Dual-Frequency GPS Explained

Q: What is dual-frequency GPS?

Dual-frequency GPS uses two GPS satellite signals at different frequencies to directly compute the ionospheric delay — the largest single error source for civilian single-frequency GPS. The two frequencies are typically L1 (1575.42 MHz, the original 1978 civilian signal) and L5 (1176.45 MHz, the safety-of-life signal added on Block IIF in 2010). Because ionospheric delay depends on signal frequency, the delay measured at two frequencies can be inverted to give the exact delay at either frequency. Single-frequency GPS receivers must estimate ionospheric delay from a model (the Klobuchar algorithm), which has up to ~50% error. Dual-frequency direct measurement reduces this to <5% of the original delay, dramatically improving overall accuracy.

Q: When did smartphones get dual-frequency GPS?

The Broadcom BCM47755 chipset, announced in September 2017 and shipping in 2018, was the first dual-frequency consumer GNSS chipset. First smartphone to use it: the Xiaomi Mi 8 (May 2018). Google's Pixel 4 (October 2019) was the second major launch with dual-frequency. From 2020 onward, dual-frequency became increasingly common in Android flagships — Samsung Galaxy S20+ series, OnePlus 8 Pro, Huawei P40 Pro, and others. Apple was a late adopter: the iPhone 14 Pro (September 2022) was the first iPhone with dual-frequency GPS, expanding to standard iPhone 14 with the iPhone 15 Pro line. By 2024-2026, dual-frequency is standard in nearly all flagship and many mid-range smartphones globally.

Q: How much more accurate is dual-frequency GPS?

Dramatically — but conditions matter. Under open sky with good satellite geometry: single-frequency typically achieves 3-5 meter horizontal accuracy; dual-frequency improves this to sub-meter (often ~0.5-1 m). Under partial sky obstruction (urban canyons, near tall buildings): the improvement is less dramatic but still significant — single-frequency might be ~5-10 m, dual-frequency ~2-4 m. Indoor performance: both degrade similarly because GPS signals can't penetrate buildings well; the marginal benefit of dual-frequency is small. The dramatic improvement applies to applications operating mostly outdoors (lane-level navigation, fitness tracking, surveying). For applications that operate mostly indoors or in heavy urban density, the practical benefit is more modest.

Q: Why are L1 and L5 used as the pair?

L1 (1575.42 MHz) is the original 1978 civilian signal, present on every GPS satellite. L5 (1176.45 MHz) is the safety-of-life signal added on Block IIF (2010+) and continuing on GPS III and IIIF. The L1/L5 pairing has several advantages: (1) Both are present on all modern GPS satellites — at least the post-2010 generation. (2) The frequency separation (~400 MHz) is large enough for excellent ionospheric correction. (3) L5 is in an ITU-protected aviation radionavigation band, with stricter interference control. (4) L5 has higher power, longer code length, and better acquisition properties than L1. (5) Equivalent signals at the same 1176.45 MHz exist in Galileo (E5a), BeiDou (B2a), and QZSS (L5) — making multi-GNSS dual-frequency natural. L1+L2 is the older dual-frequency pairing used by surveying receivers; L1+L5 is the modern consumer-friendly choice.

Q: What are the limitations of dual-frequency consumer GPS?

Several. (1) Limited L5 satellite availability historically: L5 was added on Block IIF (12 satellites, 2010-2016), then continued on GPS III and IIIF. As of 2026, ~25 of the operational satellites broadcast L5; full coverage (every visible satellite broadcasting L5) is approaching but not always available. (2) Urban canyon multipath: signals reflecting off buildings still corrupt the measurements; dual-frequency helps with ionospheric error but not multipath. (3) Indoor performance: dual-frequency doesn't help indoors where neither signal penetrates well. (4) Power consumption: slightly higher than single-frequency, though minimal in modern chipsets. (5) Antenna performance: smartphone antennas are constrained by size; both L1 and L5 must fit in a small package. The L5 signal is somewhat lower in the receivable spectrum which can favor smaller antennas. (6) Not every device is dual-frequency: budget and older devices remain single-frequency. (7) Dual-frequency doesn't eliminate the need for differential corrections (RTK) for sub-decimeter accuracy — it's a major step from single-frequency consumer GPS but doesn't replace specialized RTK receivers.

