Burst Electronics SG-8 User Manual

The SG-8

SG-8 Loss of Signal
Audio/Video ID Inserter

Manual Version 2.0

BURST ELECTRONICS INC
CORRALES, NM 87048 USA
[phone] VOICE

Made in USA

[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.

SG-8 Loss of Signal (LOS)

Audio/Video (A/V) ID Inserter

Introduction
Congratulations on your purchase of the Burst

Electronics model SG -8 LOS A/V ID Inserter. The
SG-8 is an option to the SG -3 Color Bar/Black
Burst Generator. This product includes the
addition of a Loss of Signal detector/switch and a
1 kHz tone generator. Also included are three
Black Burst outputs.

Operation
Program video and audio (balanced mono or

unbalanced stereo) is routed through the SG -8.
With program video present at the in put to the
SG-8, the video and audio outputs of the SG-8
are the program input signals. Upon loss of the
video portion of the program input, the SG -8
automatically switches to the internal SMPTE
Color Bars and 1 kHz tone.

The program audio does not need to be routed
through the SG-8. Route the audio through if,
upon loss of video, you wish to have a 1 kHz tone
appear on the program line.

The 1 kHz tone generator has the option of either

SG-8 Loss of Signal, Audio/Video, ID Inserter 2

constant on, or an alternating 5 second on, 5
second off. Factory default is constant on. Cut
jumper SW1 on the output connector board to
have a 5 second duty cycle on/off.

There are also three Black Burst outputs. These
are present at all times and are genlocked to the
internal Color Bar generator.

An ID (example “WPBS #2”) can be programmed
into the SMPTE Color Bar pattern. Consult Burst
Electronics for details.

Loss of 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, first remove the SG -8’s
front panel and top cover. There is a four position
DIP switch on the board that is suspended upside
down above the main board. The switch is factory
preset to (from left to right) Closed, Open, Open,
Open or Up, Down, Down, Down. The sync

SG-8 Loss of Signal, Audio/Video, ID Inserter 3

amplitude is set to a trigger point of –20 IRE or –6
dB. This, most strict setting, will only pass
program video with near RS -170A quality. If you
would like to accept less than perfect video, such
as a VCR in Pause mode or Non -interlaced
video, then follow the table listed below titled DIP
Switch Function.

The composite sync tip trigger threshold may be
adjusted from the factory preset of –20 IRE (-6
dB). To facilitate this adjustment, you will need a
small non-conductive screwdriver, a stable
source of video, a waveform monitor, and an
attenuator. Remove the printed circuit board from
it’s case. Input your stable source of video into
the attenuator and from the attenuator to the
video input of the SG-8. Run the video output of
the SG -8 to your waveform monitor and terminate
the monitor’s loop-out. Apply power to the SG-8.
Change DIP switch SW1-#1 to Closed. Use the
attenuator to reduce the amplitude of the
incoming video signal to the your desired trigger
level. Adjust R5 fully clockwise. Flip DIP switch
SW1-#1 to Open. Now, adjust R5 Counter
Clockwise until the SG -8 switches to it’s internal
SMPTE Bar generator (you will hear a relay
click). Remove -1 dB of attenuation, this should
be detected by the SG-8 as good video and
switch back to your stable video source. If it
doesn’t, slowly adjust R5 clockwise until your
stable video source triggers the SG-8. Confirm
that the difference of 1 dB is enough to trigger the
SG-8. Replace the SG-8 main/piggy back board

SG-8 Loss of Signal, Audio/Video, ID Inserter 4

into it’s case.
When any of the first three switches are Open,

the micro controller will test the associated input
pins for valid signals. When a switch is closed,
the test for that signal will be skipped. All enabled
tests must pass consecutively before input “A” is
considered good.

If SW1-#1 is Open, the sync tip level test is
enabled. This test detects the presence of sync
tip. The trigger point for this test can be modified
by the adjustment of R5. Burst Electronics sets
this trigger point for –20 IRE (-6 dB). If –20 IRE or
less is obtained, this test will cause the SG-8 to
switch to internal Color Bars.

If SW1-#2 is Open, the vertical sync test is
enabled. This test will detect the presence of
white noise (snow) and cause the SG -8 to switch.

If SW1-#3 is Open, the frame test is enabled.
Progressive scan video signals (VCR Blue
Screen) and VCR search/scan and pause modes
will be detected as bad video and cause the SG -8
to switch.

Detection time will increase in relation with how
many signal tests are enabled. Detect time will
substantially increase if SW1-#4 is Open. This
switch will resample the video several times, the
delay is approximately 4 seconds.

SG-8 Loss of Signal, Audio/Video, ID Inserter 5

DIP Switch Function
SW1-#1 Open Enabled Sync

Amplitude Test
(Low Amplitude Detect)
SW1-#2 Open Enabled Vertical
Interval Sync Test
(White Noise Detect)
SW1-#3 Open Enabled Frame Signal Test
(Progressive Scan Detect)
SW1-#4 Open Resample Video Tests
(Gives 4 second delay
before switching)

Options: ID, Rack Mount

Specifications

Output: 1 volt standard NTSC
Output Impedance: 75 Ohms 1%
Sync Tip: -40 IRE
Color Burst: ±20 IRE (3.579545 MHz)
Setup: 7.5 IRE
Tone Output: 1 volt, 1 kHz, 0 dBm,
1% THD (Mono)
Video Connectors: BNC
Audio Connectors: 4 Pin MiniDIN
Output Protection: Open or Short,
infinite duration
SMPTE Bars:
Fully Saturated 75% Bars (gray, yellow, cyan,

SG-8 Loss of Signal, Audio/Video, ID Inserter 6

green, magenta, red, blue)
Reverse Blue Bars (blue, black, magenta, black
cyan, black, gray)
100 IRE White Bar

-I and +Q signals
Pluge pulse signal: Whiter than Black at 11.5
IRE, Black at 7.5 IRE,
Blacker than Black at 3.5 IRE
Black Burst: Sync, Color Burst
and 7.5 IRE Setup
Wall Module: 120 Vac 60 Hz, 12 Vdc
(included) 500 mA, UL Listed
DC Powered: 11—18 Vdc
Warranty: 1 Year Parts and Labor

SG-8 Loss of Signal, Audio/Video, ID Inserter

7

SG-8 Loss of Signal, Audio/Video, ID Inserter 8