Adrian,
Nice video, but I would like to see the actual spectrum of ISM band causing
interference and detected with a real high performing SDR or analyzer. I doubt
that the dynamic range of the RTL-SDR is appropriate for such tests.
73, Helmut, DC6NY
Von: Adrian Musceac [mailto:kanto...@gmail.com]
Gesendet: Freitag, 15. September 2017 13:11
An: freetel-codec2@lists.sourceforge.net; digitalvo...@googlegroups.com
Betreff: [Freetel-codec2] Comparison between digital voice and analog
narrowband FM on weak signals with interference
Hi,
I present a three way comparison between narrow band FM (5 kHz), QPSK Codec2
1300 (2.4 kHz) and QPSK Opus 19 kbit/s (16 kHz):
https://www.youtube.com/watch?v=vApRe6R1gnk
The comparison is taking place in the ISM band of 433 MHz with interference
present from some temperature sensors in an adjacent channel.
Conditions: same antenna locations, same RX chain gain, varying transmit gain
(LCD like number on the top left of the screen)
Results: both digital modes cope better with interference and are more
intelligible than FM. The numbers on top left of RX application are expressed
in dB of amplification in the SDR transmitter chain.
Hardware: for transmit one USRP B200 with 433 MHz filter installed, for RX one
RTL-SDR filter with 433 filter installed.
Software: QRadioLink running on top of Gnuradio (GNU/Linux):
https://github.com/kantooon/qradiolink
73,
Adrian YO8RZZ
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