IEC 62028 pdf download – General methods of measurement for digital television receivers

IEC 62028 pdf download – General methods of measurement for digital television receivers
4.1General
4.1.1 Types of receivers
Digital television receivers are usually designed to be capable of receiving digital televisionsignals in a variety of ways.Examples are direct off-air reception or reception via cablednetwork in the VHFIUHF bands,and from satellite broadcasts in conjunction with an outdoorunit and a DBS tuner.Further digital signals can be delivered by the PSTN or ISDN. Thesignal will usually include information on the service supplied.
return path can be present for interactive TV applications.
For non-broadcast signals,the receiver may be used as a monitor to display pre-recordedvideo or home movies.
The methods of measurement described in this standard take into account various options.4.1.2 Peripheral connectors
Most receivers are provided with connectors for the interface with audio and video signals.Examples are the 21-pin connector described in lEC 60933-1 and lEC 60933-2 and the YICconnector described in IEC 60933-5.An example for a digital interface is described in theIEC 61883 series and an example for an analogue interface is described in IEC 61880.
4.2Basic common block diagram
4.2.1General
The basic common conceptual block diagram of digital television broadcasting system isshown in figure 1.
After audio and video signals are converted from analogue to digital, they are compressed.Data signals，which might include EPG(Electronic Program Guide), SI(Service Information),teletext program，etc.，are multiplexed with compressed audio and video signals. Afterchannel coding, the TS is modulated and transmitted via satellite, terrestrial, or cable.
ln digital television receivers，the transmitted signal is demodulated and sent to the errorcorrection block. After error correction, audio, video,and data signals are demultiplexed,andaudio and video signals are decompressed respectively.Audio and video signals are sent to aconventional (analogue)TV receiver (through the peritelevision socket) or to a display andloud speakers, and the data signal is sent to a conventional (analogue)TV receiver (throughthe peritelevision socket) or to data equipment.
4.2.2Satellite broadcasting system
When the digital television signal is transmitted via satellite，BPSK,QPSK and TC-8PSKmodulation formats are used.
4.2.3Terrestrial broadcasting system
COFDM, band-segmented OFDM and 8VSB modulation formats are used in the terrestrialbroadcasting system.
5 General notes on measurements
5.1 General conditions
General measuring conditions are according to 3.1 of IEC 601 07-1 .
5.2 Test signals
Test signals are common to all the transmission systems.
5.2.1 Video test signals
5.2.1.1 Still image video signal
The still image video signal shall be electronically generated.
a) Colour bar signal;
b) Ramp signal;
c) Modulated ramp signal;
d) Multiburst signal;
e) 5-steps signal.
5.2.1.2 Moving picture video signal
Under consideration.
5.2.2 Audio test signals
1 kHz sine-wave signal is used.
Frequency variable sine-wave signal is used for measuring frequency characteristics.
5.2.3 Data test signals
Under consideration.