NM-MODCAM
NetMedia, Inc., 10940 N. Stallard Place, Tucson, Arizona 85737 (520) 544-4567 Fax: (520) 544-0800 Email: [email protected] www.netmedia.com
MAN-MODCAM REV0704A
Q- Why do the light areas of the picture look washed out?
A- The camera’s automatic iris must decide how much to open for shadow areas or close for light areas. When a picture has both light
and shadow, the camera adjusts the iris based on the percentage of each area in the image. If it decides to open more for the shadow
portions then the light areas will be overexposed. In addition, cameras that are designed for low light or infrared sensitivity typically
favor the shadow areas and look more washed out under bright conditions. Try adjusting the image field so that more light areas are
visible and see if the iris closes to improve the picture. It is normal though, that as the lighting conditions change throughout the day,
so will the camera iris and the picture’s dark or light areas.
Q- Why are the shadow areas too dark to see much detail?
A- This is like the washed out question above except opposite. In this case, the camera’s automatic iris is opening more for the light areas
at the expense of the shadow areas. Try adjusting the image field so that more shadow areas are visible and see if the iris opens to
improve the picture. Keep in mind though, that the camera still does need some kind of light in order to see. If necessary, add some
lighting to the dark area to improve visibility.
Q- How do I find out if the camera is working when I can’t see it on any televisions?
A- Start with a basic setup: connect camera to coax, coax to power injector, power injector to TV with no amplifiers, splitters, filters, cable
boxes or other devices involved. Set the camera to a channel that matches the TV mode: 14-69 for Antenna tuning; 70-94 or 100-125
for Cable tuning. If the TV can tune channel 70 or above, then it is probably in Cable tuning mode. Set a simple channel like 20 or 120
and look for it on the TV. Check power, power injector direction, connections, cables, TV tuning mode, and camera switches to correct
any problems. You must see the camera picture to confirm that it works in this basic setup before moving on to more complex setups.
Q- Why does the camera or cable service picture go bad when the two are combined together?
A- The signals should be combined at the beginning of the distribution system before the cable service goes through any splitters. Make
sure you are not using any diplexers to split or combine. Once done, there is either interference or the signals are not balanced. Most
interference comes from invisible digital data that is on the line even when not subscribed to it. Set the camera for a clear channel, try
120, or use a filter to remove the digital/analog interference. When there is no interference you can balance the signals by amplifying
the weaker, snowy one before the two are combined. 10 to 20dBmV is usually enough, too much will degrade the other signal.
Q- Can the camera be combined with digital cable service?
A- Yes. The difficulty is in finding a clear channel for the camera. The digital data usually takes up the analog channel range of 80-117 so
channel 120 is a good place to start. Analog 120 on the TV will not conflict with digital 120 on the cable box. If you cannot find a clear
channel then you will have to use a notch or low pass filter on the cable service before you combine it with the camera. Make sure the
filter does not remove any subscribed digital services including an Internet connection. If only one location is using the digital
services and it does not need to see the camera, you can split its run off before the main line is filtered and combined with the camera.
This prevents the filter from disrupting the digital data while enabling the camera to appear on the rest of the TV’s.
Q- How can I see the camera when the TV uses a cable box?
A- There are a few ways but they all involve bypassing the cable box and using the TV tuner to see the camera. Combine the camera with
the cable service and check its picture by connecting the coax directly to the TV. Any splitters, filters, or amplifiers you use for
combining are separate from the ones used to bypass the cable box. After verifying the camera picture, split the coax two ways with
one side going to the cable box. If you use the cable box S-Video or composite output then the other side of the splitter goes directly
to the TV. If you use the cable box coax output and there is only one coax input on the TV, then you must use a ch. 3/4 filter (included
with NM-ACB3) and recombine the coaxes as shown in Figure 5. In any case, view the cable box through the appropriate TV
connection, Video 1, ANT 2, channel 3/4, then change the TV (not the cable box) to the camera channel.
Figure 5 - Bypassing a digital or analog cable box and recombining to a single coax input on the TV. The kit’s filter
removes any conflict on channel 3 or 4. Switch TV from the cable box to the camera channel.
Frequently Asked Questions
Power Injector
Camera
Main cable or
Antenna
Splitter/
Combiner
Optional NM-CNF7080 Ch. 70-80 Notch Filter
when there are no clear cable channels.
The notch filter does not bypass the cable box.
Television
Cable Box
NetMedia Cable Box
Bypass/Combiner
Kit NM-ACB3
The kit filter does not
make clear channels
for the camera.