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Betaflight GPS Rescue mode is much like “Return to Dwelling” on a DJI drone. This characteristic is designed to fly your FPV drone again to its launch level and land it robotically in a failsafe or when your video feed will get sketchy. On this tutorial, I’m going to stroll you thru organising GPS Rescue Mode, testing it, and I’ll additionally share some tips about enhancing its efficiency and troubleshooting frequent points.
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Why GPS Rescue is a Recreation-Changer
Betaflight’s default failsafe motion is dropping the quad to the bottom. Now, with the newest GPS Rescue Mode, your drone can return near its launch level and land by itself! That is extremely helpful for long-range flights. Actually, I’ve misplaced depend of what number of instances GPS Rescue has saved my drones.
Select the Finest GPS?
Listed below are the concerns when selecting GPS for Rescue mode:
- M10 GPS is the most effective.
- It Ought to Help UBLOX protocol, keep away from NMEA protocol because it solely helps 1Hz replace fee and that’s too gradual.
- Get the largest GPS you possibly can comfortably slot in your drone – greater GPS comes with greater antenna and it’s higher for sign.
- In case your GPS doesn’t reliably offer you greater than 10 satellites out of doors, it’s dangerous to make use of.
GPS Suggestions
See my GPS testing right here: https://oscarliang.com/gps-review/
Prime Performer: GEPRC M1025Q
Prime Performer: HGLRC M100 5883
Smallest Price Having: GOKU GM10 Nano V3
Smallest Price Having: FlyFishRC M10 Mini
Smallest Price Having: HGLRC M100 Mini
Choosing a smaller GPS module helps save weight, but it surely does imply you’ll sacrifice a little bit of sensitivity that comes with fashions with a big antenna.
Technology of GPS Chip
Most GPS modules for FPV drones use both an M8, M9 or M10 chip. M10 chips are the latest and provide the most effective efficiency, able to connecting concurrently to 4 International GNSS methods (GPS, Galileo, Glonass, and Beidou). This ends in sooner lock-ons and connections to extra satellites. Regardless of their superior efficiency, the worth of M10 GPS is much like M8, making them a cheap improve.
Antenna Scratches
Seen scratches in your GPS antenna’s metallic patch? Don’t fear; this isn’t essentially an indication of defect or injury. It’s typically the results of manufacturing unit tuning to make sure optimum frequency. All these antenna have a nominal tuned frequency, however are sometimes impacted by building, elements location and soldering. Putting small nicks within the centre of the lengthy edges, or corners, can tremendous tune its frequency.
Is a Barometer Wanted?
A barometer measures altitude utilizing air stress, and whereas many flight controllers include one built-in, e.g. the BMP280 (such because the Speedybee F405 V4 and RushFPV F722 V2). Barometer just isn’t crucial for Rescue mode, however it may enhance altitude estimations accuracy, ends in higher altitude management and extra dependable landings. Simply keep in mind, in case you’re making use of conformal coating for water resistance, keep away from coating the barometer.
Some GPS modules provide a built-in barometer for an additional value. In case your flight controller doesn’t have one, including a module with a barometer may very well be helpful.
Is a Compass Needed?
A compass (as referred to as magnetometer in Betaflight) is for figuring out instructions.
Some GPS modules provide built-in compass, which might be related to the FC by way of the i2c port (SCL and SDA). Nonetheless, Betaflight Rescue Mode doesn’t require a compass to work, it may work out its course from GPS information.
Actually, an improperly calibrated compass would possibly trigger extra points than it solves. In my exams, Rescue mode labored completely tremendous and not using a compass.
inform if a GPS module has built-in compass? If it has 6 wires or solder pads, it means it has a compass – 5V and GND for energy, TX and RX is for the GPS, and SCL and SDA (i2c port) are for the compass. If it doesn’t have a compass, then there ought to solely be 4 wires/pads – 5V, GND, TX and RX.
Connecting GPS to Flight Controller
Wiring a GPS module to the flight controller is kind of easy. Merely join it on to any accessible UART on the FC, (TX to RX, RX to TX), and energy it with 5V.
