Below, a systematic comparison of C4FM with DMR is presented from the perspectives of technical principles, channel utilization, voice quality, interference resistance, and edge coverage performance.
✅ 1. The fundamental difference between them (most important)
Project: C4FM (Fusion)
Format: Yaesu's proprietary digital format
Modulation method: 4FSK (wider)
Bandwidth: 12.5 kHz single slot
Voice encoder: AMBE+2 (bit rate 9600 bps)
Use case: Amateur radio (for optimizing voice quality)
Project: DMR (MotoTRBO)
Standard: ETSI international standard
Modulation method: 4FSK (more stringent)
Bandwidth: 2.5 kHz dual-slot (2-slot TDMA)
Voice encoder: AMBE+2 (bit rate 7200 bps)
Use cases: Commercial radio stations (optimized for capacity and efficiency)
Core:
🔥C4FM uses an entire 12.5 kHz channel for voice communication; DMR divides it up.
Therefore, C4FM has a higher voice bit rate and a more relaxed fault tolerance threshold.
➡️ This is the root cause of "C4FM having better audio quality."
✅ 2. Why do many people find the audio quality of C4FM to be better and more natural?
1) Higher voice encoding bit rate
DMR: One channel, two slots → Lower voice bit rate per slot
C4FM: The entire channel serves only one voice stream → High voice data rate
The higher the audio bitrate, the closer the sound will be to the original, so:
👉 C4FM provides clear, full-bodied sound that closely resembles FM.
👉 The DMR sound has a metallic quality, strong compression, and poor low-frequency response.
This is the part where user subjective feelings are most evident.
✅ 3. Edge Coverage Performance: C4FM is definitely more "graceful," while DMR is more "abruptly terminated."
When the signal is weak:
C4FM Features:
The audio quality will gradually deteriorate.
Ultimately becomes "sasa" which is incomprehensible → similar to a simulated FM gradient.
DMR Features:
Strong signal: Very clear
Reaching the critical point: Sudden and complete decoding failure → "Digital cliff"
This will make people feel:
👉 C4FM sounds more like a simulation; even with weak signals, it's still possible to understand.
👉 The DMR has low distortion, but if the signal level drops too low, it will completely cut out.
Therefore, many people using C4FM in the field or while mobile find it to be "more stable."
✅ Four, the advantages of DMR are also very obvious (but not related to audio quality).
DMR is primarily designed for "business communication," not audio quality.
1) Double slot = Twice the capacity at the same frequency.
One channel can support two people having a conversation simultaneously, which is the biggest advantage of DMR.
2) Strong network functionality
Group call, individual call, remote control, remote operation
Large-scale cluster network
A more comprehensive ID system
More suitable for businesses, law enforcement, fire departments, and construction teams.
3) Low bit rate makes the anti-interference structure more robust.
Channel coding is used extensively.
The redundancy mechanism is strong.
More stable in environments with strong interference.
👉 DMR is for business/industrial optimization, not audio quality optimization.
✅ 5. In practical, non-professional settings: Which one is better?
Use case: More suitable for
Audio quality, chat, weak signal connectivity ⭐ C4FM - Better sound, more natural
Nationwide connectivity, hotspots, TalkGroups ⭐ More mature DMR ecosystem
Many local repeaters available, diverse gameplay options ⭐ DMR Advantages
Hiking in the wilderness, weak signal calls: ⭐ C4FM provides a better listening experience and avoids sudden disconnections.
Therefore, you often hear a very common phrase:
🔥"If you want something that sounds good, use Fusion. If you want to connect to the internet and play TG, use DMR."
✅ 6. A genuine "summary of actual circumstances"
① Audio Quality: C4FM > DMR (higher bit rate)
② Signal Edge: C4FM > DMR (Digital Mobile Radio - more progressive)
③ Call capacity: DMR > C4FM (Double-slot Overlap)
④ Network Ecosystem: DMR >>> C4FM (with hotspots, repeaters, and TG functionality)
⑤ Commercial Stability: DMR > C4FM
The analysis above was generated by ChatGPT and is provided for reference and discussion purposes.
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