Model adjacent channel effects with practical radio inputs. Visualize interference, noise, and compliance margins instantly. Export results, inspect formulas, and validate designs with confidence.
This worked example uses realistic planning values for a narrowband radio link. It shows how ACIR, filter rejection, and spacing alter the final margin.
| Parameter | Example value | Unit |
|---|---|---|
| Desired signal at receiver | -67.00 | dBm |
| Adjacent signal at receiver | -15.00 | dBm |
| Wanted channel bandwidth | 200.00 | kHz |
| Channel spacing | 250.00 | kHz |
| Receiver ACS | 45.00 | dB |
| Transmitter ACLR | 48.00 | dB |
| Total additional rejection | 14.90 | dB |
| Effective SINR | 5.00 | dB |
| Margin | -9.00 | dB |
| Assessment | Fail | - |
These equations combine transmitter leakage, receiver selectivity, channel spacing, and noise. The spacing term is an engineering estimate based on the filter rolloff value you provide.
ACIR_linear = 1 / ((1 / ACLR_linear) + (1 / ACS_linear))
ACIR_dB = 10 × log10(ACIR_linear)
Spacing rejection = rolloff_dB_per_octave × log2(channel spacing / bandwidth)
Total extra rejection = base filter rejection + spacing rejection
Effective interference = Adjacent signal − ACIR − total extra rejection
Noise floor = −174 + 10 × log10(Bandwidth in Hz) + Noise figure
SINR = Desired signal − 10 × log10(Interference_mW + Noise_mW)
Final margin = Effective SINR − Required SINR
It is unwanted energy from a nearby channel entering a receiver and degrading wanted reception. Leakage from the transmitter and limited receiver selectivity usually create the problem.
ACLR describes how much unwanted energy leaks from the adjacent transmitter. ACS describes how well the victim receiver rejects that nearby channel. Both act together, so weak performance in either one can dominate.
ACIR is the combined adjacent channel interference ratio. It merges ACLR and ACS into one protection figure, making it easier to estimate effective interference at the receiver detector.
Greater spacing usually allows more filter attenuation between channels. This tool estimates that benefit with a rolloff term, which is useful during planning when a detailed mask model is unavailable.
It represents how often the adjacent interferer is active. A lower duty cycle reduces time-averaged interference, although worst-case interference still matters for strict compliance assessments.
A very strong adjacent signal, poor selectivity, weak ACLR, or insufficient rejection can still collapse SINR. Strong wanted power alone does not guarantee adequate protection.
It estimates how much more suppression is required to meet the target. You could achieve it through better filtering, improved spacing, lower adjacent power, or stronger radio performance.
It is best for engineering estimates and design screening. Formal compliance work may require measured masks, detailed receiver models, and standard-specific procedures beyond this simplified planning method.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.