Mct: add category

2018-04-11T19:15:54Z

add category

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			[[Category:Biosensor Array]]

	====== This page is part of the [[Biosensor Array]] Project ======		====== This page is part of the [[Biosensor Array]] Project ======

Hef: Robot: Cosmetic changes

2014-03-17T14:16:55Z

Robot: Cosmetic changes

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	** [http://www.sparkfun.com/products/10346 Sparkfun GPS shield + module bundle]		** [http://www.sparkfun.com/products/10346 Sparkfun GPS shield + module bundle]
	*** Available at Microcenter in Chicago, too		*** Available at Microcenter in Chicago, too
	**[http://www.adafruit.com/index.php?main_page=product_info&products_id=98 Adafruit shield]		** [http://www.adafruit.com/index.php?main_page=product_info&products_id=98 Adafruit shield]
	*** just a shield, requires seperate [http://www.adafruit.com/index.php?main_page=product_info&products_id=98 GPS module]		*** just a shield, requires seperate [http://www.adafruit.com/index.php?main_page=product_info&products_id=98 GPS module]

	== Integration options ==		== Integration options ==

	It would be good to write the [[BiosensorArray - Data Aggregator Board\|Data Aggregator Board]] software (current target board is Arduino MEGA) so that it can use RTC, GPS or both. This would provide maximum flexibility to end user depending on their resources and environment.		It would be good to write the [[BiosensorArray - Data Aggregator Board\|Data Aggregator Board]] software (current target board is Arduino MEGA) so that it can use RTC, GPS or both. This would provide maximum flexibility to end user depending on their resources and environment.

	Logic:		Logic:
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	Quote Shawn:		Quote Shawn:

	"It depends on how accurate you mean. A while ago, I had to do a study at work regarding the timing accuracy of commercial laptops for possible use, by field engineers/technicians, as NIST trace-able stopwatches/clocks with and without access to the internet for NTP (Network Time Protocol). What I found was that laptops are pretty stable for the kind of timing Bill is talking about (keeping track of the milliseconds, seconds, minutes, and even hours between measurements). However, they tend to have significant drift over days and weeks due to things like temperature fluctuations over time. Also, in the case of a laptop, because the clock is being handled by the OS (many layers abstracted from the actual hardware) running other software at the same time can cause massive time drift (seconds lost at a time) on OSs like Windows.		"It depends on how accurate you mean. A while ago, I had to do a study at work regarding the timing accuracy of commercial laptops for possible use, by field engineers/technicians, as NIST trace-able stopwatches/clocks with and without access to the internet for NTP (Network Time Protocol). What I found was that laptops are pretty stable for the kind of timing Bill is talking about (keeping track of the milliseconds, seconds, minutes, and even hours between measurements). However, they tend to have significant drift over days and weeks due to things like temperature fluctuations over time. Also, in the case of a laptop, because the clock is being handled by the OS (many layers abstracted from the actual hardware) running other software at the same time can cause massive time drift (seconds lost at a time) on OSs like Windows.

	On full PCs, NTP over an internet connection mitigates most of these problems and provides a time/date that is generally accurate to within half a second or better by using statistical methods to compensate for latency on the internet. Unfortunately, in the case of my work, we had serious questions about the traceability of that statistical method even though the time servers at the other end of the connection are connected to atomic clocks run by NIST themselves. That shouldn't be an issue for us though. Most personal PCs aren't connected to NTP but smart phones on most cell phone networks should update directly from the cell network which, I believe, uses GPS.		On full PCs, NTP over an internet connection mitigates most of these problems and provides a time/date that is generally accurate to within half a second or better by using statistical methods to compensate for latency on the internet. Unfortunately, in the case of my work, we had serious questions about the traceability of that statistical method even though the time servers at the other end of the connection are connected to atomic clocks run by NIST themselves. That shouldn't be an issue for us though. Most personal PCs aren't connected to NTP but smart phones on most cell phone networks should update directly from the cell network which, I believe, uses GPS.

	As for the Arduinos, they should be immune to many of the issues laptops have due to the fact that they don't get as hot and run in real-time. Without a reliable source to update the time/date, it will probably drift some with time anyway. However, as Bill pointed out, the kinds of tests we're looking to do don't really need accurate timestamps. They only really need to know the time since the last measurement and the time since the start of the test."		As for the Arduinos, they should be immune to many of the issues laptops have due to the fact that they don't get as hot and run in real-time. Without a reliable source to update the time/date, it will probably drift some with time anyway. However, as Bill pointed out, the kinds of tests we're looking to do don't really need accurate timestamps. They only really need to know the time since the last measurement and the time since the start of the test."

	== Related ==		== Related ==

	* [[BiosensorArray - Data Logging\|Data Logging]]		* [[BiosensorArray - Data Logging\|Data Logging]]
	* [[Biosensor Array Mother Arduino \| Mother Arduino]]		* [[Biosensor Array Mother Arduino\|Mother Arduino]]

Pdp7 at 06:42, 2 April 2011

2011-04-02T06:42:26Z

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Pdp7 at 06:42, 2 April 2011

2011-04-02T06:42:26Z

← Older revision		Revision as of 06:42, 2 April 2011
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			====== This page is part of the [[Biosensor Array]] Project ======

	== Methods ==		== Methods ==

Pdp7: /* Related */

2011-04-02T06:40:05Z

← Older revision	Revision as of 06:40, 2 April 2011
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Pdp7: /* Related */

2011-04-02T06:40:05Z

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	* [[BiosensorArray - Data Logging\|Data Logging]]		* [[BiosensorArray - Data Logging\|Data Logging]]
	* [[Biosensor Array Mother Arduino \| Mother Arduino]] ~~- Drew~~		* [[Biosensor Array Mother Arduino \| Mother Arduino]]

Pdp7: /* Methods */

2011-04-02T06:39:52Z

Methods

← Older revision	Revision as of 06:39, 2 April 2011
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Pdp7: /* Methods */

2011-04-02T06:39:52Z

Methods

← Older revision		Revision as of 06:39, 2 April 2011
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	**[http://www.adafruit.com/index.php?main_page=product_info&products_id=98 Adafruit shield]		**[http://www.adafruit.com/index.php?main_page=product_info&products_id=98 Adafruit shield]
	*** just a shield, requires seperate [http://www.adafruit.com/index.php?main_page=product_info&products_id=98 GPS module]		*** just a shield, requires seperate [http://www.adafruit.com/index.php?main_page=product_info&products_id=98 GPS module]



	== Integration options ==		== Integration options ==

Pdp7: Restructuring timestamp methods and notes

2011-04-02T06:39:18Z

Restructuring timestamp methods and notes

← Older revision	Revision as of 06:39, 2 April 2011
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Pdp7: Restructuring timestamp methods and notes

2011-04-02T06:39:18Z

Restructuring timestamp methods and notes

← Older revision		Revision as of 06:39, 2 April 2011
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	== Note on time keeping ==		== Note on time keeping ==


	Quote Shawn:		Quote Shawn:
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	* [[BiosensorArray - Data Logging\|Data Logging]]		* [[BiosensorArray - Data Logging\|Data Logging]]
			* [[Biosensor Array Mother Arduino \| Mother Arduino]] - Drew

BiosensorArray - Timestamp - Revision history

Mct: add category

Hef: Robot: Cosmetic changes

Pdp7 at 06:42, 2 April 2011

Pdp7 at 06:42, 2 April 2011

Pdp7: /* Related */

Pdp7: /* Related */

Pdp7: /* Methods */

Pdp7: /* Methods */

Pdp7: Restructuring timestamp methods and notes

Pdp7: Restructuring timestamp methods and notes