The Teensy Convolution SDR receives VLF, LW, MW, and SW from about 12kHz up to 30MHz -). Oh, I just took LW stations for the video, because they have the best reception and audio quality during daytime when there are not many stations around on shortwave. This thread is meant to discuss questions and developments of this and other SDRs built with the Teensy. record and play IQ recordings on/from SD card Noise reduction in the frequency domain: I am very interested in implementing one of those sophisticated noise reduction algorithms that work in the frequency domain, eg. automatic realtime-clock adjustment by tuning into one of the time-signal-stations, eg. Audio should be set muted temporarily in such situations at higher sample rates, tuning and filter bandwidth setting is disturbed by clicking noises. What is the SDR still lacking? -> wishlist -)
#Elektor sdr kit manual#
* manual notch filter with adjustable notch frequency and notch bandwidth * Spectrum display now also has an "AGC" that prevents empty screen for small signals * Codec gain has now its own automatic AGC * AGC now has an optical indicator for the AGC threshold and many more AGC parameters can be adjusted This is now reliably detected by the automatic IQ phase correction algorithm and the codec restarted to cure the problem * automatic test for the "twinpeak syndrome" - a fault in the mirror rejection that occurs sometimes at startup. * autotune on demand -> press a button and the carrier of an AM station is caught with an accuracy MONO, but HiFi quality when using 192ksps sample rate * needs about 46% of the processor ressources at 96ksps sample rate and SAM demodulation, about 48% at 192ksps and AM demodulation, SAM at 192ksps needs 78% because of the atan2f calculations * Zoom into the spectrum for greater frequency resolution detail: Zoom FFT enables us to have up to 10Hz resolution in the spectrum display * display up to 192kHz of frequency spectrum * demodulation of wideband FM Stereo transmissions * demodulation of real synchronous AM with selectable sideband and "stereo" option, 9 "different" AM demodulators, LSB, USB, pseudo-Stereo-USB, pseuso-Stereo-LSB (maybe more to come. * filter coefficients are calculated by the Teensy itself and the filter bandwidth can be chosen arbitrarily by the user * filtering with 513 tap FIR filter (in decimated 12ksps) -> comparably steep filters are normally available in commercial receivers from 2000$ upwards -) * FFT and inverse FFT with 1024 points using the new CMSIS DSP lib complex FFT function * reception from about 12kHz to 30Mhz (in undersampling mode 50MHz to 151MHz) * Teensy 3.6 with audio board working in floating point unlike other standalone-SDRs that use IQ-input from a QSD, the main filtering and demodulation is done in the frequency domain by Fast Convolution, this enables much steeper filters than the usual phasing approach it needs a quite simple hardware quadrature sampling detector (QSD) like the Softrock or similar xs4allnl /wp-content/uploads/2015/07/sdr_schematic.gif
#Elektor sdr kit software#
a Software defined Radio for LongWave/MediumWave/ShortWave & wideband FM Stereo
#Elektor sdr kit code#
The source code of this prototype alpha version is HERE I am quite happy now with the reception and audio quality of the very first prototype of the Teensy Convolution SDR.
The sound is a bit treble-boosted, because it was recorded with a very wide filter and the recording with the smartphone also boosted the treble and attenuated the bass a bit.
Audio sample of AM reception of Jil FM from Algeria on medium wave 531kHz received here in Central Europe yesterday night with the Teensy Convolution SDR: HERE
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