Does Quick GPS Fix really work?

 

Has anybody found that Quick GPS Fix actually results in faster acquisition of satellites? I've had it for several months now and I feel like it's just a little buggy - almost like my TomTom has more trouble starting up than not.

I had also read that some TomTom models can't even use the "ephemeris" data... is that true? I'm have an XXL 540 TM.

Thanks!
-Steve

--
TomTom XXL 540 TM

It seems to work for me

sjsanford wrote:

Has anybody found that Quick GPS Fix actually results in faster acquisition of satellites? I've had it for several months now and I feel like it's just a little buggy - almost like my TomTom has more trouble starting up than not.

I've always used it, so I can't comment on how it affects acquisition times (compared to not using it), but I don't ever recall my GO 720 taking more than about 30 seconds to "lock on" to a sufficient number of satellites once I get out of our underground parking garage. It certainly seems faster than the time it takes for my Samsung Galaxy Nexus phone to "lock on" when I activate its internal GPS.

You need to sync

You need to sync with TomTom Home regularly. That provides the necessary updates.

My wife has a TomTom that doesn't get sync'd very often and it sometimes take a minute and a half or longer to lock onto a signal.

My TomTom on the other hand gets sync'd daily and it usually takes less than 30 seconds for mine to lock on a signal. Mine is also newer, a Start55 vs her XXL 540.

--
Jim F.

Yes

sjsanford wrote:

Has anybody found that Quick GPS Fix actually results in faster acquisition of satellites? I've had it for several months now and I feel like it's just a little buggy - almost like my TomTom has more trouble starting up than not.

I had also read that some TomTom models can't even use the "ephemeris" data... is that true? I'm have an XXL 540 TM.

Quickfix can make a difference in how fast you acquire satellites. The non-LIVE models like your (and my) XXL540 cannot receive the broadcast updates, so you need to connect your GPS to the Internet via the HOME2 program to receive the updates.

A good rule of thumb is that you should connect at least weekly to get current data. (FWIW, the Quickfix data tells the GPS the current satellite positions, compensating for the drift in their position. The longer you go between Quickfix updates, the greater the error will be, and the greater the challenge to the GPS in identifying the signals.)

With best wishes,
- Tom -

--
XXL540, GO LIVE 1535, GO 620

In my personal experience it

In my personal experience it has been mixed. Most of the time it does not make a difference for me.

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http://www.poi-factory.com/node/21626 - red light cameras do not work

Thanks for the info

I had actually been syncing with TomTom Home to get the latest updates before setting out. But something I discovered today after doing some fiddling around and research... If I turn on the TomTom once I'm out of the parking garage (and turn it off before I go into the garage), the acquisition times were much better. So basically turning on/off while there's a good signal around seems to really help with the acquisition times.

--
TomTom XXL 540 TM

QuickGPSfix

sjsanford wrote:

I had actually been syncing with TomTom Home to get the latest updates before setting out. But something I discovered today after doing some fiddling around and research... If I turn on the TomTom once I'm out of the parking garage (and turn it off before I go into the garage), the acquisition times were much better. So basically turning on/off while there's a good signal around seems to really help with the acquisition times.

YES, getting QuickGPSfix updates makes a difference, even more so, with long spells between uses!!
A QuickGPSfix update is good for 7 days. Daily updates are not necessary.
I do the same as you, "get updates before setting out."
There is no technical reason for a shorter acquisition time, using your parking garage on/off theory.
FWIW, I have an office on the ground floor of a 2 story building. My desk is about 10 ft. from a north window. When booting at my desk, 9 out of 10 times my unit will be locked in at the completion of the boot process.

QuickGPSfix helps

In one of the above referenced web sites it says that without preloaded data (like QuickGPSfix) the quickest it can lock on a satelite is 30 seconds, because it needs to acquire the information directly from the satelite.

--
Jim F.

Works for me

With my GO930 I get a signal very quickly with quickfix, within a few seconds. The longer I go between connecting to TT HOME, the longer it takes. Although it has never been as bad as my GPS MAP 60CS; I've literally waited minutes before getting enough satellites to navigate.

