4 ms·

Yes, the Pi only has digital pins. I didn't really watch the video but I assume any antenna is connected to another board and that board is controlled through t

Yes, the Pi only has digital pins. I didn't really watch the video but I assume any antenna is connected to another board and that board is controlled through the Pi pins. Actually, looking at the photo of the internals, it looks like the only thing connected to GPIO is the GPS board, all the radio hardware is connected to USB ports.

amingilani 7y ago
He says he uses the GPIO 4 pin[0], and recommends using a bandpass filter [0]: https://youtu.be/Hyq6_IZ-2fE?t=1197 https://youtu.be/Hyq6_IZ-2fE?t=1197
- crankylinuxuser 7y ago
  Thats why I need to make a programmable filter network... The antennas for Tx/Rx are rated for 50MHz-1200MHz. The Rtlsdr is capable of 24MHz-1.7GHz, and the Rpitx is capable of 100KHz-1.5GHz. Using a generic bandpass from 50MHz-1200MHz would allow combing down the powers of said frequency. Whereas a proper filter network could selectively notch out a few MHz window to prevent spurious transmissions. That device would also be very useful for things like the HackRF, PLUTO, and LimeSDR. As much as they claim they generate clean signals, they still have problems with harmonics, sometimes at weird powers (as in fractional exponents, not wattage).
crankylinuxuser 7y ago
Hey! I'm the creator of the RadioInstigator. Turns out, after reviewing the interference from a GPIO pin, is actually very low (about 5% non-target frequency). I do understand I still have to deal with a comb filter output, but is minuscule from my inspections. Im working on building a programmable filter network with independent low and high bandpass filters. But nothing available for the amateur market is sufficient. There's some stuff for the Ka and Ku bands (high microwave bands 12GHz-40GHz) but nothing for 50MHz-1200MHz. Nobody except for SigInt really cares about such a broad set of frequencies.

4 ms·

Yes, the Pi only has digital pins. I didn't really watch the video but I assume any antenna is connected to another board and that board is controlled through t

by extra88 7y ago

amingilani 7y ago
He says he uses the GPIO 4 pin[0], and recommends using a bandpass filter [0]: https://youtu.be/Hyq6_IZ-2fE?t=1197 https://youtu.be/Hyq6_IZ-2fE?t=1197
- crankylinuxuser 7y ago
  Thats why I need to make a programmable filter network... The antennas for Tx/Rx are rated for 50MHz-1200MHz. The Rtlsdr is capable of 24MHz-1.7GHz, and the Rpitx is capable of 100KHz-1.5GHz. Using a generic bandpass from 50MHz-1200MHz would allow combing down the powers of said frequency. Whereas a proper filter network could selectively notch out a few MHz window to prevent spurious transmissions. That device would also be very useful for things like the HackRF, PLUTO, and LimeSDR. As much as they claim they generate clean signals, they still have problems with harmonics, sometimes at weird powers (as in fractional exponents, not wattage).
crankylinuxuser 7y ago
Hey! I'm the creator of the RadioInstigator. Turns out, after reviewing the interference from a GPIO pin, is actually very low (about 5% non-target frequency). I do understand I still have to deal with a comb filter output, but is minuscule from my inspections. Im working on building a programmable filter network with independent low and high bandpass filters. But nothing available for the amateur market is sufficient. There's some stuff for the Ka and Ku bands (high microwave bands 12GHz-40GHz) but nothing for 50MHz-1200MHz. Nobody except for SigInt really cares about such a broad set of frequencies.