Tab_02_-_Statement_of_Work.pdf

Statement of Work

For

Low Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID)

Power Distribution & Sequencing Unit

1.0 BACKGROUND: Building upon the successful 3 meter diameter Inflatable Reentry Vehicle Experiment (IRVE) flights and extensive ground testing and development efforts at various scales, the objective of the Low Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) flight demonstration is to advance Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology by performing a scaled up orbital velocity atmospheric entry experiment.

While certain aspects of material and system performance can be assessed using a variety of ground testing capabilities, only orbital velocity energy on a trajectory through the density gradient of the atmosphere and at a scale large enough to induce relevant aerodynamic shear and turbulent heating augmentation can impart the combined aerodynamic and aero-heating environments on the HIAD system in real time.

2.1. EQUIPMENT / SOFTWARE ITEMS: The Contractor shall provide two (2) Power Distribution & Sequencing Units (PDSUs) in accordance with the Function, Performance & Interface Specifications listed in paragraph 6.0. The Contractor shall provide two (2) complete sets of Electronic Static Discharge (ESD) protective caps. The Contractor shall provide the PDSU software operating system, PDSU software drivers and computer board support packages with unlimited data rights as necessary to operate the PDSU.

2.2. MANAGEMENT SUPPORT: The Contractor shall provide approximately forty (40) hours of PDSU engineering and technical support at the request of the Government for PDSU engineering development for design concept validation. The Contractor shall provide the name and contact information for the Project Manager who will have full authority and responsibility to manage and administer all phases of the development, manufacturing and testing of the PDSU.

2.3. REPORTS: The Contractor shall prepare and present a monthly technical and manufacturing status report by e-mail to the LOFTID Avionics Lead, no-later-than the five (5) days after the end of each month. The report shall be a summary of the month’s progress, schedule updates, problem areas and current activities and next months planned activities.

2.4. TESTING: The Contractor shall perform board level and assembly level functional tests of PDSU component assemblies prior to PDSU assembly. The Contractor shall verify full compliance of each board/sub-module to its functional requirements. The functional test shall be designed to verify operation in all modes and configurations and under varying input/output conditions. The Contractor shall perform and assembly level burn-in-test for a minimum of 100 hours at 23 °C ± 10 °C ambient air temperature shall be performed (see test flow). Operational hours accumulated prior to burn-in under any environmental condition may be included in the 100-hour requirement. During the burn-in test, the hardware shall be monitored continuously to detect if any anomalies have occurred.

3. 0. SHIPPING: The Contractor shall provide shipping requirements FOB Destination and as specified below:

3.1. DATA DELIVERY PACKAGE: The Contractor shall provide a Data Delivery Package with each end item listing the detail of the item to be delivered. The package shall be include, but not be limited to the following:

The deliverable item name, serial number, and part number.

Photograph Documentation (Pre-Test and Post-Test).

Certificate of Conformance (such as the results of test procedures).

3.2. PRE-SHIPPING REVIEW: The Contractor shall organize and conduct a pre-shipping review at the completion of verification tests and prior to the shipment of each hardware item to Langley Research Center (LaRC). This review shall demonstrate completion of all activities required for delivery of any hardware deliverable item to NASA/LaRC.

3.3. SHIPMENT PACKAGING: The Contractor shall package the PDSU in containers, with materials, that prevent hardware damage during shipment and storage. The hardware shall be shipped in hard cases with foam, shock absorbing material wrapped, or inserted around the product.

4.0. PERIOD OF PERFORMANCE: The Contractor shall deliver the two (2) PDSUs no-later-than 120 business days from contract award.

