?? quadrature amplitude modulation 1.htm
字號:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- saved from url=(0055)http://www.altera.com/products/ip/altera/t-alt-qam.html -->
<HTML><HEAD><TITLE>Quadrature Amplitude Modulation</TITLE>
<META content="function, core, OpenCore, solution, QAM" name=keywords>
<META content="Altera provides solutions for Quadrature Amplitude Modulation."
name=description>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1"><LINK
href="Quadrature Amplitude Modulation 1_files/style.css" type=text/css
rel=stylesheet><LINK
href="Quadrature Amplitude Modulation 1_files/style_form.css" type=text/css
rel=stylesheet><!--stopindex-->
<META content="MSHTML 6.00.2600.0" name=GENERATOR></HEAD>
<BODY bgColor=#ffffff leftMargin=0 topMargin=0 rightMargin=0 marginheight="0"
marginwidth="0"><!-- Toolbar Header -->
<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0 nowrap>
<TBODY>
<TR>
<TD>
<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0 nowrap>
<TBODY>
<TR>
<TD align=left bgColor=#0182c4><IMG height=60 alt="Altera Homepage"
src="Quadrature Amplitude Modulation 1_files/altera_left.jpg"
width=578 align=left useMap=#banner_l border=0><MAP
name=banner_l><AREA shape=RECT coords=9,16,158,55
href="http://www.altera.com/index.jsp"></MAP></TD>
<TD align=right bgColor=#0182c4><IMG height=62
alt="Altera Quicklinks"
src="Quadrature Amplitude Modulation 1_files/altera_right.gif"
width=181 useMap=#altera_right border=0><MAP
name=altera_right><AREA title=Download shape=RECT alt=Download
coords=5,8,54,54
href="http://www.altera.com/support/software/sof-download_center.html"><AREA
title=Licensing shape=RECT alt=Licensing coords=63,11,110,54
href="http://www.altera.com/support/licensing/lic-index.html"><AREA
title=Literature shape=RECT alt=Literature coords=122,10,170,56
href="http://www.altera.com/literature/lit-index.html"></MAP></TD></TR></TBODY></TABLE>
<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0>
<TBODY>
<TR>
<TD width=161 bgColor=#0182c4 height=2> </TD><!-- begin top level navigation (top) -->
<TD bgColor=#000000 colSpan=3 height=2><IMG height=19
alt="Global Navigation Bar"
src="Quadrature Amplitude Modulation 1_files/products.gif" width=617
useMap=#products border=0><MAP name=products><AREA shape=RECT
alt="Altera Home" coords=0,0,54,19
href="http://www.altera.com/index.jsp"><AREA shape=RECT
alt="Altera Products" coords=56,0,127,19
href="http://www.altera.com/products/prd-index.html"><AREA
shape=RECT alt="Altera Support Center" coords=130,0,198,19
href="http://www.altera.com/support/spt-index.html"><AREA
shape=RECT alt="Altera System Solutions" coords=200,0,315,19
href="http://www.altera.com/solutions/sln-index.html"><AREA
shape=RECT alt="Altera Education" coords=318,0,442,19
href="http://www.altera.com/education/edu-index.html"><AREA
shape=RECT alt="Altera Buy On-Line" coords=445,0,534,19
href="http://buy.altera.com/ecommerce/index.html"><AREA shape=RECT
alt="Altera Corporate" coords=538,0,608,19
href="http://www.altera.com/corporate/crp-index.html"></MAP></TD><!-- end top level navigation (top) --></TR>
<TR>
<TD bgColor=#e0e0e0 height=2><IMG height=19 alt="Search Here"
src="Quadrature Amplitude Modulation 1_files/search.gif" width=161
border=0></TD><!-- begin second level navigation (top) -->
<TD bgColor=#747474 colSpan=3 height=2><IMG height=19
alt="Second Level Navigation Bar"
src="Quadrature Amplitude Modulation 1_files/products_ip.gif"
width=617 useMap=#ip border=0><MAP name=ip><AREA title=Devices
shape=RECT alt=Devices coords=3,3,67,16
href="http://www.altera.com/products/devices/dev-index.html"><AREA
