COMSAT Standard IOT Introduction

Introduction

Summary

Our approach is based on over two decades of experience with automated in-orbit test (IOT) and communications systems monitoring (CSM) systems. For example, we designed, fabricated, and installed IOTs and CSMs for EUTELSAT, INTELSAT, and GTE, as well as ground station status and control for NASA's Advanced Communications Satellite Technology (ACTS) program.

For EUTELSAT we built and installed their IOT facility in Rambouillet (France) which has been used to test the EUTELSAT II satellites F1, F2, F3 and F4. We are currently working with EUTELSAT in upgrading their IOT facility to support an automated dual-station capability. One station transmits and measures an uplink test carrier while a second station hosting the primary IOT facility performs measurements on the downlink. IOT equipment in the uplink station is remotely controlled by the primary IOT facility located in the second station.

During 1993, we built and installed a highly automated IOT facility for Hughes' testing of their DirecTv` direct-broadcast satellites (DBS), and recently supported their IOT of the first DirecTv` satellite launched in December, 1993. In addition, we are upgrading an older Hughes IOT system, which we had built, for testing SBS satellites.

Also, we are currently constructing an IOT facility for COMSAT Technology Services, an operating unit of COMSAT Corporation, to test satellites for AMSC and other operators. In addition, we are building a transportable earth station for AMSC for performing antenna pattern measurements at different locations. The mobile, trailer-mounted transportable communicates with the main IOT station over the public telephone network.

Over the past few years, we have developed a system which we call our Standard IOT. The Standard IOT incorporates a very large set of standard software and hardware components required to build a state-of-the-art IOT facility. We have found that most IOT systems share a core set of capabilities that, once implemented and standardized, can be re-used from one IOT system to another, resulting in substantial savings of cost and development time. Our Standard IOT includes numerous IOT measurements, such as i.p.f.d. and e.i.r.p., gain transfer, G/T, inband and out-of-band frequency response, and translation frequency offset, as well as additional stability measurements for i.pf.d., e.i.r.p., G/T, and beacon e.i.r.p and frequency. In addition, we have developed and tested many other measurements including a Fastsweep frequency response and a QPSK-modulated-carrier e.i.r.p. measurement. Options can be added to increase the flexibility and capability of an IOT system.

COMSAT Laboratories' accomplishments in IOT systems development has been led by Dr. Christoph Mahle and Dr. Vasilis Riginos. These two recognized experts are at the helm of all COMSAT IOT work, providing direct project and line management responsibility and technical expertise. As Dr. Mahle reports directly to Dr. John Evans, President of COMSAT Laboratories, this project will have the highest level of management visibility and control.

Since COMSAT already has 95% of the necessary software:

• The amount of custom-build software - and its associated cost - necessary to fulfill Customer-specific requirements is minimized;
• This software has already withstood field-testing in operational IOT systems and, therefore, offers a high degree of reliability, robustness, and low-risk;
• Because customization is required for only those portions unique to a particular Customer's application , we can assemble, deliver, install and test a fully operational system to tight delivery schedules.
• We offer our Standard IOT customized as necessary, not building a system from the ground up. An alternative to this pre-tested, highly reliable customized system is a situation in which a supplier proposes to build a system from the ground up. Although this approach appears to provide what is specified, it never really does because there are hidden drawbacks. These include: As a first-of-its-kind product, the hardware design and software are unproven and generally requires extensive debugging and fine-tuning before becoming fully operational.
• The cost and time needed for labor-intensive custom software development are difficult to estimate and control. Once committed, the Customer has little choice but to work with the supplier to obtain a satisfactory system, which generally costs more and takes longer than was originally bargained for.
• Because suppliers often underestimate the time and cost involved in building such a complex system from the ground up, mounting budgetary and schedule pressure may force corner-cutting to meet approaching delivery deadlines. Quality control is often severely compromised in the rush to deliver.
• A system built from scratch does not provide long-term flexibility, nor an evolutionary growth path, to accommodate changed or expanded mission requirements that an IOT system inevitably experiences during its operational lifetime.

Our Standard IOT software undergoes ongoing maintenance to improve its reliability, functionality, flexibility, and adaptability, providing a built-in evolutionary path to a more robust system. What Our Standard IOT Offers We offer our Standard IOT with a selected set of options and a small amount of customization work for accommodating Customer-specific requirements not provided by our Standard IOT. Our Standard IOT offers a rich set of features and functionality at an attractive price. Some of the features are described below: Local and wide area networking support allows remote measurement control. Our Standard IOT supports both local area and wide area networking, including remote access and control of the IOT measurement equipment. Figure 1-1 illustrates the networked system architecture for COMSAT Laboratories' IOT systems.

