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<body class='hmmessage'><div dir='ltr'>Hi<br> <p class="ecxMsoNormal">I am a beginner with RTL and observing that the baseband spectrum is centred at 0 Hz and is asymmetric going from -1 MHz to +1 MHz. How does one filter a part of such a spectrum? For example if signal of interest lied in -300 kHz to -150 kHz. <span> </span><span> </span>The filtering techniques for typical band pass filters work with positive frequencies and have symmetric frequency selection response. As such a 150 to 300 KHz band pass filter will select signal in both 150 to 300 kHz band as well as from -150 to 300 kHz. Is there a special filtering method available to work with negative frequencies and with an asymmetric baseband spectrum. </p><p class="ecxMsoNormal"><span></span> </p><p class="ecxMsoNormal"><span>I am sure this has been addressed as preassumably the FM and other signals of interest are filtered somehow. Any indications will be appreciated.</span><span> </span></p><p class="ecxMsoNormal"><span></span> </p><p class="ecxMsoNormal"><span>Regards</span><span> </span></p> </div></body>
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