- Universal C-mount
- Enables a video camera to be attached to any medical peripheral device
that uses the same connector. These are increasingly common.
- Despite the name, this is an edge enhancing filter frequently used in teleradiology.
It is created by first generating a low-pass
filtered image, which is then subtracted from the original image. This
effectively removes part of the background, leaving an image where
contours are emphasized.
- ITU-T Rec. V.11 describing Electrical characteristics for balanced
double-current interchange circuits operating at data signalling rates up
to 10 Mbit/s.
- ITU-T Rec. V.24 listing definitions for interchange circuits between
terminal equipment (DTE) and data circuit-terminating equipment (DCE).
VCR record source control
- One-source control
- indicates if the system allows the user to push one button and start or
stop recording either end of the video conference. Several systems require
entering a complex series of commands (multiple button pushes) to initiate
or stop recording the conference, or to change which end of the conference
is being recorded. This is very cumbersome when a user only remembers
shortly after the start of a conference to turn the tape on, or when
trying to record sequential segments of the participants at both ends of a
video conference. We have not found an off the shelf system that allows
the user to record both ends of a video conference simultaneously on one
VCR Simultaneous playing of pre-recorded tape and recording of
- relates to the ability to have one VCR playing
a pre-recorded tape into the system as a video source, while
simultaneously having another VCR connected and recording the
videoconference in progress. This is necessary for those telemedicine
programs that maintain a policy of recording all consults and which
periodically use pre-recorded tapes of patient procedures or educational
tapes as part of a video conference.
Vector Adaptive Predictive Coding (VAPC)
- A proprietary audio coding algorithm primarily intended for use at the
lowest transmission aggregate bit rates.
Video Cassette Recorder (VCR)
- Real time, usually two-way, transmission of digitized video images
between two or more locations. This requires a wideband transmission
facility (frequently satellite) and bandwidths from 56 Kbps (freeze frame)
to T1 rates (full motion).
Video on Demand
- The ability to provide instantaneous access to remotely stored sources
of video. A video server stores and manages large amounts of multimedia
data and delivers it on demand to one, or many, users. Limitations to
deployment are bandwidth availability, video server price, and video
compression protocols .
- Small, stand-alone video appliance with a small camera and circulation,
not part of a computer or larger videoconferencing system, that enables
interactive audio-video communications over POTS
- An audio and video file server with hard disk capacities often measured
in the terabytes, connected to LANs
and WANs with high-speed facilities like ATMor
FDDI. Usually uses H.320,
MPEG or Motion-JPEG
video compression. Used for training on demand to the desktop and many
other purposes including marketing and entertainment.
- Currently there are three, established standards in the word for
composite, color encoded video: NTSC,
HDTV is a new international standard
that has been developed and adopted in Japan. More recently, MPEG has
appeared as a world standard for digital television broadcasting. The
adoption of a common, international standard for video transmission has
been one primary focus of the IETF.
- Packet switching, network facilities
that give the appearance of an actual end-to-end circuit. A dynamically
variable, network connection where sequential user data packets may be
Virtual Private Network (VPN)
- Private, software defined network dedicated to connecting two or more
high volume, long distance client sites.
- Graphics and visualization technologies consist of the software and
hardware which permits effortless generation of fast, high quality graphic
images from data.
Voice Grade Channel
- A telephone channel of sufficient bandwidth to transmit human voice,
usually an analog signal ranging from 300 Hz to 3,400 Hz.
Voice Over Internet Protocol (VOIP)
- A series of techniques permiting transmission of telephony over the
internet. Often makes use of ITU-T G.7xx audio compression recommendations.
- An electrical technique for opening and closing a circuit, such as
changing from one microphone to another microphone or from one video
camera to another video camera, in response to the presence or absence of
- An image compression technique that enables more or less lossless compression
ratios of 10:1 or even 20:1, compared to the standard 3:1
maximum for lossless JPEG
Wide Area Network (WAN)
- Wider in geographic scope than a LAN.
Provides digital communications (voice / video / data) over switched
56) or unswitched (fractional T1, T1)
networks. Some consider commercial dial-up networks (America OnLine, the
Internet) to be WANs.
- A software manipulation technique, using mathematical algorithms, to
compensate for a teleradiology monitor's
inability to provide the same contrast and bit
depth as the original hardcopy X-ray. Pixels
within a certain range of bit-depth values are assigned the full range of
possible grayscale values, while
those outside that range are either white or black. This allows emphasis
of contrast for those structures that lie within the grayscale "window".
(Torbjшrn Sund article, this issue)
Working Storage Unit (WSU)
- A file server that provides enough capacity and speed to combine the
functions of short term and local workstation storage by using disks (magnetic
media) operating in parallel. Digital images are stored redundantly so
that single bit errors (e.g., a single disk failure) can be detected and
corrected without any loss of RIS operations.
Total capacity and retrieval bandwidth should be sufficient for peak
requests from multiple workstations (CR image equivalent requests per
- A CCITT standard that
specifies the interface between the data terminal and packet switching,
data circuit, and terminating equipment.
- A circular three-conductor shielded connector commonly used in
professional applications for connection of low-level balanced audio
signals to and from equipment.