A site survey using Military Handbook (MIL-HDBK)-412 Site Survey and Facility Design Handbook for Satellite Earth Stations as a guide, should be completed for each Earth Terminal Complex (ETC) whenever new equipment or systems are to be installed, or when a new ETC will be constructed. The three major categories that should be addressed for each site survey are:

1. Site Pre-Survey. The site pre-survey discusses the research, coordination, and preparation required prior to conducting a site survey. The USADERMS database should be accessed to obtain existing site documentation.
2. On-site Survey (general). This general survey is concerned primarily with in-briefings, out-briefings, and the social or political environment in which the work will be performed.
3. On-site Survey (specific). The on-site specific survey completes the process under four different scenarios.

The Engineering Installation Plan (EIP) is a detailed step-by-step procedure that contains all of the project information that will be used for each site upgrade, system installation, or equipment modification. The EIP contains 4 major paragraphs.

1. Project Overview. This paragraph provides a brief description of the project for use by the installing activity to determine required capabilities, team size, and time frame.
2. Installation Team Responsibilities. This paragraph identifies actions and responsibilities that the installation team is required to perform for the project. It includes the Bill of Materials (BOM), inventory, inspection, redlining of drawings, distribution of drawings, approval of changes to the installation, use of spares to complete the installation, POC for problems with material developer provided materials, and after-action reports with deficiencies or problems identified.
3. Points of Contact. This paragraph lists the POC information the installation team may need for engineering, material developers, project management, and others as required.
4. Appendices. This paragraph identifies and describes appendices that are included as required for the project. Suggested appendices are as follow:
1. Installation Instructions.
2. Installation Drawings.
3. Bill of Materials (BOM).
4. Validation/Test Information.
5. Concurrence Documentation.

The PCM describes the project, site impact, responsibilities, scope, schedule, and agreements, and requests project concurrence from all responsible agencies. The PCM contains eight (8) major areas that must be covered or agreed upon by each of the responsible agencies. These areas are:

1. Memorandum Addressees.
2. Memorandum Subject.
3. Programmatic Direction and Site Impact.
4. Project Responsibility and Scope.
5. Scheduling Information.
6. Project Agreements.
7. Project POC.
8. Request for Concurrence.

The USADERMS is an automated networked Document Management System (DMS) that will support USAISEC requirements at worldwide user locations. It will improve the configuration management of the Army DCS Facilities by DSCS providing project and system engineers, project managers, and DCS sites with the most up-to-date standard drawings, site drawings, and project information. This database contains documents, site drawings, and images from DCS earth terminal (ET) sites throughout the world. The USADERMS data types are shown in table A1. Each site maintains a USADERMS server with a database containing data pertinent to that site. The USADERMS is a client-server application. Under this concept, a single large computer at each site maintains the USADERMS database. Individual users access the data from personal computer (PC) clients using a graphical windows-style interface. With keyboard and mouse input users can request an operation such as viewing a drawing. The client sends the request to the server, the server retrieves the drawing from the database and sends it back to the client, and the client then displays the drawing. At each site, the USADERMS server is connected to the clients through a local area network using the Transmission Control Protocol/Internet Protocol (TCP/IP) suite. Each client PC has an initialization file that contains the IP address of the USADERMS server. Additionally, the USADERMS servers can communicate among themselves using Internet routing. The master USADERMS (see Figure A1 for system diagram) database is maintained at Fort Huachuca, AZ. The remote site servers are periodically refreshed from this master database using database replication.

Figure A1. USADERMS System Diagram.

The USADERMS contains data for each of the military services, the Army, Navy, and Air Force. Each military service updates and maintains their own database as well as the master USADERMS database.

The standard drawings package for each site is generated and maintained using the USADERMS, with the master control kept at Fort Huachuca, AZ. The USADERMS contains standard drawings for the AN/FCC-98, AN/FSC-78, AN/GSC-39, AN/GSC-49, Digital Communications Satellite Subsystem (DCSS) Facilities, Heavy Terminal/Medium Terminal (HT/MT) Interconnect Facility (ICF), Integrated Digital Network Exchange (IDNX), and Technical Control Facility (TCF).

The USADERMS contains cable running lists that are composed of and include applicable Cable Standards.

