NAME

       bladeRF-fsk - command line fsk application

DESCRIPTION

       The  bladeRF-fsk  project  is  a  simple  frequency  shift  keying (FSK) based software modem implemented
       entirely on the host PC side in C code. The project uses libbladeRF to transmit/receive  samples  with  a
       bladeRF  device.  A  USB  3.0  port  is  not  required when using this modem. The project also contains a
       MATLAB/Octave simulation/implementation of the physical layer (PHY) portion of the modem.

       The top level bladeRF-fsk C program demonstrates the functionality of the modem in a  simple  bladeRF-to-
       bladeRF  data  transfer  program.  This  program can transmit/receive both text (like a chat program) and
       binary files (like a file transfer program) with a raw link rate of 250 kbps. To properly demonstrate the
       program,  two  instances  of  the  program must be run with two separate bladeRF devices (loopback is not
       supported).

       The modem modulates with continuous-phase frequency shift keying (CPFSK). Baseband I/Q CPFSK samples  are
       sent  to the bladeRF device, inside which they converted from digital to analog, mixed with quadrature RF
       carriers, and transmitted through the air.  Received signals are mixed with  quadrature  RF  carriers  to
       downconvert  to  baseband  I/Q,  sampled  with  an  ADC,  and  sent  to  the host PC program over the USB
       connection.

       The physical layer code features an FIR low-pass filter, power normalization,  preamble  correlation  for
       signal  detection,  CPFSK  modulation/demodulation, and scrambling. The link layer code features framing,
       error detection via  CRC32  checksums,  and  guaranteed  delivery  of  frames  via  acknowledgements  and
       retransmissions.

       This project is meant to be an experimental example and should not be treated as a rigorous modem.

EXAMPLES

       To run the top-level bladeRF-fsk program with defaults, type into a terminal:

              bladeRF-fsk

       To see a list of configuration options and how to set them, type:

              bladeRF-fsk -h

       _NOTE_:  On  Windows 10, if you are running two instances of the program on the same PC, you must specify
       the     bladeRF     serial     number     with     the     '-d'      option,      due      to      [Issue
       #484](https://github.com/Nuand/bladeRF/issues/484). Example:

              bladeRF-fsk -d *:serial=4e

       By  default  the  program  uses  the  first available bladeRF device, gets TX input from stdin, writes RX
       output to stdout, and uses a default set of transmit/receive frequencies and gains. Gains may need to  be
       tweaked  for  a good connection with another bladeRF running bladeRF-fsk. To transfer files, use the '-i'
       and '-o' options. If using stdin for tx data, the program will transmit data line-by-line.

       The program runs until it gets an EOF in its TX input.

       ### Example: Transferring Files ### 1) Be sure two bladeRF devices are  plugged  into  your  PC  (or  two
       separate PCs) with
          TX and RX antennas attached.

       2) Run bladeRF-fsk on one of the devices (receiver), with the output RX file specified:

              bladeRF-fsk -r 904M -t 924M -o rx.jpg

       3) Run bladeRF-fsk on the other device (sender), with opposite frequencies and the input
          TX file specified:

              bladeRF-fsk -r 924M -t 904M -i puppy.jpg

       4) The file will begin transferring, and progress will be printed in the terminal for the
          sending device.

       5) Once the transmission is complete, press [CTRL-D] on Linux/OSX or [CTRL-Z then ENTER]
          on Windows to stop the program on the receiving end.

       If  the sending device does not get any response from the receiving device, it will quit the program. Try
       increasing the gains and run it again.

KNOWN LIMITATIONS

       1) The program does not currently support the use of an XB-200 transverter expansion
          board to transmit/receive at frequencies below 300MHz. In order to add XB-200 support,
          a new configuration option as well as functions from the "Expansion boards" section
          of the libbladeRF API would need to be added to the source code.

       2) The program is currently unable to perform two file transfers in both directions
          simultaneously. Reason #1: The program runs until is gets an EOF in its TX input,
          meaning whichever side finishes transmitting its file first will quit and stop
          receiving. An EOF bit would need to be added to the link layer packet format in order
          to stop this behavior. Reason #2: The program doesn't seem to perform well during
          these simultaneous file transfers, and usually loses connection. Further investigation
          is required to debug this.

See Also

       bladeRF-cli(1)