Dual-frequency GPS uses two satellite frequencies (typically L1 at 1575.42 MHz and L5 at 1176.45 MHz) to directly compute ionospheric delay rather than estimating it from a model. The result: significantly improved accuracy — sub-meter under open sky vs 3-5 meters for single-frequency. The Broadcom BCM47755 chipset in 2018 brought dual-frequency to smartphones (Xiaomi Mi 8 was first; Pixel 4 in 2019; iPhone 14 Pro in 2022). The L5 signal and its Galileo E5a, BeiDou B2a, and QZSS L5 equivalents are at the same 1176.45 MHz frequency, simplifying multi-GNSS dual-frequency receivers. The article covers the physics, the smartphone adoption timeline, accuracy improvements, and remaining limitations.

This article extends the GPS sub-hub with the dual-frequency GPS revolution that has transformed consumer positioning since 2018. Companion to /learn/gps-accuracy-explained and /learn/why-gps-is-not-always-accurate.

What dual-frequency GPS is

A GPS receiver tracks satellite signals to compute its position. Single-frequency receivers use one signal (typically L1 at 1575.42 MHz). Dual-frequency receivers track two signals at different frequencies (typically L1 + L5 at 1176.45 MHz).

The key benefit: direct measurement of ionospheric delay rather than estimation from a model.

The ionospheric delay problem

GPS signals travel through the ionosphere — the charged-particle layer of Earth's atmosphere (50-1,000 km altitude). Charged particles refract and delay the signal:

Total Electron Content (TEC) along the signal path determines the delay magnitude.
Frequency-dependent: lower frequencies are delayed more.
Time-of-day and season variable: peaks during daytime; affected by solar activity.
Typical delay: 1-15 meters of path-length equivalent (peak during solar storms ~50 m).

For single-frequency GPS, the ionospheric delay is the largest single error source.

Single-frequency correction: Klobuchar model

Single-frequency receivers use the Klobuchar ionospheric model broadcast in the GPS Navigation Message:

8 parameters describing the ionospheric state.
Updated daily by GPS ground control.
Applies a global model to estimate delay at the receiver location and time.

Klobuchar reduces ionospheric error but doesn't eliminate it:

Typical residual: ~50% of the underlying error.
During solar storms or unusual conditions: much worse.
The model assumes a smooth global pattern; real ionosphere has structure.

Dual-frequency direct measurement

Because the delay is frequency-dependent, two frequencies give two delay measurements. The difference uniquely determines the underlying TEC:

delay(L1) - delay(L5) = TEC × (1/f_L1² - 1/f_L5²) × constant

Solve for TEC; compute the exact delay at either frequency:

delay(L1) = TEC / f_L1² × constant

The residual: <5% of the original delay — about 10× better than Klobuchar. This is the fundamental win of dual-frequency GPS.

The L1/L5 pairing

L1 and L5 are the consumer dual-frequency pair:

L1 (1575.42 MHz)

The original 1978 civilian signal (C/A code).
Present on every GPS satellite.
Tracked by every consumer GPS receiver.

L5 (1176.45 MHz)

Added on Block IIF (2010-2016).
Continued on GPS III (2018+) and GPS IIIF (2027+).
Safety-of-life signal — designed specifically for aviation precision approach.
Higher power than L1 (more transmit watts).
Longer code length — better acquisition, better multipath resistance.
In ITU-protected aviation band — stricter interference control.

The frequency separation (~400 MHz) is large enough for excellent ionospheric correction.

Why not L1 + L2?

L2 (1227.6 MHz) is the older dual-frequency pair used by surveying receivers since the 1980s. Why isn't L2 the consumer choice?

L2C civilian signal was added on Block IIR-M (2005+). L2C coverage took longer to reach full constellation.
L1+L2 ionospheric correction is mathematically similar to L1+L5.
L5 has better signal properties for consumer use (higher power, longer code, aviation-band protection).
L5 has cross-GNSS equivalents at the same frequency (see next section), enabling natural multi-GNSS dual-frequency.

Cross-GNSS equivalents

The L5 frequency (1176.45 MHz) is shared with similar signals from other GNSS systems:

Galileo E5a at 1176.45 MHz.
BeiDou B2a at 1176.45 MHz.
QZSS L5 at 1176.45 MHz (Japanese GNSS for Asia-Pacific).
NavIC L5 at 1176.45 MHz (Indian regional GNSS).

