1. What is Image Rejection Ratio (IRR)?

Definition: IRR measures a receiver's ability to reject image frequency signals, expressed in decibels (dB).

Purpose: It quantifies how well a receiver suppresses unwanted image signals that could interfere with the desired signal.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( IRR \) — Image Rejection Ratio (dB)
• \( desired\_signal \) — Amplitude of desired signal (unitless)
• \( image\_signal \) — Amplitude of image signal (unitless)

Explanation: The ratio of desired to image signal amplitudes is converted to decibels using a logarithmic scale.

3. Importance of IRR

Details: Higher IRR values indicate better receiver performance. Typical values range from 40-70 dB for good receivers.

4. Using the Calculator

Tips: Enter the amplitudes of both desired and image signals (must be > 0). The calculator will compute the IRR in dB.

5. Frequently Asked Questions (FAQ)

Q1: What's a good IRR value?
A: Generally, 40 dB is acceptable, 60 dB is good, and 70+ dB is excellent for most applications.

Q2: How is IRR different from SNR?
A: IRR specifically measures rejection of image frequencies, while SNR measures general signal-to-noise ratio.

Q3: What affects IRR in a receiver?
A: Front-end filtering, mixer performance, and local oscillator purity all impact IRR.

Q4: Can IRR be negative?
A: Yes, if the image signal is stronger than the desired signal, IRR will be negative.

Q5: How do I measure signal amplitudes?
A: Use a spectrum analyzer or receiver with amplitude measurement capabilities.