Convert NR-ARFCN ⇄ frequency across all three NR global rasters, auto-detect the NR band (FR1 & FR2), convert GSCN ⇄ SSB, and set channel bandwidth + SCS for resource blocks (NRB) — while you watch SSB beam sweeping, the frequency-driven RF wave and LOS/NLOS propagation change live. Accurate to 3GPP TS 38.104.
NR-ARFCN ?The channel number N_REF on the global raster. 0–3279165 maps to 0–100 GHz. Below 600000 = sub-3 GHz (5 kHz step).0–3279165
Decodes to RF reference frequency, band and GSCN — and drives the wave above.
Frequency ?RF reference (centre) frequency in MHz, 0–100000. Snapped to the nearest raster point when converting to ARFCN.MHz
GSCN / SSB ?Global Synchronization Channel Number (2–26639) or an SSB centre frequency in MHz, depending on direction.
Direction
Spectrum tuner3489 MHz
600 MHz3.5 GHz28 GHz100 GHz
Channel bandwidth ?Carrier channel bandwidth. FR1: 5–100 MHz; FR2: 50–400 MHz. With the SCS it sets the number of resource blocks (TS 38.104 Table 5.3.2).MHz
ARFCN → frequencyF_REF = F_offs + ΔF × (N − N_offs) — updates as you tune.
Visualization
Spectrum & band mapWhere your frequency sits on the 0.4–100 GHz log axis, the active global raster, and the NR bands it falls in.
ReferenceNR operating bands (TS 38.104)
Band
Range
Duplex
Uplink (MHz)
Downlink / TDD (MHz)
The modelHow NR-ARFCN maps to frequency
NR-ARFCN maps a channel number NREF to an RF reference frequency on the global frequency raster (TS 38.104 §5.4.2.1). The step ΔFGlobal widens with frequency:
λ = c / f // c ≈ 3×10⁸ m/s — higher band → shorter λ → narrower beams
The GSCN (Global Synchronization Channel Number) uses a separate, coarser raster (§5.4.3.1) so a UE can locate the SS/PBCH block (SSB) quickly during cell search instead of scanning every NR-ARFCN. The animation above shows this: the carrier wave tightens as frequency rises, the SSB pulse marks the sync beam, and the beam narrows in FR2 because high-frequency energy is focused into pencil beams.
Field notesReading the spectrum tuner
📶Wavelength shrinks with band
λ = c/f: 700 MHz ≈ 43 cm, 3.5 GHz ≈ 8.6 cm, 28 GHz ≈ 1.1 cm. Shorter waves mean smaller antennas and more elements per array — but also weaker diffraction and shorter reach.
🎯Higher band, narrower beam
FR2 packs many half-wavelength elements into a small array, so the beam is a tight pencil. The scene narrows the beam at mmWave to reflect this focusing.
🪜The raster widens
The global channel step grows 5 → 15 → 60 kHz as frequency rises, so a single ARFCN step shifts the carrier by more Hz up high. Always confirm which range your ARFCN sits in.
🛰GSCN vs ARFCN
The SSB lives on the coarse GSCN raster, not every ARFCN. A UE scans GSCN points to find a cell fast — that's why cell search is quick despite millions of ARFCN values.
📡SSB beam sweeping
The gNB sweeps the SS/PBCH block across beams during initial access — up to L = 4 below 3 GHz, 8 in FR1 above 3 GHz, and 64 in FR2 (TS 38.213). The scene cycles through L beams; the UE picks the strongest.
NR-ARFCN (New Radio Absolute Radio Frequency Channel Number) identifies a 5G NR carrier's centre frequency on the global frequency raster (TS 38.104), spanning 0–3279165 to cover 0–100 GHz.
How do you convert NR-ARFCN to frequency?
F_REF = F_offs + ΔF_Global × (N_REF − N_offs), with ΔF_Global = 5 kHz below 3 GHz, 15 kHz for 3–24.25 GHz, and 60 kHz for 24.25–100 GHz, and matching offsets.
What is GSCN?
GSCN (Global Synchronization Channel Number) marks the SS/PBCH block (SSB) position on a coarser sync raster, letting a UE locate the SSB quickly during initial cell search.
What is the difference between FR1 and FR2?
FR1 is sub-7 GHz (410 MHz–7.125 GHz); FR2 is mmWave (24.25–71 GHz). They use different channel rasters, subcarrier spacings and band numbering.
How is wavelength related to frequency?
λ = c / f with c ≈ 3×10⁸ m/s. So 700 MHz ≈ 0.43 m, 3.5 GHz ≈ 8.6 cm, 28 GHz ≈ 1.1 cm — higher NR-ARFCN means a shorter wavelength, narrower beams and shorter range, which is exactly what the animation shows.
What is SSB beam sweeping in 5G NR?
During initial access the gNB transmits the SS/PBCH block on a sequence of beams that sweep across the sector. The maximum number of SSB beams L is 4 below 3 GHz, 8 for FR1 above 3 GHz, and up to 64 in FR2 (TS 38.213). The UE measures each beam and selects the strongest for access — the animation above cycles through L beams.
How many resource blocks (N_RB) does a 5G carrier have?
It depends on channel bandwidth and SCS, per TS 38.104 Table 5.3.2-1/2. Examples: 100 MHz @ 30 kHz = 273 RB; 20 MHz @ 15 kHz = 106 RB; 100 MHz @ 120 kHz (FR2) = 66 RB. Each RB is 12 subcarriers, so occupied bandwidth = N_RB × 12 × SCS. Set the bandwidth and SCS in the tool to see N_RB and the carrier span on the spectrum map.
What is subcarrier spacing and numerology (µ)?
5G NR subcarrier spacing = 15 × 2^µ kHz, with numerology µ = 0–4 giving 15, 30, 60, 120, 240 kHz. FR1 uses 15/30/60 kHz; FR2 uses 60/120 kHz. Larger SCS means shorter OFDM symbols and lower latency, but fewer subcarriers in the same bandwidth.