For a project at work we're using SP1ML-915 modules. For testing I have one dongle made by ST and one PCB made in house with SP1ML module mounted and connected to USB.
After sending random strings between the two, I go into command mode and check RSSI (ATI1\r command). Usual values there are between -115 and -105 dBm. The value doesn't really change when I move the transmitter around or when I change the transmitting power.
I'm getting about 10 meters of indoor range (walls and metal between the transmitter and receiver).
What am I doing wrong?