ADVrider

Go Back   ADVrider > Riding > Layin' down tracks
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Rating: Thread Rating: 122 votes, 4.99 average. Display Modes
Old 04-08-2008, 04:35 PM   #316
Jonasolof
Adventurer
 
Joined: Apr 2008
Oddometer: 79
Outline of antenna as seen from front side. The patch antenna is mounted on the printed circuit board which is placed at the midline between the front and rear parts of the shell.
Attached Images
 

Jonasolof screwed with this post 04-09-2008 at 02:21 AM
Jonasolof is offline   Reply With Quote
Old 04-08-2008, 08:20 PM   #317
bananaman
transcontimental
 
Joined: Jun 2007
Location: Madison, Wisconsin and/or Panama, Panama
Oddometer: 7,009
I am in Chile, in the Atacama Desert. This morning I tried to show my spot to a prospector who spends weeks at a time out in the middle of nowhere. I could not get the stupid thing to blink amber.

Im still carrying it (not I keep it on top of my camel back) but I do not rely on it at all. The only reason Im still carrying it is to make sure that, if I need it, the $100,000 evac insurance will apply.

The Iridium Sat phone has been perfect. Ive used it to call home, to call for help in an almost-emergency, and to intimidate Peruvian cops.
bananaman is offline   Reply With Quote
Old 04-08-2008, 08:38 PM   #318
Lost Rider
Roadie
 
Lost Rider's Avatar
 
Joined: Oct 2006
Location: Ventura County, California Republic
Oddometer: 3,161
Question

Quote:
Originally Posted by bananaman
I am in Chile, in the Atacama Desert. This morning I tried to show my spot to a prospector who spends weeks at a time out in the middle of nowhere. I could not get the stupid thing to blink amber.

Im still carrying it (not I keep it on top of my camel back) but I do not rely on it at all. The only reason Im still carrying it is to make sure that, if I need it, the $100,000 evac insurance will apply.

The Iridium Sat phone has been perfect. Ive used it to call home, to call for help in an almost-emergency, and to intimidate Peruvian cops.
more info please.
Not to make you sound stupid, but did you change the batteries - with lithium's? I wouldn't think there's a Walgreen's nearby...
BTW the lights blink green, not amber. Does it power up?
Sounds like a sales pitch from Iridium... but then I look at your reports.
Either way enjoy your travels.
__________________
Photography for me is not about recreating what I saw through
the viewfinder but to show people the way I want to see the world.

LostRider.com
Lost Rider is offline   Reply With Quote
Old 04-08-2008, 09:08 PM   #319
aciurczak
Gnarly Adventurer
 
aciurczak's Avatar
 
Joined: Dec 2005
Location: Bay Area
Oddometer: 159
Quote:
Originally Posted by bananaman
I am in Chile, in the Atacama Desert. This morning I tried to show my spot to a prospector who spends weeks at a time out in the middle of nowhere. I could not get the stupid thing to blink amber.

Im still carrying it (not I keep it on top of my camel back) but I do not rely on it at all. The only reason Im still carrying it is to make sure that, if I need it, the $100,000 evac insurance will apply.

The Iridium Sat phone has been perfect. Ive used it to call home, to call for help in an almost-emergency, and to intimidate Peruvian cops.
Can I assume this is the replacement unit that you followed through with, right?
aciurczak is offline   Reply With Quote
Old 04-08-2008, 11:02 PM   #320
HogWild
Scott Whitney
 
HogWild's Avatar
 
Joined: Nov 2003
Location: SoCal USA
Oddometer: 2,574
Quote:
Originally Posted by bananaman
I could not get the stupid thing to blink amber.
I just read the manual cover to cover. Nowhere does it say anything about an amber light. I think you're confused about how it works.
__________________
.
New desert racing frontiers
It will be Diabolical!
HogWild is offline   Reply With Quote
Old 04-09-2008, 06:56 AM   #321
SpotMaker
Gnarly Adventurer
 
Joined: Nov 2007
Oddometer: 140
Quote:
Originally Posted by Jonasolof
The bottom of the one layer printed circuit board
Actually, It's a 6 layer board.
__________________
I work for Axonn LLC, the company that designed and manufactures the SPoT Satellite messenger. However opinions expressed here are mine and mine alone and do not necessarily reflect those of SPoT INC. or Axonn LLC.