- GPS RX – FC TX
- GPS TX – FC RX
- GPS 5V – FC 5V
- GPS GND – FC GND
- GPS SDA – FC SDA (if GPS has a compass/barometer)
- GPS SCL – FC SCL (if GPS has a compass/barometer)
Keep away from utilizing Softserial in your GPS connection, because it’s restricted to a 19200 baud fee. At 9600 baud, GPS reliability for Rescue Mode is compromised. A {hardware} serial port is your best choice for a secure and dependable connection.
Some flight controllers, just like the Speedybee F405, characteristic 4V5 pads. These are primarily the identical as 5V pads however have the additional benefit of drawing energy from USB. That is notably helpful for these instances when the GPS is taking some time looking for satellites. Through the use of the USB for energy, you keep away from the danger of your VTX overheating whereas ready on the bottom with a LiPo battery plugged in. It additionally helps the GPS lock sooner because the VTX isn’t transmitting and inflicting interference. Observe that some FCs would possibly provide 5V pads powered by USB however beneath completely different labels; verify with a multimeter if not sure.
Setup GPS in Betaflight
GPS Rescue mode in Betaflight is constantly evolving, so it’s essential to make use of the newest firmware model for brand new options and bug fixes. I like to recommend upgrading to Betaflight v4.5 for this course of: https://oscarliang.com/betaflight-4-5/
First, within the Configuration tab of the Betaflight Configurator, activate GPS for navigation and telemetry beneath the Different Options part. If GPS at all times deactivates after a reboot, it could be as a result of not deciding on GPS within the Cloud Construct choices throughout firmware flashing.
Subsequent, within the Ports tab, assign GPS to the suitable UART beneath “Sensor Enter.” Betaflight helps varied baud charges: 9600, 19200, 38400, 57600, 115200. In case you are not sure what baudrate your GPS module helps, deciding on AUTO normally works.
The really useful baud fee for 10Hz GPS information fee is 38400 or 57600. There’s little to be gained through the use of 115200 with 10hz, however utilizing decrease baud charges cut back the CPU load and are extra proof against electrical noise.
| GPS Knowledge Fee | Baud Fee | CPU Load | Feedback |
| 20Hz | 115200 | Highest | M10 solely; take a look at rigorously! |
| 10Hz | 38400 or greater | Medium | 10Hz and 57600 is really useful for GPS Rescue |
| 5Hz | 19200 or greater | Medium | Okay settings for common use |
| 1Hz-2Hz | 9600 or greater | Least | Too gradual for clean GPS rescue, OK for easy place/pace data |
Within the GPS tab, do the next:
- Choose UBLOX because the Protocol, which is the usual for many GPS.
- Allow Auto Config.
- Allow Use Galileo – it improves positioning accuracy.
- Allow Set Dwelling Level As soon as to forestall resetting the house location with every arm/disarm cycle till you unplug the battery.
- Select Auto-detect for Floor Help Kind to boost positioning accuracy.
- Save and Reboot.
After organising, the GPS indicator on the prime of the configurator ought to mild up, indicating communication with the FC. A purple icon means GPS is speaking to the FC however and not using a lock, and a yellow icon signifies a profitable GPS lock.
If the GPS indicator stays off, verify for
- GPS just isn’t powered? Attempt plugging in battery?
- Incorrect parameters, for example, unsuitable baud fee or protocol.
- Incorrect wiring, attempt swapping TX and RX.
verify if GPS is working?
Questioning in case your GPS module is speaking to the flight controller? The ‘gpspassthrough’ command within the CLI can reveal any ongoing information change. Seeing a stream of binary information means communication is occurring.
Run the ‘gpspassthrough‘ command within the CLI can reveal any ongoing information change between the FC and GPS.
Seeing a stream of hieroglyphic binary information characters means communication is occurring. When you see nothing, there could also be a difficulty with energy, UART connection, or your setup.
Ready for GPS Lock
Getting a GPS lock, or “3D repair,” requires locking onto no less than 4 satellites and may take a couple of minutes.
While you energy up the GPS module for the primary time in a brand new location, it at all times takes longer to seek for satellites, referred to as a “chilly begin”. Subsequent begins are typically faster because the module remembers satellite tv for pc positions (for instance whenever you change battery).
It’s more durable to get a lock indoor. If it’s important to take a look at this inside the home, attempt to get near the home windows with the antenna pointing to the sky.
