7
The term multiplexer was given to an electronic device that time-multi-
plexes video pictures from numerous cameras onto one VCR. This means
that one field or frame from one camera was switched to the VCR, then im-
mediately following that picture was another field or frame from another cam-
era and so on from each camera, then it started over again. This technique
maintains full resolution as does normal video switchers but reduces the time
between recorded images so the 2-3 second dead time between normal cam-
era switching was reduce to 17ms (milliseconds) times the number of cam-
eras. The multiplexer electronically marks each picture with a camera num-
ber so it can be identified upon playback.
When the recorded tape is played back through the multiplex the multi-
plexer electronically identifies the desired picture to be viewed. When the
picture is identified the multiplexer updates the viewable image on the moni-
tor so you only see the requested image or images if in the quad mode.
There exits three types of multiplexers in Black & White or Color; Sim-
plex, Duplex or Full Duplex. The Simplex models are for unattended opera-
tion since they can only view switched images when the multiplexer is in the
recording mode. Duplex models allow simultaneously recording on the VCR,
while the operator can view the total number of cameras viewed at once on
the multi-screen display. Full Duplex allows the playback of a second VCR
while viewing the multi-screen display while the first VCR remains recording.
The AVE QM line of multiplexers are Black & White Simplex. They do
however have features above the standard Simplex design. The high resolu-
tion give the QM line the most advanced performance & features of any Black
& White simplex multiplexeres. The name QM stands for Quad or Multi-
plexer since the QM series has the ability to be a real time 60 Hz quad or
sequencing Duoquad (QM8) or a high performance simplex multiplexer. With
2 monitor outputs the user can be viewing the call monitor with live images
while watching the playback on an additional monitor.
For additional information on multiplexers visit the AVE website at
www.americanvideoequipment.com and click “Education”. A more detailed
white paper on multiplexer technology is available here.
3. INTRODUCTION
