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(1) (Digital Video Recorder) A device that records video from up to a dozen or more surveillance cameras onto a hard disk. The frame rate can be switched from real time to time lapse in order to save storage space. Digital recorders are more flexible than earlier analog VHS tape systems, and the video can be easily transmitted over a computer network. See CCTV.

(2) (Digital Video Recorder) Also known as a "personal video recorder" (PVR) or "hard disk recorder," a DVR is a consumer device that allows the viewer to pause and rewind any broadcast, cable or satellite TV program as well as record and play back selected programs (see live pause). An order of magnitude more flexible than earlier videocassette tape recorders (VCRs), an entire season of programs from one or more favorite series can be recorded.

DVRs may be built into the set-top box or replace the box using plug-in modules (see CableCARD). They store incoming digital TV signals on the hard disk as well as digitize analog TV into the MPEG-2 format. The video may be compressed to maximize storage space.

Part of the Service or Stand-Alone
The DVR periodically downloads channel program guide updates as well as software updates for the unit itself. When the DVR is integrated into the cable or satellite set-top box, the downloads ride the same medium as the TV service. When the DVR is stand-alone, the downloads come in via the home network.

Before the Turn of the Century
DVRs first came on the market in 1999 with products from ReplayTV and TiVo ( They quickly made the VCR obsolete for timeshifting TV programs, and Tivo became the DVR leader. ReplayTV was later acquired by SONICblue, D&M Holdings and eventually the DirecTV satellite TV service ( See cloud DVR, multi-room DVR sharing, live pause, DVD recorder and networked DVR. Contrast with NVR.

This earlier DVR from ReplayTV appears in front of the Find Shows screen, which enables a viewer to search for programming throughout the week by keyword. (Image courtesy of ReplayTV.)
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pressure regulating valve (PRV)

A device used to reduce and maintain the water pressure automatically with predetermined design parameters, for both dynamic flow and static conditions.


McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
During the follow-up period, we obtained the patient's plasma and CSF samples and ordered PRV antibody testing.
As the PRV models evaluated were classified as ordinary pressure regulators, the mean regulated pressure ([bar.p]) shall not deviate from the declared preset pressure by more than 7%, and the coefficient of variation shall not be greater than 10% [8].
In this study, we thoroughly assessed a pseudorabies virus named "PRV FJ-2012," which was isolated from a Bartha-K61-vaccinated pig farm in Fujian Province during a PR outbreak.
The process of BSEA is as follows [16]: (1) a series of vectors are constructed from PRV signal, and for each vector, we compute their basic scale (BS).
Leafstedt, whose own farm near Alcester, S.D., was an early victim of PRV, was a member of the pork industry's PRV Eradication Task Force, and then served on the National PRV Control Board that helped write the state-federal-industry cooperative program standards.
Headquartered in Everett, PRV Aerospace is an aerospace and defense group which supplies components, subassemblies and assemblies to manufacturers of aircraft, aero-equipment and other defense platforms.
PRV Engineering provides an engineering and fabrication service for virtually all industry sectors.
PRV Metals LLC, a portfolio company of Platte River Ventures, has acquired 100 percent of the outstanding stock of TechSpec Inc.
Swagelok RHPS series PRV model proportional relief valves provide proportional venting of overpressures for piping systems up to 1 in.
International oilfield services company Expro has announced the introduction of a new Power Relief Valve (PRV) system which reduces the man-hours and rig downtime historically associated with operating and maintaining traditional mud pump relief valves and systems.