you get from a standard VGA monitor with a horizontal
frequency of 31.5 kHz is equal to the resolution you get from standard
TV at 15.75 kHz horizontal frequency. The tradeoff is that motion
isn't as smooth on an interlaced-scan display as on a progressive-scan
One issue is that many computer monitors will not
work well at a 15.75 kHz scanning rate - they're just not designed
for it. (So check the specification for the monitor you're using).
Generating unlocked synchronizing signals: good luck - you'll
need it! If you're off by a small percentage of the scan frequencies,
the picture will roll or tear. It must be exact - which is why TV
receivers all have a sync separator. Oh yes, extreme stability would
also be required - no VCOs here!
You might want to re-think
exactly what you want.