You will notice GPS associated info beneath the GPS tab, the place it exhibits the standing of your lock, your GPS coordinates and placement on a map, verifying the accuracy of your GPS lock.
LED Indicators
On most GPS such because the BN220, BN180 and BN880, there are two LED indicators, labelled “TX” (normally blue) and “PPS” (normally purple).
Flashing blue (TX) signifies UART connection. Whether it is off, then the GPS just isn’t sending information out. That is additionally an indicator of the refresh fee, in 1Hz it ought to flash as soon as per second, whereas in 5Hz it would flash 5 instances a second.
Flashing purple (PPS) signifies the 2D/3D repair standing of the GPS. If “PPS” is off then you definately don’t have a repair but.
When it will get a 3D repair, the purple LED on the BN-220 module ought to blink (along with the blue LED).
OSD
You’ll be able to show GPS data within the OSD. Try this tutorial about Betaflight OSD in case you are not conversant in it. You’ll be able to show GPS coordinates, distance and course to residence and extra.
To know what number of satellite tv for pc have been acquired, place the gps sats aspect in your OSD. 6-8 is the minimal for rescue mode to work, the extra the higher. Your GPS coordinates may even get extra correct whenever you purchase extra satellites.
You can too show HDOP subsequent to the variety of satellites. HDOP is a measurement of the well being of the GPS locks. A HDOP worth of 1 or beneath is good, which might offer you an accuracy of about 2.5 meters or much less. It could be oversimplying, however simply consider it as how a lot the drone can be drifting horizontally in meters.
To do that, go to the CLI, and enter:
set osd_gps_sats_show_hdop = on
save
Radio Telemetry
After getting GPS setup and acquired a lock, go to the radio’s telemetry web page, choose “Uncover new sensors”. Some GPS associated new sensors ought to seem together with GPS coordinates. This solely works in case your radio system helps Telemetry – comparable to ExpressLRS and Crossfire.
This lets you log GPS coordinates in your radio, it permits you to preserve monitor of the final recognized place of your plane. This may be useful for looking for the misplaced quadcopter in case you can’t see the coordinates in your DVR.
Testing Angle Mode
Betaflight’s GPS Rescue mode depends on Angle mode (a self-leveling flight mode) to stabilize the drone. Due to this fact, it’s important to make sure Angle mode is functioning appropriately.
First, confirm that the Accelerometer is enabled within the Configuration tab.
Subsequent, proceed to the Setup tab and calibrate the Accelerometer on a stage floor. Failure to take action would possibly outcome within the drone drifting whereas in Angle mode.
To check Angle mode, attempt hovering the drone to see if it’s self-levelling as anticipated. Keep in mind, Angle mode makes use of solely the Accelerometer and Gyro, so it received’t preserve the drone completely stationary like a DJI drone would. A slight drift as a result of weight distribution and wind is regular, so long as the drone stays secure. If drifting is noticeable, you possibly can trim the accelerometer within the Configuration tab to reduce it utilizing stick instructions on the bottom (however unlikely to fully eradicate it so don’t fear).
Additionally, pay attention to the throttle place throughout hover (with a half discharged battery). This worth will likely be helpful when organising Rescue mode later.
Disabling Magnetometer
As really useful by Betaflight Builders, except you might be completely positive that your Magnetometer (aka compass) has been correctly calibrated and is working appropriately, in any other case it’s best to disable it (within the Configuration tab, beneath Accelerometer and Barometer). Betaflight Rescue Mode doesn’t depend upon Magnetometer so it’s tremendous to disable it.
To verify in case your magnetometer is working, evaluate the compass worth in your telephone (set to point out True North, not Magnetic North), with the heading on Configurator’s primary opening display screen, the GPS tab in Configurator, or the Sensors tab debug line 5 in debug mode GPS_RESCUE_HEADING, and verify that each are inside 10 levels of one another. If the heading at all times begins at North, and follows quick actions shortly however then jumps to another worth, the Magazine just isn’t proper.
Keep away from Utilizing 8K/8K
As per builders suggestions, keep away from 8K PID Loop Frequency, use 4K or decrease. That is because of the CPU intensive nature of Rescue Mode, particularly with excessive baud fee comparable to 56700 or greater. Reducing PID looptime will go away extra CPU headroom for Rescue mode to work extra reliably.
