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GPS engine start-up in A-GPS mode not working. | Telit Cinterion IoT Developer Community

April 12, 2019 - 4:42am, 1638 views

Hi,

We're currently upgrading our PHS8 based tracking product to LTE using the PLS8.  The device's main microcontroller has limited RAM and to save on temporary storage, we used a "trick" with the PHS8 to avoid having to buffer an A-GPS file that's being downloaded.  We're using the UART interface and the CMUX multiplexer.  To save an A-GPS file to the modem's internal file system we initiate a download on one of the multiplexer's IP channels and then use AT^SBNW to immediately turn that data around as it arrives, back into the multiplexer where it gets sent over the command channel to be stored in the modem's file system.  Unfortunately, that strategy doesn't seem to work with the PLS8.  In the case of the PLS8, the process appears to work properly.  The modem responds with, "CONNECT AGPS READY: SEND FILE ..." at the beginning of the transfer and, "AGPS END OK" when the transfer is done.  However, when we try to inject the A-GPS data saved in the modem into the GPS engine, we get one of two responses: "AGPS: INTERNAL ERROR", when downloading an "xtra.bin", GPS only file, or "A-GPS not updated!", when trying with an "xtra2.bin", GPS + GLONASS file.  Even though there is no CRC error with the file and it seems to download ok, could you please let me know if it might be getting corrupted in the modem trying to store it this way, or if there might be some other explanation for the errors when trying to start the GPS engine in A-GPS mode?

Thank you,

Ed Haslam

Integrated Tracking Technologies Inc.