**3. Industry view: open vs. close interfaces and standards**

**Figure 7** presents the space industry view on open and close interface design. This view separates the interface design into two categories, namely, Contractor Proprietary Interface and Contractor Non-Proprietary Interface. Under this view, the interface standards are then classified into two categories, namely, Preferred and Non-Preferred Interface Standards. Based on this view, Section 3.1 defines open interface design, and Section 3.2 defines close interface design. Section 3.3 provides a list of existing popular open standards widely accepted by space industry.

<sup>1</sup> LVDS is defined as Low Voltage Differential Signaling TIA/EIA-644, is a technical standard that specifies electrical characteristics of a differential, serial communication protocol. LVDS Drivers use 80% less current than current popular Pseudo Emitter-Coupled Logic (PECL) devices.

*Future Satellite System Architectures and Practical Design Issues: An Overview DOI: http://dx.doi.org/10.5772/intechopen.92308*

#### **Figure 7.**

*Industry view on open and closed interfaces design.*

#### **3.1 Open Interface design**

From **Figure 7**, the open interface design falls into the contractor nonproprietary design category. For the interface design to be open, the interface design shall not be contractor proprietary and that the interface shall use either popular open interface standards widely accepted by space industry or open interface standards with little market support and narrowly used by space industry. Thus, a popular open interface design is a non-proprietary design that uses popular open interface standard that is widely used by space industry. The benefits of open interface design for the satellite buyers are (i) improving competition allowing various space vendors (or contractor) to build open satellite Bus and mission PL subsystem components, (ii) ease of refresh and technology upgrade allowing to swap subsystem components without impacting the overall system, (iii) ease of adapting to new requirements and operational threats, (iv) incorporating innovation by allowing operational flexibility to configure and reconfigure a mission PL quickly to meet rapidly changing operational requirements, (v) enabling cost saving and cost avoidance during the design and sustainment phases by reusing technology and Software/Hardware/Middleware (SW/HW/MW) components, and using existing standardized HW/SW/MW parts and modules, and (vi) improving interoperability where severable HW/SW/MW modules can be changed independently.

### **3.2 Close interface design**

As shown in **Figure 7**, the close interface design shall fall into contractor proprietary category. For an interface design to be close, it shall be contractor proprietary and that the interface shall use either close interface standards with little market support narrowly used by space industry or popular closed interface standards widely used by space industry. Thus, a popular close interface design is a contractor proprietary design that uses popular closed interface that is widely used by space industry. The key benefits of close interface design are the potential reduction of weight, size, power and manufacturing cost.

#### **3.3 Popular open standards**

Based on **Figure 7**, the criteria for popular open standards are (i) publicly available and widely used by both satellite Bus and mission PL vendors, (ii)

community and/or industry consensus-based that are matured and stable, and (iii) technically adequate for all future commercial, civilian and military satellite systems. Following is a list of current popular standard organizations and widely adopted open standards [18–31]:

