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The history of orthogonal frequency-division multiplexing (2009)

42 点作者 teleforce10 个月前

7 条评论

brudgers10 个月前
<a href="https:&#x2F;&#x2F;ieeexplore.ieee.org&#x2F;stamp&#x2F;stamp.jsp?tp=&amp;arnumber=5307460" rel="nofollow">https:&#x2F;&#x2F;ieeexplore.ieee.org&#x2F;stamp&#x2F;stamp.jsp?tp=&amp;arnumber=530...</a>
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Liftyee10 个月前
OFDM is one of those technologies that I haven&#x27;t been able to conceptually grasp. Thinking in a frequency&#x2F;phase space instead of a (DC) voltage&#x2F;time space hasn&#x27;t quite &quot;clicked&quot; for me yet.
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drmpeg10 个月前
Stupid OFDM tricks.<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=saac0ZtTeX4" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=saac0ZtTeX4</a>
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nakulgarg2210 个月前
Orthogonality is a beautiful concept.<p>In physics, different frequencies don’t interfere with each other—they&#x27;re always independent. However, in digital operations and mathematics, this isn’t automatically true, so we need to carefully select the right frequencies.<p>OFDM leverages this by ensuring that, in the frequency domain, certain frequencies remain completely separate, meaning changes to one frequency (in amplitude or phase) won&#x27;t affect the others.<p>This allows us to capture the maximum information with limited samples.
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01HNNWZ0MV43FF10 个月前
Sounds a little bit like CDMA. My professor in college didn&#x27;t make it obvious why CDMA is any better than just assigning one carrier frequency to each transmitter. [1]<p>The Wikipedia page for OFDM [2] says something like, if there&#x27;s interference or attenuation affecting one frequency, it&#x27;s better to spread that out instead of completely losing one channel. Which kinda makes sense, and would make more sense if I&#x27;d ever done RF work. I&#x27;d love to do SDR as a hobby some day.<p>[1] The explanation in the book was something like, &quot;See with 100 frequencies, you can create 100 chips and each user gets 1 chip, so you can support 100 users&quot; which sounded pointless to me.<p>[2] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Orthogonal_frequency-division_multiplexing" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Orthogonal_frequency-division_...</a>
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jhallenworld10 个月前
This is a great talk if you want to know how it&#x27;s implemented:<p>&quot;Recent Interesting and Useful Enhancements of Polyphase Filter Banks: fred harris&quot;<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=afU9f5MuXr8" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=afU9f5MuXr8</a>
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peterbmarks10 个月前
The codec2 project includes an HF OFDM that can be run from a command line. <a href="https:&#x2F;&#x2F;github.com&#x2F;drowe67&#x2F;codec2">https:&#x2F;&#x2F;github.com&#x2F;drowe67&#x2F;codec2</a>