227 lines
9.0 KiB
HTML
227 lines
9.0 KiB
HTML
|
|
<!doctype HTML public "-//W3C//DTD HTML 4.0 Frameset//EN">
|
|
<html>
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
|
|
|
|
<meta name="generator" content="Adobe RoboHelp 9">
|
|
<title>Non-Gap Ambient Noise Compensator</title>
|
|
<!--[if lt IE 5.5000]><style type="text/css">@import "/wiki/skins/monobook/IE50Fixes.css";</style><![endif]-->
|
|
<!--[if IE 5.5000]><style type="text/css">@import "/wiki/skins/monobook/IE55Fixes.css";</style><![endif]-->
|
|
<!--[if IE 6]><style type="text/css">@import "/wiki/skins/monobook/IE60Fixes.css";</style><![endif]-->
|
|
<!--[if IE 7]><style type="text/css">@import "/wiki/skins/monobook/IE70Fixes.css?1";</style><![endif]-->
|
|
<!--[if lt IE 7]><script type="text/javascript" src="/wiki/skins/common/IEFixes.js"></script>
|
|
<meta http-equiv="imagetoolbar" content="no" /><![endif]-->
|
|
<!-- Head Scripts -->
|
|
<link rel="stylesheet" href="HtmlHelp.css" type="text/css">
|
|
|
|
<style title="hcp" type="text/css">
|
|
<!--
|
|
span.hcp1 { font-weight:bold; }
|
|
p.hcp2 { margin-bottom:0; }
|
|
-->
|
|
</style>
|
|
</head>
|
|
|
|
<body class="ns-0 ltr">
|
|
<div id="globalWrapper">
|
|
<div id="column-content">
|
|
<div id="content">
|
|
<h1 class="firstHeading">Ambient Noise Compensator Non Gap</h1>
|
|
<div id="bodyContent">
|
|
<img src="ANC_Non_Gap.jpg" alt="" style="border-width: 2px;
|
|
border-style: solid;" width="172" height="47" border="2">
|
|
|
|
<p>Allows the level of an announcer (or other programme
|
|
material) to 'ride' on the average background (ambient)
|
|
noise level so that the programme is kept at an audible
|
|
level above that of the ambient noise.</p>
|
|
<p>It does this by dynamically measuring the level of the
|
|
ambient noise (using a suitably placed microphone), and
|
|
controlling the gain of the programme channel accordingly.</p>
|
|
<p>When a change in applied gain occurs (due to a change
|
|
in the ambient level), the rate at which the applied gain
|
|
changes to the new gain is governed by the attack and
|
|
release settings. The gain moves towards its new value
|
|
exponentially.</p>
|
|
<p>Since the gain must be controlled only by the ambient
|
|
noise, and not by the level of the programme itself, it
|
|
is important that the measurement microphone(s) used to
|
|
generate the ambient level input should be placed away
|
|
from the announcement/program speakers and should be directed
|
|
towards the ambient noise source, otherwise the microphones
|
|
will 'hear' the announcement/program material, rather
|
|
than the true ambient noise and could therefore create
|
|
a feedback loop, increasing the gain because they detect
|
|
a rise in level (due to the increased gain), and so on
|
|
until they hit the max gain.</p>
|
|
<p> </p>
|
|
<div class="editsection" border-style:="" border="0">
|
|
<h2>Inputs and Outputs</h2>
|
|
<p>Announcement (Programme) input</p>
|
|
<p>Ambient input - labelled 'Ambient'</p>
|
|
<p>Audio output</p>
|
|
<p> </p>
|
|
<h2>Control Panel</h2>
|
|
<p> <br>
|
|
<img src="NGANC_panel.jpg" alt="Image:NGANC panel.jpg" title="Image:NGANC panel.jpg" style="border-width: 2px;
|
|
border-style: solid; margin-top: 0px; margin-bottom: 0px;
|
|
margin-left: 0px; margin-right: 0px;" width="585" height="321" border="2"></p>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p>(Ambient) <span class="hcp1">Threshold</span>
|
|
control</p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P">Adjusts the ambient signal level
|
|
at which unity gain will exist.</dd>
|
|
<dd class="mvd-P">The amount by which the announcement
|
|
channel gain is increased is equal to the amount
|
|
by which the ambient level exceeds this threshold,
|
|
multiplied by the ratio setting.</dd>
|
|
<dd class="mvd-P">To lift the announcement out
|
|
of the ambient noise more, reduce the setting
|
|
of this control.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p><span class="hcp1">Ambient
|
|
Level Meter</span></p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P">Displays the current ambient
|
|
noise level. Its positioning next to the Threshold
|
|
control shows the difference between the ambient
|
|
level and the threshold.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p><span class="hcp1">Announcement
|
|
