Delay in getting signal

[+Joe_L]

Greetings

 

I’ve been geocaching for about a year now. I use a simple device – a Bushnell Backtracker 5. A problem that I occasionally have is that there are times when it takes 10 to 20 minutes to get a signal. (That is, to get read out of the latitude and longitude.) But once the signal is obtained, I never lose it. The problem seems to be random; it’s happened in overcast weather, clear weather, out in the open, or deep in the woods. Most of the time, regardless of the conditions or the terrain/vegetation, I get a signal as soon as I turn the device on. Battery condition doesn’t seem to be the issue either, and the problem has surfaced with both fresh and old batteries. And there are usually no problems even with low battery charge.

 

Is this delay is getting a signal common to all devices? If not, what aspect of the specification/design of the devices affects this?

 

Thanks

 

Joe

[+Styk]

When this happens, how long since it was last used? It is common for a GPS receiver to take longer to locate itself if it hasn't been used in a while. This happens when the GPS has to match the pattern if you will of the satellite signals/timing to it's reference almanac. From this it then can tell exactly where it is.

[MtnHermit]

Is this delay is getting a signal common to all devices? If not, what aspect of the specification/design of the devices affects this?

As Styk said, the problem you're experiencing is not a signal issue, rather a lock or triangulation issue. Sounds like you have long periods of non use so the receiver has to start from scratch to build the almanac. Think of the almanac as a look-up table of expected satellite positions.

 

You can prove this to yourself by turning off the unit after you've gotten a lock and comparing the restart lock time to the initial lock time.

[+Gitchee-Gummee]

Is this delay is getting a signal common to all devices? If not, what aspect of the specification/design of the devices affects this?

As Styk said, the problem you're experiencing is not a signal issue, rather a lock or triangulation issue. Sounds like you have long periods of non use so the receiver has to start from scratch to build the almanac. Think of the almanac as a look-up table of expected satellite positions.

 

You can prove this to yourself by turning off the unit after you've gotten a lock and comparing the restart lock time to the initial lock time.

Traveling a fair distance w/o having it turned on will also do this. Think of it this way: the unit "remembers" the satellite constellation when it was last turned off, it is busy looking for what was, not what is. It finds nothing, so then it starts all over again searching the sky for satsignals.

 

Three quite noticeable types of start-up signal acquisition time-frames:

 

Cold Start -- Seemingly long delay in achieving signal lock-up = Having been off for an extended period of time or a fair distance from when last turned off (essentially the same thing).

Warm Start -- Much shorter delay in signal acquisition = Not having been off for a long time (varies from unit-to-unit, maybe hours, maybe days).

Hot Start -- Obviously the fastest acquisition time = Turned on again within a short time-frame/same location (up to about an hour from last shut-down, usually).

 

Again, there are other variables that come into play between different units. Some makes/models are much better than others.

Bushnell has long been known for making pretty good optics...

[+Joe_L]

Thank you all for the feedback. I usually geocache on weekends, so the unit is off for a week or two. I wish I had kept better records on when and where the problem occurred. On one hand, I do recall some of the longest times have been when I’ve been in a different state. (Though during a trip to Texas, I got a signal within a few minutes on the first day, but the second day took a good twenty minutes. The two locations were probably 20 to 30 miles apart.)

 

Gitchee-Gummee touched on my second question. Since some makes/models acquire the signal faster, is it because of the chip/microprocessor? And is there any way to discern this from the product specifications?

 

Joe

[+Gitchee-Gummee]

Antenna configuration is probably the answer as far as a speedy acquisition.

 

From the date of the Garmin 60 (and its' brethren), most (not all) manufacturer's jumped on the bandwagon with high-gain or more sensitive antennae. Those that were specifically aligned to geocaching circles (marketing) took the bull by the horns.

 

Sure, the chip probably plays a part in the game, but I think the antenna is the most important part of reception. There are models out there that have available plug-in external antennae. Not usually what a geocacher would want, though.

 

20 or 30 miles doesn't usually affect any of the newer/better models. An older one, well... maybe. There are other factors involving satlock, too. Some noticeable, others not-so-noticeable. A wide open, clear sky is a good starting point but not the end-all-to-save-all. Believe it or not, fresh batteries also seem to play a part.

 

Did I mention that Bushnell has long been known for making pretty good optics...?

[+Joe_L]

 

Did I mention that Bushnell has long been known for making pretty good optics...?

 

 

Certainly, Bushnell is known for their optical devices. (Actually, I was misinformed – I thought someone said Bushmill, but I digress.) Their GPS line is hardly geocache-friendly. But the device suits me. It has a lat-long read out and I rarely go into the woods without a map anyway. Forces me to think about where I want to go. The read out at the cache is within the margin of error of the coordinates and usually dead-on. The biggest drawback – it’s not paperless.

 

Joe