SpotMaker screwed with this post 04-09-2008 at 07:17 AM
SpotMaker is offline   Reply With Quote
Old 04-09-2008, 07:09 AM   #322
SpotMaker
Gnarly Adventurer
 
Joined: Nov 2007
Oddometer: 140
Quote:
Originally Posted by Jonasolof
Two questions for Spotmaker if he is around:

To what extend does it help - or interfere - if the device is put on a flat metal surface?

From what I understand, sat orbits go up to 55 degrees. Supposedly, they dwell there for a very short time. I'm now at 50 degrees north. I do have a feeling that the SPoT can be masked if there are obstacles south of it, where the greater part of sat trajectories should be.
You're from Belgium? One of my favorite places! If you drink beer, have a lovely Belgian Trappist Ale for me!

Putting it on a metal surface does almost nothing. It might help both reception and transmission by a dB or two at the very most (due to a weakly coupled additional ground plane) but that's about it. It definitely doesn't hurt anything. The hood of my truck is a favorite place for me to lay mine while it sends a check-in message.

Both the Globalstar satellites (that the SPoT transmits through) and GPS satellites are in an inclined orbit. Above 50 degrees or so (even above 40), your best view of them is biased to the south. As evidence of this, I was recently in Lugano Switzerland (visiting Nemerix, BTW). Latitude is about 46 degrees north. I had a room in our hotel with a balcony facing almost due north. My colleague was across the hall, with a balcony facing almost due south. The balconies had a rather long concrete overhang above them. On my colleague's balcony, our SPoTs worked almost as well as they might in a wide open field. On my balcony, facing north, they barely worked at all. It was a bitch even getting them to get a GPS fix, nevermind getting a transmission through. You will also tend to have a bias on transmission in the direction of the nearest Globalstar ground station.

Here in the New Orleans Area, latitude 30 degrees north, we notice almost no directionality. That is, if your SPoT see's only the northern half of the sky here, it's performance is about the same as if it sees only the southern half. (Not terrible, either way).
__________________
I work for Axonn LLC, the company that designed and manufactures the SPoT Satellite messenger. However opinions expressed here are mine and mine alone and do not necessarily reflect those of SPoT INC. or Axonn LLC.
SpotMaker is offline   Reply With Quote
Old 04-09-2008, 07:16 AM   #323
SpotMaker
Gnarly Adventurer
 
Joined: Nov 2007
Oddometer: 140
Quote:
Originally Posted by HogWild
I just read the manual cover to cover. Nowhere does it say anything about an amber light. I think you're confused about how it works.
You are quite correct.

The LED's in the SPoT cannot produce amber. They are red/green bicolor LEDs.

Some red/green bicolor LED's can look amber-ish if you light both the red and the green half. These don't. I've put custom code in the SPoT to do that to see what happens. When you light both the red and the green in these LED's, you get a red that's shifted just a tiny bit more orange than their normal red. You have to really look closely to tell the difference between what you get in this case and the normal red.

In any case, the firmware in the SPoT never lights both the red and green at the same time anyway.
__________________
I work for Axonn LLC, the company that designed and manufactures the SPoT Satellite messenger. However opinions expressed here are mine and mine alone and do not necessarily reflect those of SPoT INC. or Axonn LLC.

SpotMaker screwed with this post 04-09-2008 at 07:30 AM
SpotMaker is offline   Reply With Quote
Old 04-09-2008, 06:41 PM   #324
acejones
Beastly Adventurer
 
acejones's Avatar
 
Joined: May 2005
Location: MS. Gulf Coast
Oddometer: 5,054
I'll be crossing the border at Mcallen TX Saturday heading down to Veracruz for a few days. My wife talked me into buying the Spot unit mainly to make her feel better. I've been testing it out and it seems to work well. Be interesting to see how it works out on the trip.
__________________
I got tired of being here, so now I'm there
acejones is offline   Reply With Quote
Old 04-09-2008, 08:56 PM   #325
bananaman
transcontimental
 
Joined: Jun 2007
Location: Madison, Wisconsin and/or Panama, Panama
Oddometer: 7,009
Quote:
Originally Posted by SpotMaker
You are quite correct.

