Real-Time LiDAR Signal Processing FPGA Modules

Sensors
Real-Time LiDAR Signal Processing FPGA Modules (GSC-TOPS-173)
Processing LiDAR data into high-resolution 3D imagery
Overview
Scanning LiDARs generate an immense amount of raw digital data which must be processed as quickly as possible in order to generate 3D imagery in real time. In order to accomplish this task for the next-generation 3-D scanning LiDAR known as the Goddard Reconfigurable Solid-state Scanning LiDAR (GRISSLi), NASA Goddard Space Flight Center has developed a FPGA module capable of processing an arbitrary number of waveforms rapidly and in parallel. This innovation enables a high-resolution 200 KHz time-of-flight solution, allows a system to process an almost limitless number of received laser pulses for LiDAR applications in real time, and is limited only by available FPGA resources.

The Technology
The developed FPGA modules discern time-of-flight of laser pulses for LiDAR applications through the correlation of a Gaussian pulse with a discretely sampled waveform from the LiDAR receiver. For GRSSLi, up to eight cross-correlation engines were instantiated within a FPGA to process the discretely sampled transmit, receive pulses from the LiDAR receiver, and ultimately measure the time-of-flight of laser pulses at 20-picosecond resolution. Engine number is limited only by the resources within the FPGA fabric, and is configurable with a constant. Thus, potential time-of-flight measurement rates could go well beyond the 200-KHz mark required by GRSSLi. Additionally, the engines have been designed in an extremely efficient manner and utilize the least amount of FPGA resources possible.
Change in Elevation Over Greenland
Benefits
  • Processes an almost limitless amount of laser pulses in real-time
  • Highly efficient: uses the minimum FPGA resources feasible
  • Produces high-resolution images

