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 Greater range techniques page 2 Tips for getting much more range out of your video transmitters. The following range extending diagrams work well for most transmission devices. |
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GREATER RANGE TECHNIQUES 2
ANTENNA LINE OF SIGHT: MEANING, TRANSMITTER AND RECEIVER
ANTENNAS ARE VISIBLE TO EACH OTHER NO BUILDINGS, TREES OR
OTHER OBSTACLES BETWEEN THEM. IMAGINE A TWELVE FOOT DIAMETER
PIPE ALIGNED WITH AND EXTENDING BETWEEN THE TRANSMITTER
ANTENNA AND THE RECEIVER ANTENNA. THIS DEFINES THE SPACE THAT
MUST BE FREE OF ALL MATERIALS (EXCEPT AIR) TO MEET THE
DEFINITION OF LINE OF SIGHT. FOR DISTANCES BEYOND 1000' THIS
IMAGINARY PIPE MUST TAPER FROM A LARGER DIAMETER AT ITS
CENTER POINT, BETWEEN ANTENNAS.
A 2000' RANGE = 20' DIAMETER, AT THE CENTER.
3000' RANGE = 30' DIAMETER, ETC.
ALL ITEMS WITHIN THE ABOVE DEFINED SPACE (L.0.S.) WILL DIMINISH
THE SIGNAL ARRIVING AT THE RECEIVER. IF THE SIGNAL GOES BELOW A
CRITICAL LEVEL THE PICTURE WILL SUFFER.
ANTENNA SIZE: THE LARGER THE ANTENNAS THE GREATER THE
RANGE. USING 2 LARGER ANTENNAS FOR TRANSMITTING AND 2
LARGER ANTENNA FOR RECEIVING CAN INCREASE RANGE.
OBSTACLES: THE FEWER, LIGHTER, THINNER AND LEAST WATER
CONTENT, THE GREATER THE RANGE. EACH INTERNAL DRYWALL IN A
STANDARD OFFICE CAN DECREASE THE RANGE BY 50% OR MORE.
INSTALLATION: ALL ANTENNA TO EQUIPMENT COAX SHOULD HAVE
LOW LOSS, MAX. 3' RG58 OR 20' RG213, (IF ANTENNA COAX ADAPTERS
ARE USED THEY MUST BE CONSTRUCTED OF LOW LOSS MATERIALS).
LONGER RUNS OF VIDEO COAX (400' OR MORE) IS ACCEPTABLE TO
FINISH OFF AN INSTALLATION. POSITION OF ANTENNA IS IMPORTANT,
SOMETIMES 6" OF MOVEMENT IN ANY ONE DIRECTION CAN MAKE THE
DIFFERENCE BETWEEN NO PICTURE AND A GREAT PICTURE. IN
GENERAL, WE SUGGEST AN INITIAL HAND HELD, TEMPORARY SET UP
TO PROVE THE SIGHT. COMMON PROCEDURE IS TO MOUNT THE
ELECTRONICS INDOORS, OR IN ENVIRONMENTAL ENCLOSURES,
AND TO MOUNT THE ANTENNAS OUT OF DOORS.
ANTENNA POLARIZATION: To SIGHT DOWN THE BARREL OR BOOM OF
THE ANTENNA, THE (TANGS OR) ELEMENTS ARE GENERALLY
HORIZONTALLY OR VERTICALLY (POSITIONED OR) "POLARIZED".
EITHER IS OK TO USE, AS LONG AS THE TRANSMITTER AND RECEIVER
ANTENNAS ARE THE SAME. CROSS POLARIZATION, (TRANSMIT
ANTENNA HORIZONTAL AND RECEIVER VERTICAL) CAN CAUSE A
LOSS OF SIGNAL EQUAL TO A DECREASE OF POWER AT THE
TRANSMITTER OF OVER 90%.
ANTENNA AIMING: THIS IS MUCH LESS CRITICAL THAN THAT OF LASER
AND MICROWAVE SYSTEMS, TYPICALLY + or - 10 TO 60 DEGREES
PRODUCES VIRTUALLY IDENTICAL PICTURE. THE BRACKET IS ON
THE REAR SIDE OF THE ANTENNA. AIM THE FRONT OF THE
TRANSMITTER ANTENNA DIRECTLY TOWARD THE FRONT OF THE
RECEIVER ANTENNA.
MULTI PATH: SOMETIMES THE POSITION OF THE ANTENNA IS MORE
CRITICAL THAN THE AIMING. AS LITTLE AS A 6" MOVEMENT UP-DOWN,
OR N-S, OR E-W, CAN MAKE THE DIFFERENCE BETWEEN GREAT AND
NO PICTURE. THE SAME EFFECT IS SOMETIMES NOTICED WHEN THE
ANTENNA IS IN MOTION, THIS IS CALLED "FLUTTER" OR WHEN LARGE
OBJECTS ARE MOVED NEAR THE ANTENNAS, WHICH IS CALLED
"DROP OUT."
