1-1 Features

The DVW-250/250P is a portable videocassette recorder in the Digital Betacam series. It allows recording and playback of sound and picture in the Digital Betacam format.

1-1-1 Features of the DVW-250/ 250P

The following are some of the features of the DVW- 250/250P.

Flexible input/output interfaces

The unit is designed to accept either analog video (component/composite) and audio signals, or D1 format serial digital video/audio signals. It is therefore highly suitable for use not only in analog systems but also in all-digital systems.

Analog input signals pass through the built-in A/D converter, and are converted to 10-bit digital video signals and 20-bit digital audio signals. Similarly, both digital and analog output signals are provided, for flexible support of mixed analog-digital systems.

Simple system configuration using the serial digital interface

The serial digital inputs to the SDI (Serial Digital Interface) connector provide for one video signal and four audio channels through a single BNC connector. When connected to other digital equipment, this makes setting up and transporting, for example on outside assignments, extremely straightforward.

High quality digital recording

This unit records both sound and vision on the tape in the Digital Betacam format (see the figure at the end of this page). Since all internal processing is digital, signal outputs are stable, and reproduction is very accurate.

Designed for field operations

The unit is compact and lightweight (main unit approximately 6.6 kg or 14 lb 8 oz), making it ideal for carrying and operating in the field. The power consumption while recording is about 26 W (with the MODE switch in the SAVE position and the CONFI switch in the OFF position), and the optional battery pack provides about two hours of continuous recording.

color playback signal is available at 24 times normal speed, making tape cuing both fast and accurate.

Two LCD units for ease of operation

The front panel includes two LCDs: the smaller shows the unit status and time indications, and the larger displays the audio level meters, the video level meters, or the setup menu.

By switching the display mode, it is possible to change the audio level indications for fine adjustment in a narrower range.

Backlighting is provided to make the displays easier to read in gloomy conditions.

1-1-2 Digital Betacam Format

Overview

The Digital Betacam format is based on the conventional Betacam and Betacam SP formats, and allows high-performance digital recording and playback.

One of the features of the Digital Betacam format is the introduction of a new technique known as “coefficient recording,” which allows the data rate of the video signal to be reduced to approximately half. This makes 120 minutes or more of recording possible with an “L” size cassette.

The compressed video signal includes error-correcting codes (ECC), which correct the signal on playback. This powerful error-correcting system provides the improved signal reliability which is another feature of the Digital Betacam format.

Recording format

The processing of the Digital Betacam video signal conforms to the D1 4:2:2 component digital format, with digitization according to ITU-R BT. 601.

The following figure shows schematically the Digital Betacam recording format on the tape. A set of six diagonal tracks contains one field of video and four channels of audio information.

Tape transport direction Cue track

Video sectors

Audio sectors (1–4)

Direction of head

OverviewviewOve 1 Chapter

1 Chapter

High speed search with color picture

movement

Video sectors

The search speed can be set to 2 times, 5 times or 8 times normal speed. Using rewind or fast forward, a

Time code track

Control track

Tape recording format for Digital Betacam

Chapter 1 Overview 1-1