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106 lines
4.4 KiB
Markdown
106 lines
4.4 KiB
Markdown
**rpitx** is a radio transmitter for Raspberry Pi (B, B+, PI2, PI3 and PI zero) that transmits RF directly to GPIO. It can handle frequencies from 5 KHz up to 500 MHz.
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Before you transmit, know your laws. **rpitx** has not been tested for compliance with regulations governing transmission of radio signals. You are responsible for using your **rpitx** legally.
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_Created by Evariste Courjaud F5OEO. Code is GPL_
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# Installation
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```sh
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git clone https://github.com/F5OEO/rpitx
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cd rpitx
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# make sure to have access to the internet to download packages
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# or download and install them manually (libsndfile1-dev and imagemagick)
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./install.sh
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```
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# Hardware
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Plug a wire on GPIO 18, means Pin 12 of the GPIO header ([header P1](http://elinux.org/RPi_Low-level_peripherals#General_Purpose_Input.2FOutput_.28GPIO.29)). This acts as the antenna. The optimal lenght of the wire depends the frequency you want to transmit on, but it works with a few centimeters for local testing.
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# Short manual
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## General
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**rpitx** is the main software to transmit. It allows to transmit from:
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- **IQ** files *.iq (can be generated by external software like [GNU Radio](http://gnuradio.org/)).
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- **Frequency/Time** files *.ft (generally used to easily implement digital modes)
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Usage:
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```
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rpitx [-i File Input][-m ModeInput] [-f frequency output] [-s Samplerate] [-l] [-p ppm] [-h]
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-m {IQ(FileInput is a Stereo Wav contains I on left Channel, Q on right channel)}
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{IQFLOAT(FileInput is a Raw float interlaced I,Q)}
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{RF(FileInput is a (double)Frequency,Time in nanoseconds}
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{RFA(FileInput is a (double)Frequency,(int)Time in nanoseconds,(float)Amplitude}
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{VFO (constant frequency)}
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-i path to File Input
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-f float frequency to output on GPIO_18 pin 12 in khz : (130 kHz to 750 MHz),
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-l loop mode for file input
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-p float frequency correction in parts per million (ppm), positive or negative, for calibration, default 0.
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-d int DMABurstSize (default 1000) but for very short message, could be decrease
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-c 1 Transmit on GPIO 4 (Pin 7) instead of GPIO 18
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-h help (this help).
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```
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## Modulation samples
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Some modulations are included in this repository and can be easily extended. These scripts create files which can be used by rpitx.
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Some output in IQ (like ssb) other in FT (like sstv).
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### SSB modulation
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**pissb** converts an audio file (Wav 48KHZ mono only!) to SSB (USB right now) and outputs it
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to an IQ file.
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Assuming your audio file is in your current working directory:
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```sh
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./pissb audio48mono.wav ssbIQ.wav
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```
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You could then transmit it on 50MHz (please set a correct frequency to be legal)
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```sh
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sudo ./rpitx -m IQ -i ssbIQ.wav -f 50000 -l
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```
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A sample script `testssb.sh` is included.
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### FM modulation
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**pifm** converts an audio file (Wav, 48KHz, 1 channel, pcm_s16le codec) to Narrow band FM (12.5khz excursion) and outputs it to a .ft file.
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Assuming your audio file is in your current working directory
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```sh
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./pifm audio48mono.wav fm.ft
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```
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You could then transmit it on 100MHZ (please set a correct frequency to be legal)
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```sh
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sudo ./rpitx -m RF -i fm.ft -f 100000 -l
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```
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A sample script : `testfm.sh` is included.
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### SSTV
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**pisstv** converts an RGB picture to an SSTV .ft file.
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If you have a JPEG picture 320x256 you can convert it to an RGB picture with:
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```sh
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imagemagick convert -depth 8 picture.jpg picture.rgb
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```
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You can then transform it to a .ft file with:
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```sh
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./pisstv picture.rgb picture.ft
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```
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And then transmit it to 100MHZ (please set a correct frequency to be legal)
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```sh
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sudo ./rpitx -m RF -i picture.ft -f 100000
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```
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A sample script `snapsstv.sh` grabs a picture from a PiCamera and then transmits it on 50.105 MHz.
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### FSQ
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**pifsq** allows to send a text with the new FSQ modulation
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It is still under development.
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A sample script `testfsq.sh` allows to send a text with FSQ
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### VFO
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A **VFO** mode is provided to allows precise frequency resolution.
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For example to set a carrier on 100MHz (please set a correct frequency to be legal)
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```sh
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sudo ./rpitx -m VFO -f 100000
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```
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# Notes
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All rights of the original authors reserved.
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Special thanks to Sylvain Azarian F4GKR for improving SSB modulation
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Inspired by
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* http://pe1nnz.nl.eu.org/2013/05/direct-ssb-generation-on-pll.html
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* http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter
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* https://github.com/richardghirst/PiBits/pull/18
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* http://www.bellard.org/dvbt/
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