POWER SUPPLIES: ALWAYS USE INCLUDED POWER SUPPLIES OR
ELECTRONIC POWER SUPPLIES THAT ARE REGULATED, NEVER
USE BATTERY CHARGERS OR AC ADAPTERS.
WEATHER PROOFING: USE CAUTION IN BUILDING YOUR OWN
ENCLOSURES. IT IS USUALLY LESS EXPENSIVE TO USE AN
OUTDOOR CAMERA ENCLOSURE WHICH MUST HAVE A FAN AND
SUN SHIELD FOR HOT DAYS, AND A HEATER FOR COLD NIGHTS, ETC.
EQUIPMENT: INCREASING TRANSMITTER POWER BY 4 TIMES CAN DOUBLE
THE RANGE. ADDING A RECEIVER ANTENNA AMPLIFIER CAN MORE THAN
DOUBLE THE RANGE, IN ADDITION IT CAN ALLOW UP TO 100' OF COAX
TO BE USED BETWEEN THE ANTENNA AMPLIFIER AND THE RECEIVER.
TWO CHANNELS OF OPERATION ARE AVAILABLE ON SOME MODELS
OPTIONALLY. THIS MEANS 2 TRANSMITTER RECEIVER PAIRS CAN
OPERATE (REAL TIME VIDEO, NO AUDIO, IN THE SAME DIRECTION)
SIDE-BY-SIDE, WITHOUT INTERFERING WITH EACH OTHER. ANY SINGLE
CHANNEL CAN BE USED AT ONE SIGHT IN UP TO 4 TRANSMISSION
SYSTEMS IF EACH SYSTEM IS 90 DEGREES APART, (4 POINTS OF THE
COMPASS) FROM ONE ANOTHER. THIS ALLOWS EACH SYSTEM TO
REJECT (IGNORE) ITS NEIGHBOR, IF INSTALLED CORRECTLY.
USING THIS TECHNIQUE A SYSTEM CAN BE CONSTRUCTED WITH UP
TO 8 SIMULTANEOUSLY REAL TIME VIDEOS BEING RECEIVED AT THE
CONTROL CENTER.
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GENERAL CAPABILITIES: LIGHTWEIGHT, PORTABLE,
WIRELESS, COMPATIBLE WITH CONVENTIONAL VIDEO
EQUIPMENT. PRICES FAR BELOW THE COMPETITION. IDEAL
FOR A VARIETY OF APPLICATIONS.
APPLICATIONS: SURVEILLANCE, SECURITY,
PROTECTION, INTELLIGENCE, ROBOTS,
TRAINING, TACTICAL, VIDEO BODY WIRES.
USED BY: INDUSTRY, PUBLIC, POLICE, FEDERAL
GOVERNMENT, LOCAL & STATE LAW ENFORCEMENT,
MILITARY.
TYPICAL TRANSMIT & RECEIVE SIGHTS:
BUILDINGS, VANS, HUMAN BODY, BOATS, CARS. REMOTELY
PILOTED VEHICLES (AIR, GROUND, WATER), ELEVATOR
CAMERA TO MONITOR THROUGH ELEVATOR SHAFT, ROBOTS,
UP OR DOWN THE SIDE OF BUILDINGS, MULTIPLE BUILDINGS
REPORTING BACK TO ONE CONTROL CENTER, ETC.
USE YOUR IMAGINATION.
RANGE: 100 ' TO 10 MILES OR MORE WITH OUR
EQUIPMENT. ALL RF TRANSMISSION SYSTEMS CAN GO
THROUGH SOME OBSTACLES, SUCH AS DRYWALL AND
WOOD SIDING, BUT WILL LOOSE MUCH OF ITS STRENGTH IN
DOING SO. SOME SURPRISINGLY SIMPLE MATERIALS CAN
REDUCE A SIGNAL TO UNUSABLE LEVELS, SUCH AS
ALUMINUM SIDING, ALUMINUM BACKED INSULATION AND
WET OBJECTS, SUCH AS TREES, STUCCO, WOOD, HEDGES,
ETC. ALL APPLICATIONS ARE UNIQUE AND MUST BE
TESTED FOR THERE USABILITY. SOME SIGHTS MAY BE
IN A HIGH INTERFERENCE AREA (SUCH AS OTHER SIMILAR UNITS
ALREADY IN OPERATION). WE SUGGEST AN INITIAL HAND
HELD TEMPORARY SET UP TO PROVE THE SIGHT.
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