SIM is necessary to get UTC and coordinate ?
As fas as I know, it depends on the calculation algorithm. For A-GPS (Assisted GPS) yes you need but for normal GPS no.
What kind of device and GPS module you are using?
I m using HL8 Series.
I tryed to send AT commands.
I receive info about device (type, serial number) but nothing about position.
For example, I sent:
and I receive:
But I sent:
AT+GPSNMEA=2 // bult also AT+GPSNMEA=0 and AT+GPSNMEA=1
but I dont reveiceve values.
The result is :
“+GPSEVSTART: 1\r\n+GPSPVT:0,00:00:00,00/00/0000,NO FIX,N 000 00’00.00”,E 000 00’00.00",+0000m\r\n+GPSPVT:1,000.0deg,000m/s\r\n+GPSPVT:2,00SV,0.0HDOP,0,0.0\r\n+GPSPVT:3,8,1,[20,N,0],[10,N,0],[22,N,0],[18,N,0],[31,N,0],[27,N,0]\r\n+GPSPVT:3,8,2,[9,N,0],[8,N,0],[19,N,0]"
“+GPSPVT:0,00:00:00,00/00/0000,NO FIX,N 000 00’00.00”,E 000 00’00.00",+0000m\r\n+GPSPVT:1,000.0deg,000m/s\r\n+GPSPVT:2,00SV,0.0HDOP,0,0.0\r
What you think about ?
I’ve completed a vehicle tracking device project with Q2687 series before at Open AT framework. I’ve never used GPS feature with AT commands and I was using an external GPS antenna as following;
Are you using an external GPS antenna? May be you also need to use an external antenna to get GPS data.
NO FIX means that your device is not connected to GPS satellites. For your reference…
You are sure that “no fix” means not connect to GPS satellites ? I thought “no fix” means accuracy > 500 meter.
Well my HL8 device is inside (embedded) in a box . The box contains pcb with cpu, sensors and HL8.
You think it’s necessary to use HL8 only outside of room or I can use into room/house too ?
Actually, “as far as I know”, no fix means not connected to enough number of satellites to get GPS data. At least 3 satellites needed to get GPS data. More satellites increases the accuracy rate.
If you are working with a GPS project, your GPS device must be under open sky to connect satellites. It is a must because even cloudy weather decreases the accuracy of GPS data.
I have another questions:
how long it’s necessary to connect GPS to satellites? half hour? one hour?
and after I connected once, HL8 keeps the positions for next connection?
Oh thanks you are very kind sorry for repeating question. But I need explanation: the open sky increases the accuracy only or the rooms impedes connection (so I have values 0 for all coordinate, date, time)
In a good weather condition, it should take about 3 to 5 minutes max.
I don’t know how the HL8 acting at that situation.
This is completely related with “no fix” issue. If the device never connected to satellites before, it is normal to show all values 0.
By the way, I’ve never used HL8 before as I mentioned. I just used several type of tracking devices and GPS antennas. I’m just sharing my experiences with you if it helps.