A receiver tracking L1+L5 automatically benefits from all four (or five) GNSS systems at L5. This is why L1+L5 became the consumer dual-frequency standard despite the older L1+L2 pattern in surveying.

Smartphone adoption timeline

The dual-frequency revolution in smartphones:

| Year | Milestone | | ---- | --------- | | 2010 | First L5-broadcasting GPS satellite (Block IIF SV-1) | | 2017 | Broadcom BCM47755 chipset announced | | 2018 | Xiaomi Mi 8 — first commercial dual-frequency phone | | 2019 | Google Pixel 4 — first US-market flagship | | 2020 | Samsung Galaxy S20+, OnePlus 8 Pro | | 2021 | More Android flagships across vendors | | 2022 | iPhone 14 Pro — Apple's first dual-frequency | | 2023 | iPhone 15 standard line; widespread Android adoption | | 2024-25 | Increasingly common in mid-range Android |

The Broadcom BCM47755

The chipset that started the consumer revolution. Announced September 2017; shipping mid-2018. Key specs:

Multi-band, multi-constellation: L1+L5 GPS, E1+E5a Galileo, B1+B2a BeiDou, others.
30-40 satellites typically visible in multi-constellation mode.
Power efficient: comparable to single-frequency chipsets despite extra capability.
Low cost: priced for mainstream smartphones rather than survey-grade equipment.

Broadcom's announcement specifically targeted sub-meter accuracy in consumer applications.

Apple's delayed adoption

Apple was a late adopter by smartphone-industry standards:

iPhone 1 (2007) through iPhone 14 (Sep 2022): single-frequency GPS only.
iPhone 14 Pro and Pro Max (Sep 2022): first dual-frequency.
iPhone 15 and 15 Pro (Sep 2023): expanded dual-frequency.

The delay was likely a combination of: Apple's strong existing single-frequency performance (good antenna design, software smoothing); proprietary chipset development; and conservative roadmap prioritization.

Accuracy improvement

The practical impact:

Open-sky environments

Single-frequency: 3-5 m typical horizontal accuracy.
Dual-frequency: sub-meter (~0.5-1 m) typical.
Best dual-frequency: ~30 cm under ideal conditions.

Urban environments

The improvement is less dramatic:

Single-frequency: 5-15 m in moderate urban; 10-50 m in dense urban canyons.
Dual-frequency: 2-5 m in moderate urban; similar 10-30 m degradation in dense canyons.

The reason: in urban environments, multipath (signals reflecting off buildings) is the dominant error, not ionospheric. Dual-frequency helps with ionosphere, not multipath.

Indoor

Both single- and dual-frequency degrade similarly indoors. GPS signals don't penetrate buildings well; the marginal benefit of dual-frequency is small.

Use-case implications

| Use case | Single-frequency | Dual-frequency | | -------- | ---------------- | -------------- | | General navigation | Adequate | Better | | Lane-level navigation | Borderline | Reliable | | Fitness tracking | Adequate | Sub-pace | | Pedestrian routing | Often fine | Better at intersections | | Photo geotagging | OK | Better building-level | | Indoor positioning | Both fail | Both fail | | Surveying | Inadequate | Better but still not survey-grade |

Multi-GNSS combination

Dual-frequency typically comes paired with multi-GNSS:

GPS L1 + L5 (USA).
Galileo E1 + E5a (EU).
BeiDou B1 + B2a (China).
GLONASS L1 + L2 (Russia, older pairing).
QZSS L1 + L5 (Japan, regional).
NavIC L1 + L5 (India, regional).

A multi-GNSS dual-frequency receiver typically tracks 30-40 satellites at any moment. Benefits:

Better geometry → better positioning.
Urban canyon performance improves substantially (more chances to see a satellite above the buildings).
Faster acquisition at startup.
Better reliability during partial signal loss.

The 2018+ smartphone dual-frequency revolution was also a multi-GNSS revolution.

Sub-meter positioning in practice

When does dual-frequency GPS actually achieve sub-meter accuracy?

Required conditions

Open sky view with at least 6-8 satellites visible.
Good satellite geometry (HDOP < 2 is typical).
No active multipath (no nearby reflecting surfaces).
Modern chipset (BCM47755 or successor).
Antenna in known orientation (smartphone GPS antennas are direction-sensitive).
Position averaging over seconds-to-minutes rather than instantaneous fix.

Under these conditions, 0.5-1 m is consistently achievable.