title="Design Software" shape=RECT alt="Design Software"
coords=77,4,172,16
href="http://www.altera.com/products/software/sfw-index.html"><AREA
title="Intellectual Property" shape=RECT
alt="Intellectual Property" coords=187,4,301,16
href="http://www.altera.com/products/ip/ipm-index.html"><AREA
title="Design Services" shape=RECT alt="Design Services"
coords=314,3,415,15
href="http://www.altera.com/products/design_services/dsv-index.html"><AREA
title="Dev. Kits/Cables" shape=RECT alt="Dev. Kits/Cables"
coords=436,3,526,16
href="http://www.altera.com/products/devkits/kit-index.html"><AREA
title=Literature shape=RECT alt=Literature coords=538,3,606,15
href="http://www.altera.com/literature/lit-index.html"></MAP></TD><!-- end second level navigation (top) --></TR>
<TR>
<TD vAlign=top align=middle width=161 bgColor=#e0e0e0 height="1%">
<SCRIPT language=JavaScript> document.writeln("<form name='search_altera' method=GET accept-charset='iso-8859-1' action='/cgi-bin/devsearch.pl'>"); document.writeln(" <table border=0 cellpadding=3 cellspacing=0 bgcolor=#e0e0e0>"); document.writeln(" <tr> "); document.writeln(" <td valign=middle height='1'>"); document.writeln(" <input type=hidden name=col value='corp'>"); document.write(" <input type=text name=qt maxlength=180 size="); if (navigator.appName.toUpperCase().indexOf("MICROSOFT")>=0) { document.writeln("11>"); } else { document.writeln("6>"); } document.writeln("<input type=image value=GO name='submit' src='/common/template/go.gif' width='27' height='27' align='absmiddle' alt='GO' border='0'>"); document.writeln(" </td>"); document.writeln(" </tr>"); document.writeln("<tr><td> <font class='footer'><a href='http://search.altera.com/?ql=a'>Advanced</a>"); document.writeln(" <a href='http://search.altera.com/help/?la=en'>Help</a></font></td></tr>"); document.writeln(" </table>"); document.writeln("</form>"); </SCRIPT>
<NOSCRIPT>
<FORM name=search_altera accept-charset=iso-8859-1
action=/cgi-bin/devsearch.pl method=get>
<TABLE cellSpacing=0 cellPadding=3 bgColor=#e0e0e0 border=0>
<TBODY>
<TR>
<TD vAlign=center height=1><INPUT type=hidden value=corp
name=col> <INPUT maxLength=180 size=6 name=qt> <INPUT
type=image height=27 alt=GO width=27
src="Quadrature Amplitude Modulation 1_files/go.gif"
align=absMiddle value=GO border=0 name=submit> </TD></TR>
<TR>
<TD> <FONT class=footer><A
href="http://search.altera.com/?ql=a">Advanced</A>
<A
href="http://search.altera.com/help/?la=en">Help</A></FONT></TD></TR></TBODY></TABLE></FORM></NOSCRIPT>
<P>
<TABLE cellSpacing=0 cellPadding=0 border=0>
<TBODY>
<TR>
<TD vAlign=top bgColor=#e0e0e0>
<TABLE style="br: 6pt" cellSpacing=0 cellPadding=0 width=161
bgColor=#e0e0e0 border=0>
<TBODY>
<TR>
<TD rowSpan=50><IMG height=4 alt=""
src="Quadrature Amplitude Modulation 1_files/spacer.gif"
width=4 border=0></TD>
<TD></TD></TR><!-- begin left navigation -->
<TR>
<TD class=category><BR><B>About IP</B></TD></TR>
<TR>
<TD class=menu> <A class=menu
href="http://www.altera.com/products/ip/altera/m-alt-overview.html">Megafunctions
Overview</A></TD></TR>
<TR>
<TD class=menu> <A class=menu
href="http://www.altera.com/products/ip/certifications/ip-certifications.html">IP
Certifications</A></TD></TR>
<TR>
<TD class=category><BR><B>IP Applications</B></TD></TR>
<TR>
<TD class=menu> <A class=menu
href="http://www.altera.com/products/ip/altera/t-alt-signalprocess.html">Signal
Processing</A></TD></TR>
<TR>
<TD class=menu> <A class=menu
href="http://www.altera.com/products/ip/altera/t-alt-comms.html">Communications</A></TD></TR>
<TR>
