New versions or linux have dvb driver witch takes RTL and do not deatach it. So when you build binaries of librtlsdr-2freq you should write:

cmake ../ -DINSTALL_UDEV_RULES=ON -DDETACH_KERNEL_DRIVER=ON

instead of

cmake ../

Hi! I try to use your lib on raspberry pi2 with rtl dongle. Image with pre-installed lib /i got from here http://www.panoradio-sdr.de/wp-content/uploads/2019/04/pi_image_tdoa_v2.zip
After entering "buid/src" and input command "rtl_sdr -f 400e6 -h 500e6 -n 1e3 test.dat", got error "invalid option -h". This is the only rtl_sdr app in image as I understand.

Hello,
i need a question about this command

/home/alarm/librtlsdr-2freq/build/src/rtl_sdr -f <freq_1_hz> -h <freq_2_hz> -n 1.2e6 filename.dat

in which i put freq1 --> 100000000 and freq2 --> 100000000 in which this is as written in code in file sdr_rtl.o
and instead 1.2e6 --> i written as written in this file
but my question on this file --> filename.dat , in which i created empty file .dat after that excute this command but this error : No supported devices found
in which i dont know any thing about this file , must found in it any code ??

please , i need your answer in as soon as please
thank you