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AERIAL SELECTION & WHY?
At the moment, the TV programs you receive are transmitted in groups. A different group is transmitted from each transmitter to avoid interference between the transmitters. The aerial you have on your property will be designed to receive as much signal from the group your transmitter is using.

With digital TV, only one group is required for all transmitters as the digital signal is not affected by interference from other transmitters, leaving the Government several groups to sell off to mobile phone companies etc…

As the Government has not yet decided what group it is going to use, your installer should be using a wide band aerial that covers all groups. If the Government uses a group that is far away from the group your aerial is designed to use, you could experience reception problems, where with a wide band aerial this will not occur.

 


 Contract TV aerialTYPES OF AERIAL: NOT SUITABLE for digital TV reception
A customer said to me: “An aerial is an aerial”. That is the problem which you the consumer faces, because when an aerial is erected how do you, the customer know that the best has been erected for your digital viewing requirements?

The aerial pictured right is called a contract aerial and is the type of aerial most of us are familiar with. This type of aerial will receive a digital signal, but  DOES NOT meet the new standards required for the long term reliability of digital TV reception.

 Non-digital connectorNon-digital connection





Far left: This cable prepared for connection DOES NOT meet digital standards.
Left: This method of connecting the cable to the aerial DOES NOT meet digital standards.


 


 Digital TV aerialTYPES OF AERIAL: SUITABLE for digital TV reception
The type of aerial pictured right is one of the types of aerial which DOES meet the required standards for digital TV reception in all areas.

The CAI approves the benchmarked quality types of aerial, cable and connections that we install, to meet the new digital standards for all new TV aerial installations.

Digital connectorDigital connection


Far left: This cable prepared for connection DOES meet all the standards for digital TV reception.
Left: This method of connecting a cable DOES meet all the standards for digital TV reception.

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Aerial Benchmarking Scheme

The basis of the scheme is to lay down minimum standards for the technical performance of UHF TV aerials based on the specific requirements for satisfactory DTT reception. It is not intended to address general quality issues, such as standard of construction, durability etc., which can largely be assessed by visual inspection and from practical experience.

This CAI benchmarking schemes at the moment cover aerials and coaxial cables only. As yet they do not cover the complete aerial installation, or installation practice. Conformance to the minimum standards is determined by independent measurements against a technical performance specification.

These standards have been compiled by an industry wide committee who will monitor the implementation of the schemes through the CAI Inspectorate and agree any necessary changes to the detailed procedures, test methods, and specifications.
The scheme allows the measurements to be carried out by any test house that is able to demonstrate that it meets the required standards of measurement accuracy.

The use of the 'mark' will be authorised for specific products by the CAI, once the 'pass' certificate and supporting documentation has been issued by the test house – or in the case of aerials – by the CAI. Testing of random samples sold to installers or retailers will ensure ongoing conformance.

The Benchmarking Schemes are at the moment purely a voluntary arrangement within the industry. They are however expected to be widely adopted, following the success of the CAI Cable Benchmarking Scheme.

Reference may be made to specific types of CAI/DTG benchmarked aerials in manufacturers literature, purchasers' requirement specifications or supply contracts.

Benchmarked equipment should always be used in conjunction with good installation practice as laid down by the CAI Codes of Practice and the recommendations in DTG R Book 2.

Benchmarked Aerials are graded in Standards 1 - 4 and the following is a definition of those Standards.

 
Standard 1 Should provide adequate DTT reception even for homes on the fringes of coverage areas
Standard 2 Intermediate standard, suitable for use within the coverage
Standard 3 Minimum standard required for good coverage conditions
Standard 4 Recommended where better wideband performance is required.
 

 
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