4G Interference to TV at Apollo Bay

19th February 2015

  

The TV interference problems that Apollo Bay is experiencing are built into the TV system and would have been known to the Australian Communication and Media Authority (ACMA) before the 4G/LTE equipment was installed.  That is why all the major Australian cities use the VHF band (Ch6 @174MHz to Ch12 @230MHz) for the Digital TV transmissions and small regional systems, such as Apollo Bay, use the UHF band (Ch28 @526MHz to Ch51 @694MHz).  Nothing in ACMA Retune Program Information indicated that interference was likely if the users UHF antenna was close to a 4G transmitter. In Apollo Bay the 4G transmitters are located on the Telstra tower opposite the CFA Fire station in Pascoe St.

To the best of my knowledge the history of TV services to Apollo Bay has been as follows:

1.  TV services in Victoria commenced transmitting in 1956 with analogue VHF (Ch 0-20) and then UHF (Ch 28-Ch69) a few years later from Mt Dandenong.  Both of these bands could be received at Apollo Bay using a high gain VHF- UHF TV antenna fitted with a masthead amplifier to boost the weak signal.  The amplifiers were usually set at the maximum allowed.

2.  In May 2004 the Colac - Otway council installed a TV translator at the Marengo Water Basin to service Apollo Bay.  This downloaded TV signals from the satellite services and rebroadcast them on the UHF TV band.  The ABC also installed a translator on the site.  The TV channels broadcast were ABC Ch2, IMPARGA Ch9/10 (NT) and SVC Ch7 (QLD).  A UHF Ch 21 to Ch69 antenna was required to receive this signal.

3.  In 2011 the government introduced the new Digital TV transmission system.  The digital TV signals transmitted from Mt Dandenong tend to drop out near Lorne and were not designed to reach Apollo Bay.  A new Digital TV translator system was installed at Marengo.

4.  On 16th June 2011 the Digital TV at Marengo was turned on.  The ABC – Ch54 continued to use a satellite download.  The TV signals for the other stations were sourced from Ballarat via repeaters on Mt Cole and Mt Tanybryn.  The TV channels provided were VTV – Ch64, BCV – Ch66, AMV – Ch67 and SBS – Ch69. These TV signals were also transmitted from Mt Tanybryn.  Transmission of the analogue TV signals ceased on that date.

5.  On 30th September 2014 the Marengo and Mt Tanybryn transmitters were Retuned to AMV – Ch46, ABC- Ch47, BVC – Ch48, VTV – Ch49 and SBS – Ch50 to remove them from the 700MHz spectrum which the government had sold for use as 4G Mobile Telephone networks.

6.  A 4G Mobile Telephone network was installed and tested in Apollo Bay in late 2014 and came into service on the 15th Jan 2015.

The standard UHF TV antenna installed were designed to pick up TV signals from Ch28 (526MHz) to Ch69 (816.5MHz).  The government has assigned the 700 MHz spectrum (694MHz to 820MHz) for use as a 4G/LTE Mobile Telephone Network.  These frequencies were previously assigned to TV Ch51 to Ch69.  Most if not all the existing UHF antennas installed will be receive these signals.  Some people also have their UHF antenna connected via an amplifier, which boosts the signal.  The tuners of all existing Digital TV sets, DVD Recorders and Set Top Boxes will receive the 4G signals.  Remember that the 4G mobile telephones and modems also transmit signals on these frequencies and interference from these sources has been reported from the USA.  The 4G signals overload the TV tuner which can causes the disruption to the program.

What is the solution?

To prevent this type of interference the 4G signals must be removed or significantly reduced before they arrive at the TV tuner.  Three ways that this can be done are listed below.  There may be other ways as well.

1.  Fit a new UHF Digital TV antenna which is built to receive Ch 28 to Ch51 UHF signals only and which is equipped with a filter to ensure that 4G/LTE signals are not passed to the TV set.

2.  Fit an inline coaxial 4G/LTE Filter between the antenna and the TV sets.  If an amplifier is fitted the filter must be installed between the antenna and amplifier.  You only need one filter in the aerial system and the TV's that it services in the building.  Two types are available.  One has a standard PAL male inlet plug and a PAL female outlet plug.  The second type has the screwed "F" Type cable connections and can be attached to the input end of an "F" type splitter.  The filters cost from $15 to $20 and can be installed by owner.  I am not aware of any waterproof filters designed for masthead use.  4G/LTE filters are built into the modern masthead amplifiers.

3.  Reduce the 4G signal strength.  Most of us still have amplifiers fitted to our antennas.  These can be removed or adjusted to reduce the signal strength going to the TV and may solve the problem.  If you require the masthead amplifier for the Melbourne VHF signals then you could use a separate filtered cable from the local UHF antenna.

Its worth knowing that tests indicate that some 4G interference can also enter the system where there are loose or poorly fitted antenna cable connections.  Check your cable connections.

4G/LTE interference is not going to go away.  I suggestion that you contact your TV antenna installer for advice on the best fix for your problems.

Ted Stuckey

apollo bay radio

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