Delay Lock Loop (DLL) - Revision history

Filipe.Pelica: Included editor logo.

2014-09-18T16:36:52Z

Included editor logo.

← Older revision		Revision as of 16:36, 18 September 2014
Line 4:		Line 4:
	\|Level=Advanced		\|Level=Advanced
	\|YearOfPublication=2011		\|YearOfPublication=2011
			\|Logo=GMV
	\|Title={{PAGENAME}}		\|Title={{PAGENAME}}
	}}		}}

Carlos.Lopez at 11:00, 23 February 2012

2012-02-23T11:00:50Z

← Older revision		Revision as of 11:00, 23 February 2012
Line 1:		Line 1:
	{{Article Infobox2		{{Article Infobox2
	\|Category=Receivers		\|Category=Receivers
	\|Editors=GMV ~~A.D.~~		\|Editors=GMV
	\|Level=Advanced		\|Level=Advanced
	\|YearOfPublication=2011		\|YearOfPublication=2011

Carlos.Lopez at 10:34, 23 February 2012

2012-02-23T10:34:07Z

← Older revision		Revision as of 10:34, 23 February 2012
Line 1:		Line 1:
	{{Article Infobox2		{{Article Infobox2
	\|Category=Receivers		\|Category=Receivers
	\|~~Title={{PAGENAME}}~~		\|Editors=GMV A.D.
	~~\|Authors~~=GMV
	\|Level=Advanced		\|Level=Advanced
	\|YearOfPublication=2011		\|YearOfPublication=2011
	\|~~Logo~~=~~GMV~~		\|Title={{PAGENAME}}
	}}		}}
	Delay Lock Loops are part of the receiver's signal [[Tracking Loops\|tracking loops]], and aim at tracking the code delay of the incoming GNSS signal. The DLL provides a correction of the current observed delay, and this correction is applied to the local replica code generators, in order to keep the local replica as "matched" as possible with the incloming signal.		Delay Lock Loops are part of the receiver's signal [[Tracking Loops\|tracking loops]], and aim at tracking the code delay of the incoming GNSS signal. The DLL provides a correction of the current observed delay, and this correction is applied to the local replica code generators, in order to keep the local replica as "matched" as possible with the incloming signal.

Rui.Pereira: moved Work in Progress:Delay Lock Loop (DLL) to Delay Lock Loop (DLL) over redirect

2011-05-27T15:53:03Z

moved Work in Progress:Delay Lock Loop (DLL) to Delay Lock Loop (DLL) over redirect

← Older revision	Revision as of 15:53, 27 May 2011
(No difference)

Rui.Pereira: moved Delay Lock Loop (DLL) to Work in Progress:Delay Lock Loop (DLL)

2011-05-11T13:30:45Z

moved Delay Lock Loop (DLL) to Work in Progress:Delay Lock Loop (DLL)

← Older revision	Revision as of 13:30, 11 May 2011
(No difference)

Rui.Sarnadas at 13:24, 6 May 2011

2011-05-06T13:24:01Z

← Older revision		Revision as of 13:24, 6 May 2011
Line 76:		Line 76:

	==Performance==		==Performance==
	In optimal conditions, the main sources of errors in the DLL are thermal noise code jitter and dynamic stress error<ref name="kaplan"></ref>. Using techniques such as [[Tracking Loops\|carrier aiding]], the dynamic stress error of the DLL can be greatly reduced, leaving thermal noise as the main error source.		In optimal conditions, the main sources of errors in the DLL are thermal noise code jitter and dynamic stress error<ref name="kaplan"></ref>. Using techniques such as [[Tracking Loops\|carrier aiding]], the dynamic stress error of the DLL can be greatly reduced, leaving thermal noise as the main error source. The thermal noise code tracking jitter (in chips) for a non-coherent DLL discriminator can be approximated by<ref name="kaplan"></ref>:

	~~The thermal noise code tracking jitter (in chips) for a non-coherent DLL discriminator can be approximated by<ref name="kaplan"></ref>:~~

	<math		<math

Rui.Sarnadas at 13:23, 6 May 2011

2011-05-06T13:23:15Z

Show changes

Teresa.Ferreira: /* Discriminators */

2011-05-05T23:07:03Z

Discriminators

← Older revision		Revision as of 23:07, 5 May 2011
Line 53:		Line 53:
	*Noncoherent Early minus Late Power (NELP)		*Noncoherent Early minus Late Power (NELP)

	<math>\frac{(I_E^2 + Q_E^2) – (I_L^2 + Q_L^2)}{2}</math>		<math>\frac{(I_E^2 + Q_E^2) - (I_L^2 + Q_L^2)}{2}</math>


Line 76:		Line 76:

	Normalized versions of the discriminators are often used in order to remove amplitude sensitivity (especially useful in environments where the carrier to noise ratio changes rapidly).		Normalized versions of the discriminators are often used in order to remove amplitude sensitivity (especially useful in environments where the carrier to noise ratio changes rapidly).


