UWB SFCW or FMCW Transceiver design?

[ali.cmi]

Does anybody know how to design a UWB Stepped-Frequency Continuoud Wave (SFCW) or Frequency Modulated Continuous Wave (FMCW) Transceiver?

If you have schematics or you can explain a relevant block diagram in detail, please reply.

Regards,
Ali

 

[Bobbywhy]

Ali.cmi, Have you searched for this information? Using Google with the search terms “UWB Stepped-Frequency Continuous Wave (SFCW)” returned 1,840 results, and “Frequency Modulated Continuous Wave (FMCW) Transceiver” returned 28,000 results.

Once you have researched these radar systems, then come back here and post your specific questions. Surely members are ready to help you find those answers.

Cheers,
Bobbywhy

 

[ali.cmi]

Hello Bobbywhy,
I have a collection of a lot of research papers and theses. All of them do not have schematics. They have block diagrams only and me being a BEE student, find them not helping enough. I hope upto 20 google search result pages are enough. :)
In addition to it, I searched the references of the papers as well. Still no help.
I've been at it for more than two weeks now.

Let me tell you what I want in detail:

"
Hello,
I am a final year student of BEE Telecom. I chose my Final Year Project to design a Transmitter and Receiver for GPR. GPR has already been developed in my institute. It uses VNA (Vector Network Analyzer) as its source.

Some features of that project are:
-> Double-Ridged Horn Antenna
-> Synthetic Aperture Radar (SAR) with UWB source (VNA) in Mono-synthetic mode
-> Only s11 (first parameter of s-parameters) was measured by VNA
-> 2.4 GHz center frequency with 1 GHz Bandwidth---a pulse with 1 ns duration transmitted by a Stepped-freqeuncy transmitter
-> Tx and Rx are in VNA
-> Only Return Loss measurements are observed
-> Data from VNA is processed in Matlab to create a rough image of observed reflections

I hope the data above is enough for you to get the idea. I have just started working in the project

Since VNA is a multipurpose device and the already-implemented project used it to find S11 only, I chose this project to introduce portability in GPR. (VNA available in my institute is bulky)

In short, my goal is to develop a Tx and Rx which function as the VNA does; thus introducing portability.

The problem is that I have no idea where to begin. I need a head start. I need to develop complete understanding of how the Stepped-Frequency Transmitter (used in already-developed project) and compatible receiver works and I have to develop the whole system without changing other features like antenna, codes etc.

Please guide me and point me in the right direction.

Regards.
"

 

[ali.cmi]

If the above information is not enough, please tell me your specific requirement.

 

[skeptic2]

Why do you want to use UWB or FMCW? If you don't already have a block diagram I think you're getting ahead of yourself. Can you describe or illustrate in block diagram terms how your system would work and perhaps how it would be different from existing systems?

 

[ali.cmi]

Why do you want to use UWB or FMCW? If you don't already have a block diagram I think you're getting ahead of yourself. Can you describe or illustrate in block diagram terms how your system would work and perhaps how it would be different from existing systems?

Is there anything else you can suggest?

let me show you a block diagram. Its of a UWB transceiver. But I think it would be too expensive to make and time duration is just 1 year. If there is a cheaper alternative, I would love to hear it. It needs not be state-of-the-art. Schematics will be appreciated. :)

 

[skeptic2]

let me show you a block diagram. Its of a UWB transceiver. But I think it would be too expensive to make and time duration is just 1 year.

Exactly. UWB is also severely power restricted. There are many GPS units on the market. Have you tried to understand how they work? Most of them just transmit a pulse and wait for the echos. Some are carried or rolled along the ground to create a two dimensional image. The depth of penetration is inversely proportional to the frequency but the resolution is directly to it. Here are a few issues to consider:

The shorter your transmitted pulse, the better your depth resolution will be. How short will your pulse be and how will you generate it?

If your pulse is only a few wavelengths long, how will you prevent ringing on the trailing edge of the pulse?

Will you use the same antenna for transmit and receive? If so, how will you switch from transmit to receive in the appropriate amount of time?

If you will be using a sample and hold to capture the echos, how will you know you are capturing the total power of the echo and not just the instantaneous power of the signal's sinewave?

 

[ali.cmi]

@ skeptic2

These are the questions I would consider if I knew where to begin with and that is why I posted here to get a head start. :) But no luck till now. ;(

Yes, I'll only be replacing the VNA (refer to my second reply to this post). Rest of the things like antenna, algorithms will remain the same.

 

[skeptic2]

I'm not sure if this qualifies as homework or not. This forum has rather strict rules about how much help can be given with homework. The more work you do yourself the more we can help you. I think you need to at least put together a block diagram. Here are some links.

http://ocw.mit.edu/resources/res-ll-003-build-a-small-radar-system-capable-of-sensing-range-doppler-and-synthetic-aperture-radar-imaging-january-iap-2011/projects/MITRES_LL_003IAP11_proj_in.pdf
Perhaps you've already seen this one. It has very detailed instructions but instead of transmitting pulses, it sweeps the frequency. The distance is calculated based on the difference between the transmit and receive frequencies. I was not impressed with the results either.

http://www.mit.edu/~lrv/cornell/publications/radar%20system%20components%20and%20system%20design.pdf
This link has some good background information and even has a block diagram.

http://www.radarpages.co.uk/theory/ap3302/sec1/reqpmr/reqpmr23.htm
This also has a block diagram.

I bet if you did a search on the internet, you could come up with some good sources too. See what you can find and we'll be glad to answer your questions.

 

[Bobbywhy]

ali.cmi, Thank you for stating clearly just what it is that you want: “In short, my goal is to develop a Tx and Rx which function as the VNA does; thus introducing portability.”

Here, please find Eight different models of handheld Vector Network Analyzers:
http://www.anritsu.com/en-US/Products-Solutions/Test-Measurement/RF-Microwave/Vector-Network-Analyzers-Handheld/

I really like this one: N9923A FieldFox Handheld RF Vector Network Analyzer, 4/6 GHz
http://www.home.agilent.com/agilent...33903.922802.00&id=1760161&cmpid=zzfindn9923a

 

[ali.cmi]

@ Bobbywhy

First of all, Thank you for replying.

Secondly, I stated that I have to develop a system (transceiver) which can remove the use of VNA in already-developed project. :) I know there are various expensive but handheld VNAs are available in the market. They are of no use to me as I can only dream of buying and poking in them. :(

So, please suggest something I should begin with. I have read some UWB Transceiver Papers but they weren't that helpful. That is why I posted my problem in this forum to get some 'genuine' help.