Nokia N900

[David Rysdam]

On 05/13/2010 08:19 AM, David Rysdam wrote:
> On 05/12/2010 06:13 PM, Joshua Judson Rosen wrote:
>>     Cold tests
>>
>>          were performed when both Pocket PC and GPS receiver were
>>          powered off (if GPS receiver has a separate power source, the
>>          GPS receiver was unplugged) for a period of between 8 to 12
>>          hours requiring a cold start.
>>
>>     Warm tests
>>
>>           Warm tests were performed when both Pocket PC and GPS
>>           receiver were powered off (if GPS receiver has a separate
>>           power source, the GPS receiver was unplugged) for a period
>>           of 30 minutes
>>  
>>     Hot tests
>>
>>           Hot tests were performed when both Pocket PC and GPS
>>           receiver were powered off (if GPS receiver has a separate
>>           power source, the GPS receiver was unplugged) for a period
>>           of 15 minutes
> 
> You missed the colder-than-cold test:
> -
> Factory is where the receiver has no knowledge whatsoever of Almanac
> data in turn to locate the satellites and retrieve Ephemeris data, and
> for a full Almanac to be downloaded can take approx 12.5 mins, hence
> most companies suggest a factory start of 15 minutes.
> -
> 
> So we already know the N810 has to be worse than it should be, due to
> multiple reports even on this list of >15 minute TsTFF.
> 
> Also, I apparently "cold test" my dedicated GPS 1-2 times per day.  It's
> always read to be a GPS before I'm ready to be a driver.  Perhaps that
> says more about how long it takes me to start driving than about how
> fast my GPS is.
> 
> That said, I'll try to test it.  I'll assume the N810 needs a factory
> start by this point and then start doing some cold timings.  Assuming it
> doesn't take so long that I have to terminate the test.

OK, so my tests are complete.  I controlled the GPS with MaemoMapper,
which shows how many satellites you've heard from (I guess) and what the
signal strengths are.

I'm basing average performance on these tests:
http://www.pocketgpsworld.com/ttffcomparisons.php

1) Until Saturday, I hadn't had a fix for many months, so I was going to
count that as a "factory" start.  Factory start allows for around 12-15
minutes.  I got a fix in under 4 minutes.  Then I realized that although
I was outside, I was still WiFi'd in to the house so it was using AGPS.
 Result: Invalid.

2) A little over an hour later, I tried from a WiFi-free location.
60-90 minutes is more than 30 minutes (warm test) but much less than
8-12 hours (cold test).  According to the baseline, cold tests should
take ~1 m, warm tests ~30s.  N810?  5 minutes.

3) As soon as I had a fix for a few seconds, I disconnected and retried.
 This would be a hot test and should take under 10-20 seconds.  N810?  5
minutes *again*.

4) Over 12 hours after that, I disabled WiFi at home and tried again.
This should be a strict cold test and again should take 1 minute.  N810?
 13 minutes.

Furthermore, I think it would have taken longer if I'd had more
patience.  It went from 0-5 satellites (I thought 4 or 5 was enough, but
it didn't complete then), then wandered down to 1, then back up to 5.
This was at the 12 minute mark.  So I pointed it up at the sky (it had
been resting on the ground) and suddenly all the signal strengths leapt
up and I got a fix within a minute after that.

Conclusion: The N810 GPS hardware and/or software definitively sucks.