	==Performance==		==Performance==

Teresa.Ferreira at 23:05, 5 May 2011

2011-05-05T23:05:53Z

← Older revision		Revision as of 23:05, 5 May 2011
Line 43:		Line 43:
	*A is the amplitude		*A is the amplitude
	*d is the navigation message		*d is the navigation message
			*<math>R_x</math> is the autocorrelation function of the x PRN code


Line 60:		Line 61:
	<math>\frac{[(I_E - I_L) I_P] + [(Q_E - Q_L) Q_P]}{2}</math>		<math>\frac{[(I_E - I_L) I_P] + [(Q_E - Q_L) Q_P]}{2}</math>

	Whenever the PLL is locked, the coherent dot product can be used, with lower computational burden:		Whenever the PLL is locked, the following coherent dot product can be used, with lower computational burden:

	<math>\frac{(I_E - I_L) I_P}{2}</math>		<math>\frac{(I_E - I_L) I_P}{2}</math>


	*Normalized Early minus Late Envelope ~~(NELE)~~		*Normalized Early minus Late Envelope

	<math>\frac{1}{2} \frac{(E - L)}{E + L}</math>		<math>\frac{1}{2} \frac{(E - L)}{E + L}</math>
Line 81:		Line 82:
	In optimal conditions, the main sources of errors in the DLL are thermal noise code jitter and dynamic stress error <ref name="kaplan"></ref>. Using techniques such as [[Tracking Loops\|carrier aiding]], the dynamic stress error of the DLL can be greatly reduced, leaving thermal noise as the main error source.		In optimal conditions, the main sources of errors in the DLL are thermal noise code jitter and dynamic stress error <ref name="kaplan"></ref>. Using techniques such as [[Tracking Loops\|carrier aiding]], the dynamic stress error of the DLL can be greatly reduced, leaving thermal noise as the main error source.

	The thermal noise code tracking jitter (in chips) for a ~~noncoherent~~ DLL discriminator ~~considering BPSK modulations~~ can be approximated by<ref name="kaplan"></ref>:		The thermal noise code tracking jitter (in chips) for a non-coherent DLL discriminator can be approximated by<ref name="kaplan"></ref>:

	<math>\sigma_{th}=\frac{1}{T_c}		<math>\sigma_{th}=\frac{1}{T_c}
Line 100:		Line 101:

	These results illustrate the fact that lower loop noise bandwidths (and longer integration times) lead to noise reduction and hence higher performances, as discussed [[Tracking Loops\|previously]].		These results illustrate the fact that lower loop noise bandwidths (and longer integration times) lead to noise reduction and hence higher performances, as discussed [[Tracking Loops\|previously]].
	The impact of the modulations is ~~mainly translated~~ by the power spectral density, i.e. the spreader the signal (~~narrow~~ correlation peaks), the higher performances can be reached.		The impact of the modulations is expressed by the power spectral density, i.e. the spreader the signal (narrower correlation peaks), the higher performances can be reached.

	==Related articles==		==Related articles==

Teresa.Ferreira at 22:59, 5 May 2011

2011-05-05T22:59:36Z

← Older revision		Revision as of 22:59, 5 May 2011
Line 9:		Line 9:


	Delay Lock Loops are part of the Tracking Loops and aim at tracking the code delay of the incoming GNSS signal, providing a correction the delay ~~that should~~ be ~~put~~ in the local code generations.		Delay Lock Loops are part of the Tracking Loops and aim at tracking the code delay of the incoming GNSS signal, providing a correction the delay to be used in the local replica code generations.


	==Principle ==		==Principle ==

	The Delay Lock Loop (DLL) tracks and estimates the current misalignment between the [[Multicorrelator\|locally generated PRN code replica]] and the incoming signal ~~phase~~, within the [[Tracking Loops\|tracking loops]].		The Delay Lock Loop (DLL) tracks and estimates the current misalignment between the [[Multicorrelator\|locally generated PRN code replica]] and the incoming signal, within the [[Tracking Loops\|tracking loops]].
	For that purpose, the DLL uses integrations, filters and Numerical Control Oscillators (NCO) – described [[Tracking Loops\|here]] – as any other loop.		For that purpose, the DLL uses integrations, filters and Numerical Control Oscillators (NCO) – described [[Tracking Loops\|here]] – as any other loop.
	~~The specificity relies on the discriminator used to assess the current delay error estimated at the receiver.~~

	The DLL ~~tracks the difference between~~ [[Multicorrelator\|two additional correlators]]: Early and Late, ~~by searching for~~ zero ~~crossings~~.		The specificity relies on the discriminator used to assess the error of the current delay estimate.
	This principle is illustrated in Figure 1, where the Early and Late correlations are shown, as well as ~~their difference, which produces~~ the ~~so-called~~ S-curve.
			The DLL actually uses [[Multicorrelator\|two additional correlators]]: Early and Late, which are delayed and advanced replicas of the prompt code. The difference between the Early and the Late correlators produces a so called S-curve. The DLL actually tracks the zero crossing of this S-curve in order to estimate the current error, which is then feedback to the local code generation block to correct the previous estimate of the incoming code delay.
			This principle is illustrated in Figure 1, where the Early and Late correlations are shown, as well as the S-curve produced by their difference.