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alzomor
Joined: 09 Jun 2005
Posts: 565
Helped: 31
Location: Cairo
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 29 May 2006 21:56 Spread spectrum module |
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Hi
I need to locate a unit within about 1000 units in about 1Km area.
My idea is to use a Tx on the target units and Rx with me and check the signal strgnth to indicate the distance from Tx to RX.
as I have about 1000 units I think of using Spread spectrum in order to avoid interferance .
Do you have any suggetions or know good and sheep spread spectrum modules?
Salam
Hossam Alzomor
www.edaboard.com
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m_llaa
Joined: 12 Mar 2006
Posts: 272
Helped: 23
Location: My Love Iran
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| 02 Jun 2006 11:25 Re: Spread spectrum module |
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Hi
r u sure u want to use SS for uor purpose ?
do u think about using GPS ?
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alzomor
Joined: 09 Jun 2005
Posts: 565
Helped: 31
Location: Cairo
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| 02 Jun 2006 19:23 Re: Spread spectrum module |
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Hi
GPS is good for accurcy of about 15m but what for less accurcy?
Salam
Hossam Alzomor
www.edaboard.com
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codeboss
Joined: 02 Jun 2006
Posts: 10
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| 02 Jun 2006 19:54 Re: Spread spectrum module |
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| to locate with a high resolution u couls use the scenario with one tx and multiple receivers. then compute from received signal, the angle of arrival and time difference of arrival (AoA and EoTD). if u have a gsm system u can use cellid and TA values also
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Joined: 27 May 2001
Posts: 284
Helped: 11
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| 02 Jun 2006 20:07 Spread spectrum module |
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what about doppler?
http://www.qsl.net/ve2emm/pic-projects/doppler3/doppler3-e.html
gps is very accurate now with selected availability switched off
regards
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m_llaa
Joined: 12 Mar 2006
Posts: 272
Helped: 23
Location: My Love Iran
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| 03 Jun 2006 5:32 Re: Spread spectrum module |
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Hi
GPS is very good, if u use GPS also by 15m resolution it is better and cost efficient.
I think if u design a system for this perpuse it is very expensive, for example u can use multiantenna to measure AoA and ToA but it is more expensive than using GPS
u say your distance is about 1000m, so 15m error is negligible -> error = 0.015 = 1.5%
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alzomor
Joined: 09 Jun 2005
Posts: 565
Helped: 31
Location: Cairo
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| 03 Jun 2006 10:33 Re: Spread spectrum module |
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Hi
| Quote: |
| if u have a gsm system u can use cellid and TA values also |
What is AT commands to get cellid & TA ? and what's TA?
and what's the accurcy of such system?
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gps is very accurate now with selected availability switched off
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How to switch selected availability off?
Salam
Hossam Alzomor
www.edaboard.com
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Joined: 27 May 2001
Posts: 284
Helped: 11
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| 04 Jun 2006 11:38 Spread spectrum module |
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SA is switched off by GPS system owner since few years now so it is quite accurate .. abt 2m.
you can get better resolution (abt tens of cm) if you will use differential GPS (DGPS). easy to do for small area
you need just 1 more gps receiver and calculations ;0))
regards
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