Archiwum

Posts Tagged ‘radio’

Acoustic spectra for radio signal DAB and FM

18 marca 2017 Dodaj komentarz

Measurement of Spectra a signal using a Fast Fourier Transform FFT in the domain of time are performed in a finite time. In other words, the measured are portions of a waveform of the signal of the specified length. Fragments extracted cyclically subjected are to the FFT. Fragments the waveform on shores contains discontinuities because are collected at intervals. Discontinuities cause blurring to spectra. The spectra of the downloaded portions of the waveform are different from the spectra of the whole continuous the signal subjected to measurement. To reduce blur spectra signal is passed the signal through a time window. The Time window reduced spillage of energy in the domain of frequency. Measurements were made for spectra of acoustic signals DAB and FM. The signal was passed through a time window. Used were of the time window: Rectangular, Bartlett, Hanning, Hamming, Blackman, Blackman-Harris, Flat-Top. The time window it is function shaping the signal measured undergone FFT. In the domain of time, signal is as function of time and was multiplying with function describing by the time window. In the domain of frequency occurs weave these functions. The result of the signal is subjected to FFT.

 

See articles :     http://sp9mco.com/articles/

Acoustic spectra DAB and FM

DAB+ technology – conclusions

1 lutego 2015 8 komentarzy

DAB works beautifully in Krakow. Great dynamics, some stations transmit slides showing album covers that are currently being played. Very nice gadget pleasing to the eye. Listening on headphones is sensational. I think technology does not develop quickly. A pity, because the technology provides a great listening outside major energy savings (less transmitters one transmitter gives some programs and not, as now one transmitter, one program), protects the environment and ourselves from excessive electromagnetic radiation (EMR), less radio transmitters are also less needed for their air conditioners cooling. So is the economic and ecological but in the broad sense. German studies accurately describe these savings and ecological aspects.
But, there is always a but, as you can see that the FM is doing well, and probably not soon, if at all will be replaced by digital technology. Receivers are now very expensive and this is what appears in the shops is rather old class tranzystorków” from the 70s. I saw recently a Sony in MediaMarkt for 280 PLN. I think this misunderstanding, a little mono radio pocket and so expensive? Something „serious” need to import from Germany. Although there too that too much is not. But the prices are.

Kategorie:DAB Tagi: , , ,

Radio DAB+ MEDION MD86955

1 lutego 2015 Dodaj komentarz

A few pictures shows radio MEDION MD86955 that uses DAB+ technologies.

The radio has no touch screen.

Has headphone socket and 3.5 mm line out.

Works perfectly. Has 2+1 stereo system.

Kategorie:DAB Tagi: , , ,

Radio DAB+ Technisat DigitRadio 500

1 lutego 2015 Dodaj komentarz

A few pictures shows radio Technisat DigitRadio 500 that uses DAB+ technologies. Software has a few bugs e.g. with translate to polish language descriptions doesn’t fit in frame window. Radio has a little long time booting after push down power button. Better is disconnecting power cord from power socket and plug on again.  The radio has neither headphone socket nor 3.5 mm line out.

Kategorie:DAB Tagi: , , ,