A033

DVB Document A033

March 1998

Reproduction of the document in whole or in part without prior permission of the

DVB Project Office is forbidden.

DVB Project OfficeMarch 1998

DSNG Commercial Users’ RequirementsIntroductionDigital compressed television is attractive to satellite news gathering (SNG) operators for twomain reasons: compared to analogue transmission, the size and quantity of equipmentrequired for the uplink terminal is reduced, and the required transponder bandwidth isreduced. Both of these factors can have a marked influence on operating costs.

Use of digital compression for SNG is increasing, and it is appropriate for the DVB to definestandards for DSNG as soon as possible. The main benefit of doing this is to maximiseinteroperability, an important requirement for most satellite network and SNG operators.This document describes user requirements for DSNG.DefinitionRecommendation ITU-R SNG.770-1 proposes the following definition of SNG:

Temporary and occasional transmission with short notice of television or sound forbroadcasting purposes, using highly portable or transportable uplink earth stationsoperating in the framework of the fixed-satellite service.

The definition of the equipment is that it should be capable of uplinking the videoprogramme with its associated sound or sound programme signals, and capable ofproviding two-way co-ordination (communication) circuits. The equipment mayprovide for data transmission and should be capable of being set up and operated by acrew of no more than two (2) people within a reasonably short time (for example, onehour).

Transportable earth stations are also applicable for meeting the SNG requirementswhen logistics dictate use of such systems and the systems meet the basic functionalcharacteristics of the SNG systems.

Distinction between fly-away and transportable terminals will be made when necessary.Functional descriptionThe main features of SNG systems are essentially defined by the uplink characteristics.Operations with the SNG uplink terminal assumes that the receiving side is appropriatelydimensioned. To ensure system compatibility and efficient operation, it is necessary tostandardize equipment characteristics and operating procedures. Interoperability is clearlymost important to both satellite and SNG operators. Evidence of this is exists in the amountof effort put into interoperability trials by ISOG/INTELSAT in 1996 and continuing in 1997.(There has been discussion, particularly in a recent meeting of ITU WP4SNG, of mandatorytables that do not seem appropriate to DSNG. An example is tuning parameters in the NIT.On the basis that a compliant receiver may expect to see valid (if irrelevant date inmandatory tables, the Technical Module should be requested to consider whether guidelinesto or definitions of their content are appropriate).The functions of the SNG system are to:

- transmit with a minimum of impairments, a vision and associated sound or sound

programme signal;

- provide limited receiving capability to assist in pointing the antenna and to monitor

the transmitted signals, where possible;

- provide two-way communication channels for operation.2

uality of audio and videoQSNG links are by nature contribution links. The quality objectives are those of contributionquality as defined in Rec. ITU-R BT. 1121. There is no need to define a lower qualityobjectives, if it is understood that due to circumstances, possible relaxation are to beaccepted by the user.For DSNG links, the typical bit-rate used by fly-away and small transportable terminals areabout 8 Mbit/s, using MPEG-2 MP@ML.However for transportable stations use of MPEG-2 422P@ML (professional profile) should besupported. ITU-T Study Group 9 is presently preparing a draft recommendation on thatmatter. In this case, bit rates should be higher than 8 Mbit/s and lower than 34 Mbit/s.MultiplexingAdvantage should be taken of the flexibility of the MPEG-DVB multiplex to consider- the addition of a multiplex of sound channels for commentary purposes

- the multiplexing of many TV programmes originating from the same point (multifeed,

3-D applications, etc…).Co-ordination channelsCo-ordination channels should optionally be provided in line with Recommendation ITU-RSNG-771 which proposes:

1. that SNG earth stations should be equipped to provide two-way satellite

communication circuits which must be available prior to, during, and after, thetransmission of the vision and associated sound or sound programme signal. Thesecircuits will provide communication between the SNG operator, the satellite operatorand the broadcaster;

2. that two or more duplex circuits should be provided, whenever possible within the

same transponder as the programme vision and associated sound or soundprogramme signal;

3. that these communication circuits should be in compliance with Recommendation

ITU-T G.703, i.e. kbit/s.Cost of equipmentIt should be noted that SNG service is inherently different from a normal broadcastingservice where complexity and costs are affected by the transmitter side and every effort ismade to lower the cost of the receiver.

SNG is professional equipment and must be robust and small. The receiving installation isusually located at the broadcaster premises and is also highly professional equipment.Therefore, the total cost of the system and its operation should be considered, and not justthe receiver cost.

A non-negligible part of the overall cost of an SNG transmission lies in the requirements forsatellite capacity. Modulation techniques, additional to QPSK, such as 8-PSK and 16-QAM,should be investigated to optimise the efficient use of satellite capacity, whilst stillmaximising, as much as possible, interworking between different suppliers products.

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Regulatory constraintSNG is a versatile and flexible uplink. Attention must be paid to respect the existingregulations. These are not only international regulations (as published in the RadioRegulation of ITU) but also regional regulations. In Europe, SNG equipment should complywith ETSI ETS 300 327.

Furthermore, the satellite operator has also set up his own regulations. As an example, SNGstation in Europe should also be registered by Eutelsat and should comply with EutelsatStandard, L.

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