Calculator Inputs
Example Data Table
| Input | Example Value | Meaning |
|---|---|---|
| Frequencies | 518.200, 519.800, 521.400 | Planned microphone carrier channels. |
| Exclusions | 520.000, 526.000 | Blocked or protected local frequencies. |
| Guard Window | 100 kHz | Review zone around each target frequency. |
| Tolerance | 25 kHz | Conflict zone for intermod products. |
Formula Used
The calculator tests common radio microphone intermodulation products within the selected receiver range.
- Third order two tone: 2f1 - f2 and 2f2 - f1
- Third order three tone: f1 + f2 - f3
- Fifth order two tone: 3f1 - 2f2 and 3f2 - 2f1
- Seventh order two tone: 4f1 - 3f2 and 4f2 - 3f1
- Carrier spacing: absolute difference between two active frequencies
- Risk check: absolute difference between product and nearest target
How to Use This Calculator
- Enter each radio microphone frequency in MHz.
- Add blocked channels or protected frequencies as exclusions.
- Set the receiver tuning limits for your equipment.
- Choose guard, spacing, and tolerance values in kHz.
- Select the highest intermodulation order to test.
- Submit the form and read the result above the inputs.
- Export the result as CSV or PDF for your crew.
Radio Microphone Intermodulation Planning Guide
What This Calculator Does
Radio microphone channels can interact inside receivers, transmitters, antenna splitters, and nearby metalwork. This calculator checks those interactions before a show starts. It accepts a list of planned frequencies, a receiver tuning range, spacing limits, and tolerance values. Then it builds common intermodulation products and compares them with active channels.
Why Intermodulation Matters
Intermodulation is not simple overlap. It is a new unwanted frequency made by mixing two or more strong signals. A product may land near a real microphone channel. When that happens, the receiver may hear noise, dropouts, or bursts of distortion. Large events are more exposed, because many transmitters operate close together. Good planning reduces these risks before equipment is powered.
Useful Planning Features
The tool checks carrier spacing, third order products, fifth order products, and seventh order two tone products. It also supports three tone products, which matter in dense wireless racks. You can enter blocked television carriers, local walkie channels, or known problem frequencies as exclusions. The result table separates carrier conflicts from calculated products. This makes the report easier to read during setup.
How To Read Results
A low risk result means the calculated product is outside the selected tolerance. A warning means the product is close enough to review. A conflict means the product falls inside the guard window around a real channel or exclusion. Check conflicts first. Then adjust the nearest microphone channel. Small frequency moves can remove several products at once.
Best Practices
Use scanned clean frequencies whenever possible. Keep transmitters away from receiver antennas during testing. Use only the power needed for the venue. Separate antenna outputs and cables with care. Do not mix old and new coordination lists without checking them again. Always recheck after adding guest microphones, in ear transmitters, or backup packs.
Practical Notes
This calculator gives planning guidance. Real systems can change because of antenna gain, cable loss, transmitter power, body absorption, and local broadcast signals. Use it with a spectrum scan and a listening test. Save the CSV for records. Export the PDF for crew sheets, rental notes, and show documentation.
Review every venue separately, because walls, stages, balconies, and camera platforms can change signal strength patterns during sound checks nightly.
FAQs
What is radio microphone intermodulation?
It is an unwanted frequency created when two or more strong radio signals mix. The new product can fall near another microphone channel and cause interference.
Which intermodulation order matters most?
Third order products are usually the first concern. Fifth and seventh order checks help when many transmitters are packed into a small tuning range.
Should I include three tone products?
Yes, for dense wireless systems. Three tone checks are useful when several microphones, in ear systems, or backup packs operate together.
What does the guard window mean?
The guard window is a review zone around carriers or exclusions. A product inside that zone may not fail, but it deserves attention.
What is conflict tolerance?
Conflict tolerance is the closer limit used for serious warnings. Products inside this distance are marked as conflicts in the result table.
Can this replace a spectrum scan?
No. It supports planning, but real venues contain local broadcast signals, reflections, antenna effects, and unexpected RF noise.
Why are exclusions useful?
Exclusions protect known problem channels. You can enter TV carriers, walkie frequencies, venue systems, or other channels you must avoid.
How should I fix a conflict?
Move the nearest microphone channel first. Then recalculate. One small move can remove multiple intermodulation products.