1、CCIR RECMN*722-1 92 4855232 0519357 994 Rec. 722-1 1 RECOMMENDATION 722- 1 UNIFORM TECHNICAL STANDARDS (ANALOGUE) FOR SATELLITE NEWS GATHERING (SNG) (Questions 13/CMT and 33KMT-) (1990-1992) The CCIR, considering a) operations and provides a valuable method of transmission for the rapid acquisition
2、and broadcasting of news events; b) that to facilitate the international coverage of news and to optimize the design of equipment, it would be desirable to adopt uniform technical standards for SNG, taking into account the possibility for interference to other satellites and systems; that Satellite
3、News Gathering (SNG) using portabIe transmitting earth stations is essential for broadcast Cl that SNG requirements include various communication and transmission support systems and that it is necessary to provide, preferably 011 the same satellite transponder, auxiliary signals for the operation o
4、f SNG euui SLtiOns; d) provisions of the Radio Regulations, and any relevant domestic regulation requirements; e) ,antenna characteristics; that SNG earth stations operate mainly in the fixed-satellite service, and should comply with the relevcant that SNG transmissions should conform to certain tec
5、hnical criteria with regard to off-axis e.i.r.p. and other f, that the technical characteristics of an appropriate identification signal should be specified, recommends 1. Annex 1; that SNG earth-station transmissions should comply with the uniform technical standards as described in 2. Recommendati
6、on 77 1. that SNG earth stations equipped to provide two-way satellite communications circuits should comply with ANNEX 1 Technical parameters applicable to SNG terminals 1. General performance An SNG terminal must be able to be rapidly deployed, to transmit (with a minimum of impairments) vision an
7、d associated sound or sound programme signals, to provide hited receiving capability to assist in the pointing of the antenna and to monitor (where possible) the transmitted signals, and to provide two-way cornunications for operation and supervision. SNG terminals consist of the following main unit
8、s: - - - - antenna and feed system with polarization adjustment; antenna mount with azimuildelevation adjustment; high-power amplifier (HPA) for visionhound and auxiliary (voice/data) communication channels; receiver unit in order to assist antenna pointing; 7- - CCIR RECMN*22-3 92 m 4855232 0539358
9、 820 m 2 Rec. 722-1 - - two-way voiceldat communication equipment; - system local/remote control paiiel; - optional power generator. baseband/modulation equipment Md IF to RF upcouverter; 2. Transmission performance requirements The baseband signal shall be transmitted with a minimum of hpairment. 2
10、.1 Video signul: refer to Recornmendaticti 567-3 (Dsseldorf, 1990). (Requirements for random noise may be rekaxed by the user.) SNG for analogue television broadcasting Audio signal: refer to Recommendation 505-4 (Dsseldorf, 1990). (Requirements for random noise may be relaxed by the user.) 2.2 Ruse
11、hund: as per Recomendatioti 504-2 (Geneva, 1982). (Requirements for random noise may be relaxed by the user.) SNG for analogue sound broadcasting 3. FW performance requirements 3.1 Off-mis e.i.r.p. density Shall comply with Recommendation 524 or the satellite operators requirements, whichever is mor
12、e stringent. 3.2 Polarization discrimination Some satellites use overlapping channels with orthogonal polarization discrimination. The cross-polarization design for linearly polarized antennas should be better than 30 dB within the -1 dB points of the main axis of the beam and 25 dB elsewhere. 3.3 E
13、.r.p. The necessary e.i.r.p. of the SNG terminal depends on the required uplink carrier-to-noise ratio C/N and satellite GR. However, e.i.r.p. is often limited by the off-axis e.i.r.p. density limits as indicated in 0 3.1. 3.4 Necessary RF bandwidth The necessary RF bandwidth for SNG can be determin
14、ed by taking into account the signal format, the required signal-to-noise ratio, the e.i.r.p., the number of associated carriers for auxiliary circuits and the available baudwidth of the transponder. SNG for unulogue television broudcusting SNG for unulogue sound broudcusting 17.5-36 MHz 100-300 kHz
15、 4. Modulation characteristics The equipment providing the modulation shall include: video lowpass filter which can be bypassed, switchable pre-emphasis networks, selectable IF bandpass filters, one or more frequency agile sound subcarrier modulators, dispersai generator where required, IF power con
16、trol, and a linear video FM modulator. The d.c. component of the video signai should be preserved to take advantage of the available bandwidth. - CCIR RECMN*722-3 92 m 4855232 0539359 767 m I Rec. 722-1 3 The upconverter should be frequency agile with a suitable frequency step size for the satellite
17、 system used. The phase noise and frequency stability should be adequate to allow upconversion of the auxiliary communication signals if necessxy. To preclude accidental interference to other traffic on the same satellite, it is recommended that the upconverter be equipped to inhibit transmission in