--
Shooter N32 39 W97 25 VIA 1535TM, Lexus built-in, TomTom Go

a technical reason

tendriver wrote:
sjsanford wrote:

If I turn on the TomTom once I'm out of the parking garage (and turn it off before I go into the garage), the acquisition times were much better. So basically turning on/off while there's a good signal around seems to really help with the acquisition times.

There is no technical reason for a shorter acquisition time, using your parking garage on/off theory.

The acquisition process, to the degree I understand it, involves a search in both frequency and code sequence timing space. All the tricks to get faster acquisition (starting with the very basic almanac, moving on to ephemeris, and so on) are just means to start the search at a favorable place. But if you turn on the receiver at a moment it cannot actually "hear" a satellite, the unit may try the search condition which would have initiated contact with that satellite and fail--moving on to search other frequency/code sequence combinations which don't currently have a satellite, before eventually trying again something close enough to work.

So I think sjsanford offers good advice here.

--
personal GPS user since 1992

Helpful When Flying to a new location

I've found that it is very helpful to get a Quick Fix update before I fly to a new location on a business trip. I've forgotten a few times, and it took a lot longer to get a signal.

--
Shooter N32 39 W97 25 VIA 1535TM, Lexus built-in, TomTom Go

parking garage on/off theory.

archae86 wrote:
tendriver wrote:
sjsanford wrote:

If I turn on the TomTom once I'm out of the parking garage (and turn it off before I go into the garage), the acquisition times were much better. So basically turning on/off while there's a good signal around seems to really help with the acquisition times.

There is no technical reason for a shorter acquisition time, using your parking garage on/off theory.

if you turn on the receiver at a moment it cannot actually "hear" a satellite, the unit may try the search condition which would have initiated contact with that satellite and fail--moving on to search other frequency/code sequence combinations which don't currently have a satellite, before eventually trying again something close enough to work.

So I think sjsanford offers good advice here.

I did a bit of testing today, using 3 multi-story public parking garages. All inside tests were started in the center of the garage ground floor. The procedure for these tests was to turn off my gps at the test starting point inside the garage. Wait 15 miutes, then turn the unit on & drive out to the area to be used for the outside test. Recorded time to lock on once I was clear of the garage. All outside test were started in a clear area outside of the garage. Gps was turned off. Wait 15 minutes, then turn the unit on & record the time to lock on. Each test was run twice at each location.
Results: It made no difference where the unit was turned off or where the unit was turned on. The lock on times were within a second or 2 of each other.

were you receiving satellites inside the garage?

tendriver wrote:

I did a bit of testing today, using 3 multi-story public parking garages.

The results you report are rather curious, to the point of extreme implausibility. Are you saying that you are receiving signals while you were inside the garage? Depending on the garage construction that is entirely possible.

Also, are your lock on times so long that when starting outside you never got fresh lock on in less time than it takes to exit the garage?

The notion that transmission obstructions have no effect on GPS startup defies both common sense and experience.

--
personal GPS user since 1992

I read that post differently

archae86 wrote:
tendriver wrote:

I did a bit of testing today, using 3 multi-story public parking garages.

The results you report are rather curious, to the point of extreme implausibility. Are you saying that you are receiving signals while you were inside the garage? Depending on the garage construction that is entirely possible.

Also, are your lock on times so long that when starting outside you never got fresh lock on in less time than it takes to exit the garage?

The notion that transmission obstructions have no effect on GPS startup defies both common sense and experience.

I read that post rather differently than you apparently did. The statement was that the recorded time was the time to obtain lock "once I was clear of the garage". I interpreted that as saying that it did not matter whether the GPS was turned on inside the parking garage or outside the garage, the time from *initial signal acquisition* was essentially the same.

Since the signal acquisition would not be expected to occur until he left the parking structure, his results appear to agree with what you believe.

With best wishes,
- Tom -

--
XXL540, GO LIVE 1535, GO 620

I agree I misread

-et- wrote:

I read that post rather differently than you apparently did. The statement was that the recorded time was the time to obtain lock "once I was clear of the garage".