Enabling GPS Rescue Mode in Failsafe
Navigate to the Failsafe tab within the Betaflight Configurator. When you can’t discover this tab, ensure you’ve enabled the “Professional Mode” choice on the prime of the display screen (subsequent to the Replace Firmware button).
Beneath Stage 2, choose GPS Rescue. Now, in case your drone enters failsafe, it would set off GPS Rescue Mode.
So, what precisely is failsafe, and what are stage 1 and stage 2? Right here’s a fast rundown: Your drone enters failsafe upon dropping radio sign. By default, it might simply drop to the bottom, however with Rescue Mode, it would try and return residence.
Throughout a failsafe, your drone will first enter Stage 1, pausing briefly (guard time) to see if the sign returns. If not, it progresses to Stage 2, activating Rescue mode to convey the quad again.
Whereas setting GPS Rescue as your failsafe technique is helpful, it’s not fitted to all environments. As an illustration, it’s not advisable in bando, forests, stadiums, or indoors. Shedding management beneath a tree or inside a constructing may outcome within the drone crashing into obstacles when Rescue mode engages.
When you’ve got no GPS lock when it failsafes, the quad will (ought to) simply drop to the bottom.
What Occurs after Rescue Mode is Activated?
Watch GPS Rescue Mode in motion right here:
Rescue mode includes 5 phases:
- Self Degree: The drone permits Angle Mode and self stage.
- Ascend: The drone climbs to a user-configured altitude.
- Rotate: It turns in the direction of the house course.
- Fly Dwelling: The drone begins its journey again to the launch level. The flight may not be a clean cruise, because the drone would possibly pitch forth and again attempting to regulate its pace.
- Descend: As soon as close to the launch level, it begins descending slowly. The descent could be uneven, with the motors making pulsating sounds because the drone tries to decelerate.
- Land: Upon touching the bottom, the drone robotically disarms, with motors terminating based mostly on influence, not based mostly on altitude.
Cease Rescue Mode
If Rescue mode was activated by way of a change, regaining full management is so simple as disengaging that change.
If activated by failsafe:
- If it’s an actual failsafe triggered by a loss radio hyperlink, the pilot should transfer the sticks greater than 30% to regain management after radio hyperlink comes again.
- If the failsafe was triggered manually by way of a change, merely disengage the failsafe change — no must wiggle the sticks.
GPS Rescue Settings Defined
Settings for GPS Rescue mode can be found within the Failsafe tab.
You must tweak the GPS Rescue settings in Betaflight to your particular setup and setting. I extremely advocate visiting the Betaflight wiki to know a full understanding of what every parameter entails: https://github.com/betaflight/betaflight/pull/11579. The default settings provide a strong start line, particularly for five″ freestyle drones.
Right here, I’ll stroll you thru the settings, sharing the values I exploit on my 5″ freestyle drone and the reasoning behind every selection.
Accessing all settings is easy by way of CLI—simply enter get gps_rescue for a complete record of GPS-related parameters. Nonetheless, adjusting them within the GUI (Failsafe tab) tends to be extra user-friendly.
Altitude Mode: It determines the altitude at which the quad returns residence.
- Most altitude is the best altitude your quad is flown throughout that flight
- Mounted altitude is only a predefined worth
- Present altitude is no matter peak that the quad is at when GPS rescue mode is activated
The only option varies with every flight’s context and setting. Most altitude generally is a protected choice, but it surely’s not at all times the proper choice. As an illustration, in case you was diving a mountain in that flight, you possibly can be losing vitality climbing again to the max altitude when Rescue mode is activated. When flying over ocean the place there’s no obstructions, mounted altitude may very well be choice. Use frequent sense, be adaptive to the completely different setting and missions.
Preliminary Climb (meters): The gap the quad will climb to this peak above the present altitude, when a rescue is initiated and the altitude mode is about to Present Altitude. Additionally added when in Max Altitude Mode.
Return Altitude (meters): Solely applies in Mounted Altitude mode. This determines the drone’s return altitude relative to its takeoff level. It must be excessive sufficient to clear any obstacles like timber and buildings however not so excessive that it excessively consumes battery throughout ascent. For my flying spots, which options tall timber and small hills, I’ve bumped this as much as 50 meters.
