GB/T 26683-2017General specification for digital terrestrial set-top box (English PDF)

3.1 Terms and definitions

The following terms and definitions as defined by SJ/T 11324-2006 apply to this document.

3.1.1 Acceptable error

The error event that was not corrected within the specified time during signal reception is less than a certain threshold.

3.2 Symbol

tD, MAX: This standard specifies the 0dB maximum echo delay that the receiver should be able to resist.

3.3 Abbreviations

The following abbreviations apply to this document.

AEF: Acceptable Error (AcceptableErrorFree)

C/N: Carrier-Noiser Ratio

ECM: Authorization Control Information (EntitementControlMessage)

EIT: Event Information Table (EventInformationTable)

EITp/f: EIT current/follow-up event table (EITpresent/folowing)

EMM: Authorization Management Information (EntitlementManagementMessage)

EPG: Electronic Program Guide (ElectronicProgramGuide)

FS: Full Scale (FulScale)

HDTV: High Definition TV (High Definition TV)

LFE: Low Frequency Enhancement Channel (LowFrequencyEnhancement)

MPEG: Moving Picture Experts Group (MovingPictuteExpertsGroup)

PID: Packet Identifier

PSI: Program Specific Information (ProgramSpecificInformation)

QAM: Quadrature Amplitude Modulation

RF: Radio Frequency (RadioFrequency)

SDTV: Standard Definition Television (Standard Definition Television)

SI: Business Information (ServiceInformation)

UHF: UltraHigh Frequency (UltraHighFrequence)

VHF: Very High Frequency (VeryHighFrequence)

Y/C: Luminance/Chrominance

4.1 Normal use conditions

The normal use conditions should meet the following requirements:

Ambient temperature: 5 °C ~ 35 °C;

Relative humidity: 25%~80%;

Atmospheric pressure: 86kPa~106kPa;

Power supply: 220V 10%-20%, [50 × (1 ± 2%)] Hz.

4.2 Graphic symbols for equipment

Graphic symbols shall comply with the relevant provisions of GB/T 5465.2.

Graphical symbols not defined in GB/T 5465.2, as specified by the product specification.

4.3 Appearance and structural requirements

The appearance of the receiver should be neat and tidy, and the surface should be free of defects such as emboss marks, scratches, cracks, burrs, mildew, etc. The surface coating should not be foamed or cracked. Fall off and so on.

Metal parts should not be corroded and other mechanical damage, and the infusion should not overflow.

The operation of switches, buttons and knobs should be flexible and reliable, and the parts should be tightened without looseness. The machine should have sufficient mechanical stability.

The characters and graphic symbols of the function shall be correct, clear, correct and firm, and the instructions shall be correct.

4.4 Interface Requirements

The interface requirements are shown in Table 1.

5.1 Overview

The block diagram of the terrestrial digital TV receiver is shown in Figure 1.

The terrestrial digital television receiver performs the conversion from the RF signal input to the terminal audio and video signal output. Input RF signal is solved Tuning, channel decoding, sending the output transport stream to the demultiplexing module for demultiplexing, and simultaneously outputting service information/program specific information (SI/PSI), electronic program guide (EPG) and other information, and the output basic stream is sent to the audio and video decoding module, decoded and sent to the baseband audio and video Output.

5.2 RF Demodulation and Channel Decoding Requirements

5.2.1 Overview

The performance and functional requirements specified in this clause refer to the requirements in the case of acceptable error (AEF). See the regulations on AEF Appendix A.

5.2.2 Frequency

5.2.2.1 Frequency range

The receiver shall be capable of receiving RF signals on all channels in the local VHF and UHF bands, VHF and See Appendix B for the UHF band frequency allocation table.

5.2.2.2 Signal bandwidth

Each channel has a bandwidth of 8MHz.

5.2.2.3 Frequency capture range

The receiver should be able to receive RF signals with a frequency offset of no more than ±150 kHz.

