It used to be super useful back in the day when data caps and low bandwidth were big problems; nowadays I feel the mindset and the compression levels are stuck in that era, often times often compressed at even higher ratio. From my experience a lot of the downloads which are heavily compressed takes seconds to download but minutes to install. In my case my bandwidth is more than capable of downloading the actual files faster rather than chugging my CPU and storage to a halt at times as it solely focuses on decompression.
Commonly called bucketheads by protesting galactic citizens, these dedicated and honorable Empire serving soldiers have an instantly recognizable sound on the silver screen. Most noticeable is the narrow bandwidth of the voice analogous to a CB radio or Walkie-talkie. This narrow bandwidth is located in the low mid to high mid frequency range and is accompanied by a 2 kHz resonant peak. The signal is also highly compressed and slightly overdriven, which gives it a lo-fi quality. Its other iconic attribute is the radio receiver squelch circuit sound heard before and after a line of dialogue. This varies in sound and can be heard as audible clicks and short noise bursts. With the analysis done, we can now move on to recreating this classic sound in our droid lab.
The key to reaching gigawatts of power is dumping all the energy in one gigantic, nearly instantaneous pulse. A pressurized gas switch prevents the Tesla transformer from prematurely dumping as it builds up for the next pulse. The switch is filled with highly compressed and nonconducting nitrogen gas. When the transformer coils reach 700 kV, the nitrogen gas breaks down, and the pulse leaps through to the electron-beam diode.
The Cluster quartet of satellites, launched in summer 2000, allows, for the first time, to separate spatial and temporal variations. This is of particular importance in a highly variable and dynamic region like the Earth's magnetotail and provides completely new insight into magnetotail dynamics [Baumjohann and Nakamura, 2004].
Possible mechanisms have already been proposed and numerical simulations developed to explain this phenomenon. However, both theoretical models and numerical simulations obviously require an accurate estimate of the BBF typical spatial scale to quantitatively describe this phenomenon. This spatial extent is composed of 3 dimensions: the dawn-dusk, the north-south and the "Sun-Earth direction" scale size. The latter can be easily estimated knowing the typical duration and the velocity of BBF.
Past comparisons of single spacecraft measurements with ground-based data led to the conclusion that their dawn-dusk extent is limited to 3-5 RE. Two-spacecraft observations led to a different conclusion: 1-3 RE.
Image 3: Excerpt of Figure 5 from [Volwerk et al., 2004c], top panel: reconnection takes place in the far tail, and Cluster is located in a compressed magnetotail; bottom panel: Cluster observes Bursty Bulk Flows or BBF (Courtesy of Dr. Martin Volwerk, Space Research Institute/Austrian Academy of Sciences, Graz, Austria).
"The velocity gradient at the duskward edge of a flow tends to be sharper than that at the dawnward edge, possibly reflecting an asymmetry in the magnetosphere-ionosphere coupling process associated with the flow", she added.
Compression: FC images may optionally be compressed by wavelet transformation. Wavelet compression: Images may be integer or floating point wavelet transform-compressed in the DPU. The integer approach produces lossless compression, while the floating point can induce distortions of +/-1 DN. The encoding of the wavelets ensures that any length of the data starting at the beginning can be decoded, thus allowing to compress further by discarding the trailing part. Windowing: In order to manage downlink resources, up to 10 portions of the image can be selected in the DPU and downlinked as subframes. The subframes are allowed to overlap. During EDR construction each subframe is stored separately and also mosaicked into the original image. Exposure Control: The exposure time of FC images is set by command for each image. Pointing: The Framing Cameras are fix mounted onto the Dawn Instrument deck, with the nominal alignment of the optical axis with the +Z axis of the spacecraft. Deviations from the nominal are documented in the calibration data. Filter selection: The FC has 8 filters at its disposal, numbered from F1 to F8. F1 is a broadband (clear) filter, sensitive in the wavelength interval from 400 to 1100 nm peaking at 700 nm. The narrow-band color filters are of the interference type, and have wavelengths ranging from 430 to 980 nm.
An FC image downlinked by the spacecraft unpacks into a succession of one or more compressed image subframes with an attached PDS headers containing housekeeping items that include full status of the instrument hardware, software configuration, temperature, voltage and current readings. The data in one EDR consists of one or more reconstructed image frames, with the accompanying header translated into text format in the label. The dimensions and location (pixel coordinates) of each frame are included for proper further processing. Each frame is formatted into one file (suffix *.IMG), with an attached label. Subframes are retained as separate entities and also are reassembled into their original coordinates in the 'summary' image. Parts of the reconstructed image not included in the subframes are given a value of zero. Darks are acquired in a different mode than normal images, leading to different cropping and therefore different image file structure. Darks are acquired as full 1092x1056 pixel images, which are cropped due to operational considerations to include 1088x1056 (Frame 0) and 4x1056 (Frame 6) allowing the complete reconstruction of the original full frame. In contrast, normal images are cropped into several smaller sections (the most prominent of which is the 1024x1024 active area), and therefore have several smaller frames. For further details on the layout of the data and the possible combinations of frames, please refer to the Software Interface Specification. The label contains all relevant housekeeping information in calibrated form (e.g. degrees Celsius, volts, or amperes).
The Dawn Mission to Vesta and Ceres (DAWN) Gravity Science (GR) Raw Data Archive (RDA) is the set of raw and partially processed radio science data collected during the Dawn mission to Vesta. The earliest data in this data set were collected on 2011-07-10. The closed-loop system used a phase-lock loop in the ground receiver to track the downlink signal, reporting both amplitude and frequency at rates typically of 1-10 times per second. Closed-loop data are efficient for characterizing slowly changing signals and are the input to operational navigation and orbit-determination processes. The data set includes one type of primary data, the ODF. TNFs (Tracking and Navigation Service Data Files) are the output of the closed-loop receiver. Orbit Data Files (ODFs) are compressed versions of TNFs. ODFs are specifically targeted to spacecraft navigators and scientists interested in gravity fields. Typical users of these data might analyze range and Doppler measurements in ODFs to reconstruct the spacecraft trajectory. Relevant questions would include the measurement uncertainties in range and Doppler at different DSN antennas; the uncertainties could set constraints on any model of Vesta's gravity field developed later, for example.
ODFs are abstracted from subsets of TNF data, the uncompressed output of the closed-loop receiver at the Deep Space Network. A full PDS label accompanies each ODF file and gives a bit level description of the content and format.
The Navigation and Ancillary Information Facility (NAIF) is the navigation node of the PDS. NAIF provides the archives for spacecraft navigation, attitude, events, clock conversion, and planetary ephemerides for most NASA missions. Additionally, NAIF provides the SPICE toolkit, containing useful algorithms to utilize and manipulate data NAIF provide. Relevant to gravity science are the following types: * CK: Spacecraft and solar array attitude orientation files * EK: Spacecraft events kernel * FK: Reference frame specification * SCLK: Conversion between spacecraft time and ephemeris time * SPK: Spacecraft and Planetary ephemeris data The NAIF PDS archive for Dawn is located at: naif.jpl.nasa.gov/pub/naif/pds/data/dawn-m_a-spice-6-v1.0/
The compressed pulses are seven times shorter than the original -- the largest compression demonstrated to date on a chip.
Until now, pulse compression featuring such high compression factors was only possible using bulk optics or fiber-based systems, both of which are bulky and not practical for optical interconnects for computers and other electronics.
This example illustrates how the on-chip pulse compressor transforms a long pulse of light into a spectrally broader and temporally shorter pulse of light. This temporally compressed pulse will enable multiplexing of data to achieve much higher data speeds.
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