Exceedance Curves for Climatic Zone N. Exceedance Curves for Climatic Zone P. Exceedance Curves for Climatic Zone Q Performance Comparison of Protocol Access Techniques Summary of Requirements. Calculated Traffic Intensity in Erlangs. Number of Minutes-Traffic Per Destination Calculated Number of Erlangs per Destination Data Transaction and Character Traffic Estimate Summary of the Network Traffic Calculation Required Number of Channels Satellite Series.
Regional Orbital Locations Hours in Outage per Availability Percentage. Capacity Cookbook Assumptions Link Types and Networks for Telephony Service Network Dimensioning Summary Table Containing the Site Locations. To be completed by contractor. Environmental Conditions. Refer to the above drawing. With a space segment reliability exceeding Our Customers 9.
Guide To Getting Connected VSATs provide users with services comparable to large gateways and terrestrial networks, at a fraction of the cost. A typical VSAT consists of communications equipment and a small antenna with a diameter less than 3. VSAT networks provide users with simple equipment that requires minimal installation and repair. They are easy to operate and simple to troubleshoot. VSAT installations do not require staff with extensive expertise. The antenna and ODU provide the radio frequency conversion and amplification for the satellite uplink and downlink.
The power requirement for each VSAT is low and in some cases solar cells supply the power. Because of its simplicity, a VSAT installation takes only a few hours and the terminals are ready for service. The hub contains the intelligence to control the network operation, configuration, and traffic. The hub also records the performance, status and activity levels of each VSAT terminal. Databases generated by the hub are also used for billing purposes. Refer to Figure The RF equipment at the hub can be packaged in an outdoor unit to reduce the transmission line losses.
If high reliability is needed, then indoor equipment with proper backup and switchover devices will be needed. The VSAT interface equipment controls and supervises the network operation, and consists of modulators, demodulators, and baseband processors.
The performance achieved by VSAT networks surpasses the performance of terrestrial networks in terms of availability and quality. Typical availability figures surpass To clarify the cost effectiveness of VSAT: Suppose that a corporation has a data network in which branch offices, each with individual LANs, that are linked to a LAN at the corporation headquarters. The branch offices are spread around the country and compose a network as shown in figure The maximum data rate is When considering dedicated lines, the corporation found the following.
By contrast, for a VSAT network, the corporation discovered the following. Figure shows a specific example of cost comparison between VSAT services and the total cost of terrestrial alternatives. In this example, VSAT services are less expensive than dial up and dedicated lines. Moreover, after recovering the capital costs, the operational cost of VSATs shrinks to only satellite and staff expenses. In addition to cost savings, a VSAT network provides the customers with: T full control over the entire communications network; T insensitivity to the distance between nodes; T faster data response time; 1 Hub equipment costs.
Users can accommodate virtually any service with confidence that, in the long term, the VSAT network will be more economic than existing terrestrial media.
In star topology, each VSAT terminal transmits and receives only to the hub. See Figure a. The majority of VSAT networks use star topology because the large antenna gain at the hub optimizes the use of the space segment and minimizes the size of the VSAT terminal. A hub must control the communication set up and tear down process, but need not be involved in carrying traffic.
Sometimes, a VSAT terminal is equipped with the network management and control equipment, and the network is said to operate hublessly. Mesh technologies are well suited for applications such as voice that cannot tolerate delay.
Hybrid topology allows a group of VSAT terminals to communicate in mesh topology while others communicate only in star topology. This topology is useful for networks in which certain terminals have larger traffic demand between themselves than the other terminals.
The terminals with higher traffic demand can be accommodated in mesh to reduce the expense of extra equipment at the hub, and satellite resources required for a double hop. The rest of the network can communicate with any of these larger terminals or each other via a star topology. Ku-band requires transmission at 14 GHz and reception at GHz. Which frequency band is better? There is no direct answer to this question.
KU-Band vs. Signals susceptible to fading during rain. Attenuation range from 6 to 10 dB. Signal less susceptible to rain fading. Rain attenuation in the range of 0. Needs slightly larger dishes when compared to Ku- band.
Higher transponder power Not available every where in the world Widely available Lower transponder power Narrower beam coverage Wider and even global beam coverage Less terrestrial interference Higher likelihood of terrestrial interference Proper network engineering can minimize the effects of Ku-band signal fading during rain.
