ITU-R S 725-1992 Technical Characteristics for Very Small Aperture Terminals (VSATs) - Section 4B1 - Systems Aspects《VSAT的技术特征》.pdf

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1、CCIR RECflNM725 92 = 4855232 0538623 367 Rec. 725 1 SECTION 4B: SYSTEMS ASPECTS - PERFORMANCE AND AVAILABILITY 4B 1: Systems aspects RECOMMENDATION 725 TECHMCAL CHARACTERISTICS FOR VERY SMALL APERTURE TERMINALS (VSATs) (Questions 23-114,5314 and 6914) (1992) The CCIR, considering a) that VSAT earth

2、stations have major features which are listed below; b) provisions of the Radio Regulations, CCIR Recommendations, and any relevant domestic regulation requirements; that VSAT earth stations operate on the fixed-satellite service, and should comply with the relevant c) for information broadcasting (

3、receive-only VS ATs) or for information exchange (transmitlreceive VSATs); that VSAT earth stations are usually implemented to form closed networks for dedicated applications, either d) be very high; that VSAT earth stations are generally directly installed on the users premises and their location d

4、ensity may e) that VSAT earth stations are often part of a network which has a “star” topology, consisting of a relatively large central station, called the “Hub” station, and many VSAT earth stations. However, some networks operate in a point-to-point or “mesh” configuration without a Hub; f) that

5、VSAT-to-VSAT transmissions usually take place through the Hub; g) that VSAT earth stations are usually unattended; h) also be used; that VSAT earth stations generally are monitored and controlled by a central facility. Local facilities may j) that VSAT earth stations usually employ digital transmiss

6、ion with a bit rate lower than 2 Mbits; k) circumstances larger diameters up to 5 m may be required; that the antenna diameters of VSAT earth stations are normally limited to 2.4 m, however, in-some 1) power must be limited for safety reasons; that VSAT earth stations usually are equipped with low-p

7、ower RF transmitters and, in any case, the RF m) that in the case where VSAT networks (either at the Hub or VSATs) need to be connected to public switched networks, such as a Packet Switched Public Data Network (PSPDN), a Circuit Switched Public Data Network (CSPDN) and an ISDN, etc., then the means

8、 for this connection (interfaces and protocols) and the possible compatibility problems could be the subject of new Recommendations; n regional use to reduce the effort of implementing VSATs, that several administrations are already applying simplified licensing procedures for their domestic or CCIR

9、 RECMN*725 92 = 4855232 0538624 2T3 2 Rec. 725 recommends that VSAT earth-station transmissions should comply for technical parameters with Recommendations 726, 1. 727 and 728; 2. 3. procedures: 4. Note 1 - The most commonly used FSS bands are 14/11- 12 GHz and 6/4 GE bands. Note 2 - The coding, mod

10、ulation and access techniques could be very diverse, corresponding to the most effective technologies. that the monitoring and control functions of VSAT networks should comply with Recommendation 729; that these Recommendations be used as guidelines for administrations to implement simplified licens

11、ing that the following Notes should be regarded as part of this Recommendation. Note 3 - TV distribution, using TVRO earth stations is not-dealt with in this Recommendation. However, the reception of video signals by a VSAT is often implemented. Note 4 - Recommendations for the interconnection of VSAT networks to public switched networks are under study.