FM Analysis > P275 FM Analyzer

Poor S/n on headphone audio output

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Jan:
The update is out:

http://pira.cz/fm_broadcast_analyzer/p275fwup.zip
http://pira.cz/fm_broadcast_analyzer/FM_Scope_Setup.exe

Richard:
Thanks Jan,

The new Firmware has improved the headphone audio.

There are still some low level noise products in the demodulated audio, but it is a lot better
than before.

Great to see improvements are happening :)

Kind Regards,
Richard
 

Jan:
Being a measuring equipment, the P275 does not contain extra audio demodulator. Doing so would need adding independent second tuner for audio only - unnecessary for all typical applications.

The audio is taken from the measuring tuner and its performance is limited by input A/D converter resolution. The A/D converter, which processes clipped IF signal, has 1-bit resolution and has sampling rate of 70 MHz. This sampling rate is converted to 169 kHz in several decimation stages while the demodulated MPX resolution increases to 9-10 bits @ 75 kHz FM deviation.

The audio output is 2x PWM, effective resolution 12 bits @ maximum volume.

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