Ascend/Descend Fee (meters/second): These charges rely in your setting, climate, and quad’s energy. For my 5″ setup, the defaults ought to work effectively. If utilizing Li-ion packs or low C-rating LiPo, take into account a decrease ascend fee.
Return floor pace (meters/second): That is the pace at which the quad travels throughout Rescue. The default 5m/s is 18km/h which I discover means too gradual for many drones, I usually double that to 12m/s (43km/h) for micro drones, or 17m/s (60km/h) for five″ and seven″ drones. The quad’s journey course can be extra correct and replace sooner in greater pace (within the absence of a compass). Don’t set it to decrease than 2m/s or orientation received’t work. Observe when getting into this worth in GUI, the unit is completely different than CLI (which is cm/s).
Most Pitch Angle: This setting caps the drone’s tilt angle. The next angle results in extra aggressive returns and better pace. Perhaps helpful for heavier, excessive drag and low authority drones. In windy situations, a better angle could be crucial for sustaining pace, particularly for smaller quads. Nonetheless, with an excessively steep angle the drone may lose altitude and crash. Not sure of what to set? Beginning with the default worth of 40 levels is a protected wager—it’s labored effectively for my 4inch and 5inch setup.
Descend Distance (meters): That is the distance from residence our drone begins to descend. I keep on with the default right here.
Throttle minimal, Throttle most, Throttle hover – these are the min, max and hover throttle values you wish to use throughout Rescue mode. Set most so the quad isn’t too quick/jerky (it must be above your hover level), set min to maintain the props spinning at an inexpensive fee (it must be decrease than your hover level). I left Throttle Min/Max at default.
To set Throttle Hover, you should decide an correct worth. Check fly your quad and see at what throttle it hovers (simply sufficient throttle to maintain the quad afloat). Use the “Throttle %” OSD aspect to get the precise worth as an alternative of simply guessing. Ideas, the best worth ought to trigger the quad to climb a bit whereas in stage mode, if the hover worth is about too low, the quad will drop early within the rescue – probably into the water! And the hover throttle worth goes to be barely completely different is dependent upon battery voltage, so that you would possibly surprise, what throttle worth ought to I exploit? Nicely you bought to ask your self, at what battery voltage you might be almost definitely going to get a failsafe? It’s acquired to be when the drone is the fartherest from you proper? And you might be in all probability simply earlier than half means via the battery, round 3.8V to three.9V. So use the hover throttle worth at this voltage.
Minimal Distance to Dwelling (meters): If Rescue begins too near residence (inside this minimal distance), the drone will fly away on its present heading till this distance from residence, and begin the traditional Rescue behaviour. I go away this on the default 15 meters.
Minimal Satellites: A minimal of 8 satellites ensures dependable Rescue mode operation. When you take off earlier than the GPS attain the minimal quantity of satellites, it received’t know the precise residence location. Extra satellites imply higher accuracy. I go away this on the default, 8.
Permit Arming With out Repair: This selection gives flexibility by permitting arming and not using a GPS lock. I allow this for the comfort of take a look at flights, however make sure you get a GPS lock for whenever you intend to make use of GPS Rescue Mode.
Beware that GPS Rescue WILL NOT work for that flight in case you arm earlier than getting a satellite tv for pc lock (as a result of it doesn’t know the house place).
When you’ve got hassle getting these many sats (or it takes a very long time), try my tutorial on how one can increase your GPS receiver efficiency. Get a brand new GPS in case you should, they solely value $15, an incredible funding for safeguarding your $300 quad!
Sanity Checks: When set to “ON”, it displays GPS Rescue mode situations, for instance:
- Is the GPS nonetheless related to the FC?
- Are we getting variety of satellite tv for pc locks?
- Are we no less than 20 meters away from residence?
- Are we getting nearer to the house, and we didn’t hit an impediment?
If any of those situations should not met, it would abort rescue mode and your quad will simply disarm and drop to the bottom. So yea, it’s not ultimate in case you are flying over unrecoverable locations like ocean or mountains, however typically, it must be on for security causes.
The Betaflight wiki additionally recommends setting Sanity Checks to “Failsafe Solely” in case you are having hassle with the choice “On” throughout testing. It turns Sanity Checks off when Rescue mode is activated by a change however solely turns it on when it’s in failsafe. That is additionally my most popular choice.
