🛠️ Interactive Tool
DVB Bitrate & Link Calculator
Pick a MODCOD and a symbol rate, get the usable transport stream bitrate, the occupied bandwidth, and every threshold the link has to clear. All 75 modes are the values published in ETSI EN 302 307-1 V1.4.1 and EN 302 307-2 V1.4.1 — extracted from the specifications programmatically rather than retyped. Runs entirely in your browser.
Forward — what does this carrier deliver?
The standard states a 0,2 to 0,3 dB penalty for short FECFRAMEs. It does not give a single figure, so both bounds are offered rather than one invented value.
Reverse — what fits in the bandwidth and C/N I have?
Symbol rate is derived from the bandwidth and roll-off: Rs = BW / (1 + α). Every mode from both standards is then tested against the C/N you have, less the margin you reserve.
How each figure is derived
| Output | Formula | Source |
|---|---|---|
| Useful bitrate | Rs × η | η is the spectral efficiency column of the standard's own table |
| Occupied bandwidth | Rs × (1 + α) | Nyquist bandwidth widened by the roll-off |
| Efficiency per Hz occupied | η / (1 + α) | Stated explicitly in EN 302 307-2, note 4 under Table 20a |
| Eb/N0 | Es/N0 − 10·log₁₀(η) | The note printed under EN 302 307-1 Table 13 |
| C/N in symbol-rate bandwidth | equals Es/N0 | Noise integrated over exactly Rs |
| C/N in occupied bandwidth | Es/N0 − 10·log₁₀(1 + α) | Same carrier, wider noise bandwidth |
| Design threshold | Es/N0 + margin + frame penalty | Your margin — the standard does not supply one |
Every tabulated threshold is an ideal figure. EN 302 307-1 obtained them by computer simulation with 50 LDPC fixed-point iterations, perfect carrier and synchronisation recovery, no phase noise and an AWGN channel — and instructs that "for calculating link budgets, specific satellite channel impairments should be taken into account". This tool cannot know your receiver's implementation margin, phase noise, interference or rain fade allowance, so the margin field is yours to fill. A design threshold computed with margin zero is not a design threshold.
The efficiency values assume no pilots. Enabling pilot symbols eases carrier recovery and reduces useful throughput, so the bitrate shown is an upper bound for a pilot-enabled carrier. Note also that S2 thresholds are specified at PER = 10⁻⁷ while S2X uses FER = 10⁻⁵ — different metrics on different objects, close enough to tabulate together but not to compare at the third decimal.
Related
- DVB Standards & C/N Reference — the full tables, the QEF definition, and what margin actually consists of
- DVB C/N Cheat Sheet — the same numbers on one screen
- The TSDuck Cookbook — measuring the bitrate this tool predicts, with
tsbitrate - TS Packet Analyzer — the other tool on this shelf