Beamforming in the context of "Multibeam echosounder"

Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target region to provide finer spatial resolution than conventional stationary beam-scanning radars. SAR is typically mounted on a moving platform, such as an aircraft or spacecraft, and has its origins in an advanced form of side looking airborne radar (SLAR). The distance the SAR device travels over a target during the period when the target scene is illuminated creates the large synthetic antenna aperture (the size of the antenna). Typically, the larger the aperture, the higher the image resolution will be, regardless of whether the aperture is physical (a large antenna) or synthetic (a moving antenna) – this allows SAR to create high-resolution images with comparatively small physical antennas. For a fixed antenna size and orientation, objects which are further away remain illuminated longer – therefore SAR has the property of creating larger synthetic apertures for more distant objects, which results in a consistent spatial resolution over a range of viewing distances.

To create a SAR image, successive pulses of radio waves are transmitted to "illuminate" a target scene, and the echo of each pulse is received and recorded. The pulses are transmitted and the echoes received using a single beam-forming antenna, with wavelengths of a meter down to several millimeters. As the SAR device on board the aircraft or spacecraft moves, the antenna location relative to the target changes with time. Signal processing of the successive recorded radar echoes allows the combining of the recordings from these multiple antenna positions. This process forms the synthetic antenna aperture and allows the creation of higher-resolution images than would otherwise be possible with a given physical antenna.

The HomePod is a series of smart speakers developed by Apple. Designed to work with the Apple Music subscription service, the HomePod incorporates beamforming and eight speakers and is sold in two colors: white and midnight. It is sold alongside the HomePod Mini, a smaller and less expensive variant introduced in 2020.

The first-generation HomePod was announced on June 5, 2017, at the Apple Worldwide Developers Conference. Its planned December launch was delayed: Apple began taking orders on January 26, 2018, and released it on February 9, 2018. The HomePod received mixed reviews: it was praised for its design and sound quality compared to other speakers of its price, and criticized for lack of third-party support and high price compared to other smart speakers. The first-generation HomePod sold an estimated 1 to 3 million units through August 2018. It was discontinued on March 12, 2021.