correlator for radar

Started by sunil_ue December 5, 2006
Hi every body,
Now I am working on radar receiver designing. The radar transmits 10MHz
31-bit pn code multiplex with 10kHz sine wave. At the receiver side, It
has
1) the 31-bit pn code and 
2) highly noise affected and delayed the transmitted signal 
Now I want to design a digital correlator to detect the delay. As soon as
I receive the noisy delayed transimmited signal I am converting it into
digital  using a ADC running at 80MHz. 
Can anybody suggest what should be next step for correlation? It will be
also helpful to me if anybody can provide refernce web/book to understand
the fundamental of radar correlator. 


sunil_ue wrote:
> Hi every body, > Now I am working on radar receiver designing. The radar transmits 10MHz > 31-bit pn code multiplex with 10kHz sine wave. At the receiver side, It > has > 1) the 31-bit pn code and > 2) highly noise affected and delayed the transmitted signal > Now I want to design a digital correlator to detect the delay. As soon as > I receive the noisy delayed transimmited signal I am converting it into > digital using a ADC running at 80MHz. > Can anybody suggest what should be next step for correlation? It will be > also helpful to me if anybody can provide refernce web/book to understand > the fundamental of radar correlator.
Multiply the transmitted and received waveforms and integrate. The peaks in the resulting waveform correspond to echoes. Make sure you scale the time axis to take into account the two-way travel time.
>sunil_ue wrote: >> Hi every body, >> Now I am working on radar receiver designing. The radar transmits
10MHz
>> 31-bit pn code multiplex with 10kHz sine wave. At the receiver side,
It
>> has >> 1) the 31-bit pn code and >> 2) highly noise affected and delayed the transmitted signal >> Now I want to design a digital correlator to detect the delay. As soon
as
>> I receive the noisy delayed transimmited signal I am converting it
into
>> digital using a ADC running at 80MHz. >> Can anybody suggest what should be next step for correlation? It will
be
>> also helpful to me if anybody can provide refernce web/book to
understand
>> the fundamental of radar correlator. > >Multiply the transmitted and received waveforms and integrate. The >peaks in the resulting waveform correspond to echoes. Make sure you >scale the time axis to take into account the two-way travel time. > >
Hi, Thanks for reply. I did the multiplication and integration with different delays (correlation). So, now I am having diffent signals corresponds to each delay. Also in this stage of design/simulation, I am not worrying about two-way travel time. Here I am assuming the target is under the range. But I did not understand " The peaks in the resulting waveform correspond to echoes. " Can you explain me it further ? I am removing the delay, I am getting periodic sine wave with some distortion after multiplication and integration.
> Hi, > Thanks for reply. I did the multiplication and integration with different > delays (correlation). So, now I am having diffent signals corresponds to > each delay. Also in this stage of design/simulation, I am not worrying > about two-way travel time. Here I am assuming the target is under the > range. But I did not understand " The peaks in the resulting waveform > correspond to echoes. " Can you explain me it further ? I am removing the > delay, I am getting periodic sine wave with some distortion after > multiplication and integration.
Take a look at the following tutorial: http://www.ittc.ku.edu/~rvc/documents/pulsecomp.pdf
> >Take a look at the following tutorial: > >http://www.ittc.ku.edu/~rvc/documents/pulsecomp.pdf
I read this document. This is the same technique, I am using in the radar receiver. But still it is not mension about the correlator output. i.e. what would be the output from the correlator? Also I can't understand the effect of overflow of the integrator.
The output from the correlator (defined by z(m) in equation 13)  is the
range profile (see figure-2). You would get a similar profile for your
case if you substitute your template waveform in the place for the
chirp signal. The peaks in the range profile corresponds to reflections
from objects.

sunil_ue wrote:
> > > >Take a look at the following tutorial: > > > >http://www.ittc.ku.edu/~rvc/documents/pulsecomp.pdf > > I read this document. This is the same technique, I am using in the radar > receiver. But still it is not mension about the correlator output. i.e. > what would be the output from the correlator? Also I can't understand the > effect of overflow of the integrator.
>The output from the correlator (defined by z(m) in equation 13) is the >range profile (see figure-2). You would get a similar profile for your >case if you substitute your template waveform in the place for the >chirp signal. The peaks in the range profile corresponds to reflections >from objects. > >
Ya, I did the simulation and now I have the distance profile where, peak of the signal showing the target distance. But, still the profile, what I am getting, is giving distance information in discreat value. I mean, is it possible to know the exact distance from the digital correlator?