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)