5.0 REFERENCED DOCUMENTS:

Document Number Document Title Revision or Release Date

MIL‐STD‐1576

ELECTROEXPLOSIVE SUBSYSTEM SAFETY REQUIREMENTS AND

TEST METHODS FOR SPACE SYSTEMS

Document Number Document Title Revision or Release Date

AIAA S‐113A‐2016

CRITERIA FOR EXPLOSIVE SYSTEMS AND DEVICES ON SPACE

AND LAUNCH VEHICLES

NASA‐HDBK‐4001

ELECTRICAL GROUNDING ARCHITECTURE FOR UNMANNED

SPACECRAFT

6.0 FUNCTIONAL, PERFORMANCE & INTERFACE SPECIFICATIONS: The Contractor shall provide two (2) PDSUs the meet the following functional, performance, and interface specifications defined in the table below:

Name Description Rationale

Power Input

Nominal System Power

The PDSU shall use

28.0 VDC, nominal, system power.

The PDSU received system power from 28.0 VDC secondary batteries during flight. During ground testing and development, programmable power supplies provide the system power.

Report System Power Consumption

The PDSU shall report the measured system power consumption to a user interfaces via an Ethernet interface.

The PDSU needs to report the measured system power consumption to a user interfaces, or test computer, to allow evaluation of system performance during development testing.

The PDSU design concept drives reporting of measurements via the Ethernet interface.

System Power Consumption

The PDSU shall consume ≤ 33.0 Watts during worst case environments.

The PDSU is allocated a power budget to ensure the system battery is adequately sized for the flight. The power consumption is based on worst case, specified, environmental conditions defined in the Atlas V Users Guide.

Sudden Removal of System Power

The PDSU shall survive the sudden, unannounced removal of system power.

Main scope is when the Avionics is using external power and operational power is suddenly removed, or when the Avionics is testing the batteries and the batteries go below the 20% charge level and system power is removed.

System Power Range

The PDSU shall meet all functional and performance requirements over the system steady state power voltage range of 24 VDC to 36

VDC.

The PDSU needs to operate in a battery, and programmable power supply, overvoltage state, and as the battery discharges during flight and during a one cell failure.

System Power Reverse voltage

The PDSU shall be capable of withstanding a reverse voltage of >36

VDC.

The PDSU needs to prevent damage due to accidental power and return miss‐wiring.

Name Description Rationale

System Power Over‐voltage Protection

The PDSU shall be capable of withstanding an overvoltage condition of up to 45 VDC for up to 50 milli‐seconds.

The PDSU needs to be compatible with DC power supplies which may introduces overshoot when enabling the power input.

System Power Voltage Dropouts

The PDSU shall meet all functional and performance requirements and continue to operate with a complete loss of power for up to 1.0 milliseconds.

The PDSU needs to continue operation with a short dropout that may occur during ground test operations.

Power Grounding

The PDSU shall have a grounding philosophy in accordance with

NASA‐HDBK‐4001,

Sections 4.2.5, 4.27, and 4.2.8.

NASA‐HDBK‐4001 establishes grounding guidelines such as circuits being isolated from the ordinance and primary circuit grounds (both analog and digital) by at least 1M ohm in accordance with NASA‐HDBK‐4001 sections 4.2.5 and 4.2.8. It is recommended to have a single low impedance path to chassis for the secondary circuits (5VDC, 12VDC, and +/‐15VDC). The power returns of switched circuits shall be independent and isolated from chassis by at least 1M ohm resistance.

System Power Distribution to Subsystems

The PDSU shall switch system power to individual subsystems.

After the PDSU is powered on and initialized, it needs to turn on, and turn off, power to the other avionics subsystems.

Nominally, during flight the PDSU will switch on, and leave on, power. Additionally, during system testing, the PDSU is expected to switch on power during a test, and switch it off after the test is done. Nominal system power is 28VDC.

Monitor System Power to Subsystems

The PDSU shall measure individual system power performance to individual subsystems.

In contingency cases, such as a short circuit, the PDSU may need to switch off power to subsystems. Current and voltage measurements are needed for this fault detection and response.

Report System Power Consumption

The PDSU shall report the individual system power performance of individual subsystems to a user interfaces via an Ethernet interface.

The PDSU needs to report the measured individual subsystem system power consumption to a user interfaces, or test computer, to allow evaluation of system power performance during development testing. The PDSU design concept drives reporting of measurements via the Ethernet interface.

