[jeffjones22]

I'm going through photos I took on a recent hiking trip in west Texas and am finding that some of the shots have the GPS coordinates recorded, yet other shots 50 feet down the trail do not. I didn't have this problem with my K-3 II even in equally remote areas. Has anyone else noticed this or is there just something I'm missing in the configuration?

[FozzFoster]

Any GPS unit will do this from time to time, especially in mountains or urban jungles.
You need to remain in 'sight' of at least (minimum) 3 GPS satellites in the sky to acquire a semi-useful position (4 if you want elevation).
Usually there are sufficient coverage to not really have a problem, but as the satellites dip behind the horizon or skyscraper you may lose contact and the device has to search for a new satellite.
This is what gives the funky readings. I don't think it's operating wrong, it's just the margin of error with fewer satellites connected.

---------- Post added 04-13-21 at 08:12 AM ----------

I miss read your post. I bet the earlier shots down the trail just hadn't connected to enough satellites to provide the coordinates so no data was transferred.

My original reading thought that your data was 50 feet out from your location...

[blackcloudbrew]

I have had this happen with my K-1, now a K-1II, and 645z, K-5, and K-3 with the GPS tracker mounted on the camera hot shoe. As FozzFoster said, you have to have sight of enough satellites...try getting a location deep in an southwestern slot canyon...not gonna happen. But being aware of this, I usually (and more so with the external GPS tracker) have to allow it to locate itself when I'm in a new area, this can take a short time to several minutes. After that I can turn on and off the camera and usually the GPS will reestablish it's position fairly quickly, but sometimes I shoot quickly thinking the camera has a good fix when it didn't have that until later shots.

My sorta rule is that I don't shoot until the satellite icon on the LCD is green or at least yellow.

That said, if you are sure that your camera has a good fix and it still does not record location, that would be a potential problem in my book, but for me this happens when I thought the GPS was good to go but it wasn't yet.

[jeffjones22]

Any GPS unit will do this from time to time, especially in mountains or urban jungles.
I bet the earlier shots down the trail just hadn't connected to enough satellites to provide the coordinates so no data was transferred.

That said, if you are sure that your camera has a good fix and it still does not record location, that would be a potential problem in my book, but for me this happens when I thought the GPS was good to go but it wasn't yet.

Thanks to both of you. it was probably spotty coverage due to being surrounded by 700-1000' rises all around. I just thought it was odd because it hadn't happened with the K3-II on trips through central Colorado and Grand Canyon North Rim. The latter didn't have the rises, but Central Colorado was the train route from Durango to Silverton and that was pretty much all surrounded by mountains.

I didn't watch the satellite indicator before just because I never had to. I'll pay more attention on the next trip and see if that's what it is or if there's really a problem.

[photoptimist]

There are three categories of causes:

Blocked signals: slot canyons, trees, buildings, large metal objects, heavy rain, and even your own body can block, weaken, or confuse the signals. Although the constellation of orbits means that the satellites can appear everywhere in the sky, at even given time, the satellites might be somewhat bunched in one part of the sky. If your body, a tree, or a cliff happen to be between the camera and the satellites, you might not get a reading.

Interference: Other nearby devices such as cellphones can jam GPS signals.

Time-To-Start: The GPS signals are recurring patterns of codes and data. If GPS has been off, it can take time for the receiver to gather that needed data, including waiting for the satellite to transmit data on the satellite's location. The result is that it can take the better part of a minute to get a lock (Time to first fix - Wikipedia). If you flick the camera on, quickly compose and fire, the camera may not have had time to get a GPS lock. (I seriously doubt the camera adds the GPS data to an already stored shot if the GPS lock doesn't happen before you hit the shutter button.)

Solutions:

1. Wait for the GPS light before shooting. (Yes, I know that may not be possible when hiking on a schedule or shooting wild critters.)

2. Turn on "GPS Time Sync" (One of the delays in getting a lock is if the camera's clock is off by more than 20 seconds.)

3. You might try turning GPS logging on at the beginning of a hike. That should increase the chance that the camera has all the needed satellite data when you want to take a shot and likely reduce the time-to-subsequent fix to a few seconds. (At the very least, GPS logging will also provide a track of your hike that you could use in conjunction with the time stamp in the EXIF to identify where you took the shot.)

Good luck and have fun out there!

