rtl_sdr:tldr:3978e

The command "rtl_sdr -f ${100000000} ${filename}" is using a command-line tool called rtl_sdr to capture raw I/Q samples from an RTL-SDR device at a specified frequency and save them to a file.

Here is a breakdown of the command:

• "rtl_sdr": This is the name of the command-line tool used to interface with RTL-SDR devices. RTL-SDR devices are inexpensive USB dongles that can function as software-defined radios.

• "-f": This option is used to specify the frequency at which the RTL-SDR device should tune in. In this case, "${100000000}" is used as a placeholder for the actual frequency value. The value within the curly brackets should be replaced with the desired frequency in Hz. For example, if you want to tune to a frequency of 100 MHz, you would replace "${100000000}" with "100000000".

• "${filename}": This is another placeholder for the desired filename to which the captured samples should be saved. The name within the curly brackets should be replaced with the desired file name. For example, if you want to save the samples to a file named "captured_samples.raw", you would replace "${filename}" with "captured_samples.raw".

Overall, this command instructs the rtl_sdr tool to tune the RTL-SDR device to a specified frequency (provided within the '-f' option) and capture the raw I/Q samples from that frequency. The captured samples are then saved to a file with the name specified after the '-f' option.