(28 VDC)

Output Quantity

The PDSU shall provide at least fifteen (15) switched, independently monitored, system power outputs.

Fifteen switched and independently monitored 28.0 VDC system power outputs are required to provide the planned outputs with a ≥ 25% margin.

Individual System Power

(28 VDC)

Output Current Drive

The PDSU individual system power outputs shall have a current drive capacity ≥ 4.5 Amps.

Individual system power outputs require ≥ 4.5 Amp drive strength given the current best estimates of subsystem power with ≥ 30% margin. It is acceptable if not all drives can use this capacity simultaneously.

Individual System Power

(28 VDC)

Output Surge Drive

The PDSU individual system power outputs shall have a current drive capacity ≥ 12 Amps for 0.50 seconds.

The PDSU provides power to subsystems that require a surge current that is approximately 5X the nominal current for a short amount of time.

Switched System Power Output voltage drop

The PDSU individual system power outputs shall have ≤

1.5 VDC voltage drop

under full load

The PDSU provides power to subsystems that require a surge current that is approximately 5X the nominal current for a short amount of time. This may cause a voltage drop, and this voltage drop measured from the system battery input to the PDSU to the PDSU system power output needs to be less than 1.5 VDC.

System Power Output Isolation

The PDSU individual system power outputs shall be electrically isolated from each other.

The PDSU needs this isolation to prevent faults on one output from propagating to other outputs.

Secondary Power Distribution

Generate +5 VDC Secondary Power for Subsystems

The PDSU shall regulate system power to +5.0 VDC secondary power for subsystems.

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC.

+5V Secondary Power Output Quantity

The PDSU shall provide at least one

(1) regulated, switched independently monitored, +5.0 VDC secondary power output.

One regulated, switched, and independently monitored +5.0 VDC secondary power output is required to supply power to other subsystems. Additional output count margin is not required.

+5 VDC

Secondary Power Tolerance Under Load

The PDSU +5.0 VDC secondary power output tolerance, under load, shall ± 5%

(VDC)

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC. The PDSU +5 VDC output requires this tolerance to provide the required, stable power to other subsystem.

+5V Max Ripple

The PDSU +5V secondary power output shall have less than 80 mV Pk‐Pk ripple voltage.

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC. The PDSU +5 VDC output requires this tolerance to provide the required, stable power to other subsystem.

+5V Secondary Power Output Current Drive

The PDSU +5V secondary power output shall have a current drive capacity ≥ 1.0 Amps.

The +5V secondary power output requires a ≥ 1.0 Amps drive strength given the current best estimates of subsystem power.

Generate +15 VDC Secondary Power for Subsystems

The PDSU shall regulate system power to +15.0 VDC secondary power for subsystems.

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC.

+15V Secondary Power Output Quantity

The PDSU shall provide at least one

(1) regulated, switched independently monitored, +15.0 VDC secondary power output.

One regulated, switched, and independently monitored +15.0 VDC secondary power output is required to supply power to other subsystems. Additional output count margin is not required.

+15 VDC

Secondary Power Tolerance Under Load

The PDSU +15.0 VDC secondary power output tolerance, under load, shall ± 5%

(VDC)

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC. The PDSU +15 VDC output requires this tolerance to provide the required, stable power to other subsystem.

+15V Secondary Power Max Ripple

The PDSU +15V secondary power output shall have less than 100 mV Pk‐Pk ripple voltage.

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC. The PDSU +15.0 VDC output requires this tolerance to provide the required, stable power to other subsystem.

+15V Secondary Power Output Current Drive

The PDSU +15.0 VDC secondary power output shall have a current drive capacity ≥ 0.5 Amps.

The +15V secondary power output requires a ≥ 0.5 Amps drive strength given the current best estimates of subsystem power.

Generate ‐15 VDC Secondary Power for Subsystems

The PDSU shall regulate system power to ‐15.0 VDC secondary power for subsystems.

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC.

‐15V Secondary Power Output Quantity

The PDSU shall provide at least one

(1) regulated, switched independently monitored, ‐15.0 VDC secondary power output.

