HL7800 GPS is way off

Have our prototype running with the HL7800. All seems to work fine except the GPS.
First, it takes the GPS almost a minute to get a GPS lock.

Secondly, and most strangely, when we do an at+gnssloc? we get a location that is about 30km away from our present location.

We are using an active ceramic antenna from Taoglas (pn: aggbp.25b), delivring about 3.5 volts to it. It’s capable of using up to 5 volts.

We are using firmware v3.4.4.3

Any ideas?

Hi Rique,

For GPS cold start, it may take a long time to fix.
For 30km issue, could you provide your result of at+gnssloc? and your exact position?

AT+gnssloc? position reported: 43 Deg 14 Min 21.97 Sec N 80 Deg 17 Min 1.22 Sec W

Our exact position is: 43°23’56.7"N 80°28’22.2"W

Hi Rique,

It seems the degrees minutes seconds (DMS) is wrong in AT+gnssloc?.
Please convert the correct DMS from GPRMC(dd.mmmmmmm).

the DMS is what I got right from AT+gnssloc?

GPRMC gives me this string

so when I plug 43.239371 -80.283706 into Google, I get the same wrong location.

The format of the GPRMC position is in Degrees Decimal Minutes (DDM) whereas the format you use in google is Decimal Degrees (DD).
What you get from GPRMC in DDM:

Degrees = 43
Minutes = 23.9371
Degree = 80
Minutes = 28.3706

In DD this would be:
Latitude: 43.398952
Longitude: -80.472843


Ah thank you for the clarity.
And I found a nice tool to convert the entire string to something useful, and I found that the location is indeed accurate in the string…So it looks like at+GNSSLOC? is converting it incorrectly.


Thanks again.