High network availability is available at both Ku- and C- band. VSAT operators prefer Ku-band to C-band because it allows them to reduce the capital investment by using smaller antennas. Voice, video, or data is transmitted from a central station and broadcast to VSATs within the satellite beam coverage.
It might seem that the signal is subject to access by unauthorized VSATs; however, the broadcaster can control access to the information to allow only the desired group of VSATs to receive the information. Examples of broadcasting applications include: T price lists, inventory records; T stock, bonds, and commodity information; T weather bulletins, sports scores, news and press releases; T sound broadcasting; T digital video for conferencing or entertainment; and T Internet distribution.
See Figure For example, the entertainment industry uses pay-per-view PPV channels for special programs and events. Subscribers can see the program list and request, via the PSTN, access to a particular program. The program provider will download the access authorization to that user at the start of the requested program.
Internet broadcasting uses a similar approach to download information from web sites to end users. Upon validation of the request, the ISP downloads the requested information via a high-speed satellite channel. The end-user receives the downloaded information using a receive-only VSAT. Furthermore, service providers can piggyback Internet traffic on to existing digital TV carriers, thereby cost effectively utilizing existing infrastructure. Interactive or two-way applications: Interactive applications allow two-way communication via the VSAT terminal.
The applications can be bundled in four categories: interactive data service, interactive voice services, interactive video services, and high-speed, point-to- point services. Interactive data services: This category consists of an application involving an inquiry from one terminal and a subsequent response from another terminal.
Some examples are: T file and batch transfers for financial institutions, stock brokers, and banks i. Interactive voice: This category consists of the following voice services. Voice Applications Examples. A VSAT terminal is flexible enough to either handle a single telephone line for very low traffic levels, or several lines which, in turn, can be connected to a local PBX. The telephones can be wireless pay phones powered by solar cells or fixed wireless phones for domestic or business users.
The coverage radius for the WLL unit is typically 12 to 20 miles. This application makes rural telephony affordable with per-line costs of about 1, to 1, dollars. This configuration allows good quality in the outbound, and rate savings in the inbound. These networks typically have a small number of VSATs, in a point-to-point configuration, and can handle up to 1.
VSAT networks remain competitive and more effective than terrestrial solutions. The performance of a network is directly affected by the protocol used, and a good network design will use protocols that achieve the highest network performance, for the specific application, while minimizing required satellite bandwidth.
FDMA, the simplest access technique used by VSATs, allows the network to share satellite capacity by using a different frequency assignment for each carrier. As pictured in Figure a, VSAT terminals share the allocated capacity by transmitting their carriers at different frequencies. The carriers need not have the same power or bandwidth, but their sum must be within the allocated capacity. TDMA, the second access technique, allows users to access the allocated capacity in a time-shared mode.
Each VSAT transmits in bursts during set time slots. As indicated in Figure 3. In CDMA, a pseudo-random sequence encodes the original signal by spreading the signal over a larger bandwidth. To restore the original signal, the receiver correlates the composite input with the original encoding sequence stored in its memory.
Most VSAT terminals carry thin traffic making it inefficient to permanently assign capacity to them. By using a network access protocol, efficiency improves. Network access protocols assign capacity to a particular terminal based on traffic demand. Capacity is requested by the VSATs and is assigned by the network controller at the hub, either on-demand, at random, or permanently. In an on-demand assignment protocol, the VSAT requests the hub to dynamically pre-assign capacity, either time slots or carriers, before transmitting.
This process implies a slower initial response time, but is highly efficient during data traffic transfer. In a random assignment protocol, each VSAT transmits its traffic when it is received from one of its data ports.
This mode offers a very short response time, but the traffic handling capability of a carrier is limited to avoid overloading the carrier. In a permanent assignment protocol, the VSAT has permanent access to a small portion of the satellite capacity.
In this case, the carrier rate limits the traffic a VSAT can carry. However, when the carrier is not used by the VSAT to which it is assigned, the capacity is wasted. There are two commonly used satellite access protocols that use a combination of on-demand assignments, random and permanent, assignments to improve the multiple-access efficiency.
Information for many different VSATs is time division multiplexed onto a single outbound carrier. Multiple outbound carriers can be used for larger sized networks.