One regulated, switched, and independently monitored ‐15.0 VDC secondary power output is required to supply power to other subsystems. Additional output count margin is not required.

‐15 VDC

Secondary Power Tolerance Under Load

The PDSU ‐15.0 VDC secondary power output tolerance, under load, shall ± 5%

(VDC)

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC.

‐15V Max Ripple

The PDSU ‐15V secondary power output shall have less than 100 mV Pk‐Pk ripple voltage.

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC.

‐15V Secondary Power Output Current Drive

The PDSU ‐15V secondary power output shall have a current drive capacity ≥ 0.5 Amps.

The ‐15V secondary power output requires a ≥ 0.5 Amps drive strength given the current best estimates of subsystem power.

Generate +12 VDC Secondary Power for Subsystems

The PDSU shall regulate system power to +12.0 VDC secondary power for subsystems.

After the PDSU is powered on, initialized, and reaches the proper timing sequence, it needs to turn on, and turn off, power to subsystems. Nominal secondary voltages are +5.0 VDC, +12.0 VDC, +15 VDC, and ‐15 VDC.

+12V Secondary Power Output Quantity

The PDSU shall provide at least two

(2) regulated, switched independently monitored, +12.0 VDC secondary power output.

Two regulated, switched, and independently monitored +12.0 VDC secondary power output are to provide the planned outputs with a ≥ 25% margin.

Individual +12V Secondary Power Output Current Drive

The PDSU +12V secondary power outputs shall have a current drive capacity ≥ 75.0 Milli‐Amps.

The +12V secondary power output requires a ≥ 75.0 milli‐Amp drive strength given the current best estimates of subsystem power.

Measure Secondary Power to Subsystems

The PDSU shall measure all secondary power performance.

In contingency cases, such as a short circuit, the PDSU may need to switch off power to subsystems. Current and voltage measurements are needed for this fault detection and response.

Report Secondary Power Consumption

The PDSU shall report all measured secondary power consumption to a user interfaces via an Ethernet interface.

The PDSU needs to report the measured secondary power consumption to a user interfaces, or test computer, to allow evaluation of system performance during development testing.

The PDSU design concept drives reporting of measurements via the Ethernet interface.

Generate Internal Secondary Voltages

The PDSU shall regulate system power to secondary power for internal electronic/electrical components.

The PSDU will not have power sources other than the 28VDC, nominal voltage.

Analog Measurements

Thermocouple Measurements

The PDSU shall measure external thermocouples.

The PDSU needs to measure the health and status of batteries, mainly temperature from thermocouples and voltage measurements.

Voltage Measurements

The PDSU shall measure external voltages.

The PDSU needs to measure the health and status of batteries, mainly temperature from thermocouples and voltage measurements.

Report Temperature Measurements

The PDSU shall report the external thermocouple measurements to a user interfaces via an Ethernet interface.

The PDSU needs to report the temperature measurements to a user interfaces, or test computer, to allow evaluation of system performance during development testing. The PDSU design concept drives reporting of measurements via the Ethernet interface.

Report Voltage Measurements

The PDSU shall report the external voltage measurements to a user interfaces via an Ethernet interface.

The PDSU needs to report the voltage measurements to a user interfaces, or test computer, to allow evaluation of system performance during development testing. The PDSU design concept drives reporting of measurements via the Ethernet interface.

Voltage Measurement Input Quantity

The PDSU shall provide at least four

(4) external voltage measurement inputs.

The PDSU needs to measure the battery voltages. There are four batteries: system battery, pyrotechnic battery, tank heater battery, and survival heater batteries.

Voltage Measurement Input Range

The PDSU external voltage measurement inputs shall measure between 0.0 VDC and

+40.0 VDC.

The PDSU needs to measure the battery voltages. There are four batteries: system battery, pyrotechnic battery, tank heater battery, and survival heater batteries. All batteries are a nominal

28.0 VDC.

Thermocouple Measurement Input Quantity

The PDSU shall provide at least twenty‐three (22) external thermocouple measurement inputs.

