Conformance
The following information is intended to assist companies wishing to introduce DTT products into the UK market. The requirements are based on:
- The MHEG-5 UK Profile Specification v1.06 *
- The BIS Digital Tick logo quality requirements
- DTG Functional Specification for Digital TV Recorders v1.1 *
Items marked * are available from the DTG Publications page by email. Registration is required.
The receiver testing carried out by DTG Testing Ltd is based on these requirements.
Please address any queries concerning this information to DTG Testing Ltd: testing@dtg.org.uk
Summary Table
| Test Suite | Current Version | Notes |
|---|---|---|
| RF performance table | As D-Book v6.1 | Target performance figures determined by DTG RF Sub-group |
| UK DTT SI/PSI | 3.0.0 | Mandatory requirements revised by DTG SI Test Suite Group |
| MHEG-5 | 4.1.0 | Version updated as of March 9th 2010 |
| Digital TV Recorder | 2.0.0 | Group 2 functionality is now required for Freeview Plus trade mark licence (9/2007) |
| Time exclusive services | 1.0 | |
| AFD | 1.0 | Test Card M can be used as an alternative |
| Basic subtitles | 1.0 | |
| Freeview HD SI/PSI | 2.0.0 | |
| Freeview HD MHEG | 2.1.0 | |
| Freeview HD Linear Services | 1 |
RF Performance
RF performance is crucial to satisfactory operation of a receiver and the following performance figures should be met or exceeded by all DTT products. There are two sets of performance figures: one set applies to measurements made on bit error rate (BER) and the other applies when the measurements are made using the criterion of the onset of visible picture impairments as the failure point. Since we are concerned with the viewer experience, it is the latter set of performance figures that are used.
A method for making the RF performance measurements is contained in the D Book.
DTG Performance Targets: Onset of picture failure
| Parameter | 2K | 8K | ||
|---|---|---|---|---|
| 64Q 2/3 | 16Q 3/4 | 64Q 2/3 | 16Q 3/4 | |
| RF Sensitivity: CH 21 | - 79.2 dBm | - 83.4 dBm | - 79.2 dBm | - 83.4 dBm |
| RF Sensitivity: CH 45 | - 79.2 dBm | - 83.4 dBm | - 79.2 dBm | - 83.4 dBm |
| RF Sensitivity: CH 68 | - 79.2 dBm | - 83.4 dBm | - 79.2 dBm | - 83.4 dBm |
| Performance with AWGN | 17.9 dB | 13.8 dB | 17.9 dB | 13.8 dB |
| Protection ratio for co-channel PAL | + 2.0 dB | - 2.0 dB | + 2.0 dB | - 2.0 dB |
| Protection ratio for N+1 adjacent channel PAL | - 37.0 dB | - 39.0 dB | - 37.0 dB | - 39.0 dB |
| Protection ratio for N-1 adjacent channel PAL | - 37.0 dB | - 39.0 dB | - 37.0 dB | - 39.0 dB |
| Protection ratio for Image channel PAL | - 48.0 dB | -.52.0 dB | - 48.0 dB | -.52.0 dB |
| Protection ratio for N+1 adjacent channel DVB-T | - 28.3 dB | - 30.3 dB | - 28.3 dB | - 30.3 dB |
| Protection ratio for N-1 adjacent channel DVB-T | - 28.3 dB | - 30.3 dB | - 28.3 dB | - 30.3 dB |
| Performance with short delay echoes | < 22.2 dB | < 19.5 dB | < 22.2 dB | < 19.5 dB |
| Performance with long delay echoes | < 22.2 dB | < 18.0 dB | < 22.2 dB | < 18.0 dB |
| Performance with a single echo | < 23.0 dB | < 22.0 dB | < 23.0 dB | < 22.0 dB |
SI Performance
The DTG SI/PSI Test Suite is used to determine conformance with the D Book requirements for SI and PSI processing in a DTT receiver, as set out in Section 8 of the D Book.
The current version of the SI/PSI Test Suite is v2.6 and the associated documentation is also v2.6.
The latest version of the test suite is available to all licensees from the DTG FTP site. If you do not have log in details for this site please contact DTG Testing immediately.
MHEG-5
For demonstrating the conformance of the MHEG-5 engine in a DTT receiver to the MHEG-5 UK Profile v1.06 (which has been a requirement since September 2006), the DTG MHEG-5 Test Suite v3.0.3 is used. 100% conformance is required.
The latest version of the test suite is available to all licensees from the DTG FTP site. If you do not have log in details for this site please contact DTG Testing immediately.
Widescreen Switching and Active Format Descriptors
Receivers must conform to section 3.4 and 3.4.2 of the D Book. This can be demonstrated through the use of:
- the appropriate video streams in Test Card M or
- the DTG AFD test suite.
In the latter case, a results sheet obtainable from DTG Testing should be used.
Time Exclusive Services
Receivers must handle the transition between the active and inactive states of a time exclusive service in an orderly fashion, presenting clean transitions into and out of video, audio and MHEG streams without presentation of any content or application not intended for the selected service. Conformance can be demonstrated by use of the DTG Time Exclusive Services test suite v1.0.
Subtitles
At the present time a basic subtitle test stream is available. This tests the colour look-up table, the positioning of subtitle rows on the screen and the timing offset between video and subtitle channels.