The LED's in the SPoT cannot produce amber. They are red/green bicolor LEDs.

Some red/green bicolor LED's can look amber-ish if you light both the red and the green half. These don't. I've put custom code in the SPoT to do that to see what happens. When you light both the red and the green in these LED's, you get a red that's shifted just a tiny bit more orange than their normal red. You have to really look closely to tell the difference between what you get in this case and the normal red.

In any case, the firmware in the SPoT never lights both the red and green at the same time anyway.
I was actually trying to brag about how cool SPOT is, and then I wasn't sure I was doing it right. I wish the instructions were printed right on it, the way they are printed on my PLB. Open the cover of the PLB, and right there, in plain English- INSTRUCTIONS! For this prospector guy, working for a major mining company, a SPOT or SPOT-like product would be perfect. Meanwhile, like me, he's carrying a heavy Sat phone.

I confess that I do not know colors. Maybe it was flashing fine. I have already posted my feeling on ease-of-use. I am carrying the instructions but at this point in my trip and my opinion of SPOT, the only thing I'll use it for is to press 911.

For a trip of this length, renting an Iridium Sat phone costs less than buying a SPOT and upgrades. If you're traveling in Mexico, I think Globalstar coverage is supposed to be pretty good, and they're cheaper then Iridium. Doesn't SPOT use Globalstar satelites?

I did not get a replacement unit because 1) I did not have time, and 2) testing it in Wisconsin it worked perfectly.

I am carrying 4 extra lithium batteries. Lithium batteries are easily available in Central and South America. I have seen them in gas stations and grocery stores and they cost the same here as in the US. Lithium batteries also last a lot longer in my GPS than regular batteries. I run the GPS directly off a 12v plug on the bike, but it's nice to have the GPS running if the bike is off. It's easy to install an extra 12v outlet.

Luckily, there are not any Walgreens here. At least I haven't seen any.

If you're in Mexico, and you happen to run into the kinds of cops they have in Peru, how is SPOT going to help you? If you carry a Sat phone, you can write down the number of the US consul, or even put it in the memory. You can also make sure your emergency contact people have the right numbers.

I know SPOT is going to save some lives, but I also wonder, how many lives will be lost because people thought they could rely on it? I suppose that if you put it on Traking mode, it might help rescuers find your body.
bananaman is offline   Reply With Quote
Old 04-09-2008, 09:57 PM   #326
alphajory
Studly Adventurer
 
alphajory's Avatar
 
Joined: Mar 2008
Location: canada
Oddometer: 589
Quote:
I know SPOT is going to save some lives, but I also wonder, how many lives will be lost because people thought they could rely on it? I suppose that if you put it on Traking mode, it might help rescuers find your body.
i hope that people don't think that this is device is a replacement for a sat phone but that it is something that augments this, much in the way that you are using it. it's an inexpensive backup and possible alernative to a phone call but will not replace the funtionality of a phone.
alphajory is offline   Reply With Quote
Old 04-10-2008, 05:07 PM   #327
jonz
Miles are my mantra
 
jonz's Avatar
 
Joined: Aug 2004
Location: CA dez (it's a dry heat)/West Yellowstone,MT
Oddometer: 2,263
Quote:
Originally Posted by acejones
I'll be crossing the border at Mcallen TX Saturday heading down to Veracruz for a few days. My wife talked me into buying the Spot unit mainly to make her feel better. I've been testing it out and it seems to work well. Be interesting to see how it works out on the trip.
On a recent ride to Baja (see B.A.R.F. in ride reports), I had a lot of trouble calling home. But I was sending "OK" messages home 2 or 3 times a day, and that kept me out of hot water for not calling more. Of course, my wife had to ask my son to open the emails and report on my current location. I ran the tracking most of the trip but opening that is way beyond what my wife will attempt on the computer. Had I not had the Spot, I'd have had to spend a lot more time and energy finding a way to call home. I tried a globalstar sat phone a few times and it was always a PITA to get coverage. Worked well when you had coverage but getting coverage was iffy. The spot always worked as far as I could tell.
__________________
JONZ
KTM 950 SE, KTM640 ADV ( Hibachi, risen from the ashes)
KTM520EXC (broken), KTM 400XC (the replacement)
Honda ST1300 ABS (newest addition to the stable)
STOC #326 IBA #217
jonz is online now   Reply With Quote
Old 04-11-2008, 12:06 AM   #328
Jonasolof
Adventurer
 