The PDSU needs to measure the battery temperatures and case temperatures. Twenty‐three inputs is based on the quantity needed with ≥20% margin.

Temperature Measurement Input Range

The PDSU external thermocouple measurement inputs shall measure between ‐10.0 VDC and +10.0 VDC.

The PDSU needs to measure the battery temperature. There are four batteries: system battery, pyrotechnic battery, tank heater battery, and survival heater batteries. All batteries are a nominal

28.0 VDC.

Sample Rates

The PDSU shall sample thermocouple and voltage measurements at 10 Hz.

This sample rate is required per the LOFTID project requirements.

Sampling Number of Bits

The PDSU shall have ≥ 14 bits of effective resolution.

This sample bit resolution is required per the LOFTID project requirements.

Ordinance Drivers

Fire Ordinance Devices

The PDSU shall fire pyrotechnic, and one time actuation, devices.

The PDSU is control the firing of pyrotechnic devices, and one time actuation devices, such as the Aeroshell restraint bag, parachute deployment, and ejection of the Ejectable data module.

Ordinance Firing Safety

The PDSU shall fire pyrotechnic, and one time actuation, devices in accordance with AIAA S‐113A‐ 2016.

Established launch vehicle and range safety guidelines for pyrotechnic, or one time actuation, device firing.

Pyrotechnic (Ordinance) Output Quantity

The PDSU shall provide at least eight

(8) redundantly fired ordinance outputs.

Eight pyrotechnic firing outputs are required to provide the planned ports with a ≥ 20% margin. The number of pyrotechnic devices is preliminary and may grow as the avionics design matures.

Individual Ordinance Output Current Drive

The PDSU ordinance firing outputs shall have a current drive capacity ≥ 9.0 Amps for 30.0 milli‐seconds per channel.

The pyrotechnic firing outputs requires a ≥ 4.5 x 2.0 Amp drive strength given the current best estimates of subsystem power.

See AIAA S‐113A‐2016 section 5.2.2.1.

Ordinance Fault Tolerance

The PDSU ordinance circuits shall be at least single fault tolerant.

The PDSU is required to comply with fault tolerance specifications as defined in AIAA S‐113A‐2016 section 5.1.4.

Ordinance Power Source

The PDSU shall use external and dedicated power.

The PDSU is required to comply with AIAA S‐113A‐2016 requirements.

Measure Ordinance Power

The PDSU shall measure the ordinance power performance.

The PDSU needs to monitor the ordinance power current and voltage for fault detection and correction purposes.

Ordinance Driver ESD Protection

The PDSU Ordinance circuits shall have ≥

10.0 kilo‐Ohms between current positive and current return output nodes.

The PDSU is required to comply with discharge specifications as defined in AIAA S‐113A‐2016 section 5.3.5.2.8.

Ordinance Circuit Isolation

The PDSU shall isolate ordinance circuitry in accordance with

AIAA‐S‐113A‐2016,

Section 5.3.5.2.2 & 5.3.5.2.6.

The PDSU is required to comply with AIAA S‐113A‐2016 requirements.

Ordinance Circuit Current Leakage

The PDSU shall provide ordinance circuitry that have a leakage current < 10.0 milli‐amps when off.

The PDSU is required to have a low leakage current to prevent excess use of battery charge.

Discrete Inputs & Outputs

Bi‐Level Isolated Command Outputs

The PDSU shall toggle Bi‐Level Isolated commands to subsystems.

The PDSU needs to assert (set to logic high) and release (set to logic low) discrete command logic states to subsystems. Discrete commands are used to start key sequence operations such as starting to inflate the Aeroshell.

Bi‐Level Isolated Command Inputs

The PDSU shall measure the logic state of Bi‐Level Isolated command inputs

The PDSU needs to determine, measure, the logic state (high, low) of input discrete commands. Discrete command inputs are used to start internal timers.

Report Bi‐Level Isolated Command Input Status

The PDSU shall report the Bi‐Level Isolated input command status to a user interfaces via an Ethernet interface.

