After seeing multiple posts recommending setting the H outside for 10 to 15 minutes to acquire the the current GPS data I've been doing this if I haven't flown for several days. While doing it today it occurred to me that this should hold true for the ST16 as well. I currently have my ST16 sitting outside next to my H. I'm wondering if the ST16, not having the latest data, may have resulted in less than optimal performance.
Acquiring GPS almanac data
- Thread starter jandjfrench
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I always start the ST-16 before the aircraft. I’ll spend this time using the hardware monitor to check the controls, I’ll set the white balance and camera exposure, install the props, and then do a second visual survey of the flight area to ensure there have been no unexpected visitors to the area.
When I am done there are usually only a few more minutes to wait and the controller gets the same GPS info as the aircraft this way.
When I am done there are usually only a few more minutes to wait and the controller gets the same GPS info as the aircraft this way.
I wanted to get the data up date as I'm planning to fly tomorrow and didn't want delays then. As you stated I also start the ST16 first but I wonder how much difference it makes as to the order. The last time I was updating the H data I started it first and after I felt it had acquired the data I started the ST16 and both the drone and the camera connected immediately. Any idea why it normally takes as long as it does for the camera to connect?
I'd have to look it up but the life of the current data is surprisingly short. Smart phones have the ability to get the latest data online which shortens the time dramatically. I recall reading an article about it not that long ago. It also discussed the relativistic effects of the speed of time due to the different altitudes. I almost understood it. I'll post if I came across it.
AH-1G and dsandson.. You don't see, you can't see anywhere that the almanack is updated! You just see a nbr of sats and the almanack can be obsolete! Stay idling for minimun 13 minutes if you haven't been in the air for 4-5days - or expect a fly away or a crash. As simple as that. Its called TFF
Read this and save money and pls don't spread rumours to drone newbies: The Almanac, Time to First Fix and Satellite Health | GEOG 862: GPS and GNSS for Geospatial Professionals
....on the other hand, if a receiver has no previous almanac or ephemeris data in its memory, it will have to perform a cold start, also known as a factory start. Without previous data to guide it, the receiver in a cold start must search for all the satellites without knowledge of its own position, velocity, or the time. When it does finally manage to acquire the signal from one, it gets some help and can begin to download an almanac. That almanac data will contain information about the approximate location.....
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How long is normally? Usually about 3 to 5 minutes for me til camera connects, then a couple more to be sure.
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From what I understand, some drones, when they lose connection to the ground station, will enter RTH mode and fly to the last home point recorded. So, your aircraft could take off and fly to wherever you were last.
Can this happen? I don’t know, I just remember reading it somewhere, and I believe it was in reference to a DJI aircraft.
For me, I’m not comfortable with not having control of the aircraft. Powered up, sitting on the ground, WITHOUT the ground station powered and connected, I have no control of that aircraft. What if it suddenly lifts off?
Again...can this happen....will this happen....what is your level of Risk Tolerance?
Don't mix time for the cam to connect with time for a complete GPS almamack TFF. Its totally diffent issues..
I understand that. I was just wondering what was the cause of the delay for the ST16 to display what the H camera is seeing. As the delay was almost non-existent when I'd had the H on for 15 or so minutes prior to turning the ST16 on it must be due to something in the H. Perhaps it's intentional for thermal considerations. I guess it's idle curiosity but sometimes someone has some interesting information.
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Going over my log book since 03/16/2017 there have numerous occasions where I've been idle 16, 11, 12 days and 3-6 days.
With the statement below there is no need to wait for 13 minutes.
I reiterate, I never had issue!!
Sometimes I feel people are over reactive. Like helicopter parents!
Warm Start:
"If a receiver has been in operation recently and has some left over almanac and position data in its non-volatile memory from its last observations, it can begin its search with what is known as a warm start. A warm start is also known as a normal start. In this condition, the receiver might begin by knowing the time within about 20 seconds and its position within 100km or so, and this approximate information helps the receiver estimate the range to satellites. For example, it will be able to restrict its search for satellites to those likely above its horizon rather than wasting time on those below it. Limiting the range of the search decreases the time to first fix (TTFF). It can be as short as 30 seconds with a warm start. "
FlushVision
Premium Pilot
I agree. One should be in control of your aircraft at all times and that means booting the controller first and let it go through it's initialization processes before powering up the aircraft.
Yes, it is possible that the aircraft can take off without any input from the controller. Rogue signals or aircraft faults can do this though only really possible if the motors have been armed and are idling. A strong gust of wind can make the motors rev up from idle while it's on the ground too (I've actually had this).
Bottom line is: at start controller on then aircraft...at end aircraft off then controller. Every time.
Then again...
If one is letting an aircraft sit for the purpose of updating the GPS almanac, and is concerned about unintended flight; some easy solutions:
1) take off the props.
2) do not idle the motors - not necessary in the first place; stated just in case someone thinks differently. Besides, models like the H520 will not allow endless idling.
The ST16 does not need to be powered on during unattended craft power up if the above precautions are followed; that is... remove the props!
Just sayin’
Jeff
If one is letting an aircraft sit for the purpose of updating the GPS almanac, and is concerned about unintended flight; some easy solutions:
1) take off the props.
2) do not idle the motors - not necessary in the first place; stated just in case someone thinks differently. Besides, models like the H520 will not allow endless idling.
The ST16 does not need to be powered on during unattended craft power up if the above precautions are followed; that is... remove the props!
Just sayin’
Jeff
FlushVision
Premium Pilot
Oh I agree. If you don't have the props on then you can power up the aircraft without the controller switched on.
My practice for when I have my aircraft sitting while updating the almanac is to have it sit without the props on. However, I do have the controller on so that I can do my camera set-up while I'm waiting..but you are right: so long as you don't have the props on you may start the aircraft without the controller switched on.
Still good practice, though, to switch controller on before the aircraft at the end of the day
Dsandson, the almanack is valid för max 3-4days, everything else is fake! If you don't agree fly after you own info.. Good luck, it's your drone.
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AH-1G you can read "all over internet" about TFF and that the almanack isn't reliable after a week or so. So 3-4days is a safe figure... But still it's up to you to decide when to fly - safe or not....
There are usually three categories TTFF is split up into:
- A "cold" or "factory" start refers to a situation in which the GPS device must acquire all data in order to start navigation, like if the device is brand new or has recently been factory reset. TTFF might take up to 12 minutes.
- A "warm" or "normal" start means the GPS has most of the data it needs in memory and will start quickly - a minute or less. A warm start happens when the device has been off for a day or so, but not off so long that its data is extremely outdated.
- "Hot" or "standby" is when the GPS device can get a signal quickly since it already has a valid position and correct almanac and ephemeris data. The device has normally been off for just a few hours. The TTFF in this situation is sometimes called "Time to Subsequent Fix" (TTSF).
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