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Old 24th July 2021, 10:40 PM   #751
MagicianT is offline MagicianT  Canada
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Unbelievable, on-screen data update rate crazy fast.

Check this out:
MCP356X Linearity test. - YouTube
It looks so slow, 10 times or even more? How it could be? ADC sampling rate is actually higher, 62.5 kHz vs 48 kHz. FFT-32k takes 0.5 sec just to fill up an array. Certainly, I can use smaller size, 8.192k or 4.096k and accelerate "visual" responsiveness, but I 'd lost noise flour. My ADC shows about -132dB ground line, vs -160dB . To get -28dB down, FFT has to be enormously bigger, 20x times or so, up to 512k.

What I'm missing? Same sampling rate with PCM4202:
pcm4202 62 5kHZ - YouTube
Video with jumping magnitude by 1dB/step also shows quite fast settling time, but I doubt your ADC is running at 5 Msps?
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Old 25th July 2021, 04:59 AM   #752
IVX is offline IVX  Ukraine
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MagicianT I'm not sure if you asking me but my setup was:
AP analyzer generated digital sine 24/48k, next SPDIF to my PC, and play that sine with Cosmos DAC(that device includes switchable LPF 1k and 10k to produce ultra-clean 1k/10k sine). 10Vrms from Cosmos DAC goes to Cosmos ADC XLRs inputs, 32/48k ADC result goes to the PC back to make there FFT 64k-bins and to resend by SPDIF 24/48k ADC result to the AP.
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Old 25th July 2021, 05:31 AM   #753
IVX is offline IVX  Ukraine
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I just did add the I2S connector footprint that was asked by PM 5 min ago
PS: frontend resistors are Susumu RR1220PD and CSR02027, opamps OPA1602, power Monolithic Power Systems and Ti, USB bridge CT7601CR as a slave, ES9822 as master. The USB power has a soft-start, hence, ADC can run even with a smartphone if needed.
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Last edited by IVX; 25th July 2021 at 05:42 AM.
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Old 25th July 2021, 05:49 AM   #754
trung224 is online now trung224
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Great. The cosmos ADC can now easily be used with DSP board like freeDSP Aurora or miniDSP miniSharc.
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Old 25th July 2021, 05:53 AM   #755
IVX is offline IVX  Ukraine
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Thank you for the idea!
PS: This picture shows how the gain control is actually implemented.
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Old 25th July 2021, 08:33 AM   #756
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Old 25th July 2021, 12:08 PM   #757
MagicianT is offline MagicianT  Canada
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Quote:
Originally Posted by IVX View Post
MagicianT I'm not sure if you asking me but my setup was:
AP analyzer generated digital sine 24/48k, next SPDIF to my PC, and play that sine with Cosmos DAC(that device includes switchable LPF 1k and 10k to produce ultra-clean 1k/10k sine). 10Vrms from Cosmos DAC goes to Cosmos ADC XLRs inputs, 32/48k ADC result goes to the PC back to make there FFT 64k-bins and to resend by SPDIF 24/48k ADC result to the AP.
O'k, 64k FFT than.

1. Sampling with 48 kHz it takes 64 /48= 1.33 seconds to fill a data array. Using 50% overlap 0.67 seconds. All digital data shown on a video updated 10x faster. Is video played at 10x speed?
2. With 64k FFT noway to get -160dB noise flour. About -140 at the best.
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Old 25th July 2021, 02:29 PM   #758
IVX is offline IVX  Ukraine
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Quote:
Originally Posted by MagicianT View Post
O'k, 64k FFT than.

1. Sampling with 48 kHz it takes 64 /48= 1.33 seconds to fill a data array. Using 50% overlap 0.67 seconds. All digital data shown on a video updated 10x faster. Is video played at 10x speed?
2. With 64k FFT noway to get -160dB noise flour. About -140 at the best.
So, the real world is fake anytime when we do not expect if something does possible?
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Old 25th July 2021, 02:38 PM   #759
MagicianT is offline MagicianT  Canada
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Check out DS: ADS127L01 SBAS607B APRIL 2016 REVISED SEPTEMBER 2016,
front page, and p.16-17.
Second law of thermodynamics says -160dB is impossible.
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Old 25th July 2021, 03:32 PM   #760
IVX is offline IVX  Ukraine
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Quote:
Originally Posted by MagicianT View Post
Check out DS: ADS127L01 SBAS607B APRIL 2016 REVISED SEPTEMBER 2016,
front page, and p.16-17.
Second law of thermodynamics says -160dB is impossible.
I did take a look at the ADS127L0, this is quite noisy ADC SNR 115db, if you'll check other ADCs(over 120db range) like PCM4222 or AK5578 you'll find much less than -140db noise-floor without Boltzmann constant trimming or elementary charge boosting in the flux-capacitor
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