The PDSU needs to report the discrete input command status to a user interfaces, or test computer, to allow evaluation of system performance during development testing. The PDSU design concept drives reporting of discrete input command status via the Ethernet interface.

Bi‐Level Isolated Command Output Quantity

The PDSU shall provide at least four

(4) Bi‐Level Isolated command outputs.

Four discrete command outputs are required to provide the planned outputs with a ≥ 25% margin.

Bi‐Level Isolated Command Input Quantity

The PDSU shall provide at least four

(4) Bi‐Level Isolated command inputs.

Four discrete command inputs are required to provide the planned inputs with a ≥ 25% margin.

Bi‐Level Isolated Command Input Logic Low

The PDSU Bi‐Level Isolated Command Inputs shall have a logic low input voltage of 0.00 VDC to

0.50 VDC.

The voltage levels are required to comply with the launch vehicle interface requirements.

Bi‐Level Isolated Command Input Logic High

The PDSU Bi‐Level Isolated Command Inputs shall have a logic high input voltage of 4.00 VDC to

36.0 VDC.

The voltage levels are required to comply with the launch vehicle interface requirements.

Bi‐Level Digital I/O

The PDSU shall provide Bi‐level, Digital, and Configurable Inputs and Outputs.

The voltage levels are required to comply with the launch vehicle interface requirements.

Bi‐Level Digital I/O Quantity

The PDSU shall provide at least six (6) Bi‐level, Digital, and Configurable Inputs and Outputs.

The voltage levels are required to comply with the launch vehicle interface requirements.

Bi‐Level Digital I/O Logic Low Voltage

The PDSU Bi‐Level Digital I/O shall have a logic low voltage of

0.00 VDC to 0.80 VDC.

The voltage levels are required to comply with the launch vehicle interface requirements.

Bi‐Level Digital I/O Logic High Voltage

The PDSU Bi‐Level Digital I/O shall have a logic high voltage of

2.40 VDC to 5.00 VDC.

The voltage levels are required to comply with the launch vehicle interface requirements.

Internal Health & Status

Measure Internal Health and Status

The PDSU shall measure internal health and status parameters.

The PDSU needs to measure, or monitor, internal health & status parameters. Internal health and status may include:

• Power consumption of internal hardware

• Temperatures

• Built in test status

• Fault conditions

Report Internal Health and Status

The PDSU shall report internal health and status to a user interfaces via an Ethernet interface.

The PDSU needs to report internal health and status to a user interfaces, or test computer, to allow evaluation of system performance during development testing. The PDSU design concept drives reporting of measurements via the Ethernet interface.

Serial & Ethernet Communication

Ethernet Port Quantity

The PDSU shall provide at least two

(2) Ethernet ports.

Two Ethernet ports are required. One Ethernet port is used as a software terminal, and the other is used to report data/status to an Ethernet switch.

Ethernet Port

The PDSU shall provide an Ethernet bit rate of 100 Mega‐ bit‐per‐second or greater (100 Base‐T).

The Ethernet port is required to be 100Base‐T or greater to send and receive data to/from an Ethernet switch. This data transfers may be greater than 10 Mbps.

Ethernet Port Electrical Standard

The PDSU shall provide Ethernet Ports that meet IEEE

802.3 specifications.

The Ethernet port needs to be IEEE 802.3 compliant to comply with interfaces with other subsystems.

Ethernet Precision Time Protocol Compliance

The PDSU shall provide Ethernet ports that are compliant to the Precision Time Protocol (PTP) version 1.

The PDSU needs to use PTP time received from an Ethernet Switch to tag telemetry and sequence events. This includes data from the IMU, internal health & status, system power consumption, and secondary power consumption.

Receive PTP Time Tag

The PDSU shall receive the PTP time tag.

The PDSU needs to use PTP time received from an Ethernet Switch to tag telemetry and sequence events. This includes data from the IMU, internal health & status, system power consumption, and secondary power consumption.

Serial Port Electrical Standard

The PDSU shall provide serial ports that meet TIA/EIA‐ 422/485 electrical specifications.

