Hammerhead/Integrators - Revision history

Kempelen: Category: -Hardware, (It's in two sub)

2008-09-15T20:37:11Z

Category: -Hardware, (It's in two sub)

Balrog: Still GPS related.

2008-04-30T00:08:34Z

Still GPS related.

Coolcat: /* Glossary */

2008-03-11T07:41:15Z

‎Glossary

Coolcat: /* Glossary */

2008-02-27T09:22:58Z

‎Glossary

Balrog at 01:55, 27 January 2008

2008-01-27T01:55:33Z

Speedevil: /* Glossary */ add cat

2007-08-01T13:38:17Z

‎Glossary: add cat

Speedevil: reword to clarify

2007-08-01T13:37:24Z

reword to clarify

Speedevil: clarify symbol

2007-07-29T16:42:03Z

clarify symbol

Speedevil: /* Glossary */ tidy

2007-07-27T23:22:49Z

‎Glossary: tidy

Speedevil: tidy

2007-07-27T23:18:58Z

tidy

@@ Line 48: / Line 48: @@
 *Symbol - the PRN - either transmitted inverted, or non-inverted, 20 times in a row, to form a '''navigation bit''' at a rate of 1Khz.
 *Navigation Bit - This is part of a navigation message - the constant datastream the satellites broadcast, giving time, orbital information, and other data.
-[[Category:Hardware]]
 [[Category:GPS]]
 [[Category:Chip]]

@@ Line 48: / Line 48: @@
 *Symbol - the PRN - either transmitted inverted, or non-inverted, 20 times in a row, to form a '''navigation bit''' at a rate of 1Khz.
 *Navigation Bit - This is part of a navigation message - the constant datastream the satellites broadcast, giving time, orbital information, and other data.
-[[Category:Hardware ]]
+[[Category:Hardware]]
-[[Category:Chip| ]]
+[[Category:GPS]]

@@ Line 49: / Line 49: @@
 *Navigation Bit - This is part of a navigation message - the constant datastream the satellites broadcast, giving time, orbital information, and other data.
 [[Category:Hardware ]]
-[[Category:Flash| ]]
+[[Category:Chip| ]]

@@ Line 48: / Line 48: @@
 *Symbol - the PRN - either transmitted inverted, or non-inverted, 20 times in a row, to form a '''navigation bit''' at a rate of 1Khz.
 *Navigation Bit - This is part of a navigation message - the constant datastream the satellites broadcast, giving time, orbital information, and other data.
+[[Category:Hardware ]]
-[[Category:Technical]]
+[[Category:Flash| ]]
-[[Category:GPS]]

@@ Line 8: / Line 8: @@
 There must be several integrators to track the GPS signal, while meeting the observed packet transfer statistics.
-As there are no periodic transfers at 1KHz/sec from each satellite, or even 50Hz/sec, it must somehow aquire, store the navigation message bits and send them on in a batch when requested.
+As there are no periodic transfers at 1KHz/sec from each satellite, or even 50Hz/sec, it must somehow acquire, store the navigation message bits and send them on in a batch when requested.
 Exactly how 'cooked' this is is an interesting question.
@@ Line 14: / Line 14: @@
 There must fundamentally be several layers.
-First there are massively parallel correlators, which read the relative timing between a local clock and the begining of each '''symbol''' by correlating the incoming signal from each satelite,  with a locally generated copy of the PRN.
+First there are massively parallel correlators, which read the relative timing between a local clock and the beginning of each '''symbol''' by correlating the incoming signal from each satellite,  with a locally generated copy of the PRN.
 This must output into 2048 bins. (1024 with an I and Q - 0 and 90 degree shifted output each)
@@ Line 31: / Line 31: @@
 Simply looking at the peak of maximum energy of the '''spreading code''' correlator will get you a psuedorange accurate to around a microsecond, or 300m.
-In order to get 1m of psuedorange error due to this source, the I and Q measurement in the '''spreading code''' correlator would have to be measured to a little worse than a degree.
+In order to get 1m of pseudorange error due to this source, the I and Q measurement in the '''spreading code''' correlator would have to be measured to a little worse than a degree.
 This is probably not possible.
@@ Line 44: / Line 44: @@
 ===Glossary===
-*PRN - the psuedo-random '''Spreading Code'''t signal that is different per satellite, that is used to decode the GPS signal. This is 1023 chips long in the case of GPS.
+*PRN - the psuedo-random '''Spreading Code''' signal that is different per satellite, that is used to decode the GPS signal. This is 1023 chips long in the case of GPS.
 *Chip - a chip is one bit of a PRN.
 *Symbol - the PRN - either transmitted inverted, or non-inverted, 20 times in a row, to form a '''navigation bit''' at a rate of 1Khz.

