ASN9 - 3rd Harmonic & QSD: Difference between revisions
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'''Third Harmonic Sampling''' |
'''Third Harmonic Sampling''' |
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<math> |
<math> |
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\sum_{n=1}^{\infty} \frac{1}{n} cos(n \omega t) = cos(\omega t) + \frac{1}{2}cos(2\omega t) + \frac{1}{3}cos(3\omega t) + \frac{1}{4}cos(4\omega t) + \cdots </math> |
\sum_{n=1}^{\infty} \frac{1}{n} cos(n \omega t) = cos(\omega t) + \frac{1}{2}cos(2\omega t) + \frac{1}{3}cos(3\omega t) + \frac{1}{4}cos(4\omega t) + \cdots </math> |
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The third harmonic is the third term |
The third harmonic is the third term |
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<math> \frac{1}{3}cos(3\omega t)</math>. The benefit of using the third harmonic in a circuit rather than than the first harmonic is that it creates an oscillation three times as fast. |
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SoftRock -40 An device uses third harmonic sampling in its software defined radio. One benefit of using thrid harmonic smapling is that it is cheaper to buy a low frequncy oscillator and the parts driven by one. The disadvantage is that the loss is -9.54dB. |
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<math> \frac{1}{3}cos(3\omega t)</math>. |
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The benefit of using the third harmonic for sampling in a circuit rather than than the first harmonic is that it creates an oscillation that is three times as fast. SoftRock -40 software defined radio for example uses third harmonic sampling as a technique to obtain faster oscillation. In addition, third harmonic sampling is that it is cheaper to buy a low frequency oscillator and the parts driven by one. The disadvantage is that it results in power loss of -9.54dB.See how Softrock uses Third Harmonic Sampling[http://www.groups.yahoo.com/group/softrock40 Soft Rock] |
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[http://www.groups.yahoo.com/group/softrock40 Soft Rock] |
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'''Quadrature Sampling''' |
'''Quadrature Sampling''' |
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A Quadrature is output signal that is |
A Quadrature is output signal that is a phase off from the output signal. For example, in a software define radio two signals that are generated from two mixers are phase shifted 90 degrees. One signal is the desired signal and the second is the quadrature signal that is used for quadrature sampling. |
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Latest revision as of 13:50, 19 December 2009
Third Harmonic Sampling
The cosine series is made up of a infintie sum of harmonics
The third harmonic is the third term
.
The benefit of using the third harmonic for sampling in a circuit rather than than the first harmonic is that it creates an oscillation that is three times as fast. SoftRock -40 software defined radio for example uses third harmonic sampling as a technique to obtain faster oscillation. In addition, third harmonic sampling is that it is cheaper to buy a low frequency oscillator and the parts driven by one. The disadvantage is that it results in power loss of -9.54dB.See how Softrock uses Third Harmonic SamplingSoft Rock
Quadrature Sampling
A Quadrature is output signal that is a phase off from the output signal. For example, in a software define radio two signals that are generated from two mixers are phase shifted 90 degrees. One signal is the desired signal and the second is the quadrature signal that is used for quadrature sampling.
Further information on Quadrature Sampling