[AstroDave]

heavy rain

Not really - at GPS frequencies, there is very little rain absorption.

[jeffjones22]

There are three categories of causes:
Blocked signals: slot canyons, trees, buildings, large metal objects, heavy rain, and even your own body can block, weaken, or confuse the signals. Although the constellation of orbits means that the satellites can appear everywhere in the sky, at even given time, the satellites might be somewhat bunched in one part of the sky. If your body, a tree, or a cliff happen to be between the camera and the satellites, you might not get a reading.

Interference: Other nearby devices such as cellphones can jam GPS signals.

Time-To-Start: The GPS signals are recurring patterns of codes and data. If GPS has been off, it can take time for the receiver to gather that needed data, including waiting for the satellite to transmit data on the satellite's location. The result is that it can take the better part of a minute to get a lock (Time to first fix - Wikipedia). If you flick the camera on, quickly compose and fire, the camera may not have had time to get a GPS lock. (I seriously doubt the camera adds the GPS data to an already stored shot if the GPS lock doesn't happen before you hit the shutter button.)

Thanks for the great info.

It could've been a blocked signal. I was near the top of one of the mountains hiking along a side trail. It's desert terrain, so the only trees around were scrub. There was a good quarter mile of space between the outside of the trail and the next rise, so it wasn't exactly a slot canyon, but I can see how having only half the sky could pose a problem.

Time-To-Start is the most likely issue. GPS Time Sync is on, but I don't have GPS logging on. I need to check my K-3 II to see if I'd turned it on as that could easily be the difference. I keep my camera off between shots to conserve battery, so the GPS would have to sync each time I took a shot, so power-on, check the settings and frame the shot, take the shot could easily all occur before the signal was acquired. I'm finding with the battery grip, battery life is no longer an issue, so leaving the switch in the on position might be a good option.

[photoptimist]

Not really - at GPS frequencies, there is very little rain absorption.

Well, I learn something new every day! Thanks!

I'd heard (from the oh so reliable internets) of rain fade with GPS and assumed it was true. But it's not! The 1.2 and 1.5 GHz signals of GPS are much lower than the 12 GHz threshold where rain fade becomes problematic. https://ascelibrary.org/doi/pdf/10.1061/9780784411506.ap02 says the L-band was chosen for GPS for it's ability to handle weather and even vegetation (although I'd swear that my experience with GPS has found it to be less reliable in dense pines.)

[AstroDave]

Well, I learn something new every day! Thanks!

I'd heard (from the oh so reliable internets) of rain fade with GPS and assumed it was true. But it's not! The 1.2 and 1.5 GHz signals of GPS are much lower than the 12 GHz threshold where rain fade becomes problematic. https://ascelibrary.org/doi/pdf/10.1061/9780784411506.ap02 says the L-band was chosen for GPS for it's ability to handle weather and even vegetation (although I'd swear that my experience with GPS has found it to be less reliable in dense pines.)

I used to live and breath this stuff! Our radio astronomical signals get to the antenna via the sky!

The similar well-used radio astronomy frequency is ~1.4 GHz - the 21 cm neutral hydrogen line frequency, and hardly ever bothered by the weather (although as I learned the hard way, a few inches of snow IN the dish really trashes things, even at 600 MHz!). Conversely, at those higher frequencies clouds and rain can be quite a nuisance. I've seen the sky go opaque (nearly complete absorption of signal) at 10.7 GHz in the middle of a really heavy thunderstorm.

Your pine tree experience is likely correct - dense trees/vegetation will absorb, even at 1.5 GHz. There are stories (perhaps apocryphal) about calibrating the Dutch Dwingeloo 25m radio telescope (used predominantly at 21 cm) in its early days by doing a "pine tree calibration" - pointing the telescope to low enough elevation to observe the local pine trees, which were assumed to be optically thick (i.e. completely absorbing) and therefore radiating radio energy at a level corresponding to their black body temperature of around 300 K. This gives a known signal level. I've done similarly with the 130' antenna at the Caltech Owens Valley Radio Observatory, except pointing it at a nearby hill and "observing" the hot dirt.

[Paul the Sunman]

Even in open terrain, GPS can take a few seconds to establish once you turn the camera on. As others have said, the green satellite is your indicator. If you are in the habit of shooting very quickly after powering up, this will inevitably happen sometimes.