<TD class=menu> <A class=menu
href="http://www.altera.com/products/ip/altera/t-alt-pci.html">PCI
& Bus Interfaces</A></TD></TR>
<TR>
<TD class=menu> <A class=menu
href="http://www.altera.com/products/ip/altera/t-alt-memory.html">Memory
Controllers</A></TD></TR>
<TR>
<TD class=category><BR><B>IP Industry Partners</B></TD></TR>
<TR>
<TD class=menu> <A class=menu
href="http://www.altera.com/products/ip/ampp.html">About
AMPP Program</A></TD></TR>
<TR>
<TD class=menu> <A class=menu
href="http://www.altera.com/products/ip/ampp/ampp1.html">AMPP
Core Partners</A></TD></TR>
<TR>
<TD class=menu> <A class=menu
href="http://www.altera.com/products/ip/ampp-sfw/amp-software.html">AMPP
Software
Partners</A></TD></TR><!-- end left navigation --></TBODY></TABLE></TD></TR></TBODY></TABLE></P></TD>
<TD width=15 rowSpan=3><IMG height=15 alt=""
src="Quadrature Amplitude Modulation 1_files/spacer.gif" width=15
border=0></TD>
<TD vAlign=top bgColor=#ffffff rowSpan=3><BR><!--startindex--><!-- begin content --><!-- begin content -->
<H2>Quadrature Amplitude Modulation</H2>
<P>Quadrature amplitude modulation (QAM) is a modulation scheme in
which two sinusoidal carriers, one exactly 90 degrees out of
phase with respect to the other, are used to transmit data over a
given physical channel. Because the orthogonal carriers occupy the
same frequency band and differ by a 90 degree phase shift, each
can be modulated independently, transmitted over the same frequency
band, and separated by demodulation at the receiver. For a given
available bandwidth, QAM enables data transmission at twice the rate
of standard pulse amplitude modulation (PAM) without any degradation
in the bit error rate (BER). QAM and its derivatives are used in
both mobile radio and satellite communication systems.</P>
<P>You can use the numerically controlled oscillator (NCO) Compiler
to design a dual-output oscillator that accurately generates the
in-phase and quadrature carriers used by a QAM modulator. The
carrier frequency of each sinusoid can be set to any precision by
defining the phase increment input to the NCO. A block diagram of
the QAM modulator is shown Figure 1. A raised cosine finite impulse
response (FIR) filter is used to filter the data streams before
modulation onto the quadrature carriers. When passed through a
band-limited channel, rectangular pulses suffer from the effects of
time dispersion and tend to smear into one another. This pulse
shaping filter eliminates inter-symbol interference by ensuring that
at a given sampling instance, the contribution to the response from
all other symbols is zero.</P>
<P><B><I>Figure 1. QAM Modulator Block Diagram</I></B></P>
<P><IMG height=217 alt="QAM Modulator Block Diagram"
src="Quadrature Amplitude Modulation 1_files/t-alt-qam_modulator.gif"
width=500 border=0></P>
<H3>Design Files Provided</H3>
<P>The QAM reference design files are located in the
<B>\refdesigns\qam\*</B> folder. Table 1 describes the files
provided with this reference design.</P>
<P>To download the reference design files, go to the <A
href="http://www.altera.com/products/ip/altera/m-alt-ncocompiler.html">NCO
product page</A> and click on the free test drive icon.</P>
<TABLE border=1>
<TBODY>
<TR>
<TD colSpan=2><B><I>Table 1. QAM Reference Design
Files</I></B></TD></TR>
<TR>
<TD><B>File</B></TD>
<TD><B>Description</B></TD></TR>
<TR>
<TD><B>qam.gdf</B></TD>
<TD>Top-level design file, which can be compiled and simulated
in the MAX+PLUS<FONT size=-1><SUP>?? 快捷鍵說明
復制代碼
Ctrl + C
搜索代碼
Ctrl + F
全屏模式
F11
切換主題
Ctrl + Shift + D
顯示快捷鍵
?
增大字號
Ctrl + =
減小字號
Ctrl + -