Engineering

Sentech’s ability to provide professional engineering services is based o­n the effective application of the fundamentals of radio frequency propagation and purpose focussed network design and operation. Our services comprise the following: 

Transmission Planning Consultation For Clients

Transmission Planning Consultation services are provided for our clients where access to quantified GIS, based scenario results, allows them to make informed decisions regarding target audiences and coverage areas.  

Technical Data Management

Sentech’s Transmission Planning department manages an extensive and accurate technical database of all licensed and theoretical broadcasting spectrum facilities in Southern Africa, including neighbouring states. Access to such data is imperative for any form of facility planning where spectrum is used. The technical database management structure can easily by applied to any country wishing to use our database management services. 

Coverage Planning

Sentech has the ability to do transmission coverage planning over a wide range of frequencies, including MF,HF, VHF, UHF, and SHF. Coverage planning determines the transmitting characteristics of a terrestrial transmission facility in order to achieve a specified RF geographical coverage or connection. Transmitting system parameters such as site location, transmitter output power, frequency band, antenna type, orientation and height above ground level as well as other data is used to compile a technical transmitting system specification for regulatory purposes. Inherent in this process is the ability to produce geo-coded maps showing the geographic area covered or the propagation path of the signal. Sentech utilises sophisticated computerised systems to provide clients with state of the art graphical representations of their coverage requirements. 

Frequency Planning

Sentech has the expertise for frequency planning in all the broadcasting and telecommunication bands. Frequency selection is done for the minimum amount of mutual interference between facilities and at multi service levels and stations. The selection process considers hardware constraints and adheres to international norms and standards as prescribed by the International Telecommunications Union. 

On-Site Electromagnetic Compatibility [EMC] Planning

Sentech has the ability to engineer its sites from an EMC point of view. The volume of transmission facilities deployed at a large number of sites requires extensive EMC management, as the potential for direct or indirect relationship interference is a constant possibility. Many Sentech sites are also used for telecommunications services further compounding the risk of inter equipment or inter band interference. In practice, and in order to minimise interference, Sentech constantly embarks o­n inter-modulation studies to identify potential offending frequencies or systems. This information, as well as the results of studies o­n electromagnetic coupling, is used to obtain the correct geometric configuration of antennas o­n a mast, provide filtering, or in certain cases, to refrain from using a frequency. 

Geographical Information System Applications

As mentioned above, Transmission Planning utilises a computer based Geographic Information System to analyse client coverage areas in respect of target audience distribution and their attributes. The GIS system employs detailed spatial data such as geographical features, borders and boundaries of metropolitan areas and communities to which the attribute data is linked in the form of demographic information. With the electronic importation of service coverage data, the GIS provides powerful capabilities in analysing a given coverage area. These absolute results may be used by the client for business planning. Advanced graphic printing facilities are employed to effectively illustrate the system results.
Propagation Measurement
Sentech's Transmission Planning obligations require constant assessments of the performance of newly installed and older installations, by measuring radiated energy and sources of interference that might affect coverage. Two methods are employed:

• Terrestrial measurements are performed by qualified personnel equipped with sophisticated, calibrated field-strength measuring equipment mounted in a utility vehicle.

• In-flight measurements are performed using a helicopter equipped with computer controlled calibrated measurement equipment and 24 integrated GPS navigation abilities. Results are assessed and evaluated against the specification. Problems are addressed and re-measured, after which the information is archived for future reference.

Network Planning

Sentech provides the services required for the composition and establishment of optimised terrestrial broadcasting networks. Link analyses, feed alternatives, network switching requirements and network node designs are key activities in establishing a new network or for altering existing networks. Specialised design abilities are available to address specific client requirements. As a result of its involvement with broadcasting signal distribution, Sentech is actively represented in local and international broadcasting associated industries and organisations. Amongst others, Sentech is a member of the following organisations in the telecommunications industry:

• Industry and Regulation Terrestrial Transmission Engineering Civil, Mechanical & Electrical Engineering

• International Telecommunications
  

• Union Development Sector

• Commonwealth Broadcasting Association

• Southern African Broadcasting Association

• Electronic Industries Federation [SA]

• Standing Committee for Electronics [SA]

• Asian Broadcasting Union

• European Broadcasting Union

• High Frequency Co-ordination Committee

In our capacity as member of these organisations, our responsibilities include the specification, procurement, installation, integration and commissioning of all transmission equipment required for the establishment, expansion or refurbishment of broadcasting stations/networks, including:

• Studio-to-Transmitter Links (STLs)

• Program Input Equipment (PIE)

• Broadcast transmitters

• Channel combining systems

• Broadcast antennas

The CMEE department is responsible for the provision and compliance of infrastructure and services for all terrestrial radio and television transmission equipment, including:

• Site establishment (including compliance with conservation/environment legislation)

• Accommodation 9building/container0 and access (roads) design and construction and compliance

• Mechanical (HVAC - Heating, Ventilation and Air-conditioning) system designs and installations

• Electrical supply/reticulation system designs and installations

• Construction of masts and antenna support structures