Introduction | Details | Specifications |
Manuals
Television's evolution into a digital medium
brings many benefits to operational broadcasting - as well
as a few headaches.
For news, the headache has been on-air latency. Between the time that a person
says or does something live in front of a camera and the time the viewer at home
sees or hears that action, hundreds of milliseconds may elapse. Please note,
that we are not referring to lip sync error - that is where the delay is different
between the sound and the action, but equal delay. Equal delay does not normally
cause any noticeable problem and the audience is unaware that it is taking place.
Lips move in-step with audible speech.
Audio Delay Issues
Equal delay becomes a problem when on-air talent
must monitor themselves off-the-air. Trying to listen to yourself
with delays of only a few tens of milliseconds can destroy
your ability to speak.
There are three paths that create delay
in a broadcast news system:
- Between
the studio and the main transmitter
- The use of satellite links to bring
feeds from the field back to the studio
- The change to COFDM
to carry video from ENG trucks back to the studio
Any
of these routes can introduce enough delay to make IFB unworkable.
When delay
is great enough, typically more than half a second, it
introduces another problem - sloppy cues. These are apparent
to even a casual observer on multihop satellite feeds. But
on a single satellite link, or even from a long studio to transmitter
delay, the latency can cause a fast paced program to suddenly
seem slow and sloppy.
PRO Channel
As the pioneer and principal supplier
of PRO Channel based IFB systems for ENG operations, Modulation
Sciences has been working on a solution to the problem of
delayed IFB to on-air personnel working in ENG situations.
We found that since the problem has several
sources, a systems solution, not a piecemeal one, was called
for.
Our solution is based on proven PRO channel
technology, the technology of choice when providing IFB to
remote news activities; PRO channel offers many advantages
over alternative technologies:
- Being part of the stations
own signal, there is no operating or per-use costs.
- Coverage
is greater than the station's video coverage because
the technology is aural only, non-intercarrier.
- Because of a
television station's lower frequency and much higher power,
there are far fewer coverage "holes" than
with cell phones.
- PRO channel is as reliable as your
station. Cell phone service can fail when you most
need IFB:
- It is subject to "blocking" in a
crisis due to high user demand.
- It can lose power
- most cell sites have only a few hours of backup power
- compared with many TV stations that measure their
emergency power capacity in days.
- In an emergency
most cellular systems are subject to preemption by
a wide range of local, state and Federal emergency service
providers.
- Mobile radio systems
were the original carriers of IFB, but today private
channels are nearly impossible to obtain - everything must
be shared. In addition, without expensive trunking, coverage
is seriously limited.
PRO Channel
Modulation
Sciences introduces PRO-3 to solve your delay problems in ENG.
PRO-3 offers two independent solutions to delay. Either of
these solutions may be used standalone, or in conjunction with
the other.
DELcor
Solution one:
Correct your delay.
The DELcor feature provides an additional
audio channel from the studio to the field for carrying
undelayed program audio. Used in conjunction with proven
CTCSS technology for selective calling to ENG trucks, this
approach allows for seamless IFB to on-air personnel if
most of the delay is between the studio and the main transmitter.
Users will not even know that there is a delay on-air.
This undelayed program audio is mutually exclusive with
the SAP channel, although it does not employ the SAP channel,
nor can it be received on conventional TV sets. Standard
SAP may operate anytime that undelayed audio is not being
supplied to the field.
DELiminate
Solution two:
Eliminate your delay. DELiminate is
a unique application of squelch technology. Squelch is
not new for IFB, but has always been unpopular because
it totally silences the on-air person's earpiece - leaving
them completely isolated from both program feed and interrupts
from the director. The Modulation Sciences solution is
unique in that it silences only the on-air signal that
includes delayed speech, while allowing the director
the freedom to send messages to specific individuals while
they are on-air. This approach is essential when significant
delay exists between the ENG/SNG location and the studio.
This is the case with COFDM microwave truck to studio
links and satellite feeds. Squelch technology allows the
on-air person to take an in-cue from the program feed,
then receive an out-cue countdown from the director.
Squelched
PRO Channel may be used to solve any delay, regardless
of where in the broadcast system it is being introduced. It
will universally solve the problem of delay interfering
with an on-air person's speech.
|
