Thus to see any of these screens anywhere in the house, we just need to
select its channel on the TV. In addition, due to the
system, I can control the viewed VCR/DVD/DVR as well.
in early 2018, we switched from the analog NTSC based video system that
allowed us to see the exterior of the house to digital cameras from
HIKVISION. They are 4 Megapixel each and have a wide 2.8mm lens.
These cameras also
have a large IR emitter for great night time viewing but have no audio
capability. I briefly used a unit with pan-tilt motors, but then decided
against it as it was much larger and would 'home' to a unuseful
location every time there was a power cycle.
Camera used was the HIKVISION 4 Mpixel cameras.
Back panel of the Network Video Recorder (NVR) DS-7604
back of the NVR shows how this interfaces. The cameras plug into
the four 100BaseT Power-over-Ethernet POE jacks. A mouse for the
GUI plugs in next to it and the two high-definition outputs are
adjacent to that. The audio jacks don't do anything useful.
Lastly, I also plugged into my home LAN, but to view the cameras
on a PC, you need to load an outdated applet that is not compatible
with recent Windows/Mac versions.
Blue oval highlights the camera for the front of the
house and the pink one is for the front door.
Phone and iPad versions of the user
interface of the NVR work quite well.
Sample images from the App store.
the NVR has the features you would expect, such as mobile support and
settable motion sensor zones. You can view one or four channels
at a time, and in landscape mode you can fill the whole screen with the
Initially, I used a VGA to
video converter, and that signal was then modulated with an analog
modulator to channel 24. This image was always a bit grainy and
noisy. For many years, I was looking for a good deal on digital
(ATSC) modulators, and they were initially quite large and expensive
(about $2k), probably used in professional setups. Finally in
2020, the price went below $400, and I decided to try to use one and
convert one of the channels to digital.
The digital (ATSC) modulator. Purchased
used for about $220 on Ebay.
part of this project, I learned a bit about these digital modulators.
To start with, there are several modulation standards for the
digital signal. The broadcast standard in the USA is 'ATSC',
while the US cable distribution format is 'QAM' aka J.83B. In
Europe, the standard is DVB-T or DVB-C, while in South America it is
ISDB. Finally, China and Asia uses DTMB. At some point, I
almost purchased an inexpensive modulator that was built in Portugal (Edision unit for $160
), but that would not have worked with my TV.
In addition, it is important to note that the physical (RF) channel may differ from the logical (virtual) one
and of course it is important to know both so that you stay away
from them. I used to have a TV that displayed the physical
channel (in a hidden menu) so I could take a listing, but now I just
try it and if there is interference, I know to move to another one.
TV in the bathroom (and several other places
around the house) allows me to monitor what
is around the house in crisp high def 1080P.