Homework Nine - Revision history

Nicholas.Christman at 21:24, 3 December 2009

2009-12-03T21:24:32Z

← Older revision		Revision as of 14:24, 3 December 2009
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	A Quadrature Sampling Detector (QSD) is used to create a cosine (or sine) waveform from a established sine (or cosine) waveform. (I say "sine or cosine" because the output waveform is simply sinusoidal -- there is really no way to distinguish between sine and cosine, we can only distinguish between 0 and 90 degrees.) At any rate, the most common QSD is known as a Tayloe Detector.		A Quadrature Sampling Detector (QSD) is used to create a cosine (or sine) waveform from a established sine (or cosine) waveform. (I say "sine or cosine" because the output waveform is simply sinusoidal -- there is really no way to distinguish between sine and cosine, we can only distinguish between 0 and 90 degrees.) At any rate, the most common QSD is known as a Tayloe Detector.

	The Tayloe Detector is essentially an array of (mechanical or digital) switches which are switched at a rate equal to the desired RF frequency. Each switch position is then connected to a capacitor which allows the switch to ~~say~~ in position for one-quarter of a cycle (when it completes all positions, it will have completed a full cycle). This ~~results in a angle shift of~~ <math> \textstyle 0^{\circ} \mbox{, } 90^{\circ} \mbox{, } 180^{\circ} \mbox{, and } 270^{\circ} </math>. This is exatly what we were seeking, because now we have a cosine-wave (<math> \textstyle 0^{\circ} \mbox{ and } 180^{\circ} </math>) and a sine-wave (<math> \textstyle 90^{\circ} \mbox{ and } 270^{\circ} </math>).		The Tayloe Detector is essentially an array of (mechanical or digital) switches which are switched at a rate equal to the desired RF frequency. Each switch position is then connected to a capacitor which allows the switch to remain in each position for one-quarter of a cycle (when it completes all positions, it will have completed a full cycle). This method establishes different angles offset by 90-degress, that is <math> \textstyle 0^{\circ} \mbox{, } 90^{\circ} \mbox{, } 180^{\circ} \mbox{, and } 270^{\circ} </math>. This is exatly what we were seeking, because now we have a cosine-wave (<math> \textstyle 0^{\circ} \mbox{ and } 180^{\circ} </math>) and a sine-wave (<math> \textstyle 90^{\circ} \mbox{ and } 270^{\circ} </math>).

	~~That~~ is essentially how QSD works, though there is much more detail and mathematics that could probably be added.		This is essentially how QSD works, though there is much more detail and mathematics that I was unable to find and that could probably be added in the future.

Nicholas.Christman at 21:22, 3 December 2009

2009-12-03T21:22:15Z

← Older revision		Revision as of 14:22, 3 December 2009
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	A Quadrature Sampling Detector (QSD) is used to create a cosine (or sine) waveform from a established sine (or cosine) waveform. (I say "sine or cosine" because the output waveform is simply sinusoidal -- there is really no way to distinguish between sine and cosine, we can only distinguish between 0 and 90 degrees.) At any rate, the most common QSD is known as a Tayloe Detector.		A Quadrature Sampling Detector (QSD) is used to create a cosine (or sine) waveform from a established sine (or cosine) waveform. (I say "sine or cosine" because the output waveform is simply sinusoidal -- there is really no way to distinguish between sine and cosine, we can only distinguish between 0 and 90 degrees.) At any rate, the most common QSD is known as a Tayloe Detector.

	The Tayloe Detector is essentially an array of (mechanical or digital) switches which are switched at a rate equal to the desired RF frequency. Each switch position is then connected to a capacitor which allows the switch to say in position for one-quarter of a cycle (when it completes all positions, it will have completed a full cycle). This results in a angle shift of <math> 0 \~~degree~~ \mbox{, } 90 \~~degree~~ \mbox{, } 180 \~~degree~~ \mbox{, and } 270 \~~degree~~ </math>.		The Tayloe Detector is essentially an array of (mechanical or digital) switches which are switched at a rate equal to the desired RF frequency. Each switch position is then connected to a capacitor which allows the switch to say in position for one-quarter of a cycle (when it completes all positions, it will have completed a full cycle). This results in a angle shift of <math> \textstyle 0^{\circ} \mbox{, } 90^{\circ} \mbox{, } 180^{\circ} \mbox{, and } 270^{\circ} </math>. This is exatly what we were seeking, because now we have a cosine-wave (<math> \textstyle 0^{\circ} \mbox{ and } 180^{\circ} </math>) and a sine-wave (<math> \textstyle 90^{\circ} \mbox{ and } 270^{\circ} </math>).