Applications
  • Real-time 3D imaging
Technology Details

Sensors
GSC-TOPS-173
GSC-17215-1
11016183
Similar Results
Seaweed Farms in South Korea acquired by The Operational Land Imager (OLI) on Landsat 8
Non-Scanning 3D Imager
NASA Goddard Space Flight Center's has developed a non-scanning, 3D imaging laser system that uses a simple lens system to simultaneously generate a one-dimensional or two-dimensional array of optical (light) spots to illuminate an object, surface or image to generate a topographic profile. The system includes a microlens array configured in combination with a spherical lens to generate a uniform array for a two dimensional detector, an optical receiver, and a pulsed laser as the transmitter light source. The pulsed laser travels to and from the light source and the object. A fraction of the light is imaged using the optical detector, and a threshold detector is used to determine the time of day when the pulse arrived at the detector (using picosecond to nanosecond precision). Distance information can be determined for each pixel in the array, which can then be displayed to form a three-dimensional image. Real-time three-dimensional images are produced with the system at television frame rates (30 frames per second) or higher. Alternate embodiments of this innovation include the use of a light emitting diode in place of a pulsed laser, and/or a macrolens array in place of a microlens.
NASA robotic vehicle prototype
Super Resolution 3D Flash LIDAR
This suite of technologies includes a method, algorithms, and computer processing techniques to provide for image photometric correction and resolution enhancement at video rates (30 frames per second). This 3D (2D spatial and range) resolution enhancement uses the spatial and range information contained in each image frame, in conjunction with a sequence of overlapping or persistent images, to simultaneously enhance the spatial resolution and range and photometric accuracies. In other words, the technologies allows for generating an elevation (3D) map of a targeted area (e.g., terrain) with much enhanced resolution by blending consecutive camera image frames. The degree of image resolution enhancement increases with the number of acquired frames.
https://www.flickr.com/photos/gsfc/47435507852/
SpaceCube 3.0 Mini Processor Card
The SpaceCube 3.0 Mini Processor Card represents orders of magnitude increase in performance and capability over typical radiation-hardened processor-based systems and significant advances over the previous generation of SpaceCube technology. The primary processing engine of the card is a radiation-tolerant FPGA. This processor card is very low weight, can fit within the 1U CubeSat form-factor (10cm x 10cm x 10cm), and will be low power. Much of the SpaceCube 2.0 Micro design is incorporated into the SpaceCube 3.0 Mini design. In addition, lessons learned from the SpaceCube 2.0 Mini card are applied. Instead of using a rigid-flex design, the SC3.0 Mini uses a backplane architecture. The processor card plugs into a backplane that routes signals to other card slots. In order to meet the numerous high-speed I/O interfaces required by the latest generation science instruments and applications, a high-density backplane connector is needed. The SpaceCube 3.0 Mini uses a high-density connector to plug into the backplane. The FPGA has flash memory attached that is used for storing algorithm and application code for any hosted soft processors. The processor card also has a nanominiature front-panel connector that adds even more I/O to support instrument interfaces such as Camera Link or SpaceWire. The SpaceCube 3.0 Mini Processor Card features a rad-tolerant FPGA, but the radiation mitigation can be tailored for harsher environments by adding an external rad-hard device that configures and monitors the FPGA over the backplane. The processor card pushes transceiver quantity, routing, and performance for spaceflight. The card is designed to fit in the compact 1U CubeSat form factor. The SpaceCube 3.0 Mini supports scalability by networking multiple processor cards together.
Spacecube in pieces. SpaceCube is a next-generation computer system developed at the Goddard Space Flight Center in Greenbelt, Md. The potentially revolutionary computer system, which provides up to 25 times the processing power of a typical flight processor, will be testing special software techniques that would make the computer more immune to upsets that happen when radioactive particles affect the computer. The SpaceCube was demonstrated during the Hubble Servicing Mission earlier this year.
SpaceCube 3.0 Flight Processor Card
SpaceCube 3.0 features the rad-tolerant multi-core T2080 processor and the rad-tolerant Kintex UltraScale FPGA. The SpaceCube 3.0 Flight Processor Card meets the industry standards in lightweight systems specifications. In addition, the flight processor card can be installed with an expansion card option to allow a tightly-coupled, mission unique card to be installed. The mission unique expansion card can support a variety of capabilities to make SpaceCube 3.0 a powerful instrument processor, including A/D converters, D/A converters, gigabit ethernet, and additional co-processors. Furthermore, the flight processor card is extremely flexible. Algorithms can be implemented in both the Kintex UltraScale FPGA and the T2080 processor. More sequential portions of the algorithm can be implemented quickly and efficiently on the processor, while other algorithms that are more parallel in nature and computation heavy can be accelerated in the FPGA. Using a hybrid system, each can be optimally implemented to take advantage of the features of both. The SpaceCube 3.0 Flight Processor Card design consists mostly of NASA-qualified flight parts and has many features to mitigate radiation effects on the processor system. The processor card can configure the FPGA to scrub configuration memory. In addition, it can monitor the health of the processors, the FPGA, and any coprocessors on the expansion card using watchdog timers. The FPGA uses error detection and multiple redundant copies to mitigate against radiation upsets to the configuration files, which are stored in external non-volatile memories.
Pulsed 2-Micron Laser Transmitter
The new NASA LaRC Pulsed 2-Micron Laser Transmitter for Coherent 3-D Doppler Wind Lidar Systems is an innovative concept and architecture based on a Tm:Fiber laser end-pumped Ho:YAG laser transmitter. This transmitter meets the requirements for space-based coherent Doppler wind lidar while reducing the mission failure risks. A key advantage of this YAG based transmitter technology includes the fact that the design is based on mature and low-risk space-qualified YAG host crystal. The transmitter operates at a 2096 nm wavelength using Ho:YAG, resulting in high atmospheric transmission (>99%), versus a transmitter operating at 2053 nm using co- doped Tm:Ho:LuLiF, which suffers limited transmission (90%) due to water vapor interference. In-band pumping through Tm:Fiber pump Ho:YAG architecture offers lower quantum defect from 1908 to 2096 nm (9.1%) compared to traditionally used co-doped Tm:Ho:LuLiF of 792 to 2051 nm (61%). The transmitter has an efficient pump compared to LuLF, since YAG has 27% higher pump absorption and 52% lower reabsorption of the emitted 2-micron, resulting in higher efficiency and lower heat load. Being isotropic, YAG is amenable for spatial-hole burning mitigation which supports linear cavity architecture without compromising injection seeding quality. This attribute is important in designing a compact, stable, high seeding efficiency laser. A folded linear cavity for long pulse (>200 ns), transform limited line-width (2.2 MHz) and high beam quality (M2 = 1.04) - the most critical parameters for coherent detection - are easier to achieve using YAG compared to LuLF. Lower heat load results in high repetition rate (>300 Hz) operation, which allows higher probability of wind measurements through broken clouds, off clouds, and below clouds, thus reducing errors and increasing science data product quantity and quality.
Stay up to date, follow NASA's Technology Transfer Program on:
facebook twitter linkedin youtube
Facebook Logo Twitter Logo Linkedin Logo Youtube Logo