Burst VDS, VDS-3, VSA Users Guide

The VDS,

Video Detector Switch
VDS-3 and
VSA

VDS Video Detector Switch
VDS-3 Video Detector Switch, 3 Channel
VSA Video Detector Switch with Audio

Manual Version 3.0

BURST ELECTRONICS INC

ALBUQUERQUE, NM 87109 USA

[phone]

[phone] FAX

www.burstelectronics.com

Hardware, software and manual copyright by Burst Electronics. All rights reserved. No part of this publication may be
reproduced or distributed in any form or by any means without the written permission of Burst Electronics.

Made in USA

Video Detector Switch

Description:

The Burst Electronics Model VDS (and the VDS-3, a 3 channel
version) detects the presence of composite video at its A input,
and outputs this video. If loss of video on the A input is detected
then the unit switches to the B input, lights a Red LED (VDS only)
and energizes an internal “tally” relay (standard on VDS and VSA,
optional on VDS-3). This relay may be used to control external
devices. The tally relay has both normally closed and normally
open contacts (Form C relay). The Model VSA includes stereo
audio switching, audio follow video.

The video detection process utilizes a sophisticated sync separa­tor circuit and a micro controller IC to analyze the A input. The
composite sync tip amplitude, vertical sync, horizontal sync, and
frame pulse are all analyzed by the micro controller to determine
the quality of the incoming video on the A input.

Setting the DIP Switch:

The DIP switch sets the video accept/reject criteria. To set the
switch, remove the cover. There is a four position DIP switch on
the board that sets the loss of video software options and a pot that
adjusts the sync tip reject point. The switch is factory preset to Up,
Up, Up, Down. The sync amplitude is set to -20 IRE trip point.

1 Video Detector

For the DIP switch, this is the most strict setting. This setting will
only pass video with near RS-170A quality. If you would like to
accept less than perfect video, such as a VCR in the Pause mode or
non-interlaced Blue Screen mode, then set the switch to Down,
Down, Down, Down.

The composite sync tip trigger threshold may be adjusted from
the factory preset of -20 IRE. To adjust this trigger point, a wave­form monitor, a source of stable video and an attenuator are re­quired. Input the desired sync level and adjust the pot. DIP switch
position 1 must be up.

When any of the first three switches are up, the microcontroller
will test the associated input pins for valid signals. When a switch
is down, the test for that signal will be skipped. All enabled tests
must pass consecutively before input A is considered good.

Detection time will increase in relation with how many signal tests
are enabled. Detect times will substantially increase if Sw 4 is up,
loss of video detect will take approximately 4 seconds.

If the frame test is enabled, progressive scan video signals (blue
screen) and VCR search and pause modes will be detected as bad
video.

DIP Switch Function

Sw1 Up Test the sync tip level
Sw2 Up Test the vertical sync (good for end of tape)

Sw3 Up Test the frame signal (Blue screen test)
Sw4 Up Sample each enables input 10 times

2 Video Detector

Forcing the B Input

The presence of the B input can be confirmed with the “Force B”
feature. With the VDS and the VSA, ground the appropriate pin of
the MiniDIN connector. This will force the unit to select the B
input. See the diagram at the end of the manual for the connector
pinout.

The VSA also offers a front panel test switch to check for the
presence of the B input.

The VDS-3 also has a front panel switch to force B. The remote
Force B and Tally outputs are factory options for the VDS-3.

3 Video Detector

Specifications:

Video

NTSC and PAL (autodetects)

Tally Relay:

Form C (NO and NC contacts)
Connector: 4 pin miniDIN

Relay Rating: 1A 30 Vdc, 0.5A 125 Vac

General:

Video Connector: BNC

Audio Connector (Model VSA): RCA Phono Type
Power: 9 to 16 Vdc, polarity insensitive

Current: VDS 100mA

VDS-3 300mA

VSA 125mA

Wall Module Power Supply Included

4 Video Detector