5.2.3 Working mode

The receiver shall be able to receive and correctly demodulate the working mode 1~ working mode 7 listed in Table 2, and apply it to the single frequency network.

The receiver should also support working mode 8~ working mode 10. The performance parameters of this standard are specified according to the mode in Table 2.

5.2.4 RF input port

The receiver shall have at least one RF input that meets the technical requirements of the VHF/UHF band RF input interface in SJ/T 11327-2006. The port connector impedance is 75ohm and the reflection loss should be greater than or equal to 5dB.

5.2.5 RF Loop Output Port

As an option, the receiver can have a VHF/UHF band RF loop output interface technology in accordance with SJ/T 11327-2006. Required RF loop output port. The port connector impedance is 75ohm.

The RF signal gain of the loop output should be between -1dB and 3dB. The signal loop output should be independent of the receiver receive status.

5.2.6 C/N performance requirements

The receiver C/N threshold should meet the requirements of working mode 1~ working mode 7 in Table 3, and it is applied to the receiver under single frequency network conditions.

The requirements of working mode 8 to working mode 10 in Table 3 should be met.

The Rice channel model and the Rayleigh channel model are shown in Appendix C.

5.2.7 Minimum received signal power

The minimum received signal power of the receiver in the receivable frequency range should meet the requirements of working mode 1~ working mode 7 in Table 4.

The receiver applied to the single-frequency network condition should also meet the requirements of the working mode 8 to the working mode 10 in Table 4.

5.2.8 Maximum received signal power

The receiver should work normally when receiving RF signals not less than -10dBm.

5.2.9 Suppress analog TV adjacent channel interference capability

Pre-receives terrestrial digital television signal power and analog television signal power from adjacent channels in case of acceptable error reception The ratio is C/I. The receiver's ability to suppress adjacent-channel (N±1) analog TV signal interference should meet the working mode 1~ working mode in Table 5.

For the requirements of Equation 7, the receiver applied to the single-frequency network condition should also meet the requirements of the working mode 8 to the working mode 9 in Table 5.

5.2.10 Suppress analog TV co-channel interference capability

Predicting the power of pre-received terrestrial digital television signals and the power of analog television signals from the same channel in the case of acceptable error reception The ratio is C/I. The receiver's ability to suppress the interference of the same frequency analog TV signal should meet the requirements of the working mode 1~ working mode 7 in Table 6.

The receiver applied to the single-frequency network condition should also meet the requirements of working mode 8~ working mode 9 in Table 6.

5.2.11 Suppressing the ability of digital TV adjacent frequency interference

Pre-receives terrestrial digital television signal power and terrestrial digital television signals from adjacent channels in case of acceptable error reception The power ratio is C/I. The receiver's ability to suppress the interference of adjacent-frequency digital TV signals should meet the working mode 1~ working mode 7 in Table 7.

The requirements applied to the receiver under single-frequency network conditions should also meet the requirements of working mode 8~ working mode 9 in Table 7.

5.2.12 Suppressing the ability of digital TV to co-channel interference

Pre-receives terrestrial digital television signal power and terrestrial digital television signals from the same channel in case of acceptable error reception The power ratio is C/I. The receiver's ability to suppress the interference of the same frequency digital TV signal should meet the working mode 1~ working mode 7 in Table 8.

The requirements applied to the receiver under single-frequency network conditions should also meet the requirements of working mode 8~ working mode 9 in Table 8.

5.2.13 Suppressing 0dB echo capability

When the receiver receives the two-path static 0dB echo RF signal, the maximum delay of the echo that the receiver should be able to resist should meet the work in Table 9.

The requirements of mode 1~operation mode 7 shall be applied to the receiver under single frequency network conditions and shall also satisfy the working mode 8~ working mode 9 in Table 9. Claim. When the echo delay is 30µs, the receiver C/N should meet the requirements of the working mode 1~ working mode 7 in Table 9, and apply to the single frequency. […]