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ik1xpv / ExtIO_sddc

ExtIO_sddc.dll - BreadBoard RF103 / HDSDR
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define ht length #227

Open ik1xpv opened 2 years ago

ik1xpv commented 2 years ago

define HTLEN in fft_mt_r2iq.cpp allows manual test other lenght

ik1xpv commented 2 years ago

define _SOFT_TONE_DEBUG in config.h

enables the generation of soft tone close to 1MHz with ADC clk 64MHz, the tone period is an integer factor of transferSamples. GUI Rand CheckBox activates the software generated tone.

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ik1xpv commented 2 years ago

Here the comparison of some ht lengths with real signal stream input bandwidth 2 MHz. HTcompare2 The distortion increases when length increases toward N/2+1. The difference does non shows when the _SOFT_TONE_DEBUG is selected instead of the real one. ? maybe related to the transferSamples burst length used by _SOFT_TONE ?

ik1xpv commented 2 years ago

If we use a large FFTN_R_ADC (32768) // FFTN used for ADC real stream DDC tested at 2048, 8192, 32768, 131072 in config.h the ht length increases to HTLEN ( HALF_FFT / 4 + 1) => 8193 or even HTLEN ( HALF_FFT * 3 / 8 + 1 ) => 12289. HTLEN ( HALF_FFT / 2 + 1 ) shows always distortion...