[time-nuts] Relationship between fixes and time duration?
What is the relationship between the T'Bolt survey fixes number (e.g. 2000) and number of hours duration of the survey? Is it one fix per second or something? What number of fixes should be input to accomplish a 24 hour or a 48 hour survey? Second question: how is the survey duration set on the Jackson-Labs Fury and can the survey be saved in the Fury if it looses power? Many thanks, Jim Robbins N1JR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Relationship between fixes and time duration?
Hi I believe it's one fix per second on the TBolt. LH is your friend when it comes to long surveys on the TBolt. Being able to see what's going on is *very* useful. Bob On May 5, 2013, at 10:15 AM, James Robbins jsrobb...@earthlink.net wrote: What is the relationship between the T'Bolt survey fixes number (e.g. 2000) and number of hours duration of the survey? Is it one fix per second or something? What number of fixes should be input to accomplish a 24 hour or a 48 hour survey? Second question: how is the survey duration set on the Jackson-Labs Fury and can the survey be saved in the Fury if it looses power? Many thanks, Jim Robbins N1JR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Relationship between fixes and time duration?
Usually the survey is accomplished by one fix per second so for a 24hour survey you need 86400 fixes. About the second question, you'll have to read the manual but I think that the position hold can be stored to be retained after power cycles. Usually the survey length can be set. On Sun, May 5, 2013 at 4:15 PM, James Robbins jsrobb...@earthlink.netwrote: What is the relationship between the T'Bolt survey fixes number (e.g. 2000) and number of hours duration of the survey? Is it one fix per second or something? What number of fixes should be input to accomplish a 24 hour or a 48 hour survey? Second question: how is the survey duration set on the Jackson-Labs Fury and can the survey be saved in the Fury if it looses power? Many thanks, Jim Robbins N1JR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Relationship between fixes and time duration?
On 05/05/2013 04:15 PM, James Robbins wrote: What is the relationship between the T'Bolt survey fixes number (e.g. 2000) and number of hours duration of the survey? Is it one fix per second or something? What number of fixes should be input to accomplish a 24 hour or a 48 hour survey? If there is too few sats to get a fix, then it waits until it has sufficients sats for the next fix. So, rather than a fixed time, you get a fixed number of fixes, and the reception situation will decide how long time it takes to get the same minimum quality fix. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Relationship between fixes and time duration?
i only know about the fury: the scpi command GPS:POS:SURV:STAT ONCE starts an auto-survey and lasts about three hours as 10,000 acquisition points are needed. if reception is bad this may take longer. you can specify the maximal number of points with GPS:POS:SURV:MAXP [0,1]. 10,000 is the default and also the maximum number (unfortunately). after the auto-survey the position (and other parameters) will be kept in memory in case of power interruption as there is a backup battery in the device. best regards, hans ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Relationship between fixes and time duration?
There are multiple variables that effect the minimum number of fixes that will yield a particular position accuracy (and hence a time accuracy when using that position as truth). (1) The ability of the antenna to see the entire sky. If a mountain, tall building or tree is between you and a satellite that signal may be lost. In this case your position fix will be degraded due to poor trilateralization geometry. (2) If you are in a place where you get a bounced GPS satellite signal then multipath occurs and will degrade that satellites signal and because it is a bounce the signal path will be longer, resulting in an increase in time for the signal to reach the receiver. This results in a time error and is usually the predominate error when it occurs. Although repetitive, the resultant geometry changes with time of day. There are 'good' times and 'bad' times. So if you take a one hour fix (3600 points) then it is the luck of the draw whether you get a good position fix. There are programs on the net which provide plots of HDOP versus time (or GDOP, TDOP, PDOP etc). One such product is available from ARINC, Inc. at http://www.arinc.com/gps/gpsapps/sem.html. My recommendation is to do the longest survey you can, with a 48 hour goal, in the end there is no downside Michael / K7HIL On Sun, May 5, 2013 at 11:18 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 05/05/2013 04:15 PM, James Robbins wrote: What is the relationship between the T'Bolt survey fixes number (e.g. 2000) and number of hours duration of the survey? Is it one fix per second or something? What number of fixes should be input to accomplish a 24 hour or a 48 hour survey? If there is too few sats to get a fix, then it waits until it has sufficients sats for the next fix. So, rather than a fixed time, you get a fixed number of fixes, and the reception situation will decide how long time it takes to get the same minimum quality fix. Cheers, Magnus __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