The USADERMS database contains site baseline drawings which include the DSCS Floor Plans, TCF Site, and Configuration Documents.

Table A1. USADERMS Data Types.

9. Satellite Link Budget

Link Budget is a term used to describe a series of mathematical calculations designed to model the performance of a communications link. In a typical simplex (one-way) satellite link, there are two link budget calculations: one link from the transmitting ground station to the satellite, and one link from the spacecraft to the receiving ground station. Many link budget analysis tools are available to the SE, these tools include:

1. Link Budget Model

• Uplink and downlink C/KT.
• Satellite receive power flux density.

• ET to satellite slant range.
• ET antenna elevation and azmiuth.
• Uplink and downlink doppler frequency shift.

• Clear air attenuation.
• Rain fall attenuation.
• Atmospheric signal scintillation.

• Noise equivalent bandwidth.
• Modulation spectral efficiency.
• Demodulator implementation loss.
• Probability of detection of error.
• Convolution channel coding gain.

• Antenna model.
• Receive system model.
• Transmit system model.

• Uplink noise power.
• Uplink signal power.
• Downlink signal power.
• Transponder signal and noise power sharing.
• Transponder uplink power flux.

The following items are needed to produce a link budget calculation for a spacecraft to ground station link

• Earth Station North Latitude.
• Earth Station Longitude.
• Spacecraft Longitude.
• Downlink Frequency.
• Antenna Gain.
• Antenna Noise Temperature.
• Noise Temperature.
• Ortho Mode Transducer Loss.
• Effective Isotropic Radiated Power.
• Intermediate Frequency (IF) Receive Bandwidth Hertz (Hz).
• Transmit Data Rate.

For non-processing satellite transponders, (UFO, DSCS, COMSAT), a single link budget is performed that incorporates the uplink path, transponder transformer characteristics, and downlink path. For a MILSTAR processing transponder, a separate link budget is performed for the uplink and downlink. The uplink and downlink transmission error rates and delays are included in this calculation. Path loss is primarily due to spreading which is not frequency dependent.

10. Look Angle

The antenna pointing calculation is used to determine the Look Angle of the ETC antenna. Three items of information are required to complete this calculation. The satellite west longitude which is normally given in decimal form rather than a degree, minute, and second (DD MM SS) format. This number represents the number of degrees west of the Prime Meridian that the spacecraft is located at above the equator. Next is the north latitude of the ETC location. The format for this location is given normally in the degree, minute, second (DD MM SS) format. Finally the west longitude for the ETC location is needed.

11. Satellite Footprint

The projection of the energy of a satellite on the face of the earth is commonly called the satellite footprint. Figure A2 shows a typical narrow beam coverage area. It is actually an aggregation of multiple beams, normally elliptically shaped, and individually steerable. This information reflects the actual spacecraft and the energy patterns of the individual transponders, and should be kept in a database. However, much of the information in the fields is highly technical, and will be supplied by an applications program through which the analyst establishes desired coverage areas, orbit locations, etc. This applications program must generate coverage areas which reflect both the power source and the antenna sidelobe for each beam generated by the spacecraft. For this specific coverage area, the aggregated EIRP, G/T, and input flux density contours are generated by multiple elliptical beams which often overlap. Each of these beams will be described by pointing coordinates, major axis angle, minor axis angle, rotation angle, input power density, antenna gain, etc. This allows the engineer to see the visual coverage pattern of a desired service area.

The rates that the CSCI program will apply include one-time non-recurring costs and recurring costs. These include costs that are directly allocable to the customer and a weighted cost for those items that are shared by more than one customer.

Non-recurring costs may include site survey's, host nation landing fees and licenses, and systems engineering and design services. The estimated cost for those services and features will be established as part of the working agreement with each customer.

