Two GPS related questions

[replay]

Hi, I have two GPS related questions:

1.) AGPS: How exactly does a GPS module connect to a local server in assisted GPS mode (AGPS)? In other words: I have a SIMCOM evb kit that has two antennas - main and GPS one. I only need GPS antenna for standalone mode, so my question is: do I need both antennas (GPS and main) for AGPS mode?

2.) Question about cold start (TTFF): Since I've seen different explanations about it, I'd like to make it clear what exactly does it mean. Is it:
a.) the time from turning on GPS mode (via AT commands) to getting the first fix, or
b.) the time from turning on/powering the whole module to getting the first fix?


Thanks in advance.

 

[salmanliaquat]

1.) AGPS: How exactly does a GPS module connect to a local server in assisted GPS mode (AGPS)? In other words: I have a SIMCOM evb kit that has two antennas - main and GPS one. I only need GPS antenna for standalone mode, so my question is: do I need both antennas (GPS and main) for AGPS mode?

Among the two antennas, one is for GPS and the other is for GSM. AGPS device downloads the orbital information of satellite from the servers (in your case probably SIMCOM's servers) using either gprs or wifi(in your case it will be gprs). So yes, you will have to connect both the antennas for AGPS option.

2.) Question about cold start (TTFF): Since I've seen different explanations about it, I'd like to make it clear what exactly does it mean. Is it:
a.) the time from turning on GPS mode (via AT commands) to getting the first fix, or
b.) the time from turning on/powering the whole module to getting the first fix?

It should most probably be option (a) but still i would suggest you to read the details from your module's manual.