Michael Feilen 03.07.2014
Michael Feilen 03.07.2014
Outline Introduction to Wavesink Architecture Performance DAB vs. DRM (incoherent vs. coherent) DRM+ in VHF III
What is Wavesink? Software-defined VHF radio demodulator FM/RDS, DRM+, DAB+ Fixed-point C Cross-platform UI RF frontends: USRP, RTL2832, Funcube, RAW
Architecture Wavesink App
Architecture RF driver SDL Wavesink App Audio driver
Architecture RF driver Network Handling Screen Rendering SDL Event Processing Android JNI Audio driver Wavesink App
Architecture RF Interface Receiver Management Interface Audio Interface RF driver Network Handling Screen Rendering SDL Event Processing Android JNI Audio driver Wavesink App
Architecture RF Interface RF Monitoring Demod Service Mgmt. Data Mgmt. Receiver Management Interface Audio Buffer Mgmt. Audio Interface RF driver Network Handling Screen Rendering SDL Event Processing Android JNI Audio driver Wavesink App
Architecture RF post-processor Srv. DB Data DB Audio pre-processor RF Interface RF Monitoring Demod Service Mgmt. Data Mgmt. Receiver Management Interface Audio Buffer Mgmt. Audio Interface RF driver Network Handling Screen Rendering SDL Event Processing Android JNI Audio driver Wavesink App
Architecture source Baseband Proc. IF sink RF Interface RF Monitoring proc() RF post-processor Srv. DB Data DB Audio pre-processor Demod Service Mgmt. Data Mgmt. Receiver Management Interface Audio Buffer Mgmt. Audio Interface RF driver Network Handling Screen Rendering SDL Event Processing Android JNI Audio driver Wavesink App
Architecture source DAB DRM+ FM/RDS Baseband Proc. IF... sink RF post-processor RF Interface RF Monitoring proc() Demod Srv. DB Data DB Audio pre-processor Service Mgmt. Data Mgmt. Receiver Management Interface Audio Buffer Mgmt. Audio Interface RF driver Network Handling Screen Rendering SDL Event Processing Android JNI Audio driver Wavesink App
FM/RDS Demod CMA channel equalizer PLL demod with IIR-phase equalizer Pilot PLL with group delay equalizer SNR-based difference-signal weighting Coherent DBPSK RDS demodulator with phase and amplitude tracking
DRM+ Demod Demod not 192 khz based (faster) :) Bilinear channel estimation (no MMSE) Clock, frequency, time offset tracking LLR energy tracking Soft-decision Viterbi decoding (no MLC dec.) DCP MDI output
DRM+ Performance Wavesink DRM+, r=1/2, EEP, QPSK
DAB+ Demod Optimized FFT with combined deinterleaving Frequency, time offset tracking Soft-decision Viterbi decoding IR estimation
DAB+ Performance Wavesink DAB+, r=1/2, EEP, DQPSK Mean BER C/N in db
And now... to something somewhat different
Coherent (DRM) vs. Incoherent (DAB) Quelle: Wikipedia
Coherent (DRM) vs. Incoherent (DAB) Quelle: Wikipedia 2,5 db performance loss @ BER 10^-4
Coherent (DRM) vs. Incoherent (DAB)
Coherent (DRM) vs. Incoherent (DAB) 2,5 db performance difference
DRM+ in VHF Effect of frequency offset DRM+ Noise 0 Hz f
DRM+ in VHF Effect of frequency offset DRM+ DRM+ Noise Noise 0 Hz f 0 Hz f
DRM+ in VHF Effect of frequency offset Lost signal energy DRM+ DRM+ Noise Noise 0 Hz f 0 Hz f
DRM+ in VHF Effect of frequency offset Lost signal energy DRM+ DRM+ Noise Noise 0 Hz f 0 Hz f Can cause problems during acquisition
DRM+ in VHF DRM+ clock accuracy requirements (max. 5% signal power loss) clock offset ppm 80 70 60 50 40 30 20 10 0 70 120 170 220 270 Tx. frequency in MHz
DRM+ in VHF
DRM+ in VHF Receiver moves Doppler freq. shift Doppler shift Time-selective fading Pilot-period in time must satisfy Shannon- Nyquist theorem (channel estimation)
DRM+ in VHF Receiver moves Doppler freq. shift Doppler shift Time-selective fading Pilot-period in time must satisfy Shannon- Nyquist theorem (channel estimation)
DRM+ in VHF Receiver moves Doppler freq. shift Doppler shift Time-selective fading Pilot-period in time must satisfy Shannon- Nyquist theorem (channel estimation)
DRM+ in VHF Receiver moves Doppler freq. shift Doppler shift Time-selective fading Pilot-period in time must satisfy Shannon- Nyquist theorem (channel estimation) f t dt
DRM+ in VHF DRM+ mobile rx performance max. velocity in km/h 900 800 700 600 500 400 300 200 100 0 70 120 170 220 270 Tx frequency in MHz
Conclusion Low-cost software-defined receiver available SDR allows update functionality (no new HW) Internet backlink on smartphones DRM+ feasible for VHF Band III