doppler problem
 

how accurate can we get with doppler shift when we have a digitally
modulated signal as its source?compared to a unmodulated CW signals
which has a tone frequency,whats the reliability of an FSK signal?

doppler problem
 

On 7 Mar 2006 06:04:13 -0800, "mazerom"
wrote:

how accurate can we get with doppler shift when we have a digitally
modulated signal as its source?compared to a unmodulated CW signals
which has a tone frequency,whats the reliability of an FSK signal?

Hi OM,

You've got too many factors running through this. For one, digitally
modulated is not digital data mode (FSK). There are a world of
modulation types and some are strictly derived from a bit stream (not
all bits equal in width either). Sometimes even the carriers are
digitally derived (not a sine wave).

Doppler is going to give rise to dispersion (often a term confined
these days to fiber optics, but whose derivation arose from waveguides
- LF Optics).

73's
Richard Clark, KB7QHC

doppler problem
 

exactly sir but im referring to the spectral content of the signal its
carrier and sidebands for that matter.how significant will be the
doppler shift of its spectral components other than its carrier
signal?thanks

doppler problem
 

What's the formula for Doppler shift? Why would you think it does not
apply exactly to all the spectral components of your signal? Do you
think you are dealing with a nonlinear system when you combine doppler
shift with a complex signal?

Cheers,
Tom


mazerom wrote:
exactly sir but im referring to the spectral content of the signal its
carrier and sidebands for that matter.how significant will be the
doppler shift of its spectral components other than its carrier
signal?thanks

doppler problem
 

mazerom wrote:

exactly sir but im referring to the spectral content of the signal its
carrier and sidebands for that matter.how significant will be the
doppler shift of its spectral components other than its carrier
signal?thanks


Doppler shift is applicable to all frequency components of a signal.

It is a percentage change of the base frequenc[ies] as a function of the
rate of closure or divergence between an observer and the originator of
the signal.

So, for FM it applies to the carrier frequency at ONE doppler shifted
value. It applies to the individual frequency [secondary] components as
another doppler shifted component for each frequency. In practice, the
doppler shifted frequenc[ies] among the secondary components are
extremely small when compared to the prime frequency.

For spread spectrum, it is applicable to ALL frequencies.
For AM, it is applicable to ALL frequencies.
For SSB, it is applicable to ALL frequencies.
For CW it is applicable to ALL frequencies
For FM/NBFM/WBFM, it is applicable to ALL frequencies.
For unmodulated carriers, it is applicable to ALL frequencies.
For audio, it is applicable to ALL frequencies.
For ...., it is applicable to ALL frequencies.

doppler problem
 

On 7 Mar 2006 16:29:45 -0800, "mazerom"
wrote:

.how significant will be the
doppler shift of its spectral components other than its carrier
signal?thanks

How much dispersion can you tolerate? "Significance" is an emotional
measure (which is to say it isn't a measure at all). If you cannot
quantify what you mean by this, no one can offer how significant it
is. I've a career of measuring very small differences out to 12
places. What was significant to me was a matter of utter indifference
to 99.999999% of the population - if that many.

73's
Richard Clark, KB7QHC

doppler problem
 

how can you say that seconday components are "EXTREMELY SMALL"
compared to the prime frequency when your signal is in fact a
broadband?
and you forgot one;
For UWB,it's applicable to ALLLLLL frequencies

doppler problem
 

On 8 Mar 2006 05:21:07 -0800, "mazerom"
wrote:

...any comment on this or
suggestion or objection sir?thanks

Perhaps later, first, how much dispersion can you tolerate?

73's
Richard Clark, KB7QHC

doppler problem
 

On 8 Mar 2006 07:37:07 -0800, "mazerom"
wrote:

another thing...you're not answering the question..im not asking if its
possible for two EM source to produce doppler shift when at least one
is moving relative to the other because a 5th grader knows that.
what im asking is how significant.....

dont answer if u intend to insult!

Would you mind quoting what it is you are repling to?

doppler problem
 

kb7qhc wrote, "Doppler is going to give rise to dispersion..."

Doppler alone? Care to elaborate on that?