Thanks for adding to the blog, you are quite correct of course in all your points.
Thank you for reminding us all.

I do agree with your points, very much so, in the P8000 product literature we do provide a dynamic range and a separate noise floor. Which I believe is your point.

“The ratio of the rms value of the actual input signal to the rms sum of all the other spectral components below the Nyquist frequency, including harmonics but excluding dc”. I questioned why that the Noise Floor and the Dynamic Range are not directly compatible, here u have given me a clear answer, thanks.

Ordinary ADC/DAC says:

SFDR (Spurious Free Dynamic Range) indicates in dB the ratio between the powers of the converted main signal and the greatest undesired spur.

SNR (Signal to Noise Ratio)indicates in dB the ratio between the powers of the converted main signal and the sum of the noise.

SNDR (Signal to Noise and Distortion Ratio) indicates in dB the ratio between the powers of the converted main signal and the sum of the noise and the generated harmonic spurs

I agree with Mr.Wren “Dynamic Range or Signal to Noise Ratio (SNR)”. I see here yr SNR means the SNDR, u already gave yr definition in yr anawer while deliberately avoiding further definition details. Do u agree with this saying: Dynamic range is the reciprocal of the smallest value of SNDR, after converted off the dB?

u said “Noise floor or Spurious Free Dynamic Range”, if u mean that Noise floor directly consponds to Spurious Free Dynamic Range, i doubt it. because under the above definitions, SFDR depends on the biggest harmonic peak, it considers the linearity of the system. Harmonic peaks are signal dependent value, while Noise floor’s main component is thermal noise.

I think maybe it will be better to give out both the Dynamic Range and SFDR in prosig’s P8000 specification, not only Dynamic Range parameter, at least it will be convienent to different users, how do u think about this? maybe u can only give me a personal opinion, for me that’s ok .

Again we thank you for your comments.

I do not think it is possible to add or take away from each other the Dynamic Range and the Noise floor. They are in fact different quantities.

All our stated values are actual measured quantities, not mathematically calculated values. These are the real values you get in the real world with a P8000 series.

I’ll try to explain, the P8000 series, in this case has the following characteristics,

Noise Floor = -120dB

Dynamic Range = 105dB

Noise floor or Spurious Free Dynamic Range.

This means in straight forward terms that if the signal your trying to measure is below -120dB you will not be able to measure it with the P8000. This is because it would, at any particular frequency, be obscured by the noise introduced by the P8000 itself.

Dynamic Range or Signal to Noise Ratio (SNR)

The Signal to Noise Ratio, sometimes called Signal to (Noise and Distortion) Ratio is defined as ‘The ratio of the rms value of the actual input signal to the rms sum of all the other spectral components below the Nyquist frequency, including harmonics but excluding dc.’

This means the Dynamic Range is the ratio of the rms of the input signal to all of the components including noise below the Nyquist frequency.

Or more simply, the Dynamic Range is the voltage of the Input signal divided by the voltage from all components already present in the system, this includes the harmonics from the input signal.

So you can see that the Noise Floor and the Dynamic Range are not directly compatible.

The Noise floor is the lowest level at which the P8000 can measure a signal at any particular frequency.

The Dynamic Range is the ratio of the largest input the P8000 series can measure to the smallest signal that is not obscured by all the components present in the system, including the frequency content of all of the noise and any other components present.

Thank you for your comments.

You are correct, we at Prosig are as honest and straight forward as possible. We strongly believe it is bad idea to confuse our customers with numbers that are not correct. We are after all English gentlemen, we pride ourselves on our honesty and our good relationships with our customers.

Spurious Free Dynamic Range is defined as ‘The difference between the rms amplitude of the input signal and the peak on the spurious signal’. So in this case the Spurious Free Dynamic Range (SFDR) is the difference between the RMS of the input signal and the peak of the Noise created by the system itself.

We call this the Noise Floor.

The P8000 series has up to a -120 dB noise floor, depending upon which P8000 input card you purchase.

Can i say it as following way ?
compare to full range, if signal level below -120dB, P8004 can not distinguish it; if signal level betweetn -120dB and -102dB, P8004 can see the signal, but cannot measure it with accuracy; only if signal level above -102dB, P8004 can do its measurement with enough accuarcy.

if the saying is ok, then there is an 8dB gap, between P8004′s perceptive and capable, can i know yr basic argument of this 8dB, or what cause this 8dB and why it is 8dB basicly.

If any amplifier used in P8004, and in ADC, maybe nonlinearity will cause harmonic peaks, Have the higher order peaks level already been deducted from the range? now, my problem is I need to know whether P8004′s dynamic range already cover this issue because other co. product often give out the SFDR parameter. customers need a comparasion between products to be convinced.

thanks in advance.

Before this article,I suspected that the Prosig’s dynamic range maybe almost the same as spurious free dynamic range which often given out in other ADC device, now i realized that prosig doesn’t use this parameter. thnks.