See Figure b. Before data can be transported with these protocols, the data must be packetized. Each packet contains an address that identifies a data terminal within the VSAT network domain. A receiver, either the VSAT or the hub, acknowledges successful receipt of any packet. If noise, a collision or other impairment corrupts a packet, it will prevent the packet from reaching its destination.
Typical BER threshold values are for digital voice links, and for data links. Select the curve that corresponds to the outer code that you want to use. Calculate the BER-in value X- axis. The result will be:. Uplink and downlink margins See Figure The values of the uplink and downlink margins depend on the availability target that is being planned. The margins define the link availability. Moreover, the addition of the margins to the threshold allows the link to operate with higher quality during clear sky conditions.
How are the margins defined? Margins are very important, especially in Ku-band, because they counter the effect of rain attenuation and allow the link to be available for longer periods of time. Adding margins allows the network to achieve the availability target set forth during the planning process. To understand margins, rain attenuation must be understood first. Rain absorbs RF energy.
The amount of absorbed energy is directly related to the drop size and intensity of the rain, as well as the operating frequency, elevation angle, size of the clouds, and the geographical region. The heavier the rain, the higher the attenuation. Using meteorological data, attenuation is calculated statistically for a region. The meteorological data consist of statistical information collected over several years.
It includes the rain pattern in millimeters per day as a percentage of the time. This statistical information can be used to calculate the rain attenuation pattern results, and presented in an attenuation chart, called the Attenuation Exceedance Curve. The attenuation exceedance curve represents the maximum attenuation calculated for a given percentage of any year.
For example, Figure 6- 13 shows the maximum attenuation for an uplink between Rio de Janeiro and a satellite located at Figure shows that The remaining 0. To counter this attenuation, the margins will need be at least 7 dB for Ku-band and 0. Several methods have been developed to calculate rain attenuation. All the methods make use of the database of meteorological data collected by the ITU. These climatic zones describe the rain intensity in the globe from the arctic to the tropics, and are labeled zones A through Q.
Percent Time Ordinate Exceeded. To calculate the rain attenuation, the reader can use the curves provided in Appendix B. Appendix B contains the exceedance curves for all climatic zones. The curves were calculated assuming an antenna with an elevation angle of 20 degrees in and located at meters above the sea level. Number of carriers Refer to Figure Returning now to the LST software, it is necessary to enter the number of identical carriers for each link type.
Click on Done to proceed. The two options are shown in Figure An interpretation of the information in the summary table follows. A negative value means the e. Total e. Utilized This value shows the total satellite e. Available Indicates the total e. Margin The difference between used and available e.
Alternately, additional traffic can be supported in the lease resource. If the link is limited by bandwidth, the PEB represents the actual carrier allocated bandwidth. It may happen that the e. The bandwidth margin will be zero. There are several steps to take to reduce the satellite-leased bandwidth, all of which can be tested by reiterating the calculations in the LST4x spreadsheet. Factors Affecting the Required Satellite Bandwidth in Any Network The factors that affect the bandwidth in any network are: antenna sizes, carrier parameters, BER threshold, offered traffic, call loss probability, efficiency of the multiple access protocol, and satellite link availability.
It defines the e. If the application can tolerate additional delay, include the Reed Solomon RS outer code, or choose sequential decoding rather than Viterbi decoding for FEC. However, RS cannot be used for bursty traffic. In voice systems, for example, a threshold BER of is considered adequate, while for data users a typical value is Offered Traffic This parameter affects the number of satellite channels required for a given network.
Its value depends on a number of factors including the traffic pattern during the peak busy hour PBH and the tariff structure for the service. Reducing the offered traffic reduces the number of carriers and, therefore, the required bandwidth. However, in many cases, where operators introduce new services, the tendency is to underestimate the traffic demand.
Consequently, care should be exercised in traffic dimensioning because underestimating the traffic will lead to congestion.
Efficiency of the Multiple-Access Protocol For data networks, rather than reducing the offered traffic, the VSAT service provider can select a multiple-access protocol with higher efficiency. Greater efficiency requires fewer carriers. Voice Compression minimizes bandwidth requirements. DAMA systems use voice compression without compromising the voice quality.
