FPV Frequency Guide

All frequencies and channel assignments used by Skwad's optimizer.

Analog Bands

Analog pilots select which bands their VTX supports. Default is Race Band only.

R — Race Band (20 MHz)

Channel	Freq (MHz)
R1	5658
R2	5695
R3	5732
R4	5769
R5	5806
R6	5843
R7	5880
R8	5917

F — Fatshark Band (20 MHz)

Channel	Freq (MHz)
F1	5740
F2	5760
F3	5780
F4	5800
F5	5820
F6	5840
F7	5860
F8	5880

E — Boscam E Band (20 MHz)

Channel	Freq (MHz)
E1	5705
E2	5685
E3	5665
E4	5645
E5	5885
E6	5905
E7	5925
E8	5945

L — Low Race Band (20 MHz)

Channel	Freq (MHz)
L1	5362
L2	5399
L3	5436
L4	5473
L5	5510
L6	5547
L7	5584
L8	5621

Frequency Overlaps

When multiple analog bands are selected, the optimizer deduplicates by frequency. The only overlap across all four bands is:

Freq (MHz)	Channels
5880	R7, F8

All other frequencies are unique across R, F, E, and L.

HDZero (20 MHz)

Uses Race Band channels (R1–R8). Same table as analog Race Band.

DJI V1 / Vista (20 MHz)

Stock (4 channels)

Channel	Freq (MHz)
DJI-CH3	5735
DJI-CH4	5770
DJI-CH5	5805
DJI-CH8	5839

FCC Unlocked (8 channels)

Channel	Freq (MHz)
DJI-CH1	5660
DJI-CH2	5695
DJI-CH3	5735
DJI-CH4	5770
DJI-CH5	5805
DJI-CH6	5878
DJI-CH7	5914
DJI-CH8	5839

DJI O3

Stock 20 MHz (3 channels)

Channel	Freq (MHz)
O3-CH1	5769
O3-CH2	5805
O3-CH3	5840

FCC 20 MHz (7 channels)

Channel	Freq (MHz)
O3-CH1	5669
O3-CH2	5705
O3-CH3	5769
O3-CH4	5805
O3-CH5	5840
O3-CH6	5876
O3-CH7	5912

FCC 40 MHz (3 channels)

Channel	Freq (MHz)
O3-CH1	5677
O3-CH2	5795
O3-CH3	5902

Stock 40 MHz (1 channel)

Channel	Freq (MHz)
O3-CH1	5795

DJI O4

Stock 20 MHz (3 channels)

Channel	Freq (MHz)
O4-CH1	5769
O4-CH2	5790
O4-CH3	5815

FCC 20 MHz (7 channels)

Channel	Freq (MHz)
O4-CH1	5669
O4-CH2	5705
O4-CH3	5741
O4-CH4	5769
O4-CH5	5790
O4-CH6	5815
O4-CH7	5876

FCC 40 MHz (3 channels)

Channel	Freq (MHz)
O4-CH1	5735
O4-CH2	5795
O4-CH3	5855

Stock 40 MHz (1 channel)

Channel	Freq (MHz)
O4-CH1	5795

60 MHz (1 channel)

Channel	Freq (MHz)
O4-CH1	5795

Race Mode (Goggles 3 / N3)

Uses Race Band channels (R1–R8) when race mode is enabled with compatible goggles.

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Standard Stock (4 channels)

Same as DJI V1 Stock (DJI-CH3, CH4, CH5, CH8).

Standard FCC (8 channels)

Same as DJI V1 FCC (DJI-CH1–CH8).

Race Mode (8 channels)

Uses Race Band channels (R1–R8).

OpenIPC (20 MHz)

Channel	Freq (MHz)
WiFi-165	5825

Spacing Rules

The optimizer enforces minimum center-to-center spacing between any two pilots:

Required Spacing = (Bandwidth_A / 2) + (Bandwidth_B / 2) + 10 MHz guard band

Pilot A	Pilot B	Required Spacing
20 MHz	20 MHz	30 MHz
20 MHz	40 MHz	40 MHz
40 MHz	40 MHz	50 MHz
40 MHz	60 MHz	60 MHz
60 MHz	60 MHz	70 MHz

Transmit Power and Channel Separation

The optimizer's guard band — the minimum frequency gap it enforces between pilots beyond their occupied bandwidth — isn't a fixed number. It depends on how much power the VTXs in the session are transmitting. Higher power means more spectral splatter and stronger adjacent-channel interference, which demands wider spacing.

Common VTX Power Steps

Most FPV video transmitters offer adjustable power in fixed steps. The exact steps vary by manufacturer, but these are the most common:

Power	dBm	Typical Use
25 mW	14 dBm	Indoor, pit area, crowded racing
100 mW	20 dBm	Close-range outdoor, warm-up
200 mW	23 dBm	Standard outdoor group flying
400 mW	26 dBm	Freestyle, moderate range
600 mW	27.8 dBm	Long range
800 mW	29 dBm	Extended range
1000 mW	30 dBm	Maximum power

The dBm scale is logarithmic: every +3 dB doubles the power, but it takes +6 dB (4x the power) to double your range. Going from 200 mW to 800 mW is only +6 dB — noticeable, but not transformative for range.

