We are often asked: "How long can the cable be from our
Active Antennas to the Headend?".
- Coax cable has higher losses at higher frequencies and
this is what is known as TILT~!
- This can also be referred to as "SLOPE" and needs to
be considered in any coaxial CATV cable run.
- Our antennas have an internal amplifier that is
designed to compensate for 100 ft or 30 meters of RG-6 cable.
- Tilt compensation has been applied in the amplifier to
boost
the higher UHF signals so that when they reach the head end the levels
are more or less equal. Longer lengths will attenuate beyond the
capability of the amplifier. It is possible that weak signals in the
high UHF band will be driven close or into the noise floor where they
cannot be recovered.
- The amplifier also compensates equally for
approximately 150
ft of RG-11 Cable. For longer lengths, up to 200 ft use RG-213 or a
cascadable tilt amplifier placed in a critical position on the string
or branch.
- We commonly supply 15dB Tilt Amplifiers for use on
Navy
ships to boost signals coming from a CATV shore source and have a long
run across the pier and then to the Headend. Ref. PRA-420T, PRA-422T Power
supply and Line Amplifier (Tilt
version)
- Tilt
or Slope loss
can also affect video on video cables with long runs and thus reduces
the bandwidth or high frequency content of the video signal, which, in
turn, reduces the picture sharpness. At Satellite Baseband frequencies
the effect is very pronounced but the signal is relatively narrow band.
For runs greater than 150ft., fiber optics is often used.
Our active antennas are 75 Ohms
impedence normally but we can supply at 50 ohms when requested. It is
mearly a small ferrite change in the internal amplifier and a different
50 ohm cable is used and of course a different connector. We use F
connectors at 75 Ohms and BNC connectors at 50 Ohms. |
