On Fri, 27 Aug 2021 03:30:28 -0400, time-nuts-requ...@lists.febo.com
wrote:
> Send time-nuts mailing list submissions to
> time-nuts@lists.febo.com
time-nuts Digest, Vol 208, Issue 20
> --
>
> Message: 1
> Date: Thu, 26
Just to be clear, the shift has to be in phase, not time per se. A 90 deg
phase
shifter based on a constant delay will not work well at other frequencies.
That's
why phasing-type SSB exciters got so messy in the audio phase
splitter department
(in the old days).
Nowadays with digital processing,
I think Dana's explanation is a much clearer way to think of what is going
on in an I-Q receiver.
Until you are really far down the signal chain, at the demodulator, where
you might process the I and Q signals differently,
there is no 'splitting' or division of the signal into I and Q.
The signal
Hi Jim,
I think the best way is to view the signal as a phasor, with any
noise present adding a
random trajectory (a fuzzball) to the tip of the signal vector.
Conceptually speaking,
this eliminates needing to worry about the distribution of power between I
& Q, etc.
It lets you view the whole
Lux, Jim writes:
>I'm looking for a simplified treatment of the uncertainty of I/Q
>measurements. Say you've got some input signal with a given SNR and you
>run it into a I/Q demodulator - you get a series of I and Q measurements
>(which might, later, be turned into mag and phase).
>
of precise time and frequency measurement'
Subject: [time-nuts] Re: uncertainty/SNR of IQ measurements
HI Jim...
>From my admittedly limited understanding of IQ demodulators, the first thing
>done is to split the signal power (signal,
noise, and all) evenly between two paths, which then i
Hi
Once you get things down to baseband, you (likely) shove the I and Q into some
sort of arc tangent math. Depending on just how you do that math, there can be
some bumps in the road. It’s implementation dependent so I don’t know of a
“generic” answer. I’m not all knowing so there may be one
HI Jim...
>From my admittedly limited understanding of IQ demodulators, the first thing
>done is to split the signal power (signal, noise, and all) evenly between two
>paths, which then ideally feed identical double balanced mixers (I'm thinking
>of a hardware implementation, obviously) whose
