# Using a set of data to determine values on the same line

• ka0ttic
In summary, the conversation is about developing a RF loss calculator for work and finding the math formula to determine the insertion loss based on a given frequency using data from a manufacturer data sheet. The suggested method is regression analysis and linear interpolation can be used if the data looks like a line. Non-linear data may require different methods.
ka0ttic
Hey everyone,

Firstly, I apologize if there is a more suitable forum. I think this would be considered a calculus problem, but I'm not sure. I'm trying to develop a RF loss calculator for work that can calculate RF loss over a given length of cable or through a passive device at a given frequency. My math is not that great, so I'm hoping you guys can put me on the right track.

As an example, here's a manufacturer data sheet for a 2way coax splitter (rated 5-1000MHz):

Code:
Frequency (MHz)                             Insertion Loss (dB/mV)
5                                                   4.2
40                                                  3.8
50                                                  3.8
450                                                4.3
550                                                4.4
750                                                4.6
870                                                4.9
1000                                              5.5

I would like to figure out the math that would allow me to find out the insertion loss based on any given frequency using that data to find it. For example, if I wanted to find out what the insertion loss would be at 300MHz, the data sheet goes from 50-450MHz with nothing in-between. Obviously, with the small amount of change, I could guess and be close enough, but if I'm going to write an application to do the math, I want it to be as accurate as possible.

I know that slope is involved but I'm not really sure about calculating slope for a curved line. I also am unsure of what I need to do once I figure out the slope to determine the insertion loss for a given freq.

Is anyone able to point me in the right direction? I'm totally for learning this myself, but I've had a hard time trying to do that, just because I don't necessarily know all the correct math lingo to research it.

Thanks for any help,
Aaron

What you need is regression analysis and someone with good knowledge of Statistics and experiment design.

ka0ttic said:
I would like to figure out the math that would allow me to find out the insertion loss based on any given frequency using that data to find it.

Are you willing to use a different formula for each different type of data table?

If you plot the data in a table and it looks approximately like a line then you can use "linear interpolation".

If you encounter tables where the plot is very different than a line then there are other methods. At a glance, the example you gave looks non-linear. If you post some plots of type of data you encounter then perhaps someone will suggest good methods to use.

## What is the importance of using a set of data to determine values on the same line?

The use of a set of data to determine values on the same line allows for a more accurate and thorough analysis of the relationship between variables. It helps to identify patterns and trends that may not be visible when looking at individual data points.

## What factors should be considered when using a set of data to determine values on the same line?

Some important factors to consider include the quality and reliability of the data, the type of relationship between the variables, and the potential presence of outliers or other influencing factors.

## What methods can be used to determine values on the same line using a set of data?

There are several methods that can be used, such as graphing the data and visually identifying the line of best fit, using statistical tools like regression analysis, or manually calculating the equation of the line using the data points.

## What is the purpose of determining values on the same line using a set of data?

The purpose of this process is to better understand the relationship between variables and make predictions or conclusions based on the data. It can also help to identify any discrepancies or errors in the data and improve the accuracy of future measurements.

## What are some limitations of using a set of data to determine values on the same line?

One limitation is that it assumes a linear relationship between the variables, which may not always be the case. Additionally, it may not account for all possible influencing factors and can be affected by outliers or errors in the data. It is important to carefully consider the limitations and potential biases when using this method.

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