Gain Meter</span></p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P">Indicates the current announcement
|
|
channel gain. This also operates when the ANC
|
|
is bypassed giving a visible indication of what
|
|
the applied gain will be when bypass is disengaged.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p><span class="hcp1">Min
|
|
Gain</span> control</p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P">Determines the minimum gain that
|
|
will be applied to the announcement channel.</dd>
|
|
<dd class="mvd-P">This should be set (with the
|
|
aid of the Min Gain button) during quiet ambient
|
|
levels so that an adequate announcement level
|
|
is obtained.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p><span class="hcp1">Min
|
|
Gain</span> button</p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P">Forces the gain to the minimum
|
|
setting for set-up purposes.</dd>
|
|
<dd class="mvd-P">Illuminates when activated.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p><span class="hcp1">Max
|
|
Gain</span> control</p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P">Determines the maximum gain that
|
|
will be applied to the announcement channel.</dd>
|
|
<dd class="mvd-P">This should be set (with the
|
|
aid of the Max Gain button) during high ambient
|
|
levels such that sensible operating levels, free
|
|
of distortion etc. are maintained.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p><span class="hcp1">Max
|
|
Gain</span> button</p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P">Forces the gain to the maximum
|
|
setting for set-up purposes.</dd>
|
|
<dd class="mvd-P">Illuminates when activated.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p><span class="hcp1">Ratio</span>
|
|
control</p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P">Determines the ratio of the gain
|
|
that will be applied to the announcement channel.
|
|
At a ratio of 1:1, if the ambient level is 4dB
|
|
over the threshold, the gain will be 4dB. If the
|
|
ratio is 5:1, the applied gain will be 20dB. If
|
|
the ratio is 0.1:1, the applied gain will be 0.4dB,
|
|
and so on.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p><span class="hcp1">Attack
|
|
and Release</span> controls</p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P">Attack and release should be
|
|
adjusted to allow the applied gain to track the
|
|
ambient level for the given application. For example,
|
|
fairly short attack and release times could be
|
|
used on railway platforms to allow an announcement
|
|
to quickly adjust as a train pulled into a station,
|
|
whereas longer ballistics could be used in a stadium
|
|
to gradually turn up announce levels as the stadium
|
|
fills before a match.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<ul>
|
|
<li class="p"><p><span class="hcp1">Bypass</span>
|
|
button</p></li>
|
|
</ul>
|
|
<dl>
|
|
<dd class="mvd-P"><p class="hcp2">Removes
|
|
the processor from the signal path. Bypass overrides
|
|
all controls and sets the gain to 0dB almost instantaneously.</p></dd>
|
|
<dd class="mvd-P">Use bypass to set up the nominal
|
|
announcement level.</dd>
|
|
</dl>
|
|
<p> </p>
|
|
<h2>Notes</h2>
|
|
<p>The ambient microphone should be connected to an
|
|
analogue input on a BLU-80 or BLU-16 Signal Processor.</p>
|
|
<p>The input gain should be adjusted to achieve a sensible
|
|
operating level.</p>
|
|
<p>When setting the Ambient Threshold control, the
|
|
input gain should be taken into account.</p>
|
|
<p>The Ambient microphone should be positioned clear
|
|
of non-representative sources of sound and, to prevent
|
|
tampering, preferably a place not accessible to the
|
|
public.</p>
|
|
<p>In a large environment, several microphones could
|
|
be used with a mixer object in Soundweb to get an
|
|
average of the levels.</p>
|
|
<p><span class="hcp1">!</span> This object
|
|
is capable of raising signal levels beyond the clipping
|
|
point, so care should be exercised when using positive
|
|
Maximum Gain values.</p>
|
|
<p><span class="hcp1">!</span> It is
|
|
recommended that a Limiter be used on the output of
|
|
the Ambient Noise Compensator so that short term high-level
|
|
signals are not allowed to pass through to the output.</p>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<p class="hcp2"> </p>
|
|
</div>
|
|
</body>
|
|
</html>
|