Voice Activation. VOX reduces the required bandwidth and, in pools of channels or more, VOX provides a net reduction of satellite power utilization of up to 2. Typical voice activity factors range from 50 percent to 75 percent. Call Loss Probability This factor applies to voice networks and defines the number of call attempts that will be dropped during the PBH.
If the call loss probability is high, the number of channels will be lower than if the probability is low. Satellite Link Availability An easy way to reduce the satellite bandwidth is by reducing the rain margin. Though it reduces the satellite bandwidth, it also reduces the network availability.
Table contains a calculation of the number of hours in outage in a year as a function of the availability. DPC increases the e. However, implementing DPC increased the overall equipment cost. It is important to realize that all these factors interrelate. For example, link availability can influence the call loss probability and will add to the blockage.
The VSAT service provider must carefully consider the selection of these parameters. Some users of LST may want to consider changing the Defaults to reduce the bandwidth. The Defaults option allows users to change values like the intermodulation, adjacent satellite interference ASI , terrestrial interference, and transponder backoff, among others.
The preset values presume the worst case scenario and will ensure that the link performance meets the requirements under the most stringent conditions. To perform the discussed changes, go to the menu and select Enter Data, and select Update, and follow the screen menus. BWB File.
BDT File. This method is more efficient and only saves the users input data. BWB files. BDT file name. To calculate a bandwidth using the cookbook follow the procedures below:. If the rate is not available, calculate it by scaling the 9.
Round the value to the nearest KHz. The antenna sizes will be 1. Therefore the value for 64 can be scaled to by multiplying them by 6. Assuming that Spot beam 3 provides the coverage, refer to Table 6- 19 , the results are as follows. Efforts to standardize the VSAT market at the level of applications and protocols have, by enlarge, been unsuccessful. Each VSAT vendor offers a proprietary product that operates as a closed network. However, there are several regulations that apply to the radio portion of VSATs and these are reviewed in this chapter.
This Section presents an overview of the major issues. Antenna diameters are typically no more than 2. It is usually assumed that digital modulation is used, that FEC coding is applied, and always beneficial, and that the information bit rate has a range from 4. Low-power RF transmitters are used, consistent with economy and safety. Recommendation S. Several drafts of the new recommendations have been prepared for future approval.
The limits set forth in Recommendation are summarized in Figure 7. The on-axis spurious limit is 4 dBW in any 4 KHz band. Limits for Off-Axis Spurious Emissions. This ratio must be maintained within the 0. For angles away from the 0.
These requirements are covered in Rec. Only Ku-band systems are covered in S. For networks operating in regions with satellite separation of 2 degrees, the off-axis e. To achieve this reduction in off-axis e. The use of type-approved antennas for VSAT networks is strongly encouraged.
The use of such stations avoids the time and cost of antenna verification testing on every antenna in the network. See IESS and These case studies also demonstrate some of the technical tradeoffs necessary when translating user requirements into a network design.
Each case study presents the user requirements, the service provider's concerns, design trade-offs, and the results. Rooftop antennas are needed for each branch office. The minimum services requested are: financial account inquiries, batch file transfer, electronic mail, and remote printing. The service requirements are detailed in Table Traffic will be divided equally between each of the branch offices. The design will begin by considering the star topology and how Ku- band will comply with the stipulation of rooftop antennas.
The initial antenna sizes will be 1. To minimize the bandwidth requirement, the availability will be Now, we need to convert the information in Table into bits per seconds and carriers. Table shows the result of converting the transaction during the PBH into bits per second. To calculate the number of carriers, we needed to make some traffic calculations.
The following assumptions will be used for the calculations. These carriers are calculated following the guidelines given in Chapter 4. Notice that, even though the file transfer protocol FTP provides a better efficiency, the file transfer still drives the network size by consuming 87 percent of the inbound capacity.
Satellite bandwidth to lease: 0. Carrier allocated bandwidth: 0. The actual power needed for the VSAT link at its initial stage is about 1 watt. Several parameters affect equipment size, network performance, and satellite bandwidth. Those parameters must be selected after a trade- off. A brief discussion follows. As expressed before, the network size in the inbound traffic direction is driven by the file transfer traffic.
