Abstract: A portable ultrasonic imaging probe is adapted to connect to a host computer via a passive interface cable, e.g., a standard USB 2.0 peripheral interface cable or a standard IEEE 1394 “Firewire” peripheral interface cable. In accordance with an embodiment, the portable ultrasound imaging probe includes a probe head, a logarithmic compressor, an envelope detector, and analog-to-digital converter and interface circuitry, all of which receive power from the host computer via the passive interface cable. To simplify the portable ultrasonic imaging probe, none of electronic beamforming, time gain compensation, gray-scale mapping and scan conversion are performed within the probe. This abstract is not intended to describe all of the various embodiments of the present invention, or to limit the scope of the invention.

Abstract: Disclosed are, inter alia, instantaneously restartable clocks and their use. For example, instantaneously restartable clocks can be used to receive data from another independently clocked subsystem in a manner that removes the possibility of metastability errors. A restartable clocking signal generator, relying on oscillating signals typically generated by a continuous oscillating source, is used to generate a restartable clocking signal which can be asynchronously restarted in response to one or more control signals. In one implementation, an apparatus includes multiple independently clocked subsystems and a clockless sequencing network, with the clockless sequencing network being used to initiate the start of a restartable clock in order to reliably receive and process data between the independently clocked subsystems.