[gps-talkusers] Sendero's take on the Freedom Key chain 2000 and other receivers

As many of you know, you can create a Replay file, which is a second by second recording of your GPS track.
When we test receivers, we literally have them side by side. We take two BrailleNotes, each with a different receiver and record a replay track. In the open, most of these receivers work just fine. It is among trees or among tall buildings that we see major differences.
We send the files for each receiver to Charles and he can visually look at the lines representing each receiver on a map. Among buildings, he will see the GPS line suddenly head off to the side or it will jump one street over. This happens to all receivers in urban canyon situations.
What we are looking for is a receiver that jumps around the least. As receivers become more sensitive in order to acquire a position faster, there is the risk that they are also more seceptable to multi path variations. They pick up bad bouncing signals as well as the good stuff. It is difficult to figure out these differences without looking at them on a screen side by side. Hence the comparisons I have described.
The other simple test anyone can do is to fire up your receiver, make sure the pedometer is set to zero and then see how much the pedometer accumulates even though you don't move. This somewhat represents larger GPS spikes. When you notice too that you are getting readings like 3 miles per hour and you aren't moving, this is not good if it happens often.
If you do this test inside a house, you somewhat represent the challenges of a tall building situation since the GPS signal is distorted by going through the structure of your house.
Whenever we have tested small footprint receivers like the Holux 240 and the Freedom key chain receiver, it is likely that the smaller antenna they are forced to use makes the reception worse.
That is our take on receiver testing and we are always playing with any receiver that looks interesting. We won't switch to a new receiver until we find one that has a consistently demonstrable improvement over the M1000. 

Mike
Thanks for your information and work on this Chris. I hope someone posts this to the blind cool tech list where I saw the original announcement about that receiver claiming that it was better than the M1000. Jim 

----- Original Message ----- From: "Chris Grabowski" <chris@xxxxxxxxxxxxxxxx>
To: "gps-talkusers" <gps-talkusers@xxxxxxxxxxxxx>
Cc: "GPS: Mobile Geo Users List" <mgeo_mailing@xxxxxxxxxxxxxxx>
Sent: Wednesday, December 24, 2008 4:23 AM
Subject: [gps-talkusers] Senderos take on the Freedom Keychain 2000



In November of 2008 Sendero purchased the freedom keychain GPS
receiver  and did our own independent tests of this
receiver and this is what we found....

When placing the receiver on a desk by a window using the odometer
function of the Sendero GPS we were able to watch the distance

accumulate.  The receiver was not moved within a 5 minute time fraime

the receiver s distance cumulated a quarter of a mile.
when the receiver is stationary and is accumulating distance this
shows that the receiver is more susceptible to multi path
environments.  If it is accumulating distances when in a controlled
situation with little to no multi path it will be more susceptible to
multi path in city's such as New York or San Francisco.

Another test, we walked at pedestrian speeds in a rectangle that's
directions are East, South, West, then finally North.  Tests were done
with the receiver clipped to the shoulder strap and again in the back
pocket.

The receiver had a hard time maintaining the direction.  For example
when the receiver went from west to north for two blocks  the receiver
thought it was heading North West instead of due North.  The receiver
finally changed direction once it made the final right and was heading
East once again.


Based on our results Sendero does not recommend this receiver.
Chris Grabowski
- Customer Support and Product testing
Sendero Group
"The GPS company." Also, distributors of the mPower, PK, Victor
Stream, Voice Sense, Braille Sense, KNFB Mobile Reader, Talks, Miniguide and ID Mate 

Phone: 888-757-6810 EXT. 113
Email: chris@xxxxxxxxxxxxxxxx





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Michael G. May

CEO Sendero Group
"The GPS company:" Featuring Sendero GPS on the BrailleNote as well as Sense Nav and the new Mobile Geo for Windows Mobile devices. Also distributing Trekker, Victor Stream, KNFB Mobile Reader, Talks, Mobile Speak, Tiger embossers, Miniguide and ID Mate
Crashing Through, a book about Mike May, by Robert Kurson, available at http://www.CrashingThrough.com 

MikeMay@xxxxxxxxxxxxxxxx
http://www.SenderoGroup.com

1-888-757-6810, Fax (530) 757-6830, Mobile (530) 304-0007
Sendero Group, LLC
429 F Street, Davis, CA 95616, USA

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