The leased bandwidth can be reduced to 0. What if the client is willing to reduce the BER threshold to 1 x but needs an availability of The availability is expressed in rain margins; by increasing the availability to The change results in an increase in the leased bandwidth39 to 1 MHz. Notice that the clear sky BER will be better than 1 x What if the hub antenna is 3.
If the antenna size changes to 3. We are reducing from Notice that we assumed the conditions established in the previous paragraph. The network will provide 2 to 4 channels per site, and will grow from 75 nodes to nodes over a 2-year period. Remote to remote connectivity will be allowed using double hop. The double hop channels will be switched at the station in city A. In addition, 10 channels are required for intercity traffic between cities A and B. The central station at City A will provide the network management and control facilities.
The network must employ digital voice at 9. The design will consider VSAT dishes of 1. Figure presents a block diagram of this network. To reduce the space segment requirement, voice activation will be used with an activity factor of 50 percent. The threshold BER is selected at because this is a voice-only network intended to provide an economical service. The links between large antennas will have an availability of The LST calculation gives the following results.
The LST results indicate that the downlink power margin is 3 dB. This positive margin indicates that the network is bandwidth-limited, and that the bandwidth can only be reduced if the number of required satellite channels is reduced. To reduce the bandwidth, the VSAT service provider could consider reducing the erlangs per line.
The reduction will cut the number of carriers and the bandwidth as a result. However, customers may not accept the resulting blockage increase. The size of the antennas can be reduced to 3. This takes advantage of the fact that the network has power margin in the downlink. The power requirement at the 3. VOX can be used to further reduce the satellite bandwidth on power- limited networks. However, because this network is bandwidth-limited, changing the VOX values will not reduce the satellite resource.
BPSK would be needed only if the on-axis emission constrains are exceeded. The user requirement is to extend Internet access to 12 sites in Eastern Europe. Each site will have access to the European backbone via asymmetric links. Of particular significance is the asymmetry of the link, the size of the central antenna, and the rate of the outbound carrier. The BER threshold is Satellite Earth Station Hub Site. The link must have an availability of The services will be multiplexed in the outbound carrier, and the asymmetry makes the service highly cost effective in comparison with terrestrial alternatives.
The LST gives the following results. Satellite bandwidth to lease: 3. Number of carriers: 1 Inbound 12 Outbound. So by choosing sequential decoding the VSAT service provider can reduce the space segment to 2. The clear sky BER will surpass 1 x The charges will be carrier-based. The space segment cost will be reduced by 16 percent compared to the lease cost. The service provider need not engineer the link. The equipment size remains within the previously calculated values.
The enhancements are the multicasting protocol, the quick start algorithm, and the asymmetrical links. These enhancements improve the performance of the Internet. These initiatives are undertaken to help the industry and service providers cope with the enormous increase in Internet traffic by ensuring that the Internet operates smoothly over satellite.
Finally, the adoption of the extension of IBS to VSATs was the last stitch needed to provide customers with off-the-shelf and standardized solutions that allow swift implementation of services. List of Acronyms Page - Exceedance Curves Page - These curves are intended to provide a rough estimate for the rain margins in C- and Ku-band. Select the appropriate ITU climatic zone for your location from the attached maps.
Select the appropriate curve for the climatic zone and frequency band. Select the appropriate rain margin based on the availability target.
See Figure B El Salvador is located in climatic zone P. The exceedance curves for climatic zone P are provided in Figure B Finally, if Ku-band is chosen, the rain margin values can be calculated from the upper curves. It is important to note the difference in the uplink and downlink curves, and in the values for the different frequency bands. Attenuation dB 4.
E xc eed ed. Attenuation dB. Figure B Attenuation dB 6. Attenuation dB 6 4. Attenuation dB 6 8. Attenuation dB 10 6 8. Attenuation dB Exceedance Curves for Climatic Zone L. Attenuation dB 8 12 10 6 8.
Exceedance Curves for Climatic Zone M. Attenuation dB 12 15 10 8 10 6. Attenuation dB 15 Attenuation dB 20 This appendix gives an overview of the issues that need to be considered in preparing these documents. It must include the objectives of the project and a brief description of the work. A list of details to consider when preparing the SOW follows:.
Use language that is as accurate as possible and avoid contradictions. Make certain that every piece expected from the contractor is accurately described, and that the responsibility for each task is clearly defined. The writer must realize that this document will be read and interpreted by people of various backgrounds.
