Some questions about your sea clutter coding

DingdongD commented 3 years ago

Hey，Sir，can you tell me the exact meaning of “Re”、“Range1”、“Range2” in your code？ I try to use it in my simulation，but i fail to complete it.

microsato commented 3 years ago

Hello,

Please note the following: @. As well as : @. So, I am assuming you are referring to line 417 in the code. This falls within the function “loopRangeBins(R1,R2)” where the data from several range bins are concatenated together. For instance if loopRangeBins(3,5) is called, the data from range bin 3 to range bin 5 will be concatenated.

The image below shows what Range1 and Range2 would be in this example. Note that the range resolution in the dataset I used was 15m. @.***

The reason these ranges need to be calculated is because if we are concatenating the data from multiple range bins, we need to average the grazing angle (Equation 2.4) and therefore illuminated area (Equation 2.6) over these range bins in order to be able to calculate the reflectivity (Equation 2.3) . That is because the grazing angle of the radar will obviously change as the range increases/decreases (as it is dependent on range) and so will the area illuminated by the radar (as this is dependent on grazing angle and range).

So in the code, on line 414 and 415 we obtain the distance to R1 and R2 that were passed into the function. (Note that R1 and R2 will always be integer values).

On line 415, Re is the “effective radius” of the earth, calculated using Equation 2.5.

Now, on line 417 and 418 we calculate the grazing angles at R1 and R2 (Note this is the exact same as Equation 2.4 if you do the math).

We then average these two values in 419 to achieve an average grazing angle over range bins R1 to R2.

On lines 424 and 425, the area illuminated by the radar in equation 2.6 is calculated using Range1 and Range2 and then averages. This is required to calculate the sea clutter reflectivity (Equation 2.3). Note that to calculate the area illuminated by the radar (equation 2.6), p is the range resolution (in my case 15m) but if you don’t have the range resolution, p=c/2B where c is speed of light and B is the radar pulse bandwidth.

I hope this helps, feel free to ask any more questions that you may have. May I ask what your simulation entails?

Kind Regards Michele Rosato

From: DingdongD @.> Sent: Wednesday, August 11, 2021 4:59 AM To: microsato/Honours-Project-Statistical-Analysis-of-Sea-Clutter-Amplitude-and-Reflectivity @.> Cc: Subscribed @.***> Subject: [microsato/Honours-Project-Statistical-Analysis-of-Sea-Clutter-Amplitude-and-Reflectivity] Some questions about your sea clutter coding (#1)

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Hey，Sir，can you tell me the exact meaning of “Re”、“Range1”、“Range2” in your code？ I try to use it in my simulation，but i fail to complete it.

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DingdongD commented 3 years ago

Hello,

It's my honor and luck to get your reply.

I think I should understand their meaning. I am currently doing work for the realization of two-dimensional space-time correlation coherent K distribution of sea clutter simulation, which will provide data support for my next target detection. But I currently only K distribution relative to the implementation of the slow time dimension on sea clutter simulation, I need to consider on the fast time dimension of sea clutter.

The realization of fast time sea clutter needs to consider spatial correlation. I want to use TSC model to determine the shape parameters and scale parameters of K distribution in different distance units, so as to extend the original one-dimensional sea clutter to two-dimensional sea clutter. However, the shape parameters and scale parameters I calculated are far from my expected values. I'd like to ask if you have done relevant work? If possible, I would like your help very much.

-----原始邮件----- 发件人:"Michele Rosato" @.> 发送时间:2021-08-11 16:21:43 (星期三) 收件人: microsato/Honours-Project-Statistical-Analysis-of-Sea-Clutter-Amplitude-and-Reflectivity @.> 抄送: DingdongD @.>, Author @.> 主题: Re: [microsato/Honours-Project-Statistical-Analysis-of-Sea-Clutter-Amplitude-and-Reflectivity] Some questions about your sea clutter coding (#1)