Generic Receiver Description - Revision history

Claudia.Prajanu at 19:40, 2 September 2018

2018-09-02T19:40:29Z

← Older revision		Revision as of 19:40, 2 September 2018
Line 40:		Line 40:
	The design and selection of a [[Receiver Types\|receiver type]] is tightly linked to the target user application: for example, a multi-constellation GNSS receiver will certainly improve solution availability (critical, for instance, in urban environments), whereas if the user application is focused on improved accuracies, then the selected receiver will probably turn to carrier-based technologies, or differential and augmented solutions. This choice is usually a result of trade-off analysis that take into account several (and often related) factors, such as target application, performance, accuracy, power consumption, or cost.		The design and selection of a [[Receiver Types\|receiver type]] is tightly linked to the target user application: for example, a multi-constellation GNSS receiver will certainly improve solution availability (critical, for instance, in urban environments), whereas if the user application is focused on improved accuracies, then the selected receiver will probably turn to carrier-based technologies, or differential and augmented solutions. This choice is usually a result of trade-off analysis that take into account several (and often related) factors, such as target application, performance, accuracy, power consumption, or cost.

	Deriving from the characteristics of radionavigation systems, electromagnetic wave propagation, and receiver architectures, different receivers yield different performances. As of today, there is still ongoing debate on the qualification and quantification of error measurements, receiver accuracy, and how they relate<ref>http://www.gpsworld.com~~/lbs/infrastructure/gnss-accuracy-lies-damn-lies-and-statistics-1771~~</ref>.		Deriving from the characteristics of radionavigation systems, electromagnetic wave propagation, and receiver architectures, different receivers yield different performances. As of today, there is still ongoing debate on the qualification and quantification of error measurements, receiver accuracy, and how they relate<ref>http://www.gpsworld.com</ref>.

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

Filipe.Pelica: Included editor logo.

2014-09-18T15:21:12Z

Included editor logo.

← Older revision		Revision as of 15:21, 18 September 2014
Line 4:		Line 4:
	\|Level=Basic		\|Level=Basic
	\|YearOfPublication=2011		\|YearOfPublication=2011
			\|Logo=GMV
	\|Title={{PAGENAME}}		\|Title={{PAGENAME}}
	}}		}}

Filipe.Pelica: /* Receiver overview */

2013-11-30T18:43:38Z

Receiver overview

← Older revision		Revision as of 18:43, 30 November 2013
Line 11:		Line 11:

	==Receiver overview==		==Receiver overview==
	Although receiver architectures are tailored to the different [[GNSS ~~systems description~~\|GNSS systems]] available and to different [[GNSS Applications\|target applications]], the basic building blocks of a generic GNSS receiver are as shown in Figure 1:		Although receiver architectures are tailored to the different [[GNSS signal\|GNSS systems]] available and to different [[GNSS Applications\|target applications]], the basic building blocks of a generic GNSS receiver are as shown in Figure 1:

	*<b>[[Antennas\|Antenna]]</b> - L-band antenna, capturing GNSS signals, noise and possible interference.		*<b>[[Antennas\|Antenna]]</b> - L-band antenna, capturing GNSS signals, noise and possible interference.

Teresa.Ferreira: /* Related articles */

2013-02-28T19:53:50Z

← Older revision		Revision as of 19:53, 28 February 2013
Line 46:		Line 46:
	*[[Receiver Operations]]		*[[Receiver Operations]]
	*[[System Design Details#Applications Processing\|Applications Processing]]		*[[System Design Details#Applications Processing\|Applications Processing]]
			*[[Interfaces and Protocols\|Interfaces and Protocols]]

	==References==		==References==

Carlos.Lopez at 11:01, 23 February 2012

2012-02-23T11:01:31Z

← Older revision		Revision as of 11:01, 23 February 2012
Line 1:		Line 1:
	{{Article Infobox2		{{Article Infobox2
	\|Category=Receivers		\|Category=Receivers
	\|Editors=GMV ~~A.D.~~		\|Editors=GMV
	\|Level=Basic		\|Level=Basic
	\|YearOfPublication=2011		\|YearOfPublication=2011

Carlos.Lopez at 10:34, 23 February 2012

2012-02-23T10:34:44Z

← 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=Basic		\|Level=Basic
	\|YearOfPublication=2011		\|YearOfPublication=2011
	\|~~Logo~~=~~GMV~~		\|Title={{PAGENAME}}
	}}		}}
	GNSS receivers are responsible for processing the L-band Signals In Space (SIS) coming from the GNSS satellites. Each satellite transmits a continuous signal in the GHz range, modulated by a periodic digital code (called a pseudo-random noise code, or [[GNSS signal\|PRN code]]), and further modulated with a data message. User receivers search for the presence of these radio signals that travel through space, and try to synchronize with them. This way, a GNSS receiver can be seen as a radionavigation user device that aims at tracking the GNSS signals, in order to correctly demodulate and extract the measurements and navigation information - one example is to decode the transmitted navigation message and calculate the user's position.		GNSS receivers are responsible for processing the L-band Signals In Space (SIS) coming from the GNSS satellites. Each satellite transmits a continuous signal in the GHz range, modulated by a periodic digital code (called a pseudo-random noise code, or [[GNSS signal\|PRN code]]), and further modulated with a data message. User receivers search for the presence of these radio signals that travel through space, and try to synchronize with them. This way, a GNSS receiver can be seen as a radionavigation user device that aims at tracking the GNSS signals, in order to correctly demodulate and extract the measurements and navigation information - one example is to decode the transmitted navigation message and calculate the user's position.