The PDSU needs differential serial ports for signal compatibility with other subsystems.

Serial Port Communication Protocols

The PDSU shall provide serial ports that have UART and

HDLC/SDLC

communication protocols.

The PDSU needs these communication protocols to comply with interface requirements with other subsystems.

Serial Port Maximum Bit Rate

The PDSU shall provide serial ports that have a maximum bit rate of 500 kilo‐ bits‐per‐second.

The PDSU needs these bit rate to comply with interface requirements with other subsystems.

Serial Port Quantity

The PDSU shall provide at least four

(4) serial ports.

Three serial ports are required to provide the planned ports with a ≥ 25% margin.

Global Position System

GPS Position and Time

The PDSU shall obtain GPS position and time.

The PDSU need to determine the GPS position and time after the reentry vehicle separates from the RV, during reentry, and after reentry.

Report GPS Position and Time

The PDSU shall report GPS position and time to a user interfaces via an Ethernet interface.

The PDSU needs to report the GPS position and time to a user interfaces, or test computer, to allow evaluation of system performance during development testing. The PDSU design concept drives reporting of GPS position and time via the Ethernet interface.

GPS Acquisition Time

The PDSU shall obtain GPS position and time, in the relative Doppler environment, in ≤ 2.0 minutes from a cold start.

The PDSU needs to lock on to the GPS signal with two minutes to ensure enough time is available to transmit the key performance data to ground operators before reentry begins.

GPS Doppler Environment

The PDSU shall obtain GPS position and time with a ± (TBD) Hz Doppler shift.

A STK analysis is required to derive the Doppler environment given the LOFTID orbital and reentry trajectory. It is TBD at this time. Note: the reentry velocity is ~8km/s

Software & Data Processing

Receive IMU Data

The PDSU shall receive data from an IMU via a serial interface.

The PDSU need to receive, and process, IMU acceleration data.

The acceleration data is used to determine the reentry vehicle orientation during key flight segments.

Process IMU Data

The PDSU shall process IMU data to calculate changes in orientation.

The PDSU need to receive, and process, IMU acceleration data.

The acceleration data is used to determine the reentry vehicle orientation during key flight segments.

Report Processed and Raw IMU Data

The PDSU shall report raw and processed IMU data to a user interfaces via an Ethernet interface.

The PDSU needs to report the raw and processed IMU data to a user interfaces, or test computer, to allow evaluation of system performance during development testing. The PDSU design concept drives reporting of raw and processed IMU data via the Ethernet interface.

Receive Data From Subsystems

The PDSU shall receive data from other subsystems via an Ethernet interface.

The PDSU needs to receive subsystem data in order to gather key aerothermal and Aeroshell status (key performance data) during flight. This key performance data is used to create a data packet that is transmitted to ground operators during the flight.

The PDSU design concept drives receiving this data via the Ethernet interface.

Gather Key Performance Data from Subsystems

The PDSU shall gather key performance data from other subsystems.

The PDSU needs to receive subsystem data in order to gather key aerothermal and Aeroshell status (key performance data) during flight. This key performance data is used to create a data packet that is transmitted to ground operators during the flight.

The PDSU design concept drives receiving this data via the Ethernet interface.

Report Key Performance Data

The PDSU shall report the key performance data from other subsystems to a user interfaces via an Ethernet interface.

The PDSU needs to report the key performance data from other subsystems to a user interfaces, or test computer, to allow evaluation of system performance during development testing.

The PDSU design concept drives reporting of key performance data from other subsystems status via the Ethernet interface.

Send Key Performance Data to Satellite Communication Transceiver

The PDSU shall send key performance data to a satellite communication transceiver via a serial interface.

The PDSU needs to receive subsystem data in order to gather key aerothermal and Aeroshell status (key performance data) during flight. This key performance data is used to create a data packet that is transmitted to ground operators during the flight.

The PDSU design concept drives sending the data via a serial interface.

Software Terminal

The PDSU shall interface with a software (user) computer via a separate Ethernet interface.

