Hello,
I am using the nrf9160 to develop a cellular product but am seeing inconsistent end-to-end connectivity results. For the nrf9160-dk and a custom board based on the nrf9160, I am using the demo code (HTTPS Client) and (Asset Tracker) configured with I believe the default (LTE CAT M1). But, with HTTPS Client, oftentimes, the program hangs, goes into a sleep mode, and rarely connects to google.com. Even when it does, I am not confident it retrieves all of the expected bytes.
The asset tracker also is inconsistent with its success with reaching the web endpoint. This is equally true for both boards. I believe my received signal strength could be a factor, as I am in a rural area of the United States. When I use my cell phone, I measure a signal strength of between -112 and -120 dBm.
For my custom board, when running the AT command (AT+CESQ) when there is connectivity I get:
- 99,99,255,255,0,32
- 99,99,255,255,1,31
- 99,99,255,255,0,31
- 99,99,255,255,7,21
Note that my custom board, since it's still in development, connects the cellular RF pin to an RF SMA coax connector to a tuned evaluation antenna board.
For the nrf9160-dk, when things work, the same AT command result is:
- 99,99,255,255,7,11 (-130dbm)
- 99,99,255,255,10,32 (-109dbm)
- 99,99,255,255,5,28 (-113dbm)
But both boards oftentimes are either 99,99,255,255,0,0 or 99,99,255,255,255,255.
My cell phone does operate in this same area (though doesn't have many signal bars).
In short these are my questions:
- What is causing this unpredictability?
- How I can get this system to perform better?
- What power levels is the nrf9160 system designed to work with?
- Should I use NB-IoT if signal is weaker?
- Is there a way to compensate the weak signal with an RF amplifier connected to the antenna? Or is there some software configuration change I can try?
Thanks again.