It’s dangerous to show off Sanity Verify completely, you would possibly get an indefinite flyaway. In Betaflight 4.4, there may be now a restrict of 20s of sanity failure even when all sanity checks are off. It’s a security factor. By no means fly with all sanity checks off.
Manually Activate GPS Rescue?
In addition to failsafe, you may have the choice to manually set off GPS Rescue by flipping a change in your radio transmitter. This characteristic turns out to be useful throughout emergencies, comparable to dropping your means or encountering points together with your FPV system, permitting your drone to autonomously return residence.
Go to the Modes tab in Betaflight Configurator and assign an AUX channel particularly for GPS Rescue Mode. When you’re new to configuring modes, try my tutorial right here: https://oscarliang.com/betaflight-modes/
Throttle Channel Fallback
Throughout Stage 1 of a failsafe, your drone goes into channel fallback, which means every radio channel is about to predefined values. It’s clever to overview these values to make sure security.
By default, the Channel Fallback for Throttle is about to “Auto,” which reduces the throttle to zero, ends in the motors stopping momentarily through the guard time. This interruption may destabilize the drone earlier than GPS Rescue kicks in, doubtlessly failing a sanity verify and inflicting the drone to drop to the bottom.
One resolution is to regulate the Throttle Channel Fallback from “Auto” to “Maintain,” sustaining the final throttle worth all through the guard time, stopping motor stalling.
Nonetheless, I personally want setting the throttle to the hover worth, in addition to centering all roll/pitch/yaw channels (set them to 1500 or auto), and prompts the change for Angle mode. This manner, the quad ranges itself out when failsafe occurs, earlier than GPS Rescue engages.
Keep in mind, by no means set throttle to zero throughout Stage 1 of failsafe!
Check GPS Rescue
Testing GPS Rescue is an important step earlier than counting on it in real-world situations. Right here’s my strategy to making sure it really works as anticipated.
The Setup
First, assign a change in your radio to GPS Rescue to verify it may certainly convey your drone residence. Ought to something not go in accordance with plan, flicking the change off ought to instantly return management to you.
Subsequent, allocate one other change to Failsafe within the Modes tab. This simulates a full failsafe occasion, similar to dropping RC sign, however in a a lot safer method since you possibly can exit the mode every time crucial utilizing the change. It’s essential to notice that this setup is strictly for testing functions. When you’re completed, keep in mind to take away Failsafe within the Modes tab.
With the propellers eliminated, head to the Modes tab and make sure that activating the Failsafe change certainly triggers Rescue mode, throughout which your radio sticks will likely be momentarily locked out. Confirm in case you can exit failsafe mode and regain management easily.
Whereas bench testing with a USB connection, the Rescue mode indicator may not illuminate as different flight modes do. Nonetheless, so long as the small yellow bar bar strikes into the activation zone, it’s working appropriately.
Incorporating GPS-related info into your OSD is helpful, offering insights into the drone’s standing. The Flight Mode indicator is especially useful, displaying “RESC” when in Rescue mode, “Air” in fee mode, and “Angle” in angle mode.
Area Testing
For an precise take a look at, select an open space free from obstacles and folks, with gentle grass. Guarantee you may have a sound residence level earlier than taking off – ideally the OSD ought to present no less than 8 satellites or extra.
Take off and fly 50-100 meters away, near the bottom, then set off Failsafe mode utilizing the change. The quad ought to promptly change to GPS Rescue mode, indicated by flight mode within the OSD because it adjustments from AIR to RSC.
Take note of the house arrow within the OSD; when it’s pointing up, means you’re heading residence, when pointing down means you’re flying away. Initially, the arrow would possibly level within the unsuitable course in case you are not utilizing a magnetometer, which is regular because it takes 5 to 10 seconds for Betaflight to work out which course it’s heading—simply make sure the drone isn’t flying the exact opposite course after 10 seconds.
You’ll be able to give up failsafe mode at any time by flipping the change, regaining full management instantly.
When you select to not disengage, the drone will proceed flying again to the launch level. Upon arrival, it would hover briefly earlier than beginning a gradual descent, throughout which the motors could pulsate, till it safely lands and disarms robotically.
Chances are you’ll wish to repeat this course of just a few instances, till you’re assured within the system’s reliability. After thorough testing, don’t neglect to take away Failsafe from the Modes tab.
