Analog to digital converter.

An actual signal appearing where it should not.

Subsystem of the SSE that stores selected data.

Allen Telescope Array

Signal processing system that uses the output(s) of the ATA.

A limited range of frequencies.

A band that (typically) includes DC.

A narrow patch of the sky selected by the ATA beamformer.

Device that sums the samples from individual antennas with appropriate complex weights to produce a beam.

Usually one of the very narrow bands used by the SonATA detectors, but can also be used more generally, for example a channel.

Relatively small but very fast memory cohabiting with a CPU.

A statistically significant signal worthy of further observation, e.g. not already known as RFI.

Center for Astronomy Signal Processing and Electronics Research at UCB.

Critical design review.

The result of the first, relatively coarse division of the input frequency band, currently ~400 kHz in width.

Subsystem of the SonATA that produces channels.

Cloud computing is Internet-based computing, whereby shared resources, software, and information are provided to computers and other devices on demand, like the electricity grid. (From Wikipedia http://en.wikipedia.org/wiki/Cloud_computing)

Coherent averaging means averaging the Re and Im parts of samples separately, usually used in coherent detector.

Redetection of a candidate ET signal by independent observers at another observatory.

A shared library of compiled code that provides the core algorithms used to create DFBs.

Central processing unit.

A “continuous wave” signal, i.e. one that looks sinusoidal over some time interval. In SonATA usage we call a signal that has a slowly changing frequency, of order a few Hz/s, a “drifting CW” signal.

Doubling Accumulation Drift Detection, a detection algorithm that finds slowly drifting CW signals in a set of M spectra with order Mlog2(M) operations instead of the order M^2 operations required by the ‘brute force’ method.

Nominally “direct current” but used for signals near zero frequency, as in DC band.

Data Distribution Subsystem of SonATA.

A statistical process that finds specified signals with a low probability of false alarms due to noise alone.

A hardware or software process that performs detection.

Digital filter bank.

Distance measuring equipment, a radio-navigation system used by most aircraft.

Detector Subsystem of SonATA.

An ATA antenna plus its associated electronics.

Extra-terrestrial or extra-terrestrial technology.

A hardware protocol for exchanging data between computers. Usually, Ethernet protocol specifies the wire-level signals that carry IP packets between nearby computers.

Front end, the cryogenic, low-noise amplifier directly connected to the feed of each ATA element.

A passive microwave assembly that couples the incoming waves at the focus of an antenna to the transmission line that drives the FE.

Fast Fourier Transform.

Field-Programmable Gate Array.

"Giga-," prefix for 10^9.

Gigabit, 10^9 bits.

Gigabyte, 10^9 bytes.

Gigabit Ethernet.

10^9 floating point operations per second.

Gigahertz.

Global Positioning System.

Gaussian white noise.

Hardware Support Subsystem of SonATA.

Heating, ventilating, and air-conditioning.

Input/output.

Imaginary part (of a complex number).

Incoherent averaging means averaging the powers (squared modulus) of samples, usually used in incoherent detector.

Internet Protocol.

Orbiting sources of RFI.

1) kilo, 10^3, or 2) Boltzman's constant.

Karhunen–Loève Transform

kilowatt.

Local area network.

Low earth orbit or a satellite in such an orbit.

The first local oscillator in a frequency conversion system.

mega-, 10^6

Megahertz.

Multicast is the delivery of packets to a group of destinations simultaneously using an efficient strategy to deliver the data over each link of the network only once by creating copies when the links to the destinations split. Multicast is typically used to refer to IP Multicast, the implementation on the IP routing level.

Random voltages caused by thermal motion.

Nonrecurring engineering, one-time engineering costs associated with a project.

National Science Foundation.

New Search System, a precursor to SonATA.

A formatted block of information carried over an IP network. Varieties include, TCP, UDP, unicast, and multicast packets.

Pulse detector.

Programmable Detection Module, the detector unit of the NSS.

Polyphase filter bank, a particular implementation of a DFB, sometimes inaccurately used for a WOLA DFB.

A virtual data connection between computer programs through a computer network. The IP uses the port number to direct information to a specific process on a computer.

The NSS running on the ATA is the Prelude to SonATA.

A running instance of a computer program, which may create and control many threads. Generally, separate processes do not directly share memory with one another (as opposed to threads).

The process of representing an analog signal using integers.

Redundant array of inexpensive disks.

Random access memory.

Remote direct memory access, a method to reduce Ethernet overhead.

Real part (of a complex number).

Radio frequency, in the context of the ATA the signal as received directly from the sky before frequency conversion.

Radio frequency interference.

Variation in the in-band response of a filter.

Root mean square.

The result of a single act of quantization or such a result (representing a signal voltage) after further processing.

Number of samples acquired per unit time.

A computer, usually configured for rack mounting, intended for tasks requiring heavy I/O and/or computing.

Search for extraterrestrial intellience.

The SETI Institute.

Single instruction, multiple data.

A type of SETI that covers a large amount of solid angle in the sky.

Signal power to noise power ratio.

A communication end point on an internet protocol (IP) network. A socket may be specified with a protocol (e.g. TCP, UDP), IP address, and port number.

SETI on the ATA, a SETI search system designed to work well with the ATA.

Search System Executive, the control subsystem of SonATA.

Result of sub-dividing a band, most often used to describe the approximately kHz bands into which the first stages of DX divide the incoming channels.

A hardware device to interconnect computers over a network (usually Ethernet).

"tera-," prefix for 10^12.

International Atomic Time (TAI, from the French name Temps Atomique International). The ATA control software uses TAI as a resolution of nanoseconds internally for ephemeris and tracking.

A type of SETI that looks at a (large, often) list of specific targets, i.e. positions on the sky.

Transmission Control Protocol/Internet Protocol; a high reliability protocol for computers to send messages to one another. TCP provides reliable, in-order delivery of data from sender to receiver (compare with UDP). TCP does not support multicast, and does not control time of delivery.

10^12 floating point operations per second.

A way for a running computer program (process) to split itself into two or more simultaneously (or pseudo-simultaneously) running tasks. Multiple threads that are created by the same process may access the same memory. Threads allow a single process to take advantage of multiple CPUs.

A sequence of samples acquired at steady intervals over some period of time.

TCP Offload Engine, a method to reduce Ethernet overhead.

System temperature, a measure of noise at the FE, or the amplified versions of that noise in later stages of signal processing.

For the ATA, one of four RF bands selected using on of four LO1's.

The University of California, Berkeley.

User Datagram Protocol/Internet Protocol; a protocol for computers to send short (typically < 16 kB) messages to one another. UDP messages are not guaranteed to be in-order or always to arrive at all at their destination (compare with TCP). UDP supports multicast, and data sent via UDP will arrive at its destination within a calculable time window.

Unicast is the delivery of packets to a single destination.

Uninterruptible power supply.

In the conext of SonATA, organized for efficient computation using SIMD.

Follow-up observations of a candidate ET signal performed with SonATA, possibly in conjunction with another radio telescope using VLBI, made to verify that the candidate signal meets all the tests we can think of to discriminate real ET signals from other signals. The first stages of the verification process are performed by the SSE automatically. See confirmation.

Very long baseline interferometry.

Weighted overlap and add, a particular implementation of a DFB.