- #1

Kartik.Sulakh

- 8

- 0

What is Image Rejection Ratio (IRR)

and How to calculate an Image Rejection Ratio (IRR)?

and How to calculate an Image Rejection Ratio (IRR)?

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In summary, Image Rejection Ratio (IRR) is a measure of how well a radio receiver can reject signals in the image frequency range. The formula for calculating it is provided in a Wikipedia article.

- #1

Kartik.Sulakh

- 8

- 0

What is Image Rejection Ratio (IRR)

and How to calculate an Image Rejection Ratio (IRR)?

and How to calculate an Image Rejection Ratio (IRR)?

Engineering news on Phys.org

- #2

vk6kro

Science Advisor

- 4,079

- 41

In radio, the image rejection ratio, or image frequency rejection ratio, is the ratio of (a) the intermediate-frequency (IF) signal level produced by the desired input frequency to (b) that produced by the image frequency.

The image rejection ratio is usually expressed in dB.

When the image rejection ratio is measured, the input signal levels of the desired and image frequencies must be equal for the measurement to be meaningful.

- #3

Kartik.Sulakh

- 8

- 0

Can anyone solve this for clarification...

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Suppose, if a superheterodyne receiver with an IF of 3.1 MHz is tuned to receive a carrier of 78 MHz and the radio frequency tuning stage has a Q-factor of 100. What is the Image Rejection Ratio (IRR) in dB?

Given is |V

- #4

vk6kro

Science Advisor

- 4,079

- 41

http://books.google.com.au/books?id=coQ6ac-fh6QC&pg=PA104&lpg=PA104&dq=image+rejection+ratio+formula&source=bl&ots=qCD2xD0a67&sig=YM0Yz18hM3hO21trQX-utAqmFag&hl=en&ei=oxoJTs6mBZHsvQOM-uzWDg&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFYQ6AEwCTgU#v=onepage&q=image%20rejection%20ratio%20formula&f=false

They calculate the reciprocal of what your formula would give.

You calculate it in dB by taking 20 * log ( voltage ratio).

I plugged your numbers in and it seems to work OK. I can confirm if your result is the same as mine if you like.

- #5

Kartik.Sulakh

- 8

- 0

- #6

Kartik.Sulakh

- 8

- 0

- #7

vk6kro

Science Advisor

- 4,079

- 41

I don't know about that book. It is on Google books.

You could try Amazon.

I hope you noticed the typo in the first example. They had a "*" instead of a "+" sign. The formula was right but the calculation was wrong, although the answer was right. So, it was a simple typo.

- #8

Kartik.Sulakh

- 8

- 0

- #9

vk6kro

Science Advisor

- 4,079

- 41

Decibels are only ever concerned with comparing ratios of power.

If you have two powers, you can compare them in dB by using the formula:

10 log

For the special case where you know two voltages across the same impedance, you can use the 20 log

The 20 in the formula takes care of the squaring of voltages you would normally do to work out the powers.

There are a lot of special units where you compare the power you have with some reference.

It might be milliwatts, microwatts or something else.

There is a list of them here:

http://en.wikipedia.org/wiki/Decibel

You just use them the same way as above except that one of the measurements is already decided for you and you provide the one you have measured.

Image Rejection Ratio (IRR) is a measurement used to evaluate the performance of a radio frequency (RF) receiver. It refers to the ability of the receiver to reject or suppress unwanted signals, such as images or spurious signals, while amplifying the desired signal.

IRR is calculated by taking the ratio of the desired signal power to the image signal power. It is typically represented in decibels (dB) and a higher IRR indicates a better performance of the receiver.

IRR is important because it directly affects the quality and reliability of the received signal. A higher IRR means the receiver is better able to reject unwanted signals and therefore, the received signal will have less distortion and interference.

The main factors that can affect IRR include the design and quality of the receiver components, such as filters and amplifiers, the frequency of the desired signal, and the presence of any external interference.

There are several ways to improve IRR in a receiver, including using higher quality components, implementing better filtering techniques, and reducing external interference. Additionally, adjusting the receiver's frequency and bandwidth can also help improve IRR.

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