Ideas and Troubleshooting
Finest Locations to Mount GPS Module
Ensuring your GPS module’s ceramic patch antenna has an unobstructed view of the sky is essential for fast and dependable satellite tv for pc lock-on. Something protecting it, notably conductive supplies like carbon fiber, electrical wires, or metallic, can considerably weaken the GPS sign.
Avoiding EMI
Electromagnetic interference (EMI) from different electrical elements in your quad also can have an effect on GPS efficiency. Notable sources of RF interference embrace HD cameras and video transmitters. To mitigate this, mount your GPS as far-off from these units as potential.
Correct Mounting Orientation
A standard error is mounting the GPS the other way up. The receiver antenna, identifiable by its flat sq. form with a small metallic round half within the heart, ought to at all times face upwards. Guarantee no elements impede this facet. Within the following picture for instance, the ceramic antenna is dealing with up.
The place to Mount GPS
Listed below are the concerns when mounting your GPS on a quad:
- Tthere’s nothing blocking the GPS unit
- The ceramic antenna is pointing to the sky
- Supreme mounting spots embrace the highest of your quad, far-off from VTX and RX antennas
- Stay away from potential radiation sources like HD cameras which may lack correct EMI shielding
Listed below are just a few mounting concepts:
On prime of your GoPro/HD digital camera.
On prime of the body if utilizing an under-slung battery setup.
On a mast to raise the GPS away from the quad. Nonetheless, be cautious of proximity to VTX antennas.
One in every of my favorite methods is to put in the GPS on the battery strap.
Getting a GPS Lock Quicker
Most GPS modules characteristic a small battery to retailer satellite tv for pc information and time, aiding sooner lock-on. As soon as the GPS has locked onto satellites, it retains their positions for fast reconnection after battery adjustments. In case your GPS persistently takes lengthy to lock, verify if its battery is depleted utilizing a multimeter. Reduce interference as a lot as potential—for example, by relocating a strong VTX, particularly in case you’re on a 1.3GHz FPV setup. Climate situations like cloudy days also can influence GPS sign high quality.
For extra tips about optimizing BN220 for elevated satellite tv for pc locks, try my devoted tutorial: https://oscarliang.com/gps-settings-u-center/
Solutions instantly from Betaflight Builders
I like to recommend 10 satellites. [And] Await 30s after [you have] 10 satellites for altitude to stabilise [before taking off].
All the time verify regular GPS Rescue behaviour at first of a essential flight by testing with the failsafe change. Set the change to instantly enter Stage 2. You’ll be able to enter and go away GPS Rescue by way of the change with rapid on and off impact. Verify that the quad rotates and flies in the direction of residence and does the proper issues earlier than you might be so far-off {that a} true failsafe could happen.
ALWAYS CHECK that the Dwelling Arrow factors instantly again in the direction of residence after takeoff! Typically, in case you take off and spin round throughout arming or instantly on takeoff, the quad’s perspective info can develop into corrupted, and the Dwelling Arrow can level the unsuitable means. It’s finest to arm cleanly and fly away from Dwelling in a straight line at an inexpensive pace instantly after takeoff. Watch the Dwelling Arrow rigorously to make sure it shortly factors again to Dwelling. If the Dwelling Arrow factors the unsuitable means when a failsafe happens, the GPS Rescue will initially fly off within the unsuitable course, and in some circumstances, it’s possible you’ll lose the quad.
Improper Route in Rescue Mode?
With no compass, rescue mode ought to nonetheless work because the quads calculate course via GPS information comparability.
Originally, your quad could be wandering round and even flying in the direction of the unsuitable course however finally it ought to self-correct. With weak GPS connection, it may take longer to right.
In case you are utilizing a compass and it’s flying the unsuitable course, then perhaps there’s one thing unsuitable with the compass, or perhaps it’s not calibrated correctly. On this case attempt turning off magnetometer in Betaflight and take a look at once more. If it really works now, it proves your compass is the supply of the issue.
In case your yaw is jerky throughout Rescue mode, your GPS could be updating too slowly (e.g. 1Hz), attempt to enhance it to 5Hz and even 10Hz following this information (solely works on sure GPS modules).