Our software is of such modularity that it allows the software system to execute in a distributed processing system architecture spanning a number of dissimilar workstations. Several programs can be running on several different machines, which provides a more robust and flexible system.

For instance, separation of the user interface from the measurement allows for a distributed execution environment and measurement scheduling. Because the measurement user interfaces (MUI) are logically and physically separate programs from the measurement program, they can execute in different computers connected to the local area network at different times. Communication between them is via an interprocess mail subsystem that we developed for this purpose that operates across machine boundaries. i.e., our mail subsystem supports intermachine interprocess communications. The narrative in the next section shows MUIs in action, as would be experienced by an operator or engineer conducting IOT measurements.

Figure 1-2 illustrates the idea of a distributed execution environment that allows multiple workstations and users, adding richness and flexibility to our Standard IOT design.

The user interfaces are implemented as OSF/Motif windows that permit easy to use point-and-click mouse input. Input errors (e.g. input out of range or wrong type) are detected and the user notified, so that bad input is caught before measurements are scheduled and executed.

The Graphic Mimic Panel, described in Section 4, displays status and configuration in real time and enables the user to control hardware switches.

Data-driven measurements provides low-cost easy customization of the system's behavior.

Our microwave measurements and supporting software are data-driven to the maximum extent possible so that customization is accomplished by editing static ASCII-encoded data files rather then modifying code. Code modification is a much more costly and time-consuming process. Customization of the system is readily accommodated in our data-driven design.

With our scheduler, measurements can be scheduled by the user at the user interface window to run at any time, day or night, and to be repeated at a specified frequency over a specified duration.

Non-interactive measurements (those that do not require an operator to be in attendance when the measurement is running) can be scheduled to run at any user-specified time and the measurement can be repeated at user-specified intervals.

Our Standard IOT supports multi-user operation when additional workstations are added.

We provide capability for measurement database search and retrieval for printing and plotting.

Print and plot style is controlled by style files which are easily customized as they are ASCII files and can be easily edited.

Our Standard IOT was developed to achieve tested, high-reliability IOT measurements and processing and control software. Because it is reusable, we offer high-quality, robust, tested software and system functionality at modest cost compared to custom-built software. This subsection discusses some of the rationale underlying our Standard IOT.

Although cost, schedule, and approach for the hardware aspect of IOT and similar measurement systems are generally well-understood and well-controlled, it is increasingly the volume, sophistication, and complexity of the software, often real time in nature and involving human interaction, that has come to dominate IOT systems' cost and schedule.

A principal method for reducing the cost of new systems is to reuse previously tested high-quality software, thus significantly lowering both schedule and performance risks associated with new software development.

To facilitate the efficient development of measurements and complete systems, COMSAT Laboratories developed over the past several years a generic microwave measurement software system built upon an engineered ``platform'' of reusable software services and facilities that are common to IOT measurements and systems. The Measurement Processing and Control Platform (MPCP) provides modular, tested software components for interprocess/intermachine mail communications; scheduling of IOT measurements at any time of day and resource management; a system-wide shared information depository; object-code libraries of functions for user interface support, measurement support, instrument control, IEEE-488 bus management, error handling, mathematical functions, and utility functions (e.g., string and time processing) that can be linked into applications programs; and supporting subsystems for database management, report generation (prints and plots), and interactive editing of plot files.

The approach of developing a robust software-engineered platform architecture and implementation is applicable to new IOT systems faced with escalating software demands which must be cost-, schedule-, and quality-controlled. The engineered platform methodology and implementation results in desirable software characteristics in terms of design and development effort, life cycle characteristics (reusability, maintainability, expandability, portability, evolution), quality (methodology, robustness, consistency, flexibility) and capability (remote control, networking, concurrent measurements, distributed systems, user-driven changes) when compared to an ad hoc software development methodology. Appendix A, a reprint of a conference paper presented by Steven Teller in 1992 at ``The 14th International Communication Satellite Systems Conference and Exhibit'' sponsored by the American Institute of Aeronautics and Astronautics (Washington, D.C., March 22-24, 1992), provides additional discussion of our choice of developing our Standard IOT.

