I was successfully connecting to Hologram with three of them until last week. I’m about 15 km from the cell tower with signal levels averaging between -90 and -105 dBm, so I wanted to try to diagnose that further. I’ve done no configuration changes that should have caused this and have issued AT&F0 commands to each one of them to force them back to factory defaults.
Our application will be in rural locations, so we need robust performance at low signal strength. We are expecting to use antennas in most deployments, but I’m not reassured by the lack of stability I have experienced so far. I’m using an outdoor antenna for testing, BTW.
The stability question is why serial response is a blocking issue for me. Because of the shared serial port, I already have to figure out a way to turn off the UART RX every time I open the comms with the modem, because I need to interrogate it to find out whether the session is still up or needs to be reinitiated. This adds both hardware and software complexity to the application.
One more data point: Here is the reply if I query URC:
10:23:38.032 -> Modem response after start:
10:23:38.032 -> AT+qurccfg="urcport"
10:23:38.032 -> +QURCCFG: "urcport","usbmodem"
10:23:38.032 -> OK
10:23:42.070 -> BG77 power up!