It is important to avoid ambiguity, to not overlook details, and to not be repetitive. Be specific. It is better to WKH 5 3 concentrate on required end-results, rather than on methods or work process descriptions. Specifications should stress quality, and be concise. Avoid unnecessary design and schematics, or information that is difficult to update.
Do not over-specify because this can inadvertently reduce the number of vendors who will submit proposals. Include the hub location and geographical coordinates for each site. Describe the satellite to access. See Table C Provide as much traffic information as possible and include the most recent forecast to analyze the network potential growth.
Refer to Tables C-2 and C Include what you expect in terms of: quotation format, review meetings, progress reports, test reports, in-plant testing, and documentation.
The compliance should be indicated in a table for all systems and sub-system of the RFP. Any non- compliance must be indicated by the contractor along with proper explanation. Indicate which documents are to be delivered, and when. A typical list of documents include, network manuals, network operations manuals, equipment manuals, cabling manuals, test reports, test procedures, and equipment layout.
Indicate the period and state the response time you expect to fix a failed system or equipment. For example, the purchaser may provide a building or antenna foundation.
These schedules must be indicated. Request that the contractor provide costs for the options separately. Include the number of trainees, expected duration, training location, language and required training material. Onsite training will allow the largest number of staff to be trained. Indicate a preference for hour or online support. Some companies contract on-site technical support during a period of time, e.
NODE 1 2 3 4 5 6 TOTAL 1 0 2 0 3 0 4 0 5 0 6 0 Total 13,, Table C The total number of channels in the right-most column will be used to calculate the total network requirements in terms of leased bandwidth, antenna sizes, and number of channels. Convert this information to number of channels using the guidelines in Chapter 4.
A similar format MUST be followed for all chapters of the specifications. Note to the user: While you are required to understand the basics of calculating the network size, the ultimate responsibility for delivering a network that is properly sized resides on the bidder or manufacturer. Therefore, make your estimates for the network size but do not try to calculate the network for the bidder. Rather, provide as much information on the applications as you can collect.
A design life of [ 15 ] years is established as an overall network objective. The overall design objectives and the operation and maintenance philosophy must ensure a minimum equipment availability of [ Safety devices must be implemented so that false operation of any control does not entail damage to personnel or equipment.
Safety shields must be provided over all moving parts in which personnel could become entangled or caught. This provision includes ladders and stairways. All cabinets, racks, and chassis of all motors and generators, all external metal parts, meter cases, control shafts, and adjusting devices must be grounded. Cautioning notes and appropriate labels must be provided where voltages are in excess of V peak A. Earth devices rods, etc.
Power cables must be segregated from cables carrying communications and control signals. Cabinets and RF connections and all RF enclosures must be designed to protect personnel from radiation hazards. TXLSPHQW Suitable protection devices must be provided in such a way that failure of any component or unit does not entail failure of other components or units. Provide a complete grounding system for lightning protection, safety of personnel, and suppression of radio frequency interference.
The value of Earth resistance must be [10 Ohms] for lightning protection and less than [1 Ohm] for system grounding. There must be isolation between the lightning and power grounding systems. The bidders must ensure that the selected locations will not be affected by RFI.
If a location is affected by RFI, the bidders must provide alternate suggestions for consideration. Chassis and Drawers: All drawers and chassis must permit frontal access to the components, wiring, connectors, and test points of any unit. Plug-in Units and Modules: The use of plug-in replaceable units or modules is preferred.
Sufficient test points must monitor all circuit parameters. Spare space: All cabinets, racks, consoles, trenches, cable trays, etc. Additionally, all outdoor equipment and surfaces must be painted or galvanized to avoid corrosion. The cable trays and their accessories must be protected against corrosion.
The documentation must be offset printed, written in plain [ English ], and contain all pertinent descriptions of all equipment in the network. The bidders must provide at least [4] copies of all the documentation. The bidders must provide a training program consisting of theoretical and practical hands-on instructions to accomplish the following:.
The system training program must address the following objectives. The system operation and maintenance training program must address the following basic requirements. The test must demonstrate that actual performance meets specifications with a sufficient margin of error. All necessary test equipment must be provided by the Bidder, who must be able to demonstrate its correct calibration.
