a 4G transmitter, the potential for signal disruption exists. The second and perhaps ironic scenario is where 4G filters have been installed in
a satellite system to protect it from 4G interference – but it will now block some Sky Q channels that sit around TV channel 61. This may be
quite complex to solve and we recommend discussing the issue with Solutions Group before attempting any modifications.
Communal COAX systems
The traditional coax systems use a 5 cable trunk running around the building. At appropriate locations, a tap is installed to “tap off” some of
the trunk signals to supply the four satellite polarities and terrestrial signals to a switch. This switch has a number of outputs that each mimic
a separate “standard” LNB.
Each STB is connected to the switch by a single coax cable and the switc
h automatically selects which polarity and which half of the band
the STB is demanding. In addition, the switch adds the terrestrial TV signals to the cable. This allows one cable to carry satellite and TV
signals simultaneously, reducing the cost of coax cable and speeds installation. In these cases the wall plate will have filters built-in, splitting
the satellite signals from the terrestrial signals. So the consume
r has a TV socket and a separate satellite socket. In recent years most
installations include a second satellite connection for Sky+ functionality.
The new wideband LNB must not pass through a wall plate with a filter, so this type of install requires a new wall plate and will not deliver
terrestrial TV without adding another coax cable.
Some coax cables installed in communal systems may be 30m long or more
. Vision switch systems support CT100 type cables as long as
80m. At these lengths, the new higher frequencies will incur quite high losses, potentially making delivery over these distances quite
problematic. In fact the loss itself is just part of the problem. Because the range of frequencies is now much larger, signal levels at 300MHz
could be as much as 20dB bigger than the higher frequencies, possibly outside the dynamic range of the STB. This could mean overload at
the lower channels or insufficient signal levels at the higher channels. Both are undesirable.
It is possible to add a device that takes in four traditional polarities and converts them into two wideband outputs, suitable for Sky Q. This
can be achieved by tapping into the existing 4 wire backbone (terrestrial can’t be added) and connectin
g a new interface to the two existing
cables to the consumers STB. If required, the terrestrial signal can also be tapped off and a new cable installed for terrestrial TV added. Great
care must be taken to maintain signal levels on the remaining system. The length of the consumer cables, the cable construction and any
wall plates must be taken into consideration too.
Although considerably more expensive, i
t is also possible to use a new version digital SCR device to provide the feeds for the twelve tuners
in a Sky Q STB down a single coax cable. These devices take the four bands in from the LNB and then generate 12 separate signals, all
passed down one coax cable to the STB. The STB sends data to the SCR, telling it which 12 channels it needs and the SCR does the rest. The
advantage of this approach is the satellite signals are above 950MHz, leaving room for terrestrial signals to co-exist on the same coax cable.
Some digital SCR units will also accept a terrestrial signal and diplex it onto the coax cable. The old outlet plate will still work too and the
cable losses are not an issue either. To connect such a devic
e to an existing IRS installation requires the addition of a five port tap or splitter.
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