IOT system development at COMSAT Laboratories has been led by Drs. Mahle and Riginos. During their 20-year tenure at COMSAT Laboratories, they pioneered techniques for testing satellites in orbit. As they wrestled with the challenges of testing, monitoring, and investigating in-orbit satellites, they and their colleagues formulated a general solution to the IOT problem of the best strategy for building high-reliability IOT systems in a manner that could be easily reproduced from one system to the next without requiring extensive and costly customization each time. Hardware and software were developed by the same people, ensuring close coordination and integration of the two domains. The solution - a distillation of this cumulative experience - resulted in hardware, measurements, and processing and control software for a universal IOT system, but which is directly applicable to Customer-specific systems. Prior to 1995, Steven Teller was responsible for all measurement development in the Standard IOT. Since 1995, Steven Teller was the principal measurement systems achitect and led all future development.

During over twenty years of experience in designing, building, and installing IOT systems, we have observed that IOT systems are quite similar in their functionality and operational requirements. This insight led to the development of COMSAT Laboratories' Standard IOT in which most of the commonality across IOT system was developed in as general a manner as possible. Thus, for any particular IOT system requirement 95% (or more) of the requirements are accommodated in the Standard IOT and selected options. The particular and unique requirements then require a relatively small amount of customization work.

Although a new IOT system has some unique features and requirements, our task in building a reliable, robust IOT system is principally one of modifying our Standard IOT physical design somewhat and assembling a system rather than developing a fully-custom system from the ground up.

However, because our Standard IOT embodies a pre-existing solution, cost effectiveness to our potential customers is preserved when customization effort is minimized. As customization effort increases, cost and schedule are impacted and quality approaches that of any custom system.

Therefore, although our system is deliberately implemented with respect to maximizing generality, expandability, and flexibility in terms of ongoing software development, maintenance, and improvement, it can accommodate a reasonable amount of requested customization and we can perform this customization.

It is more appropriate to consider our Standard IOT as assembled to order, not made to order. We are not offering a custom-built system from the ground up. Rather, starting from the requirements, we modify somewhat our existing off-the-shelf Standard IOT with a selection of options chosen to fulfill Customer-specific requirements to provide the most cost-effective solution.

To maintain an overall modest cost (given the functionality of our Standard IOT and substantial value-added features such as networking and additional, non-required IOT measurements), wherever possible, we favor the most-effective approach to provide a functional, compliant system at the least cost.

The principal alternative to our Standard IOT solution is a build-to-order procurement in which the supplier bids to build a custom system. The custom-build system apparently offers the Customer what he wants: a custom-built system that ultimately works. However, the disadvantages of the custom-built system must be carefully considered and weighed.

The custom-built system, by definition, is a one-of-a-kind, first-of-its-kind product. Custom-built systems are usually very difficult to implement against tight required delivery schedules. Typically, custom-built software takes longer and costs more than originally planned or budgeted. A supplier of a custom-built system typically underestimates the schedule and cost and, because of mounting budget and schedule pressures, cutting corners to meet the delivery deadlines may result, with additional work usually required to bring the system into specifications, added costs, and delays. As a result, quality may be compromised. Because the software (and hardware configuration and system design) are custom, overall system quality and reliability are suspect.

An analogy illustrate the pitfalls of custom-built systems. When an engineer requires a spectrum analyzer, he (or she) goes to Hewlett-Packard, Tektronix, Anritsu, or another supplier and purchases an off-the-shelf instrument. One then ``customizes'' it by selecting from among a set of options offered by the manufacturer. The manufacturer may sell the basic spectrum analyzer for tens of thousands of dollars and options are extra. Delivery is typically a few weeks to a few months. The engineer can trust the underlying quality of the instrument because the manufacturer has spent a great deal of effort, time, and money to produce the highest quality, highest performance instrument for a specified price.

Now consider a second engineer who also desires a spectrum analyzer. Rather than buying a ``standard'', commercial off-the-shelf instrument, he seeks a custom system because of special requirements. If the ``customization'' is relatively cosmetic and not basic, a manufacturer may be willing to customize his standard unit to the particular requirements. But, as the ``specials'' move from cosmetic to the basic ``guts'' of the instrument, the cost and time increase rapidly, while quality, because of the one-of-a-kind nature of the special, suffers. After all, if the manufacturer hopes to sell many of his standard spectrum analyzers, he will invest resources to ensure high quality, but if he hopes to sell only one ``custom'' instrument, then his motivation to ensure quality is not the same, nor will the customer be able to pay for the same. Whereas a standard, commercial spectrum analyzer is obtainable for tens of thousands of dollars in a few weeks or months, a truly custom instrument may cost hundreds of thousands of dollars and may require well over a year.

For more information contact Steve Teller via email at teller@iotsystems.com .

Last Modified: Fri Oct 13 10:37:29 EDT 1995

Last Updated: Thu Nov 15 14:03:49 EST 2018