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Nextel's Off-network Walkie-Talkie

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realgeo

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Good evening, everyone.

Recently, I've seen some ads for Nextel's I275 phone which boasts of an "off-network walkie-talkie" feature that allows communication between I275 users, up to 6 miles away.

Does anyone know how this is accomplished? Is the off-network communication something that can be monitored with a scanner, such as the BDC396T?

Thanks, and 73's
 

MacombMonitor

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It's highly unlikely you will get six miles either. More like one, or two on the average.
 
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N_Jay

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MacombMonitor said:
It's highly unlikely you will get six miles either. More like one, or two on the average.
Have you played with them?

I have heard they have incredible range in the clear, but quickly fall to range similar to FRS in clutter.

I have not had a chance to use them yet.
 

MacombMonitor

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N_Jay said:
Have you played with them?

I have heard they have incredible range in the clear, but quickly fall to range similar to FRS in clutter.

I have not had a chance to use them yet.
Yes, I had a couple of i325's. They worked very well, but similar to GMRS/FRS...line-of-site thing. I never tried them in a clear unobstructed environment. I suppose the six mile claim might apply under those circumstances.
 

KE4ZNR

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Mototalk (or DirectTalk) is based in the 900Mhz ISM Band and is spread spectrum like said earlier in this thread so it cannot be monitored on any police scanner....believe me I know as I used to 1) used to work for Nextel & 2) know more about their phones than any sane person should :D
 

flyingwolf

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Ok then KE4ZNR, time to ask you a question, why the hell does the GPS in my I355 take up to 10 minutes to acquire my position. And 90% of the time does not work?

Are these actually GPS units in these phones or what?
 
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N_Jay

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flyingwolf said:
Ok then KE4ZNR, time to ask you a question, why the hell does the GPS in my I355 take up to 10 minutes to acquire my position. And 90% of the time does not work?

Are these actually GPS units in these phones or what?
Unlike most cellular phones, the GSP in iDEN is true GPS.

I have not played with those, but the usual issues that case long acquisition time is insufficient processing power and a poor antenna.
 

KE4ZNR

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flyingwolf said:
Ok then KE4ZNR, time to ask you a question, why the hell does the GPS in my I355 take up to 10 minutes to acquire my position. And 90% of the time does not work?

Are these actually GPS units in these phones or what?
It is actually AGPS or "Assisted GPS"...meaning that the phone uses a combination of the sub-par GPS in the phone + tower triangulation to give you lat/long....I agree that the AGPS is slow but one way to help speed it up a little is make sure your software on your phone is updated to the latest version (HERE) so that the AGPS Almanac is current and make sure you are outside with a clear view of the sky with the antenna extended...I do not guarantee that this will make the AGPS perfect but it should help a little...
 

KE4ZNR

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N_Jay said:
Unlike most cellular phones, the GSP in iDEN is true GPS.

I have not played with those, but the usual issues that case long acquisition time is insufficient processing power and a poor antenna.
Not correct N_Jay...I suggest reading over current IDEN software documents...it is AGPS or "Assisted GPS"....Let me look in my Moto files and I will post proof :cool:
 
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N_Jay

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KE4ZNR said:
Not correct N_Jay...I suggest reading over current IDEN software documents...it is AGPS or "Assisted GPS"....Let me look in my Moto files and I will post proof :cool:
Really, that is a shift away from the earlier iDEN implementations.

You could be right, I have been out of the iDEN world for a few years, but had not heard of a change.
 

KE4ZNR

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N_Jay said:
Really, that is a shift away from the earlier iDEN implementations.

You could be right, I have been out of the iDEN world for a few years, but had not heard of a change.
There is a "True" GPS unit in the phone but lat/long is derived from a combo of GPS+ tower triangulation or AGPS...and "Sprintel" is not alone in using AGPS...most cell carriers are doing the same thing to meet FCC regulations for E911 compliance...again: yes, I know too dang much about nextel phones including the code that makes up the firmware :D l33t haxx0r hee hee
 
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N_Jay

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KE4ZNR said:
There is a "True" GPS unit in the phone but lat/long is derived from a combo of GPS+ tower triangulation or AGPS...and "Sprintel" is not alone in using AGPS...most cell carriers are doing the same thing to meet FCC regulations for E911 compliance...again: yes, I know too dang much about nextel phones including the code that makes up the firmware :D l33t haxx0r hee hee
A-GPS typically refers to the fact that the system and the phone share the task of calculating the location.
It is not sop much the addition of cell location or cell triangulation, but rather true GSP, just typically with the phone's GPS chip receiving a data set from the network (the same data an autonomous GPS unit gets during start up).
This greatly reduces the time to acquire the first fix and the power used to get a fix.

This may also be augmented in the network by triangulation or other cell based location technologies. (outside of the A-GPS technology)

When did they drop autonomous GPS?

Edit:
Before some "know it all" starts up.

http://en.wikipedia.org/wiki/AGPS
http://www.snaptrack.com/technology/advantages.jsp
http://www.sirf.com/Downloads/Collateral/Press_Releases/SiRFLoc Client Product Insert.PDF
http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=12287
 
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KE4ZNR

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N_Jay said:
A-GPS typically refers to the fact that the system and the phone share the task of calculating the location.
It is not sop much the addition of cell location or cell triangulation, but rather true GSP, just typically with the phone's GPS chip receiving a data set from the network (the same data an autonomous GPS unit gets during start up).
This greatly reduces the time to acquire the first fix and the power used to get a fix.

This may also be augmented in the network by triangulation or other cell based location technologies. (outside of the A-GPS technology)

When did they drop autonomous GPS?
Supposed to speed up lat/long Acquisition time from what I was told from a buddy of mine in Plantation :roll: although I have NEVER seen a Nextel A-GPS phone aquire lat/long in less than 4-5 mins...I understand the main purpose is for E911 but if you are going to PROMOTE the GPS in the phones as much as Nextel does then you better have the quick response time in terms of picking up lat/long :cool: of course I am just being too picky...

Edit: i just realized you asked "WHEN" not why...sorry about that...getting a little tired and senile in my old age<grin>decision was made when the falcon platform was being worked on...again reliable info from a buddy down at Plantation....

Edit #2: I love your sig...might have to steal that for some other message boards :) hee hee
 
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N_Jay

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flyingwolf said:
Ok with all of the known lag time in getting a fix, why pimp the GPS based services so much like they do.

Obviously they are going to have unhappy customers.
I know several people who are happy with it.

Might be a perception thing.
e.g. if you are a "real GPS" user you think it sucks,
where if it is your first navigation experience you think it is cool.

Just a guess.
 
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