Re: [time-nuts] Down-conversion to IF and sampling

Am 11.01.2018 um 10:57 schrieb Stephan Sandenbergh: I plotted the result for a few oscillator drift rate values. It seems that the 'extra' error introduced by the imperfect ADC time base would be negligible for many applications for OCXO drift rates or better. This is likely the reason why it is

Re: [time-nuts] Down-conversion to IF and sampling

Hi, A happy New Year to you all! Also, thank you to everyone who replied in such detail. It is always a privilege being able to bounce ideas off of the time-nuts community. I have found that it is often the case that the error introduced by ADC sampling is ignored. However, there is an error

Re: [time-nuts] Down-conversion to IF and sampling

On Sat, 23 Dec 2017 21:00:39 + Stephan Sandenbergh wrote: > I guess I'm just worried that I might be missing something obvious here? > And I know there is no better place to ask such a question other than on > time-nuts :) No, your derivation is correct. Though

Re: [time-nuts] Down-conversion to IF and sampling

Hi, The goal would be to be able to tell what the phase and frequency of the down-converted and sampled signal is. So no modulation on the carrier (for now). So given the RF signal is perfect sinusoid, and given that you know the parameters x(t) = xo + yot (time and fractional frequency offset)

Re: [time-nuts] Down-conversion to IF and sampling

Hi What is the Time Nut goal here? Are we after the carrier frequency or after the modulation on the signal? Bob > On Dec 23, 2017, at 10:46 AM, Stephan Sandenbergh > wrote: > > Oops, I noted a sign error in the previous diagram. The attached seems > better... > > On

Re: [time-nuts] Down-conversion to IF and sampling

Oops, I noted a sign error in the previous diagram. The attached seems better... On Sat, Dec 23, 2017 at 4:46 PM Stephan Sandenbergh wrote: > Hi All, > > Consider the following very common scenario: A perfect RF signal is > heterodyne down-converted to baseband using an

Re: [time-nuts] Down-conversion to IF and sampling

It would be (as you point out) a bad idea to have the the ADC sampling rate to be exactly the same as the downconversion oscillator. In many cases they would both be derived from the same master oscillator. But the ratios would be consciously chosen to not be simple integer multiple relations so

Re: [time-nuts] Down-conversion to IF and sampling

Hi Assuming you are trying to extract timing from the signal (time ticks on WWVB), the downconversion really does not matter. The ADC samples are what will “tag” your time data. If you are trying to extract frequency from the signal (you are after the center frequency of WWVB) then both the