Why Power Affects Required Spacing

Two factors drive the relationship between TX power and required channel separation:

1. Spectral splatter. No VTX transmits a perfectly clean signal on exactly one frequency. Some energy leaks into adjacent frequencies — this is called out-of-band emission or spectral splatter. Higher power amplifiers produce proportionally more splatter because they're driven harder and closer to their nonlinear region. A VTX running at 800 mW has noticeably worse spectral purity than the same VTX at 25 mW.

2. Receiver filter limitations. FPV receivers use bandpass filters (typically ~18–20 MHz wide at -3 dB) to reject signals on other channels. These filters have a finite rolloff — they don't brick-wall at the passband edge. The filter attenuates an interfering signal by roughly 20 dB per decade of frequency offset beyond the passband edge. At low power, even modest attenuation is enough. At high power, the interfering signal is strong enough to punch through the filter skirt.

The Math: Deriving Guard Band from TX Power

The receiver needs a minimum carrier-to-interference ratio (C/I) of ~20 dB for clean video. Several factors determine how much frequency separation is needed to achieve that:

Capture effect: Your own quad is typically much closer to your receiver than other pilots' quads. In typical group flying geometry this gives your desired signal a ~20 dB advantage over other pilots' signals.
Filter attenuation: The receiver's bandpass filter (typically ~20 MHz wide at -3 dB) rejects signals at offset frequencies. Attenuation is approximately 20 × log10(offset / (BW/2)) dB beyond the passband edge.
Spectral splatter: Higher TX power degrades spectral purity. We model the additional interference as 3 × log10(P_tx / 25) dB relative to a 25 mW baseline. This is calibrated against the known-good 10 MHz guard band at 25 mW.

The condition for clean video:

filter_attenuation(offset) >= C/I_required - capture_advantage + splatter_penalty

With these calibrated values, the guard band formula becomes:

guard_band = 10 × 10^((3 × log10(P_mW / 25)) / 20)  MHz

This produces 10 MHz at 25 mW (matching the current proven default) and scales gently through the low-power range (25–200 mW). Above 400 mW the formula output stays below 18 MHz, but the table values are manually calibrated overrides designed to place the raceband cliff between 400 and 600 mW.

Recommended Guard Band by Power Level

The theoretical formula above provides a continuous curve, but in practice we calibrate against a key constraint: Race Band channels are spaced exactly 37 MHz apart. This creates a hard cliff — at ≤17 MHz guard band (required spacing ≤37 MHz), all 8 raceband channels are conflict-free. Above 17 MHz, you can only use every-other channel (4 max).

We calibrate so this cliff falls between 400 mW and 600 mW, aligning with community consensus that 400 mW is the upper limit for comfortable group flying:

Session Power Ceiling	Guard Band	Required Spacing (20 MHz)	Raceband Channels
25 mW	10 MHz	30 MHz	8
100 mW	12 MHz	32 MHz	8
200 mW	14 MHz	34 MHz	8
400 mW	16 MHz	36 MHz	8 (1 MHz margin)
600 mW	24 MHz	44 MHz	4
800 mW	28 MHz	48 MHz	4
1000 mW	32 MHz	52 MHz	4

Key observations:

≤400 mW: All 8 raceband channels remain usable. The guard band grows gently from 10 to 16 MHz, staying safely below the 17 MHz cliff. This matches real-world experience — pilots routinely use adjacent raceband channels at these power levels.
600+ mW: The cliff hits. Only every-other raceband channel is conflict-free (R1/R3/R5/R7 or R2/R4/R6/R8). This is where leaders should consider the race day channel set feature or accept buddying up.
The jump from 400→600 mW is intentionally dramatic — it signals a real change in the interference environment and matches the community rule of thumb: "stay under 200–400 mW for group flying."

The Raceband Cliff

The sharp transition at 37 MHz required spacing deserves emphasis because it's unintuitive. Race Band was designed with 37 MHz channel spacing — just barely enough for low-to-moderate power group flying. This means:

At 36 MHz required spacing (400 mW ceiling): 8 channels, 1 MHz margin. Everyone fits.
At 38 MHz required spacing: 4 channels. Half the capacity vanishes instantly.

There is no gradual degradation between 8 and 4 on Race Band because the channels are uniformly spaced. With mixed analog bands (R+F+E), the non-uniform spacing provides more intermediate options, but for pure raceband the cliff is real.

For sessions at 600+ mW, the race day channel set feature becomes essential — the leader should pre-select which 3–4 well-spaced channels to use and let the optimizer buddy up from there.

Assumptions and Limitations

The capture advantage (20 dB) assumes typical geometry where your quad is closer to your receiver than other pilots' quads. On a tight race course with stacked quads, this drops to ~10–15 dB, effectively pushing all guard bands wider.
The splatter model is calibrated to match the current 10 MHz default at 25 mW, not measured from specific VTX hardware. Cheap VTXs with poor PA linearity will splatter more.
These calculations assume 20 MHz occupied bandwidth. For DJI O3/O4 at 40 or 60 MHz, the bandwidth terms in the spacing formula dominate and the guard band contribution matters less.
IMD (intermodulation distortion) is a separate concern not captured by this model. See the IMD section below.

