After we have the 'anything receiver', in the form of the rtl_sdr DVB-T USB stick, the challenge is now to make an 'Anything_Transmitter (c) Jan Panteltje 2013 All Rights Reseved, violaters will be shot into space etc, you get the message blah blah lawyers, lions, mosquitos (and those survided (at least the larvea) on the outside of the ISS, no gavity to speak of...) hey, getting carried away, Anyways tests show the Raspberry Pi (or pie?) can do about 5 M I/O flips per second, to 'retransmit (sometimes also called 'replay attack", _anything_ recorded by rtl_sdr at 2048000 samples per second (makes 4096000 bytes per second, QI remember), we should (shoot?) be able to do that replay, on a Raspberry, wasitnot for the task interrupts. But for that we can use a FIFO. We alse need some handshake in case of FIFO, just a simple 'send more request as long as FFO is not full... It so happens if I counted it right the Raspberry has 17 available IO pins (called GPIOs), and that makes 16 data plus one data request.
So, the task switch interrupts seem to be less than 1us, that is < 2048 16 bit words, so 2 4k x 8 FIFO chips should do, followed by some demuxer to feed it into a AD9761 dual DAC with 10 bits input (simply zero bit 0 and 1), and then into an AD8346 quadrature modulaotr. In the diagram below the red round cicles indicate 'still needs to be done', the Analog Devices chips have been ordered a while ago...
Now here is the first 'Transmit Anything' circuit. We can feed this DVB-T, recorded GPS, any radio band, maybe even make your cellphone ring AGAIN, or do other 'Things' that I cannot talk about here as NSA and CIA is listening, and you never know with these drones and 0bama fatahs etc etc. Anyways, the project is afoot, most has been tested (frequency syntesizers, FPGA is programmed, Raspberry is working, need some more I/O code, how fast can I read from SDCARD? root@raspberrypi:~# dd if=/dev/mmcblk0 of=/dev/zero
467378+0 records in 467377+0 records out 239297024 bytes (239 MB) copied, 8.38896 s, 28.5 MB/s Seems to be enough... faster than my PC!Ciruit block diagram:
Disclaimer, blah blah blah, do not feed digital chips to your cat,