18、 the event of off-frequency operation. All controls such as main deviation, operating carrier frequency, subcarrier frequencies, subcarrier deviation, pre-emphasis, dispersai, power adjustment, etc., should bc readily accessible. It may be desirable to provide remote access to the power on/off and r
19、aise/lower controls from the satellite operators communication control centre or from the broadcasters premises. 4.1 SNG for analogue television transmission Mociidutioti: FM Deviutiori: 8-28 MHz pecak-to-pezak for 1 V peak-to-peak basebmd signal input Setue of moddution: Positive (positive-going vo
20、ltage for positive-going frequency) Associuted audio: Subc,urier or sound-in-sync (SIS) techniques may be used 4.2 SNG for analogue soutid transmission Modirlutioti: FM Deviutioti: 50-300 kHz peak-to-peak for modulating signal of 1 kHz at +9 dBmOs Pre-emphusis: 75 ps Energy dispersal: Fixed/adaptive
21、, depending upon requirement to meet Recommendation 524 (see $ 3.1) 5. Identification signal Tr,ansmitted by suitable means (method to be further studied). 6. Antenna and feed system The antenna should be small in diameter, lightweight, easy to assemble and easy to transport. The antenna radiation p
22、atterns in the plane of the orbital arc at the earth station location are such that the off- ,ais radiation will comply with 3.1. The cross-polarization discrimination shall comply with $ 3.2. Repeated assembly and disassembly of the antenna shall not affect the radiation xid cross-polarization disc
23、rimination performance. 7. Auxiliary communications (see Recommendation 77 1) SNG uplink signais are often originated from remote areas. In these cases, communicatiou using the public switched telephone network (PSTN) is difficult or impossible. The SNG terminal should therefore be equipped to provi
24、de ail of its own communications through the satellite to both the satellite operators communication control centre and the broadcasters premises, with the following facilities: between SNG terminuls und the sutellite operators communicution control centre: a minimum of one, two-way narrow-band, voi
25、cedata communication circuit. This should be available at all times and not be restricted to the transponder booked times. It is desirable that these circuits are provided in the same transponder as the programme vision and sound; - -_ - - CCIR RECMN*722-3 72 W 4855232 0537360 487 W 4 Rec. 722-1 - b
26、etween the SNG terminal und the broudcusters premises: four (4) two-way, narrow-banc., voicel - engineering coordination; - programme-related data transmission: - more than one broadcaster; - more than one language. 7.4 Communication channels for SNG (sound) For SNG sound broadcasting, many of the c
27、oncepts contained in Q 7.1 to 7.3 apply. The minimum requirements for an SNG (sound) terminal are as follows: - one two-way voice communication circuit between the SNG terminal and the satellite operators communication control centre; two two-way voice/data communication circuits between the SNG ter
28、minal and the broadcasters facilities. - 8. Video/audio/RF monitoring equipment To allow the SNG terminal operator to properly set up the terminal, monitoring equipment is essential. To simulate the satellite tr,uisponder it is advantageous to provide a loop-test translator and videohudio receiver t
29、o verify the performance of the uplink equipment. CCIR RECMN*722-1 72 4855212 0517361 315 Rec. 722-1 5 Due to the low Gf of the SNG antenna system and the particular operational configuration of the satellite system, it is riormally not possible to inonitor the transmitted video and audio signals at
30、 full quality. In such cases, nwow IF bandwidth monitoring of the satellite receive signal may provide Limited monitoring capability. However, Gf should be adequate for cointnunication channels. Y. Other design considerations The SNG terminal can be designed with all the equipment next to the antenn
31、a or with the HPA at the antenna and the other equipment located some distance (e.g. less than 50 m) away from the antenna. The latter option, which is operationally preferable, allows the SNG terminal to be operated (and monitored from indoors after antenna alignment. The HPA must be located as clo
32、se (as possible to the antenna to minimize the waveguide losses. The system should be designed to accept redundant high power amplifiers. System interconnections must be reduced to a minimum to ailow quick and easy Set-up under all weather conditions, al1 external connections must be waterproof. It
33、is desirable that the SNG tenninal can accept a power input of 100-250 V/50-60 Hz, and that the power consunption should not be greater than 2.5 kVA. The design of the shipping cases should dlow the terminal to be operated in direct rain with the lids reinoved. The cases must provide a controlled en
34、vironment for the electronics to allow proper operation during extremes of both high and low temperatures. The SNG tenninal must be designed to offer the maximum possible safety to the operator. 10. Additional technical parameters Considerations on pointing accuracy and spurious emission to be developed.