Real-world variability

Outside ideal conditions, dual-frequency degrades:

Partial sky obstruction: 2-4 m.
Urban canyon: 5-15 m.
Underground / indoor: meaningless (no GPS signal).
Heavy foliage: 3-8 m.
Solar storm: degraded but still better than single-frequency.

The headline “30 cm accuracy” is under ideal conditions; typical real-world use is 1-3 m for dual-frequency vs 3-10 m for single-frequency.

Limitations

L5 coverage gaps

L5 was added on Block IIF (2010-2016, 12 satellites). GPS III continues L5 (10+ satellites by 2026). Total L5-broadcasting satellites: ~25+ of the ~31 operational. Not every visible satellite broadcasts L5. Where L5 coverage is sparse, dual-frequency benefits are limited.

Full L5 coverage (every operational satellite broadcasting L5) approaches with GPS IIIF deployment in the late 2020s.

Antenna constraints

Smartphone antennas are physically small. Supporting both L1 and L5 requires either:

Dual-band antenna (with both feeds).
Two antennas (often integrated).
Wideband antenna covering both.

Trade-offs: smaller antennas have less gain, particularly at lower frequencies (L5 at 1176 MHz needs slightly more antenna area than L1 at 1575 MHz). Modern smartphone antennas handle this within constraints but with some performance compromise vs larger external antennas.

Power consumption

Dual-frequency receivers consume modestly more power than single-frequency:

Additional RF chain for the second frequency.
More signal-tracking compute.
Multi-GNSS processing typically pairs with dual-frequency.

In modern smartphone chipsets, the power overhead is small (~5-10% more battery during continuous GPS use). Practical impact on phone battery is modest.

Multipath remains

Dual-frequency doesn't help with multipath — signal reflections off buildings still degrade performance in urban canyons. Multipath is mitigated by signal-processing techniques (LOS/NLOS detection, advanced correlation) rather than dual-frequency.

Indoor failure

Indoor positioning needs alternatives (Wi-Fi positioning, Bluetooth beacons, IMU dead reckoning, visual SLAM). Dual-frequency GPS doesn't penetrate buildings any better than single-frequency.

Not survey-grade

Dual-frequency consumer GPS is better than single-frequency but not at survey-grade accuracy (~cm). For that:

RTK (Real-Time Kinematic) GPS — see /learn/rtk-gps — uses base stations + smartphone reception combined.
PPP (Precise Point Positioning) — uses precise orbital data and atmospheric models.

Smartphone dual-frequency is mid-tier; survey-grade needs dedicated equipment.

Applications enabled

The sub-meter accuracy unlocks new applications:

Lane-level navigation

Roads have lanes typically 3-3.7 m wide. Sub-meter positioning distinguishes the lane the user is in. Used in: Google Maps lane guidance, Apple Maps detail layers, automotive turn-by-turn navigation.

Sports tracking

Cycling: distinguish parallel paths.
Running: better split-pace accuracy.
Golf: ball-position relative to fairway features.
Skiing: better trail-following.

Photo geotagging

Sub-meter accuracy lets photo apps record location to building precision, supporting reverse geocoding to specific addresses (instead of “somewhere on this block”).

Augmented reality

AR applications anchor virtual content to real locations; sub-meter accuracy supports more believable AR placement.

Delivery and logistics

Last-mile delivery accuracy: knowing within a meter where the customer's door is. Significant for e-commerce delivery operations.

Vehicle-to-everything (V2X)

Connected vehicles communicate positions; sub-meter accuracy supports safe automated driving features.

Surveying (informal)

Sub-meter accuracy supports light surveying tasks that would have needed dedicated equipment a decade ago: locating utility lines, marking property corners (informal — not legally surveyed), GIS data collection.

The future

GPS IIIF and continued L5 deployment will provide full L5 coverage by ~2030. Combined with multi-GNSS dual-frequency (Galileo, BeiDou, QZSS, NavIC all at the same 1176.45 MHz), the practical dual-frequency performance will continue to improve.

Beyond L5: L1C (added on GPS III, designed for Galileo interoperability) and Galileo E1 at the same 1575.42 MHz frequency enable dual-frequency without using L5. Less common in practice but viable for high-end applications.

The combination of dual-frequency + multi-GNSS + improving chipsets will continue to drive consumer GPS accuracy improvement through the 2020s and 2030s.

