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Q: spy cam tech information ( Answered 4 out of 5 stars,   0 Comments )
Subject: spy cam tech information
Category: Science > Technology
Asked by: dtholm-ga
List Price: $5.00
Posted: 29 Jun 2004 09:42 PDT
Expires: 29 Jul 2004 09:42 PDT
Question ID: 367714
What is the difference between the 1.2 Ghz and the 2.4 GHz. wireless spy cams?
Lookin for information on picture quality and distance between the
receiver and cam.  big tip for any pictures compairing the two.
Subject: Re: spy cam tech information
Answered By: andrewxmp-ga on 29 Jun 2004 13:47 PDT
Rated:4 out of 5 stars
Hi dtholm,

First, we need to clarify what appears to be a confusion about how
frequency affects this type of device, and then we?ll look at your
questions.  Also, I am assuming you are referring to the sort of spy
cameras that are often used in homes, and not high-powered
transmitter/receiver devices generally used for industrial purposes.

?1.2? and ?2.4? simply refer to the frequency that the video is
transmitted on and, for the consumer at least, actually has nothing to
do with the range of the camera.  An analogy would be how a radio
station may be broadcast on 95.1 mhz (megahertz, just another unit for
frequency) or 100.1 mhz, but can contain the same music or video
information, but the two stations could be heard from equally far away
from their broadcast towers and be just as clear as each other.  The
different number simply represents ?where? on the electromagnetic
spectrum the information is being carried along.

The reason different frequencies ARE used is because many devices
today transmit data at certain frequencies, such as wireless telephone
handsets, wireless computer access points, and so on.  If they all
send information at one frequency, there is going to be interference,
which will prevent any of them from working properly.  So,
manufacturers have begun using different frequencies to minimize this
overlap (although still in accordance with FCC and other regulations),
with the most recently adopted standard frequency being 2.4 ghz. 
Older cameras used 1.2 ghz, 900mhz, and some others.  These are

?The three primary frequencies are 900MHz, 1.2GHz, and 2.4GHz.
900MHz receivers have a tuning knob that you must tune until you get a
clear, sharp picture. There is no interference between 900MHz cordless
phones and 900MHz wireless cameras.
1.2 and 2.4GHz have channels. The receivers can change channels but
the transmitter,which is located inside the hidden camera, cannot be
[ ]

2.4 ghz cameras appear to have a slightly but not really significantly
longer range than do those with a lower frequency, however this has
much more to do with the power of the individual unit than the
frequency it uses to transmit the video.

?6. What is the range of a wireless camera? How far can I get?
The industry uses "Line of Sight" as a base measurement for range. LOS
means absolutely nothing is in the way, mountain top to mountain top,
perfectly in line with each other in regard to direction and height.
Standard wireless cameras have a range of approx. 900 feet LOS (line of sight)?
? ?

The range of 2.4 ghz cameras is often listed for products as ?up to
700 feet?, such as at:
[ ]
[ ]

The bottom line about wireless range is that they (both 1.2 and 2.4
ghz) will transmit up to about 700 feet away if there is nothing
between the transmitter and receiver, but for practical use in say a
home setting, the real range is about 300 feet, but could be more or
less depending on the surroundings.  Because of this variability, few
manufacturers will give an exact value for ?range? other than the LOS
range described above.  A good summary can be found at:
[ ]


While the range may have some influence on the range of a camera, it
has almost nothing to do with the image quality.  Image quality is
measured in the number of horizontal lines that are in any given frame
of video.  Almost any of these cameras will transmit ?standard
resolution? and some will transmit ?high? resolution, both of which
are comparable to or better than a standard broadcast TV signal.  They
are described:

?Another issue in camera selection has to do with whether the camera
has "standard" or "high" resolution. Put simply, the higher the
resolution, the sharper the picture will appear on the monitor.
Resolution is measured in terms of horizontal lines across the screen
that create the picture that you see on the monitor. For black and
white cameras, standard resolution usually means 380 lines, and high
resolution means 580 lines. For color cameras, standard resolution
means 330 lines, and high resolution means 460 lines. Most monitors
have more than enough lines of resolution for either color or black
and white cameras. However, most VCRs are limited to 240 lines of
resolution in color, and 330 lines of resolution in black and white,
unless you buy an S-VHS unit which can record at a higher resolution.?
[ ]

In summary, when buying a camera, the frequency does not have a very
big influence on the performance, unless you already have a lot of
devices transmitting on the same frequency, which might cause
interference.  Both transmit approximately the same image quality over
approximately the same range

You also mentioned that you would like to see images from the two
cameras for comparison, but hopefully you now realize that there is no
visual difference between the two.  Just so you know approximately
what they look like, however, an image from a 420-line black and white
camera can be found at:
[ ]

I trust these resources have shed light on your question, but if you
require a clarification, please request one, especially before rating
this answer.  Thank you for bringing this question to Google Answers!


Search strategy:

wireless cameras range feet
2.4 ghz cameras have range feet
wireless cameras resolution
dtholm-ga rated this answer:4 out of 5 stars and gave an additional tip of: $4.00
Your post was easy to understand and answered my questions. Two of the
links explained Qestions I was going to post later.

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