Understanding UHF, VHF, AM, and FM in the F/A-18C Hornet

Effective radio communication in the F/A-18C Hornet depends not only on proper frequency presets but also on understanding the  radio bands and modulation types used: UHF , VHF , AM , and FM . These terms describe how and where a signal is transmitted and received. 

 

 📡 Radio Bands: UHF and VHF 

 

 

 

 

 

 Band 

 Frequency Range 

 Use in F/A-18C 

 Notes 

 

 

 

 

 UHF (Ultra High Freq.) 

 225.000 – 399.975 MHz 

 Primary for military ATC, AWACS, strike coordination, and aircraft-to-aircraft comms 

 Most default military channels are UHF 

 

 

 VHF (Very High Freq.) 

 30.000 – 174.000 MHz 

 Used for ground comms (JTAC), ATC (civilian), and some regional towers 

 VHF is often used for ground-based ops or coalition forces 

 

 

 

 

 

 

 

 

 

 

 The ARC-210 radios in the F/A-18C can operate in both UHF and VHF bands. Frequencies are manually entered or selected via preset channels. 

 

 

 Most airborne assets (AWACS, tankers, flights) will use UHF . 

 

 

 Ground-based assets (JTAC, civilian ATC, regional towers) may use VHF . 

 

 

 

 🎚️ Modulation Types: AM and FM 

 

 

 

 

 

 Modulation 

 Use Case 

 Supported in F/A-18C 

 Notes 

 

 

 

 

 AM (Amplitude Modulation) 

 Standard for aviation comms 

 ✔ Yes 

 Used for most UHF/VHF radio calls (ATC, AWACS, flights) 

 

 

 FM (Frequency Modulation) 

 Ground forces, JTAC, and CAS 

 ✔ Yes 

 Typically used in VHF band (30–88 MHz); more resistant to static/interference 

 

 

 

 

 

 

 

 

 

 

 AM is default and is used for nearly all aviation communications in DCS. 

 

 

 FM is used when talking to JTACs or ground units via VHF (e.g., 30.00–76.00 MHz). The ARC-210 supports this, and DCS will auto-modulate based on frequency. 

 

 

 

 🛠️ How to Know What You're Using 

 

 

 When tuning radios in DCS, you don’t explicitly select AM or FM— the modulation is determined by the frequency entered . 

 

 

 Example: 

 

 

 251.000 → UHF AM 

 

 

 30.000 → VHF FM 

 

 

 127.500 → VHF AM 

 

 

 

 

 As a rule: 

 

 

 Above 108 MHz = AM 

 

 

 Below 88 MHz = FM 

 

 

 Between 108–174 MHz = AM unless specifically in FM JTAC band 

 

 

 

 

 

 ✅ Quick Comms Summary 

 

 

 

 

 

 Frequency 

 Band 

 Modulation 

 Typical Use 

 

 

 

 

 251.000 

 UHF 

 AM 

 AWACS / Tower 

 

 

 127.500 

 VHF 

 AM 

 Carrier ATC / Civil ATC 

 

 

 30.000 

 VHF 

 FM 

 JTAC / Ground troops 

 

 

 320.000 

 UHF 

 AM 

 Strike package net 

 

 

 268.000 

 UHF 

 AM 

 Tanker (Texaco) 

 

 

 

 

 

 

 

 

 

 🧠 In Practice (DCS Tips) 

 

 

 Use AM for all aircraft/airfield comms unless you're talking to JTAC or infantry units . 

 

 

 If using SRS (Simple Radio Standalone) , make sure your SRS settings allow auto modulation switching based on frequency. 

 

 

 The Hornet’s radios do not allow manually selecting modulation type —it’s automatic based on freq.