Joined: Apr 2008
Oddometer: 79
Quote:
Originally Posted by SpotMaker
Actually, It's a 6 layer board.
Thanks. I wanted to say that all the components are on either side of a single PCB (as far as I saw). Thus no stacking.

The patch antenna is much larger than the ones we're used to see in antennas for GPS receivers and thus should have greater apex gain (Emtac reported 0 dB for 12 mm patch antennas, +5 dB for 25 mm antennas. This one is double that.)

I have read that the slot allows designers to achieve dual resonance frequencies. It appears to a radio amateur, which I am, that the radiation pattern of the slotted antenna could be a lot more irregular than that of a single frequency narrow bandwidth antenna and thus add an element of unpredictability for satellite uplinking. This at least for non repeated messages.

Would you have any comment on this?

Thanks for your valuable comments on the effect of going to high latitudes. I believe it is important for users to understand this, e.g. if you are in a forest in northern Sweden (65 degrees north) , be sure to be in the northern side of an open area in order to get as good a view south as possible. With dense forests, such as in British Columbia, finding an opening might be difficult. It would be interesting to have test results from such areas.

Does it help to tilt the device somewhat towards the south - or rather in the direction of a ground station? For the simplex ground station in France, this would mean aiming the unit about SW if you're in Sweden. (There is a European ground station south of Sweden, but it seems dedicated to phone only).

Global Star's map of simplex coverage shows ground stations in Europe in SW France and in Turkey. However, the Phone coverage map shows a ground station in also in Northern Italy plus one or two in Russia. Over all, simplex coverage appears much more limited than Phone coverage and not all Phone ground stations will receive simplex communication. Furthermore, different Global Star maps are not consistent as it comes to ground stations.

Using the SPoT attached to a belt, be it in a ventral, dorsal or lateral position seems to be pretty suboptimal if you want to use tracking mode - or any other mode for that matter.

While walking around in Whistler village, B.C. (abt 50 degrees North), holding the SPoT in my hand, I noticed that the unit lost its fix in open streets. There was non synchronous flashing. I believed this was due to dense multipath signals because of metallized windows. Would you have any comments on the GPS receivers vulnerability to multipath?

I also noticed that there is synchronous blinking for several minutes (10 in the event) even if you enter e.g. an underground garage under a five storey building, where it is dificult to believe that the unit would get a GPS signal. How soon will the unit report a lost fix?

What happens if you pass an object, such as a house or a tree, which blocks GPS signals for a couple of seconds just before the unit plans to transmit, will the position be extapolated or will there just be a postponement of transmission?

Having the buttons and the LEDs on the front side makes the user prone to hold the unit so that the LEDs are easily visible. For the first week of trials I held the unit vertically in my hand, also drawing from my experience with hand held GPS receivers which often have internal vertically mounted quadrifilar helical antennas (Garmin 76C is one example). This proved to be wrong. "Logo up" is still ambiguos and the manual only mentions that the Logo should face the sky when the unit is in water, on the last page. They could have said: The unit's antenna is between the buttons and the SPoT logo. Turn the unit so that the Logo faces the sky and avoid having your hand cover the antenna.

I agree with Banaman that there should be more explicit instructions on the unit. But not in the form of metallized stickers that risk blocking transmissions if put in the wrong place. A further note to Bananaman: You are not alone in trying to evaluate the SPoT with a critical eye to understand its limitations for the good purpose of getting the best result from it when it is really needed. So let's just report our sometimes negative results in an objective manner. Btw, if you check the map of Global Star Simplex Coverage, you'll see that Primary coverage ends at the peruvian-Chilean border

http://www.globalstar.com/en/satelli...x_coverage.php



There is an obvious dilemma: SPoT marketing oversimplifies the use of the device (IMHO). OTOH, if this makes more people buy it, some might be saved which would not have had it if a more complex picture had been presented (it seems that many units are bought by wives or parents). Some might also die because of insufficent understanding of the limitations. By providing more information in forums the implications of the dilemma are reduced. Some might even go from considering a SPoT to buying a PLB (in countries were these are allowed for land use - not all, notably the UK). I for one wasn't aware of land use of PLB until I learned about the SPoT. It was allowed in my native country Sweden only last year.

