Detecting Multi Peaks in a FFT

Hello, I am trying to detect mutiple peaks in a FFT. 90% of the time the
primary peak (Highest magnitude) is the only return i am interested in.
But sometimes i have multi peaks and i need a way to detect these peaks.
It gets tricky especially with the noise in the fft resembles mini-peaks.
I get multi peaks when i have reflections in a signal, and i want to
determine these reflection points when they happen. 
Thanks in advance! GC

On Jul 16, 5:57 pm, "gchamsine" <gus_...@hotmail.com> wrote:
> Hello, I am trying to detect mutiple peaks in a FFT. 90% of the time the
> primary peak (Highest magnitude) is the only return i am interested in.
> But sometimes i have multi peaks and i need a way to detect these peaks.
> It gets tricky especially with the noise in the fft resembles mini-peaks.
> I get multi peaks when i have reflections in a signal, and i want to
> determine these reflection points when they happen.
> Thanks in advance! GC

hmm... the any jump in value greater than from TBD above the 'nominal
value' can be qualified as a peak?
Btw, how does reflections result in generation of additional frequency
components. If you have
any pointers, it might be helpful.

Krishna
http://dsplog.blogspot.com

>On Jul 16, 5:57 pm, "gchamsine" <gus_...@hotmail.com> wrote:
>> Hello, I am trying to detect mutiple peaks in a FFT. 90% of the time
the
>> primary peak (Highest magnitude) is the only return i am interested
in.
>> But sometimes i have multi peaks and i need a way to detect these
peaks.
>> It gets tricky especially with the noise in the fft resembles
mini-peaks.
>> I get multi peaks when i have reflections in a signal, and i want to
>> determine these reflection points when they happen.
>> Thanks in advance! GC
>
>hmm... the any jump in value greater than from TBD above the 'nominal
>value' can be qualified as a peak?
>Btw, how does reflections result in generation of additional frequency
>components. If you have
>any pointers, it might be helpful.
>
>Krishna
>http://dsplog.blogspot.com
>
>
>
I am using a laser based radar to determine range, and when the laser
bounces off multiple surfaces within the depth of focus of the laser, i
see peaks in the fft for each surface the laser bounced off. Thats where i
need to determine a method to define "what is a peak" that is robust
enough.If i just look at the highest magnitude peak, then i may return the
"reflected peak" which i don't want. And returning the max peak is easy,
but when i want to determine how many peaks exist it gets tricky, i know i
need to determine a threshold and say everything above that line is
considered peaks...but that doesnt work for all cases, i need a more
robust way. 
Thanks in advance for ur sugestions!