Common misconceptions

“Dual-frequency GPS is survey-grade.” Better than single-frequency, not survey-grade. Survey-grade needs cm-level accuracy through RTK or PPP techniques; consumer dual-frequency is ~0.5-1 m under ideal conditions.

“Every smartphone since 2018 has dual-frequency.” Not every — flagship Android phones since 2018; iPhones since Sept 2022 (only Pro line initially). Budget phones often still single-frequency.

“Dual-frequency works indoors.” No — GPS signals don't penetrate buildings; both single- and dual-frequency fail similarly indoors.

“Dual-frequency eliminates GPS errors.” Reduces ionospheric error specifically. Multipath, satellite-clock errors, atmospheric tropospheric delay, antenna orientation all remain.

“L5 and L1 are interchangeable.” Both are civilian GPS signals but they have different properties (frequency, power, code length, band protection). The pair gives different information than either alone.

“Dual-frequency drains battery.” Modestly more than single-frequency, but the overhead is small (~5-10% during active GPS use). Modern chipsets are power-efficient.

“Multi-GNSS and dual-frequency are the same thing.” Different: multi-GNSS = multiple constellations (GPS + Galileo + ...); dual-frequency = two frequency bands within any one constellation. They typically come together in modern smartphones but are conceptually distinct.

“Sub-meter accuracy is always available with dual-frequency.” Under ideal conditions yes; in urban canyons, indoor, heavy foliage, real-world accuracy is more modest.

“Apple was first to dual-frequency.” Late adopter. Xiaomi (2018), Google Pixel (2019), Samsung Galaxy S20 (2020) — Apple iPhone 14 Pro (2022). Apple's 4+ year delay was unusual.

“Dual-frequency reduces multipath.” No — multipath is independent of frequency. Reflections from buildings, vehicles, trees affect both L1 and L5 similarly. Multipath mitigation uses different techniques (correlator design, antenna gain patterns, machine-learning NLOS detection).

“The next iPhone will be even more accurate.” Marginal. Once dual-frequency multi-GNSS is in place, the limiting factors are antenna performance, urban-environment multipath, and processing software. Each new generation adds small refinements; revolutionary jumps are rare now that the major architectural transition (single → dual frequency) is done.

“Dual-frequency works everywhere equally.” L5 coverage matters. As of 2026, about 25 of ~31 operational GPS satellites broadcast L5; not every visible satellite has it. In some areas (specific times, specific constellations), dual-frequency reduces to effectively single-frequency for some satellites.

“You need a special antenna for dual-frequency.” Modern smartphone antennas handle both bands. External survey-grade receivers use larger purpose-built dual-band antennas with better performance, but the consumer smartphone form factor works adequately.

“Dual-frequency eliminates the need for network corrections (WAAS / EGNOS / SBAS).” Reduces but doesn't eliminate. SBAS augmentations provide additional corrections (satellite orbit / clock) that benefit even dual-frequency receivers. The combination of dual-frequency + SBAS achieves better accuracy than either alone.

How GPS Works— The pillar
GPS Accuracy Explained— Where dual-frequency fits in the accuracy landscape
Why GPS Is Not Always Accurate— Ionospheric error is the dominant single-frequency error
RTK GPS— The cm-level survey-grade alternative
Methodology— How content is sourced and verified

Frequently asked questions

What is dual-frequency GPS?

Dual-frequency GPS uses two GPS satellite signals at different frequencies to directly compute the ionospheric delay — the largest single error source for civilian single-frequency GPS. The two frequencies are typically L1 (1575.42 MHz, the original 1978 civilian signal) and L5 (1176.45 MHz, the safety-of-life signal added on Block IIF in 2010). Because ionospheric delay depends on signal frequency, the delay measured at two frequencies can be inverted to give the exact delay at either frequency. Single-frequency GPS receivers must estimate ionospheric delay from a model (the Klobuchar algorithm), which has up to ~50% error. Dual-frequency direct measurement reduces this to <5% of the original delay, dramatically improving overall accuracy.

When did smartphones get dual-frequency GPS?