The PDSU needs to have a separate Ethernet interface for use as a software terminal, or user terminal. This interface is used to upload new software, manually enter commands and configurations, monitor software status, etc.

Telemetry Time Index Tagging

The PDSU shall apply the PTP time tag to all data reported via the Ethernet interface.

The PDSU needs to use the time index from an Ethernet Switch to tag telemetry and sequence events. This includes data from the IMU, internal health & status, system power consumption, and secondary power consumption.

Time Tag Accuracy

The PDSU shall have a time tag accuracy of +/‐ 10.0 milli‐seconds.

The PDSU needs to time tag data with a second of measurement. This is not a driving factor in the design.

Interconnecting Bus

The PDSU shall have an interconnecting bus that connects subcomponents.

Examples of interconnecting busses include cPCI, IBUS, PLB.

Mechanical, Environmental & EEE Parts

Size Limit

The PDSU shall fit within an 11.0 inch x

13.0 inch x 25.0 inch (Height x Width x Length) dimensional space.

The dimensional constraints were established from the reentry vehicle reference design.

Mass Limit The PDSU shall have a mass ≤ 10.0 kilograms.

This is a mass allocation established from the reentry vehicle reference design around the time of project SRR.

7.0 POWER DISTRIBUTION & SEQUENCING UNIT DESIGN CONCEPT:

The Power Distribution & Sequencing Unit (PDSU) subsystem was derived from a larger avionics design concept. The primary functions are:

Receiving a command from the Launch Vehicle to switch on.

Switch, monitor, and distribute 28 VDC operational power to other subsystems.

Regulate, switch, monitor, and distribute secondary power to internal components and other subsystems.

Control the sequence of power switching to the other subsystems

Fire pyrotechnic/ordinance and one time actuation devices.

Measure and monitor internal Health & Status (H&S).

Determine Global Positioning System (GPS) position and time while moving at ~8km/s

Receive Inertial Measurement Unit (IMU) data and process acceleration data to determine orientation.

Contains the processing functions to embed the Flight Software (FSW).

Electrically interfaces with the other subsystems.

Packages data sends it to a network, Ethernet, interface

Time tag and data transmission with the Ethernet, Precision Time Protocol

Packages data and sends it to a satellite communication transceiver.

An example functional diagram is provided on the next page.

Power Distribution & Sequencing Unit

Ordinance Control & Drivers

IMU

System Power Distribution

Subsystem

Analog Measurements

GPS Antenna

Satellite Communication Transceiver

System Battery

(28.0 VDC)

Ethernet Switch

5V

EMI

Filter

Pyrotechnic Battery A

Discrete Inputs & Outputs

GPS

Power

Flight Data

Commands

LEGEND

Subsystems/ Elements

• Key Functions

Pyrotechnic Battery B

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

I&VMon

Secondary Power Distribution

I&V Mon

+15V

I&V Mon

‐15V

I&V Mon

+12V

I&V Mon

Internal V

I&V Mon

I&V Mon

Internal Loads

Load

Load

Load

Load

Load

Load

Load

Load

Load

Load

Load

Load

Load

Load

Pyro

Pyro

Pyro

Pyro

Pyro

NED

Bi‐Lvl Cmd Out

Bi‐Lvl Cmd Out

Bi‐Lvl Cmd Out

Bi‐Lvl Cmd Out

Bi‐Lvl Cmd In

Bi‐Lvl Cmd In

Bi‐Lvl Cmd In

Bi‐Lvl Cmd In

Serial Ports & Ethernet

RS422/485

RS422/485

RS422/485

100Base‐T100Base‐T Software Terminal

Computer & Software

Processor

RAM

Flash

Mux A/D Tank Heater

Battery

(28.0 VDC)

Voltage Measurements

Mux A/D

Temperature Measurements

I&V Mon

Each pyro unit consists of two independent explosive components

Chassis/Case Temp

Locations

Switch Indicators

Digital In/Out

Digital In/Out

Digital In/Out

Digital In/Out

Digital In/Out

Digital In/Out

Digital In/Out

Digital In/Out