README.md
1# sdr-wspr -- A WSPR receiver/decoder using libsdr.
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3[WSPR](https://en.wikipedia.org/wiki/WSPR_(amateur_radio_software)) (Weak Signal Propagation Reporter) is a technique (actually the name of a software) to probe the propagation conditions in various amateur radio bands. Each station participating, sends its call sign, location and output power using a very slow (about 1.5 Baud) but robust digital mode (usually called WSPR). This implementation embeds the [original Fortran code](http://physics.princeton.edu/pulsar/K1JT/wspr.html) into a [libsdr](https://github.com/hmatuschek/libsdr) processing node, allowing to assemble a WSPR receiver for various sources easily.
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6## WSPR and RTL2832 Dongles
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8First of all, TV USB dongles using the RTL2832 chip and E4000 or similar tuners are limited on frequencies above 60MHz (depending on the tuner, see http://rtlsdr.org for details). For the reception of short-wave radio, especially WSPR signals an [upconverter](http://blog.kf7lze.net/2012/09/14/round-up-of-rtlsdr-upconverter-choices) is needed.
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10The second problem with these dongles is their poor frequency stability. Please note, that a WPRS signal consists of 4 frequencies only about 1.5Hz apart. Hence a relatively high frequency stability is required. Although the WSPR algorithm by Joe Taylor can handle (small) linear frequency drifts of the signal during the reception, any large drift or non-linear change in frequency will render the decoding impossible.
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13## License
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15sdr-wspr -- A WSPR receiver/decoder using libsdr. Copyright (C) 2014 Hannes Matuschek.
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17This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
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19This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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21You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/
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