The Broadcom BCM47755 chipset, announced in September 2017 and shipping in 2018, was the first dual-frequency consumer GNSS chipset. First smartphone to use it: the Xiaomi Mi 8 (May 2018). Google's Pixel 4 (October 2019) was the second major launch with dual-frequency. From 2020 onward, dual-frequency became increasingly common in Android flagships — Samsung Galaxy S20+ series, OnePlus 8 Pro, Huawei P40 Pro, and others. Apple was a late adopter: the iPhone 14 Pro (September 2022) was the first iPhone with dual-frequency GPS, expanding to standard iPhone 14 with the iPhone 15 Pro line. By 2024-2026, dual-frequency is standard in nearly all flagship and many mid-range smartphones globally.

How much more accurate is dual-frequency GPS?

Dramatically — but conditions matter. Under open sky with good satellite geometry: single-frequency typically achieves 3-5 meter horizontal accuracy; dual-frequency improves this to sub-meter (often ~0.5-1 m). Under partial sky obstruction (urban canyons, near tall buildings): the improvement is less dramatic but still significant — single-frequency might be ~5-10 m, dual-frequency ~2-4 m. Indoor performance: both degrade similarly because GPS signals can't penetrate buildings well; the marginal benefit of dual-frequency is small. The dramatic improvement applies to applications operating mostly outdoors (lane-level navigation, fitness tracking, surveying). For applications that operate mostly indoors or in heavy urban density, the practical benefit is more modest.

Why are L1 and L5 used as the pair?

L1 (1575.42 MHz) is the original 1978 civilian signal, present on every GPS satellite. L5 (1176.45 MHz) is the safety-of-life signal added on Block IIF (2010+) and continuing on GPS III and IIIF. The L1/L5 pairing has several advantages: (1) Both are present on all modern GPS satellites — at least the post-2010 generation. (2) The frequency separation (~400 MHz) is large enough for excellent ionospheric correction. (3) L5 is in an ITU-protected aviation radionavigation band, with stricter interference control. (4) L5 has higher power, longer code length, and better acquisition properties than L1. (5) Equivalent signals at the same 1176.45 MHz exist in Galileo (E5a), BeiDou (B2a), and QZSS (L5) — making multi-GNSS dual-frequency natural. L1+L2 is the older dual-frequency pairing used by surveying receivers; L1+L5 is the modern consumer-friendly choice.

What are the limitations of dual-frequency consumer GPS?

Several. (1) Limited L5 satellite availability historically: L5 was added on Block IIF (12 satellites, 2010-2016), then continued on GPS III and IIIF. As of 2026, ~25 of the operational satellites broadcast L5; full coverage (every visible satellite broadcasting L5) is approaching but not always available. (2) Urban canyon multipath: signals reflecting off buildings still corrupt the measurements; dual-frequency helps with ionospheric error but not multipath. (3) Indoor performance: dual-frequency doesn't help indoors where neither signal penetrates well. (4) Power consumption: slightly higher than single-frequency, though minimal in modern chipsets. (5) Antenna performance: smartphone antennas are constrained by size; both L1 and L5 must fit in a small package. The L5 signal is somewhat lower in the receivable spectrum which can favor smaller antennas. (6) Not every device is dual-frequency: budget and older devices remain single-frequency. (7) Dual-frequency doesn't eliminate the need for differential corrections (RTK) for sub-decimeter accuracy — it's a major step from single-frequency consumer GPS but doesn't replace specialized RTK receivers.

Sources

GPS.gov — GPS.gov — L5 signal specifications and dual-frequency civilian use · https://www.gps.gov/systems/gps/modernization/civilsignals/ · Accessed May 25, 2026.
Broadcom — Broadcom BCM47755 — first dual-frequency consumer GNSS chipset (2018 announcement) · https://www.broadcom.com/ · Accessed May 25, 2026.
ESA — ESA Galileo — E5a/E5b signal specifications · https://www.esa.int/Applications/Satellite_navigation/Galileo · Accessed May 25, 2026.
European GNSS Agency — EUSPA / European GNSS Agency reports on dual-frequency smartphone GNSS adoption · https://www.euspa.europa.eu/ · Accessed May 25, 2026.

Cite this article

APA format:

Steve K. (2026). Dual-Frequency GPS Explained. Coordinately. https://coordinately.org/learn/dual-frequency-gps-explained

BibTeX:

@misc{coordinately_dualfrequencygpsexplained_2026,
  author = {K., Steve},
  title  = {Dual-Frequency GPS Explained},
  year   = {2026},
  publisher = {Coordinately},
  url    = {https://coordinately.org/learn/dual-frequency-gps-explained},
  note   = {Accessed: 2026-06-05}
}