A note on SMS messages. European operators rarely offer the personal phonenumber @ operator.com mail2sms service which many Northamerican operators do and which Spot SMS delivery depends on. The rep office for Europe told me the other day that SPoT will offer a common SMS gateway for European users. This is welcome news.

Spotmaker, if your wanderings bring you to Brussels, there are 200+ beers here to try out. Not all are as strong as the ones named Delirium Tremens and Mors subite (Sudden Death), but still taste a lot better than Budweiser - subjective opinion - . Just PM me.

Jonasolof screwed with this post 04-11-2008 at 01:27 AM
Jonasolof is offline   Reply With Quote
Old 04-11-2008, 08:00 AM   #329
SpotMaker
Gnarly Adventurer
 
Joined: Nov 2007
Oddometer: 140
Quote:
Originally Posted by Jonasolof

I have read that the slot allows designers to achieve dual resonance frequencies. It appears to a radio amateur, which I am, that the radiation pattern of the slotted antenna could be a lot more irregular than that of a single frequency narrow bandwidth antenna and thus add an element of unpredictability for satellite uplinking. This at least for non repeated messages.

Would you have any comment on this?
Golbalstar is extremely strict about certifying a transmitter or antenna pattern for their network.

As a result, that antenna is optimized for it's radiation pattern on the transmissions to Globalstar's network (otherwise, they wouldn't have certified it) and sacrifices a little bit of pattern symmetry on the GPS (compared to a dedicated GPS antenna). Interestingly, GPS gain is biased slightly in the direction of the buttons and LED's, which means GPS sensitivity is rather crappy on your belt. Flat on it's back is truly best. If hiking, with a backpack, the optimal way to carry it would be to wedge it inside a compartment of the backpack with it's face facing up (as much as possible). Any fabrics that backpacks are made of are transparent to the RF, as far as I know. Or, clip it to the backpack strap, with it's face facing up, as much as possible.

The transmit pattern, on the other hand, is an even broad cone-shaped pattern. It's very close to Globalstar's ideal example of what a simplex transmit antenna is supposed to do on their network.

Quote:
Originally Posted by Jonasolof
Does it help to tilt the device somewhat toward the south - or rather in the direction of a ground station?
Maybe, but be careful not to overdo it. The radiation pattern is very broad. With the unit flat on it's back, the pattern is quite even in a cone from about 10-15 degrees from horizontal to 90 degrees straight up. So, if you tilt it more than 10 - 15 degrees, you're doing little more than sending potentially useful RF energy into the ground.

Safest bet for optimum transmission performance is always to have the unit laying flat on its back. However, if you're at a latitude greater than 45 degrees north or so, a clear view of the southern sky is important. The further north you go, the more important a clear view to the south is and less important the view to the north is.

Quote:
Originally Posted by Jonasolof
Using the SPoT attached to a belt, be it in a ventral, dorsal or lateral position seems to be pretty suboptimal if you want to use tracking mode - or any other mode for that matter.
True, some of us actually argued against the unit having a belt clip, as it may be misleading. It's performance is spotty if worn on a belt. (The other side of the argument, of course, is ease of carrying the unit over a variety of situations.)

Quote:
Originally Posted by Jonasolof
While walking around in Whistler village, B.C. (abt 50 degrees North), holding the SPoT in my hand, I noticed that the unit lost its fix in open streets. There was non synchronous flashing. I believed this was due to dense multipath signals because of metallized windows. Would you have any comments on the GPS receivers vulnerability to multipath?
Actual multipath conditions don't bother it much. "Multipath", in this case, being defined as a mixture of direct and reflected signals, assuming they are all above the receivers sensitivity threshold. I'd guess if you lost GPS lock it was plain ol' signal attenuation from the tall buildings blocking GPS signals, as opposed to reflecting them.


