25-August-2023: Brought up to date with latest Osmocom upstream, and added some new features like auto-direct sampling. Also made the force bias tee function stronger, so it cant be turned off when the bias tee is forced, even when calling the bias tee function. Remove the rtl_tcp ringbuffer changes as this seems to cause more trouble that it helps.
1) VCO PLL current fix - Improves stability at frequencies above ~1.5 GHz https://www.rtl-sdr.com/beta-testing-a-modified-rtl-sdr-driver-for-l-band-heat-issues/
2) Enabled direct sampling for rtl_tcp
3) Hack to force the bias tee to always be on by setting the unused IR endpoint bit to 0 in the EEPROM. Example to force the BT to be always ON "rtl_eeprom -b 1", to remove forced BT "rtl_eeprom -b 0"
4) Repurposed "offset tuning" to toggle bias tee ON/OFF. We can now use the "offset tuning" button in SDR# and other programs to toggle the bias tee if there is no specific button in the GUI.
5) Support added for R828D RTL-SDR Blog V4 based dongles.
6) Auto direct sampling. For R820T/R860 dongles like the RTL-SDR Blog V3 the code will automatically change to direct sampling mode when the frequency is below 24 MHz. It will also automatically change back to normal sampling when the frequency is above 24 MHz. There is no need to manually change the sampling mode anymore for these dongles.
BIAS TEE NOTE: Always take care that you do not enable the bias tee when the device is connected to a short circuited antenna unless there is an inline LNA. However. if you did by accident, don't worry as the circuit is dually protected with a self-resetting thermal fuse and built in protection on the LDO. Just try not to short it out for days at a time, otherwise you could eventually degrade the thermal fuse.
Note that hack 3) will only work if your system is using this driver. If your system or software is using another driver fork, then the EEPROM information will not be read. So make sure you completely clean your system of the previous drivers first (with the information below) and ensure you run sudo make install after compiling. On Windows, make sure you are using this code's rtlsdr.dll file.