← Older revision		Revision as of 13:38, 1 August 2007
Line 48:		Line 48:
	*Symbol - the PRN - either transmitted inverted, or non-inverted, 20 times in a row, to form a '''navigation bit''' at a rate of 1Khz.		*Symbol - the PRN - either transmitted inverted, or non-inverted, 20 times in a row, to form a '''navigation bit''' at a rate of 1Khz.
	*Navigation Bit - This is part of a navigation message - the constant datastream the satellites broadcast, giving time, orbital information, and other data.		*Navigation Bit - This is part of a navigation message - the constant datastream the satellites broadcast, giving time, orbital information, and other data.
		+
		+	[[Category:Technical]]
		+	[[Category:GPS]]

@@ Line 2: / Line 2: @@
 The GPS signal comprises several levels.
-First there is the carrier, at 1.2Ghz(?) which is multiplied by the 1023 element long '''spreading code''' - the PRN, which varies per satellite, at a '''chip rate''' of 1.023Mhz, leading to a '''symbol rate''' of 1Khz.
+First there is the carrier, at 1.2Ghz(?) which is multiplied by the 1023 element long '''Symbol''' - the PRN, which varies per satellite, at a '''chip rate''' of 1.023Mhz, leading to a '''Symbol rate''' of 1Khz.
-Then the navigation messages are modulated onto these '''symbols''' at a rate of 50Hz, so a '''navigation bit''' spans 20 '''symbols'''.
+Then the navigation messages are modulated onto these '''Symbols''' at a rate of 50Hz, so a '''navigation bit''' spans 20 '''Symbols'''.
 There must be several integrators to track the GPS signal, while meeting the observed packet transfer statistics.
@@ Line 46: / Line 46: @@
 *PRN - the psuedo-random '''Spreading Code'''t signal that is different per satellite, that is used to decode the GPS signal. This is 1023 chips long in the case of GPS.
 *Chip - a chip is one bit of a PRN.
-*Symbol - the PRN is either inverted or not, when broadcast, this gives the '''Symbol''', at a rate of 1Khz.
+*Symbol - the PRN - either transmitted inverted, or non-inverted, 20 times in a row, to form a '''navigation bit''' at a rate of 1Khz.
 *Navigation Bit - This is part of a navigation message - the constant datastream the satellites broadcast, giving time, orbital information, and other data.

← Older revision		Revision as of 23:18, 27 July 2007
Line 40:		Line 40:
	Perhaps long enough integration and accurate tracking can produce an accurate enough signal without this.		Perhaps long enough integration and accurate tracking can produce an accurate enough signal without this.
	Another question is do the +-5 degree correlators - if present - get any meaningful signal.		Another question is do the +-5 degree correlators - if present - get any meaningful signal.
		+
		+
		+
		+	===Glossary===
		+	*PRN - the psuedo-random noise signal that is different per satellite, that is used to decode the GPS signal. This is 1023 chips long in the case of GPS.
		+	*Chip - a chip is one bit of a PRN.
		+	*Symbol - the PRN is either inverted or not, when broadcast, this gives the '''Symbol''', at a rate of 1Khz.
		+	*Navigation Bit - This is part of a navigation message - the constant datastream the satellites broadcast, giving time, orbital information, and other data.