Appendix A - Attachment 1.pdf

Appendix A

1.0 INTRODUCTION

This appendix provides high-level requirements that would be applicable in any potential effort to assess the audio system for commercial feasibility of development and certification. The information in this appendix includes detailed data, reference materials, and additional content that is intended to help the vendor understand and provide clarity on the Audio Distribution System for Human Spaceflight.

2.0 ENVIRONMENTS

2.1 Ionizing Radiation

Incorporation of radiation tolerant or radiation hardened electronic components with proven to not be susceptible to destructive effects induced by the expected radiation environments. The system must be capable of detecting and automatically recovering from radiation-induced functional interruptions.

2.2 Thermal

Cooling via passive heat conduction and radiative cooling methods only. Forced convection cooling is not desired.

2.3 Electromagnetic Interface/Electromagnetic Compatibility (EMI/EMC) Electromagnetic compatibility with other integrated spacecraft avionic systems including conducted and radiated susceptibility and emissions. Specific susceptibility and emissions parameters will be provided.

2.4 Structures

Ability of hardware enclosures and internal components to withstand structural vibration and acceleration loads induced by spacecraft launch and landing. Specific induced loads will be provided.

2.5 Ambient Pressure

The audio hardware must be able to operate from 9 to 14 Pounds per Square Inch Absolute (PSIA) static pressure, be capable of surviving prolonged exposure to vacuum, and withstand rapid changes in ambient pressure.

3.0 SOFTWARE

3.1 Software Development Standards

Software development and certification processes must be compliant with NASA NPR-7150.2D requirements for Class A software and AS9115.

3.2 Reconfigurability

In situ ability to update software post-deployment to accommodate required functional or operational changes and extensibility.

4.0 FUNCTION AND PERFORMANCE

4.1 Extensibility

The system must support audio architecture growth to accommodate an increasing number of 2-way audio endpoints to a minimum of 64.

4.2 Audio Codecs

The system must support conferencing of up to 8 endpoints simultaneously using ITU G.729 (Annex A) codecs and up to 32 endpoints simultaneously using ITU G.711 (u-law).

4.3 Health and Status Reporting

Health and status data of the primary and backup hardware must be provided to indicate current condition and operability. Additional detailed status information that supports failure analysis and trending is desirable.

4.4 Operating and Shelf Life

The audio system components must be capable of providing continuous operation for 30-day missions at a rate of 1 mission per year for 10 years. Relaxed operating life requirements can be negotiated if components are designed to be easily replaceable with spare hardware.

4.5 Audio Recording and Playback

The system must be capable of recording audio for multiple audio sources/mixes.

Required record capacity will be determined later. The ability to selectively retrieve and playback recorded audio is required.

4.6 Crew Audio Interfaces

Fixed and/or portable panel switches and indicators and/or GUI displays for configuration, control and monitoring of audio system conferences, modes and status must be provided.

Astronaut crew audio peripherals and interfaces to support voice communication such as panel mounted and portable microphones, headsets and speakers. Audio controls must include push-to-talk (PTT) and voice operated transmitter (Vox) mode select, channel/conference select, earphone/speaker volume control.

4.7 Speech Intelligibility

It must be demonstrated that voice communication channels provide at least 90% speech intelligibility as determined by test methods described in ANSI S3.2 when tested in the anticipated acoustic environment including reverberation and ambient noise using representative audio peripheral equipment (microphones, earphones and speakers).

4.8 Echo and Noise Cancelling

Inclusion of acoustic and line echo cancelling as well as noise cancelling and noise reduction functions as required to meet speech intelligibility requirements in the integrated acoustic environment.

5.0 SPACECRAFT INTERFACE

5.1 Network

The system must accommodate control, status reporting and voice streaming via an Institute of Electrical and Electronics Engineers (IEEE) 802.3 Standard for Ethernet interface. The system must utilize centralized & redundant audio processing cores connected to edge devices (eg. speakers, microphones, transcoders, media converters, General Purpose Input/Output (GPIO) pins, control surfaces/touch panels, and I/O expansion breakout boxes, etc.) via a dual path redundant Internet Protocol (IP) infrastructure. The network shall utilize a digital audio distribution standard such as AES67 or Dante audio protocols. Precision Time Protocol Version 2 (PTPv2) shall be used for network wide grandmaster clock selection & synchronization. Control commands and telemetry data shall also flow across the same network architecture for system interface, commanding, and monitoring.

5.2 Power

Compatibility with 120 Volts Direct Current (VDC) and 28 VDC supply power inherent in the design or by provision of power supply specific variants.

5.3 Redundancy

The audio system must be a minimum of 1 fault tolerant with no single failure including loss of redundant power resulting in loss of voice communication and alarm annunciation functionality. Detection of lost functionality and automatic switching to redundant hardware.

6.0 OPTIONAL FEATURES

6.1 Text-to-Speech and Speech-to-Text

Local text-to-speech and speech-to-text engines for long haul communication where latency makes voice communication impractical is desirable. Text-to-speech may also be used for flexible generation and annunciation of Caution and Warning events and conditions to supplement audible tones with additional information on off-nominal conditions.

7.0 APPLICABLE DOCUMENTS

ANSI/ASA Standard S3.2 Method for Measuring the Intelligibility of Speech over

Communication Systems.

ITU-T Recommendation G.729 Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP)

ITU-T Recommendation G.711 Pulse Code Modulation (PCM) of Voice Frequencies

AS9100D Quality Management Systems – Requirements for

Aviation, space and Defense Organizations

AS9115 Quality Management Systems – Requirements for

Aviation, Space and Defense Organizations – Deliverable Software

NPR 7150.2D NASA Software Engineering Requirements