Thanks, Tom.

I latched an impression from a later sentence which could be read either way, but I agree that I should have retained the clear meaning you quoted. My response was seriously off-key.

I still think people will have less trouble (for example with multipath) if they turn on their receiver in good viewing conditions than otherwise.

--
personal GPS user since 1992

After the party

Several of us left the large parking garage at the same time. Of course the GPSs all boot up when the key is switched on. "Ready to Navigate" appeared before I actually turned onto the street. My brother-in-law said that his 7x5 did not acquire a fix until 3 blocks later.

--
1490LMT 1450LMT 295w

Misread

archae86 wrote:
-et- wrote:

I read that post rather differently than you apparently did. The statement was that the recorded time was the time to obtain lock "once I was clear of the garage".

Thanks, Tom.

I latched an impression from a later sentence which could be read either way, but I agree that I should have retained the clear meaning you quoted. My response was seriously off-key.

I still think people will have less trouble (for example with multipath) if they turn on their receiver in good viewing conditions than otherwise.

1 point for clarification. In all 12 tests the boot time was not recorded. Only the lock on time after booting. In an actual application, the gps started inside will be ready to navigate sooner than the gps started outside the garage, since the inside device has the advantage of booting while departing the garage, rather than waiting until in a clear area to boot.

archae86,
No problem my friend. I respect another person's opinion, unless it is "off the chart outrageous"!!

Re: power on/off location(s)

I ran a few tests of my own and the results seem to support sjsanford's findings that where you power the TomTom off and on can affect how long it takes to re-establish its position when it "wakes up".

Yesterday, before leaving to run some errands, I powered-up my TomTom in the underground parking garage and confirmed that it could see 0 satellites. I waited about 5 minutes (so the device said "signal lost 5 min ago") and then exited the garage. My TomTom took 36 seconds to lock onto enough satellites to establish its position.

My first stop took about an hour, and when I got back into the car and powered-up the TomTom it showed my position immediately after the boot screen went away. No "waiting for GPS signal" or "signal lost 'n' minutes ago".

On returning home I powered-down my TomTom before entering the underground parking garage. That is, my TomTom was "locked-in" when I put it to sleep.

This morning I waited until I was at my first destination before powering-up the device. This was to see how it would behave if it "woke up" somewhere different than where it "went to sleep". It showed its old location (just outside home), then the "waiting for GPS signal" message appeared, and 11 seconds later it updated the display with its current location.

My conclusion is that it can matter where you power-down and power-up your TomTom if doing so can avoid losing signal. If you power it down while it is still locked-in then when it wakes up it will try to carry on as if nothing happened. If the visible satellites have not changed significantly from when it "went to sleep" then there is no discernible interruption in operation.

However, if your TomTom does lose signal then it starts its search sequence to try and get a fix, and as archae86 suggested, it could take a bit of time to re-acquire the previous satellites. It also seems reasonable that the longer the unit has been without signal the longer it could take to re-acquire because it might start looking farther afield for satellites on the off chance that it "went to sleep" in Toronto and "woke up" in Vancouver.

Tests

VersatileGuy wrote:

My conclusion is that it can matter where you power-down and power-up your TomTom if doing so can avoid losing signal.

I don't think 3 tests, one of which was not conducted in the scenarios being discussed, can be conclusive.

I think we have beat on this dead horse enuf. Everybody is entitled to his or her own opinion.
It's time to move on.

.

tendriver wrote:
VersatileGuy wrote:

My conclusion is that it can matter where you power-down and power-up your TomTom if doing so can avoid losing signal.

I don't think 3 tests, one of which was not conducted in the scenarios being discussed, can be conclusive.

I think we have beat on this dead horse enuf. Everybody is entitled to his or her own opinion.
It's time to move on.

"He who is losing is always first to unilaterally declare a draw."
- Confucius, or Churchill, or maybe some other dead smart guy

smile

Quote

VersatileGuy wrote:

"He who is losing is always first to unilaterally declare a draw."
- Confucius, or Churchill, or maybe some other dead smart guy

smile

That is not the case here!!!