Note: The acceptance tests must demonstrate that the subsystems, equipment, and units have not suffered from its transport and final integration on-site, and that they comply with the SOW and planned applications. Final acceptance tests must include live applications demonstrations via the VSAT network. The bidder must guarantee that major faults will not occur for a minimum period of [12 months] after successful completion of the provisional acceptance.
Any replacement, within the stated timeframe must be done free of charge. The proposal must contain a detailed description of the methodology to be used to manage the implementation of the VSAT network.
The panel must include alarms, remote controls, meters, and monitoring indicators. The Bidders must provide appropriate safety features such as brakes, stowing devices, buffers, or mechanical stops, interlocks, RF, and AC power disconnect switches, grounding, disable switches, and battery powered emergency lights, lighting automatically controlled aircraft warning lights , and other devices needed to ensure safety of personnel and proper operations.
The following minimum controls and displays must be available at the ACU. Where: G is the gain of the sidelobe envelope relative to an isotropic antenna in the direction of the geostationary orbit in dBi.
Solar Radiation BTU per square feet. The 1 sigma value is the standard deviation for a normal distribution of wind gusts about the fastest kilometer wind and 3 sigma represents the peak gust. The receive chain must perform as follows. The HPA must provide the following performance:. It includes the following parts. In case of a two-polarization operation: Provide a combiner for each polarization. The IF combiner must have a minimum of 50 percent of free input ports.
The combiner network must be rack-mounted on a front panel plate above the up- converters. Receive subsystem includes the following parts:. The proposed dividers must be [ ] for each polarization with 50 percent of unused ports. The IF dividers must have a minimum of eight 8 output ports. The divider network must be rack-mounted on a front panel plate above the down-converters. Type BNC Connectors must be used with coaxial cables as patching cords. The requirements for each unit follow.
Modularity: The equipment must be modular to allow future expansion. The bidder has to explain how the equipment will expand. It is preferred to have an E-1 interface to the PST rather than 4-wire interfaces at the hub. Optional features: The bidder is invited to provide these optional features to the proposed equipment. The VCU must provide capabilities to transmit synchronous and asynchronous data on-demand. The controller must have the following characteristics:.
The network controller must provide real-time link quality monitoring to dynamically adjust the system uplink power to overcome the rain attenuation. PC requirements: TBD by bidder. Display: Color oriented graphical display with a series of windows showing the different functions of the system. Menu presentation: Drop down menus or buttons for mouse selection. Language: [ English. Quote prices for a Spanish or French text display ]. To this aim, the bidder must provide a laptop computer with a modem and the required software.
The bidders must demonstrate that the redundancy scheme of the proposed GCE system must meet the availability objectives set forth in the SOW. The bidders must fully describe the power supply arrangement and demonstrate the reliability figure of these modules.
The Bidder must state any particular operational constraints caused by the proposed redundancy scheme. The bidder will be responsible for:. The 3XUSRVH purpose of the operation console is to gather, within the same operational room, the control and monitoring information of all the subsystems comprising the Earth station. A single person should accomplish all operation and control of the network.
The bidder will optionally decide whether this facility is an integral part of the DAMA network controller. Indicators and alarms must cover all essential operations of the Earth station, including at least the following. The bidders must indicate the spare capacity available. It must adhere to the following specifications. Channels per VSAT: [2 or 4 channels] with capabilities to expand to [4 and 8 channels].
Where: G is the gain of the sidelobe envelope relative to an isotropic. Outdoor unit functions: Power amplifier, LNA, and frequency converters. Even if these were not explicitly defined in the paragraphs above.
IESS No. Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next. Circuit-switched networks. Microterminal networks portable communi- networks fractional transponder use. Section 5 cations applications. Data trunsuction V S A T networks demand assignment capability in the network. Finally, Section 6 presents some general con- Data transaction networks constitute the most clusions.
Other applications such as voice, video and facsimile fax may be present in some cases, zyxwv zyxwvuts zyxwvut et al. Messages protocol processing capability and can support the assigning satellite capacity are contained in the out- most common data protocols. Protocol processing bound TDM frame.