Monthly recurring costs principally include the transponder lease costs based upon power and bandwidth required. Other recurring costs include unique features or services and shared gateway costs. These costs are directly allocable to specific customer requirements. The CSCI program incurs other costs such as the operation and maintenance of the Bandwidth Management Center (BMC). These costs will be allocated among all customers on a proportional basis. In addition, customers will be liable for termination costs if full-year agreements are not completed.

a. Costs allocated to customers

• Antenna Subsystem
• Low Noise Amplifier Subsystem
• High Power Amplifier Subsystem
• Electric Subsystem
• Terminal Control & Monitor Subsystem
• Material & Labor
• System Integration
• Tail Circuits
• Site Survey Preparation
• Installation
• Postage, Shipping & Handling
• Unique features or services
• Early Termination Costs

b. Costs shared by customers

• Operations
• Equipment & Facility
• Planning Subsystem
• Maintenance

Each customer will be expected to provide a funding account from which the CSCI program will withdraw funds in accordance with a monthly itemized bill. A listing of itemized charges (statement of account) will reflect the terms and conditions of the CSCI Memorandum of Agreement (MOA). The MOA will be signed by the customer and the CSCI program representative prior to the initiation of any service.

12.3 Transponders Costs

Shown in Table A2 below are the CSCI Transponder rates for fiscal year 98. A typical coverage pattern of the Worldnet satellite system is shown in Figure A3 below.

Table A2. CSCI Representative Transponder Rates and Representative T-1 Costs.

 

Figure. A6 End to End System Example

 
13. Timing Requirements.

Network timing and synchronization are critical issues for communications planners. The basic operational requirement for network synchronization is the need for each system to maintain bit count integrity to provide end-to-end communications security and acceptable data transmission. For satisfactory system operation, stringent requirements must be satisfied with regard to the timing variations that are allowed both within and among the digital transmission groups. Several different synchronous and asynchronous concepts are employed to provide network synchronization. In the independent clock approach, network timing is established by employing a frequency standard at each node to provide stable local timing reference. This technique is inherently asynchronous since the frequency standards will vary slightly from node to note. The differences between the basic data rates of the incoming digital groups and that of the local timing source are accommodated through the use of buffers to retime the incoming digital data streams to the timing used at the node. To minimize the differences between timing sources, highly accurate clocks such as the cesium beam frequency standard and the rubidium standard are used to implement the independent clock approach.

The basic timing elements of the independent clock network timing approach include a modem, a buffer, and a highly accurate frequency standard. The modem is used to regenerate the incoming digital data stream and to convert the line signal (CDI, dipulse) to baseband (NRZ). The clock is used to absorb differences between the frequency of the local clock at the receiving node and the frequency that is associated with the incoming digital data stream.

The buffer is an asynchronous first-in, first-out (FIFO) shift register. With asynchronous operation, data can be entered into the buffer and withdrawn at different rates. Data is clocked into the buffer by the clock associated with the received data and is clocked out of the buffer by the local clock. Since the output rate of the buffer is controlled by the local clock, the incoming digital bit stream is retimed with the frequency of the local clock. If the received clock rate is slower than the local clock rate, the buffer will eventually underflow and then recenter. Conversely, if the receive group clock rate is faster than the local clock rate the buffer will eventually overflow and then recenter. Each time a buffer recenters (or resets), bit count integrity is lost and frame and CRYPTO synchronization must be reestablished.

Determining the timing system configuration for the network is a task that must be done at the planning level. However, much of the information necessary to make network timing decision is not available in the equipment technical orders and manuals. In planning a network timing system, the planner must consider the following.

Timing Sources. If different sources are used; i.e., the independent clock approach, the system must have adequate buffering, Otherwise the differences in the clock frequencies will cause bit count integrity to be lost each time the accumulated error between the two clocks reaches the time duration of one bit. Each timing source has its own accuracy. Inaccurate timing sources increase the need for buffering. If only one source of timing is used in the system, consideration must be given to the effect of failures in the network. If different timing sources are used, data must be buffered at each interface point.

Trunk Encryption Device (TED) Timing. Figure A7 shows the TED and typical LGM operation from a timing standpoint. Timing T1 is inserted in the TED black station clock (BSC) input. The TED uses T1 to clock the encrypted data out of the TED. The TED provides a red station clock (RSC) that is synchronous with timing T1 to the terminal equipment. The RSC is used by the terminal equipment to send red data to the TED. In the opposite direction the black data and timing T2 are received by the black side of the TED. The data is decrypted, and red data and timing T2 are output from the red side of the TED to the terminal equipment.

Figure A7. Timing Flow