Quote:
Originally Posted by Jonasolof
I also noticed that there is synchronous blinking for several minutes (10 in the event) even if you enter e.g. an underground garage under a five story building, where it is dificult to believe that the unit would get a GPS signal. How soon will the unit report a lost fix?
The unit puts the GPS chipset into a "standby" mode between transmissions to save battery power. In this standby mode the Real Time Clock still runs and the ephemeris and almanac data are retained. As a result, after a shut off of only 10 minutes, the restart is what is known in the GPS world as a "hot start", and assuming the GPS signal strengths are at all trackable, it re-acquires them in about 1 - 5 seconds.

But, since the GPS chipset is in standby between the track-mode transmissions, it might be up-to 10 minutes before it "notices" that there's no GPS signal anymore and blinks the LEDs out of sync. So, what you observed is normal.

Speaking of parking garages: Really interesting note: In the New Orleans Airport's parking garage, they've implimented some sort of broad-band passive repeater system, apparently to make XM and Sirius radios work. This passive system also allows GPS units to work and allows the SPoT to transmit out! My SPoT works anywhere inside the New Orleans Airport parking garage (including lower floors, near the center of the structure) almost like being in the clear outdoors for both GPS reception and transmission!! Floored me when I first discovered it. (My several-year-old, not-very-sensitive Garmin Nav unit works fine in this garage too!)

Quote:
Originally Posted by Jonasolof
What happens if you pass an object, such as a house or a tree, which blocks GPS signals for a couple of seconds just before the unit plans to transmit, will the position be extapolated or will there just be a postponement of transmission?
I'm treading dangerously close to reveling some trade secrets here, so please understand, if my answer seems evasive, its to protect trade secrets and keep me from getting fired for being more specific...

But: depending on many variables and metrics, the unit does "track" certain metrics that give it "confidence" in the GPS accuracy. If it sees a down-tick in overall confidence, it usually will wait up to a few seconds for the confidence to get better (many variables in the algorithm). So, the situation you described, in simplified terms, would usually postpone the transmission for a few seconds.

Rest assured, however, if it has a fix at all, it has "bail out" criteria that will transmit whatever it has eventually (well within the 10 minute window between messages in Track mode or the 5 minute window in 911 or Help modes) even if the various "confidence criteria" metrics are failing to settle down.

If it is "time to report" (10 minute interval in track, 5 minute in 911 or help), and it gets a fix, and just before it transmits the GPS signals disappear entirely, it will wait a few seconds, then if the signals don't return, it will transmit the last GPS co-ordinates it had.

Quote:
Originally Posted by Jonasolof
Spotmaker, if your wanderings bring you to Brussels, there are 200+ beers here to try out. Not all are as strong as the ones named Delirium Tremens and Mors subite (Sudden Death), but still taste a lot better than Budweiser - subjective opinion - . Just PM me.
When Budweiser and Miller are the only choices, I order Coke or Sprite.
__________________
I work for Axonn LLC, the company that designed and manufactures the SPoT Satellite messenger. However opinions expressed here are mine and mine alone and do not necessarily reflect those of SPoT INC. or Axonn LLC.

SpotMaker screwed with this post 04-11-2008 at 08:17 AM
SpotMaker is offline   Reply With Quote
Old 04-11-2008, 10:10 AM   #330
moto-treks
Back Home
 
moto-treks's Avatar
 
Joined: Dec 2007
Location: Spokane Washington
Oddometer: 1,776
Quote:
Originally Posted by Jonasolof
Btw, if you check the map of Global Star Simplex Coverage, you'll see that Primary coverage ends at the peruvian-Chilean border

http://www.globalstar.com/en/satelli...x_coverage.php
Ive been following this thread for a while now while I try to decide if I should get a spot unit for an upcoming trip to South America. A lot of really good information here.

What does the simplex modem data coverage have to do with the usability of the spot unit. If you look at the findmespot site its coverage area is much larger.


http://www.findmespot.com/ExploreSPOT/Coverage.aspx

-Jeff
moto-treks is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 09:52 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014