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Automatic Vehicle Location using GPS and GSM

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sathish316

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Hi friends
Im currently working on an Automatic Vehicle Location(AVL) system using GPS and a GSM mobile phone. Im using the Lassen SQ GPS module and a Nokia 3310 Mobile phone with an F-bus interface for my project.
Im currently having a few problems.

I interfaced the GPS module to my PC. Im using SQ Monitor downloaded from Trimble website(www.trimble.com). Initially the GPS module was partially working. It indicated the date correctly and was tracking upto 3 satellites. The Feed line/Antenna was oscillating between "Feed Line Fault" and "Feed Line OK". But currently it indicates only "feed line fault"
Can anyone please help me identify the source of this problem and a possible solution
Thank you
 

papyaki

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Hi,

The coaxial cable of the antenna is probably open, so the antenna is no more detected by the receiver. Check the cable connexion at the connector end and at the antenna end.

Try to replace the antenna if you have a second one.
 

sathish316

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The problem was with the Power supply. The specified range was 3.0 to 3.6 V and 3.3V typical. I was all along trying with 3.1 V. When i switched over to 3.6 V, everything seems to be working in order.
I was also able to track 8 satellites when i changed the location of the Receiver from my balcony to the terrace. Hope this info helps other GPS developers
 

Tulkas

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Hi, I have seen you are using Lassen SQ GPS. I am using it to put in hour a seismograph net. The timing system is formed by a Lassen SQ GPS, RTC from PHILLIPS and a LCD (and a microcontroller). When the GPS system have UTC time in the lcd appears two asterisc indicating that i have UTC time, then UTC time pass to the RTC and i can to put in hour the seismograph through I2C. After 3 month i have seen that time stored in the seismograph is in GPS time not in UTC time, but specifications of GPS says it only sends UTC time, it is correct??.

thank you, sorry for my english.
 

brmadhukar

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Hi Tulkas,
GPS can send both the UTC time and in many cases other times as well. But if you are not doing anything in the uC then the GPS rx is manipulating the time. So do check what is the configuration msg sent to RPS from the uC. It holds the answer.
B R Madhukar
 

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