For CDMA in-bound trans- allows for adequate network response time and missions, the demand assignment feature is, in gen- more efficient use of the satellite channel. In this situation, some made via a continuous digital carrier BPSK or form of channel overload control may be used. Infor- sive network management capabilities. Outbound carriers are co-located with the hub station and includes: preassigned to the hub and contain a framed baseb- and signal which includes timing and control infor- i monitoring of link operation and perform- mation, as well as asynchronous data packets, ance at the VSAT or the port level addressed to specific VSATs.
In-bound and out-bound carriers share the satellite capacity in FDMA mode, the 2. Circuit-switched VSA T networks majority of the transponder power resource being In general, circuit-switched networks have a mix- required for the out-bound link.
Mesh or star topologies since transponder sharing between the set of in- are commonly used. Voice transmission plays a bound carriers and the out-bound carrier is still major role in these networks, with data transmission done in FDMA. Products using CDMA are usually having secondary importance.
Assignment of voice restricted to lower data rates as compared to those circuits on demand is done either from a network that use TDMA for in-bound transmissions. Since many applications have low duty-cycle Data circuits are constituted of point-to-point clear traffic requirements, fixed assignment is inefficient channels which are generally preassigned.
Video for in-bound transmissions. As a consequence, some conferencing applications may be also available. In order to fulfil this require- or TDMA carriers. Modulation is either BPSK or ment, each equipment manufacturer employs a pro- QPSK, with convolutional encoding of different prietary algorithm for satellite capacity assignment rates e. In the latter case, the satellite capacity assignment function can either be performed from a central point or be distributed MCPC equipment in the VSATs.
Satellite capacity is examined in more detail in Section 3. FEC coding can be used. Often, by each traffic terminal which is updated by control the sets of in-bound and out-bound traffic carriers messages exchanged among them.
Therefore, in occupy different bands in the transponder i. In addition to transmitted in the network. In TDMA messages and information pertaining to satellite systems, control and traffic messages share the capacity assignment.
For a star network, the out- TDMA frame. Transponder capacity power and 2. Videoluudioldatu distribution networks a specific spreading code are permanently assigned Very often, broadcast capabilities are superim- to this carrier.
In-bound control carriers are also zy posed on two-way star networks, as described in spread and also share a band in CDMA with in- section 2. However, all in-bound control work products include this feature. However, there carriers use the same code and, therefore, collisions are network products which are exclusively intended occur when more than one in-bound control carrier for one-way operation.
These have. Products using a BPSK carrier which is spread by a PN sequence are also encoun- The provision of economical thin-route satellite ser- tered. Typically, infor- predicated upon the use of a 4. The combination of VSAT technologies 2. Microterminal networks portable with advanced digital baseband processing tech- communicatioris upplicutions niques, mainly through voice, data and fax com- The distinguishing characteristic of these networks pression and packetization can now allow the intro- is the portability of the terminals antenna diameters duction of less costly thin-route services using less than 60 cm.
Because of the wide antenna terminals with multi-channel capabilities. The results of the subjective evaluation ommendations and Voice is expected to of various processing techniques carried out during be the basic application for microterminal networks.
It was found that a voice cations can also be accommodated. Microterminal networks are, typically, ithms such as codebook excited linear predictive circuit-switched networks and have a star single CELP coding and time domain harmonic scaling hub Configuration. Operation in a multi-star con- TDHS. Two multiplexing schemes are used for the combi- Although a K,-band hub was used in this field nation of voice, fax and data channels: time division trial strictly for convenience reasons, it is expected multiplexing TDM , and packet and statistical mul- that thin-route VSAT networks of this type will tiplexing.
Although the latter technique is capable make use of C-band hubs such as Standard A, B, of yielding a higher number or channels than TDM, and F3 in a star configuration. BPSK was selected it implies a somewhat more complex terminal. The for two major reasons: selection of one multiplexing technique over another the off-axis emission CCIR Rec.
Similarly to voice compression, considerable pro- Transponders carrying traffic to VSAT ter- gress has been accomplished by the industry in data minals will normally operate in a power-limited and fax compression in recent years.
Equipment to condition, and therefore the extra bandwidth digitize C C I n Group fax and compress data by required for BPSK transmissions compared to an average ratio of 4:l is commercially available QPSK is not relevant for the overall system and has been tested and demonstrated in the efficiency. Combined with the 4.
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