Rui.Pereira at 11:36, 27 June 2011

2011-06-27T11:36:12Z

← Older revision		Revision as of 11:36, 27 June 2011
Line 31:		Line 31:

	[[File:Acq_example.png\|right\|thumb\|320px\|'''''Figure 2:''''' Example of an acquisition process, showing the Doppler / code delay search space and correlation peak that indicates presence of a signal with code delay of 650 chips and Doppler frequency of -1750 Hz.]]		[[File:Acq_example.png\|right\|thumb\|320px\|'''''Figure 2:''''' Example of an acquisition process, showing the Doppler / code delay search space and correlation peak that indicates presence of a signal with code delay of 650 chips and Doppler frequency of -1750 Hz.]]
	The correlation principle is first used to search for the satellites in view. After a receiver starts operating, it first needs to know which satellites are in view and can be tracked for extracting measurements. This process is known as <b>acquisition</b>, and it is based on several correlations between the incoming signal and multiple replicas of the possible "expected" signals, generated for different code delays and Doppler frequencies. In fact, because the signal is originated by moving satellites, there is a Doppler<ref>~~http~~:~~//en.wikipedia.org/wiki/~~Doppler_effect</ref> and code delay effect observed in the received signals. Therefore, the first two unknowns in detecting GNSS signals is the amount of delay and relative motion between the transmitted signal and the receiver. To search for the signals, different local replicas (corresponding to different code delay / Doppler frequency pairs) are generated and correlated with the input signals. When the local replica and the incoming signal are aligned, their correlation generates a peak (see Figure 2), and the code delay / Doppler frequency pair corresponding to this peak is assumed to be a good estimate to initialize the <b>tracking</b> process.		The correlation principle is first used to search for the satellites in view. After a receiver starts operating, it first needs to know which satellites are in view and can be tracked for extracting measurements. This process is known as <b>acquisition</b>, and it is based on several correlations between the incoming signal and multiple replicas of the possible "expected" signals, generated for different code delays and Doppler frequencies. In fact, because the signal is originated by moving satellites, there is a Doppler<ref>[[Wikipedia:Doppler_effect\|Doppler Effect in Wikipedia]]</ref> and code delay effect observed in the received signals. Therefore, the first two unknowns in detecting GNSS signals is the amount of delay and relative motion between the transmitted signal and the receiver. To search for the signals, different local replicas (corresponding to different code delay / Doppler frequency pairs) are generated and correlated with the input signals. When the local replica and the incoming signal are aligned, their correlation generates a peak (see Figure 2), and the code delay / Doppler frequency pair corresponding to this peak is assumed to be a good estimate to initialize the <b>tracking</b> process.

	In the [[Tracking Loops\|tracking loops]], correlations are also used to refine the local replica generation, so as to match as best as possible the incoming signal. The correlation results are then applied to support different tracking loops in providing a measurement of tracking quality. Typically, the receiver tracks each signal using dedicated channels running in parallel, where each channel tracks one signal (i.e. for single frequency users, each channel tracks one satellite), providing pseudorange and phase measurements, as well as navigation data and additional signal information, such as carrier-to-noise ratio (C/N0). For details on the signal processing blocks, see the [[Digital Signal Processing\|signal processing]] section.		In the [[Tracking Loops\|tracking loops]], correlations are also used to refine the local replica generation, so as to match as best as possible the incoming signal. The correlation results are then applied to support different tracking loops in providing a measurement of tracking quality. Typically, the receiver tracks each signal using dedicated channels running in parallel, where each channel tracks one signal (i.e. for single frequency users, each channel tracks one satellite), providing pseudorange and phase measurements, as well as navigation data and additional signal information, such as carrier-to-noise ratio (C/N0). For details on the signal processing blocks, see the [[Digital Signal Processing\|signal processing]] section.

Teresa.Ferreira: /* Related articles */

2011-06-15T07:52:57Z

← Older revision		Revision as of 07:52, 15 June 2011
Line 46:		Line 46:
	*[[Receiver Types]]		*[[Receiver Types]]
	*[[Receiver Operations]]		*[[Receiver Operations]]
	*[[Applications Processing]]		*[[System Design Details#Applications Processing\|Applications Processing]]

	==References==		==References==

Teresa.Ferreira: /* Receiver overview */

2011-06-15T07:52:21Z

Receiver overview

← Older revision		Revision as of 07:52, 15 June 2011
Line 20:		Line 20:
	*<b>[[Baseband Processing\|Baseband signal processing]]</b> - Several [[Digital Signal Processing\|signal processing]] routines are used to acquire and track the different signals.		*<b>[[Baseband Processing\|Baseband signal processing]]</b> - Several [[Digital Signal Processing\|signal processing]] routines are used to acquire and track the different signals.

	*<b>[[Applications Processing\|Applications Processing]]</b> - Depending on the envisaged application, the receiver performs different tasks with the resulting GNSS information, and provides meaningful results to the user.		*<b>[[System Design Details#Applications Processing\|Applications Processing]]</b> - Depending on the envisaged application, the receiver performs different tasks with the resulting GNSS information, and provides meaningful results to the user.

Carlos.Lopez at 08:28, 2 June 2011

2011-06-02T08:28:56Z

← Older revision		Revision as of 08:28, 2 June 2011
Line 23:		Line 23:


	[[File:Generic_Receiver_Architecture.PNG\|center\|thumb\|628px\|'''''Figure 1:''''' Generic Receiver Architecture. See this [[Block Diagram\|block diagram]] for a detailed view.]]		[[File:Generic_Receiver_Architecture.PNG\|center\|thumb\|628px\|'''''Figure 1:''''' Generic Receiver Architecture. See this [[Receiver Block Diagram\|block diagram]] for a detailed view.]]