Impact Summary

The fundamental trade-off: more power = wider guard band = fewer unique channels = more buddying up.

For a session leader, the practical question is simple: do you need everyone on a unique channel, or is buddying acceptable? If unique channels matter, keep the power ceiling at 400 mW or below. If power matters more than density, set the ceiling higher and plan for buddying.

DJI Dynamic Power Control

DJI O3 and O4 video systems use automatic power control — the VTX adjusts transmit power dynamically based on link quality. Pilots have no manual mW setting. This has several implications for session power ceilings.

How DJI dynamic power behaves:

Power scales with link quality, which depends on distance, obstacles, and antenna orientation — not a single variable
At typical meetup distances (~100m line-of-sight), DJI tends to stay at low power (community estimates suggest under 200 mW)
Power ramps up progressively at range, approaching the maximum EIRP (up to 33 dBm / ~2W for O3/O4 Pro in FCC mode, 30 dBm / ~1W for standard O4) beyond ~500m or through obstacles
These are community observations from spectrum analyzer measurements, not manufacturer specifications — DJI does not publish their power control curves
The exact power at a given distance varies significantly with environment, antenna choice, and interference

Why bandwidth matters more than power for DJI:

Bandwidth is the lever DJI pilots actually control. Switching from 40 MHz to 20 MHz mode saves 10 MHz of required spacing per neighbor — a bigger impact than most power ceiling steps. The math:

DJI Bandwidth	vs 20 MHz neighbor (14 MHz guard*)	vs 40 MHz neighbor (14 MHz guard*)
20 MHz	34 MHz spacing	44 MHz spacing
40 MHz	44 MHz spacing	54 MHz spacing
60 MHz	54 MHz spacing	64 MHz spacing

*14 MHz guard band = 200 mW power ceiling step. Each 20 MHz step in DJI bandwidth adds 10 MHz to required spacing — equivalent to going from a 200 mW guard band to a 600 mW guard band.

Practical experience:

Groups of 6–8 mixed DJI/analog pilots fit comfortably on raceband channels when DJI pilots use 20 MHz bandwidth and fly within a confined area. The dynamic power at these distances stays within a range where the default guard band provides adequate separation.

Intermodulation Distortion (IMD)

When two VTXs transmit simultaneously, their signals can mix nonlinearly (in the RF front-end of nearby receivers, or even in the transmitters themselves) to produce phantom signals at new frequencies. This is intermodulation distortion.

How IMD Works

The strongest IMD products are third-order, calculated as:

F_imd = (2 × F1) - F2
F_imd = (2 × F2) - F1

For example, pilots on 5760 MHz and 5800 MHz produce IMD at:

(2 × 5760) − 5800 = 5720 MHz
(2 × 5800) − 5760 = 5840 MHz

If a third pilot is on 5840 MHz, they'll see interference from this IMD product even though neither of the other two pilots is on their channel.

IMD Ratings

IMD quality for a set of frequencies is measured on a 0–100 scale, where 100 means no IMD products land near any active channel:

Pilot Count	Recommended Channel Set	Frequencies (MHz)	IMD Rating
2 pilots	R1, R8	5658, 5917	100
3 pilots	R1, R4, R8	5658, 5769, 5917	100
4 pilots	R1, R3, R6, R8	5658, 5732, 5843, 5917	100
5 pilots	ET5A	5665, 5752, 5800, 5866, 5905	88
6 pilots	IMD 6C (MultiGP standard)	5658, 5695, 5760, 5800, 5880, 5917	29

The sharp drop at 6 pilots illustrates why IMD matters: there simply aren't 6 frequencies in the 5.8 GHz band that avoid all third-order products. The IMD 6C set is a practical compromise that minimizes the worst cases.

IMD Scoring Methodology

Skwad calculates IMD scores using proximity-weighted quadratic penalties, inspired by ET's IMD Tools. The approach:

Compute all third-order IMD products for every pair of active pilots
For each product within 20 MHz of an active channel, calculate: penalty = (20 - distance)²
A product landing directly on a channel (0 MHz distance) scores 400 penalty points. A product 15 MHz away scores only 25.
Final score: 100 - (penalty_sum / (5 × pilot_count)), clamped to 0-100

This produces a gradient rather than a binary hit/miss — a product 2 MHz from your channel is a real problem, while one 18 MHz away is barely noticeable. The 20 MHz threshold aligns with typical FPV receiver filter bandwidth.

IMD vs. Guard Band

IMD and guard band spacing address different problems:

Guard band prevents direct adjacent-channel bleed from a single interferer
IMD prevents phantom signals created by the interaction of two interferers

A channel can be perfectly spaced from all active channels but still receive IMD interference. Both must be considered for robust multi-pilot sessions.

References

ET's FPV IMD Tools — IMD calculator and optimal frequency set generator
RCForces 5.8 GHz Guide — channel tables and IMD-aware pilot recommendations
PhaserFPV Group Flying Guide — practical channel sets by group size