			That is essentially how QSD works, though there is much more detail and mathematics that could probably be added.

Nicholas.Christman at 21:14, 3 December 2009

2009-12-03T21:14:48Z

← Older revision		Revision as of 14:14, 3 December 2009
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	'''Quadrature Sampling Detector'''		'''Quadrature Sampling Detector'''

	A Quadrature Sampling Detector (QSD) is used to create a cosine (or sine) waveform from a established sine (or cosine) waveform. (I say "sine or cosine" because the output waveform is simply sinusoidal -- there is really no way to distinguish between sine and cosine, we can only distinguish between <math>\~~textstyle O~~ \~~deg~~ \mbox{ and } 90 \~~deg~~</math>.)		A Quadrature Sampling Detector (QSD) is used to create a cosine (or sine) waveform from a established sine (or cosine) waveform. (I say "sine or cosine" because the output waveform is simply sinusoidal -- there is really no way to distinguish between sine and cosine, we can only distinguish between 0 and 90 degrees.) At any rate, the most common QSD is known as a Tayloe Detector.

			The Tayloe Detector is essentially an array of (mechanical or digital) switches which are switched at a rate equal to the desired RF frequency. Each switch position is then connected to a capacitor which allows the switch to say in position for one-quarter of a cycle (when it completes all positions, it will have completed a full cycle). This results in a angle shift of <math> 0 \degree \mbox{, } 90 \degree \mbox{, } 180 \degree \mbox{, and } 270 \degree </math>.

Nicholas.Christman at 21:01, 3 December 2009

2009-12-03T21:01:31Z

← Older revision		Revision as of 14:01, 3 December 2009
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	'''Quadrature Sampling Detector'''		'''Quadrature Sampling Detector'''

			A Quadrature Sampling Detector (QSD) is used to create a cosine (or sine) waveform from a established sine (or cosine) waveform. (I say "sine or cosine" because the output waveform is simply sinusoidal -- there is really no way to distinguish between sine and cosine, we can only distinguish between <math>\textstyle O \deg \mbox{ and } 90 \deg</math>.)

Nicholas.Christman at 20:56, 3 December 2009

2009-12-03T20:56:23Z

← Older revision		Revision as of 13:56, 3 December 2009
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	[[Nick Christman\|<b><u>Nick Christman</u></b>]]<br/>		[[Nick Christman\|<b><u>Nick Christman</u></b>]]<br/>
	----		----

			'''Third Harmonic Sampling'''

	The ''Softrock 40'' software defined radio (SDR) uses a special technique when sampling the data -- this technique is referred to as '''3rd Harmonic Sampling'''. The purpose of 3rd Harmonic Sampling is to eliminate the need to use a high frequency oscillator which is useful economically and physically. (In other words, a high frequency oscillator is expensive and is often incompatible with "cheaper" switches.) However, nothing in this world is perfect and because of this imperfection, Third Harmonic Sampling have a signal loss of <math>\textstyle 20 \log_{10} (\frac{1}{3}) = -9.54 db</math> (Max Woesner).		The ''Softrock 40'' software defined radio (SDR) uses a special technique when sampling the data -- this technique is referred to as '''3rd Harmonic Sampling'''. The purpose of 3rd Harmonic Sampling is to eliminate the need to use a high frequency oscillator which is useful economically and physically. (In other words, a high frequency oscillator is expensive and is often incompatible with "cheaper" switches.) However, nothing in this world is perfect and because of this imperfection, Third Harmonic Sampling have a signal loss of <math>\textstyle 20 \log_{10} (\frac{1}{3}) = -9.54 db</math> (Max Woesner).
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	<br/>		<br/>
	Of course, the segment of this series we are particulary interested in is the third harmonic, or <math>\textstyle \frac{1}{3}cos(3\omega t)</math>. Notice the constant <math>\textstyle \frac{1}{3}</math> in front of the cosine -- this is where the 9.54 db loss originates from (mathematically). From here, we simply use the third harmonic cosine as our local oscillator frequency.		Of course, the segment of this series we are particulary interested in is the third harmonic, or <math>\textstyle \frac{1}{3}cos(3\omega t)</math>. Notice the constant <math>\textstyle \frac{1}{3}</math> in front of the cosine -- this is where the 9.54 db loss originates from (mathematically). From here, we simply use the third harmonic cosine as our local oscillator frequency.
			<br/>
			<br/>

