I am having trouble powering my LimeSDR solely from the USB connector of the RPi3. Does anyone have a solution to the power issue?
The external power for the Lime is between 6 and 12 V using J20 or J21. Is it harmful to supply 12V through the USB connector by splicing in the external power there?
Running at USB 2.0 data throughput rates (~10x lower than USB 3.0) you will still need to provide 4.5 watts.
You should be able to achieve your maximum data throughput rate over the isochronous USB 2.0 HS (~30 MB/sec at a guess on most USB 2.0 hardware, which could be much much lower on RPi hardware), provided no other USB devices are connected (no keyboard/no mice/nothing at all connected to any USB port) and all communications to/from the RPi3/3+ is using the onboard WiFi (5MB/sec [1 meter away] to 10MB/sec[5 meters away]) and not the USB NIC which is part of the internal 4 port USB hub chip. Point number two here highlights other issues you will have.