			'''Quadrature Sampling Detector'''

Nicholas.Christman at 20:52, 3 December 2009

2009-12-03T20:52:44Z

← Older revision		Revision as of 13:52, 3 December 2009
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	The ''Softrock 40'' software defined radio (SDR) uses a special technique when sampling the data -- this technique is referred to as '''3rd Harmonic Sampling'''. The purpose of 3rd Harmonic Sampling is to eliminate the need to use a high frequency oscillator which is useful economically and physically. (In other words, a high frequency oscillator is expensive and is often incompatible with "cheaper" switches.) However, nothing in this world is perfect and because of this imperfection, Third Harmonic Sampling have a signal loss of <math>\textstyle 20 \log_{10} (\frac{1}{3}) = -9.54 db</math> (Max Woesner).		The ''Softrock 40'' software defined radio (SDR) uses a special technique when sampling the data -- this technique is referred to as '''3rd Harmonic Sampling'''. The purpose of 3rd Harmonic Sampling is to eliminate the need to use a high frequency oscillator which is useful economically and physically. (In other words, a high frequency oscillator is expensive and is often incompatible with "cheaper" switches.) However, nothing in this world is perfect and because of this imperfection, Third Harmonic Sampling have a signal loss of <math>\textstyle 20 \log_{10} (\frac{1}{3}) = -9.54 db</math> (Max Woesner).

			So how does Third Harmonic Sampling work? Well, let's take for example a very basic SDR (similar to the one designed in Electronics II). In the most basic SDR there is a local oscillator that outputs a wave in the form of a square wave. Now, this square is not the product of 21st century sorcery, but instead it is the result of an "infinite" sinusoidal series that is evaluated at the desired local oscillation frequency. This sinusoidal series is refereed to as a Fourier series and is defined as
			<br/>
			<br/>
			<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>
			<br/>
			<br/>
			Of course, the segment of this series we are particulary interested in is the third harmonic, or <math>\textstyle \frac{1}{3}cos(3\omega t)</math>. Notice the constant <math>\textstyle \frac{1}{3}</math> in front of the cosine -- this is where the 9.54 db loss originates from (mathematically). From here, we simply use the third harmonic cosine as our local oscillator frequency.

Nicholas.Christman at 20:36, 3 December 2009

2009-12-03T20:36:43Z

← Older revision		Revision as of 13:36, 3 December 2009
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	[[Nick Christman\|<b><u>Nick Christman</u></b>]]<br/>		[[Nick Christman\|<b><u>Nick Christman</u></b>]]<br/>
	----		----

			The ''Softrock 40'' software defined radio (SDR) uses a special technique when sampling the data -- this technique is referred to as '''3rd Harmonic Sampling'''. The purpose of 3rd Harmonic Sampling is to eliminate the need to use a high frequency oscillator which is useful economically and physically. (In other words, a high frequency oscillator is expensive and is often incompatible with "cheaper" switches.) However, nothing in this world is perfect and because of this imperfection, Third Harmonic Sampling have a signal loss of <math>\textstyle 20 \log_{10} (\frac{1}{3}) = -9.54 db</math> (Max Woesner).

Nicholas.Christman: New page: '''1. How does Third Harmonic Sampling work? (''The [http://www.groups.yahoo.com/group/softrock40 Soft Rock] receiver uses it.'')'''
'''2. How does the quadrature sampling detector (...

2009-11-30T01:24:52Z

New page: '''1. How does Third Harmonic Sampling work? (''The [http://www.groups.yahoo.com/group/softrock40 Soft Rock] receiver uses it.'')''' '''2. How does the quadrature sampling detector (...

New page

'''1. How does Third Harmonic Sampling work? (''The [http://www.groups.yahoo.com/group/softrock40 Soft Rock] receiver uses it.'')'''
 
'''2. How does the quadrature sampling detector (QSD) work? (''Look at the [http://www.flex-radio.com/News.aspx?topic=publications SDR-1000 QEX] articles.'')'''

 

[[Nick Christman|Nick Christman]] 
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