Checking GPS Accuracy (HDOP/PDOP)
HDOP and PDOP are measurements of how correct your GPS is. Decrease values imply higher accuracy. In INAV they use HDOP and in Betaflight 4.5, they use PDOP.
HDOP (Horizontal Dilution of Precision) and PDOP (Place Dilution of Precision) are each measures of GPS accuracy, however they deal with completely different facets. HDOP primarily displays the accuracy of horizontal place (longitude and latitude), whereas PDOP considers the accuracy of each horizontal and vertical positioning (latitude, longitude, and altitude).
You’ll be able to show PDOP in Betaflight OSD by getting into set osd_gps_sats_show_hdop = ON within the CLI. Here’s what the worth means:
- 1.0 to 1.5: Wonderful accuracy, very secure GPS lock.
- 1.5 to 2.0: Acceptable, minor drifting would possibly happen.
- 2.0 to three.0+: Poor accuracy, important place drift is frequent.
Extra satellites sometimes decrease your PDOP/HDOP, enhancing GPS accuracy. Digital interference, particularly from units like GoPro cameras or Wi-Fi, can negatively have an effect on PDOP/HDOP and trigger instability in GPS maintain mode.
Keep away from Softserial
Keep away from utilizing Softserial for GPS Rescue because it’s too gradual. Chances are you’ll use it to show GPS associated data on the OSD, but it surely’s merely not dependable sufficient for GPS Rescue. It’s finest to make use of a {hardware} serial port (any TX and RX pins on the FC), and set baudrate to no less than 57600.
Not Getting GPS Lock
Interference out of your quad’s electronics, such because the VTX, telemetry-equipped radio receivers, and even wires carrying important present, can hinder your GPS’s skill to lock onto satellites. When you’re dealing with difficulties attaining a GPS lock, take into account the next steps:
- Energy the Flight Controller (FC) by way of USB to verify if it powers the GPS module. If not, transfer the GPS module’s energy connection to a special pad on the FC that will get energy from the USB port.
- Isolate the FC’s Energy Provide: Powering solely the FC with out the VTX may also help you get a faster GPS lock. However, it’s advisable to mount your GPS so far as potential from each the VTX and RX antennas to reduce potential interference.
- Shielding Electrical Wires: shielding wires that conduct important present can mitigate interference. These wires can act like antennas, doubtlessly disrupting GPS indicators.
GPS satellites function on two frequencies, L1 1575.42MHz and L2 1227.60MHz. Consequently, a 1.3GHz FPV setup would possibly intervene together with your GPS. Nearly all of pilots use 5.8GHz, which typically avoids this drawback. Nonetheless, given the weak GPS sign—originating from satellites in house—even sturdy close by indicators could cause interference. Thus, positioning the GPS module away from any transmission sources is essential.
Operating GPS wires beneath the VTX could cause points, notably if the VTX lacks enough RF shielding. This RF noise can compromise GPS performance. For instance, the Avatar VTX V1 was recognized to trigger GPS issues when wires are routed beneath it. A possible repair includes grounding the VTX’s shielding. Alternatively, shielding the wires between the GPS and FC—and making certain they’re grounded—would possibly provide an answer.
I attempted to defend wires with foil in one in all my builds, then related the foil to a floor pad on the FC. After wrapping it with material tape to forestall short-circuiting the body, I observed minimal enchancment. Whereas some have reported optimistic outcomes with this modification, it’s price exploring if different easy options are unavailable.
Didn’t Activate GPS After Updating Betaflight
When you’re unable to allow GPS after flashing the newest Betaflight model, it’s potential that some options together with GPS have been excluded from the compiled firmware – a brand new characteristic referred to as Cloud Construct System.
To confirm if that is the issue, enter the next command within the CLI:
characteristic gps
Ought to the CLI reply with “gps not accessible,” it signifies that the GPS performance was not included in your FC’s Betaflight firmware. To resolve this, you’ll must reflash your FC. This time, make sure that the GPS choice is chosen within the Cloud Construct system throughout compilation: https://oscarliang.com/flash-update-betaflight/#Cloud-Construct-System
Understanding GPS Coordinates Precision
When displaying GPS coordinates within the OSD, you’re supplied with choices to decide on the variety of decimal locations proven—at present, solely 4 and seven decimal choices can be found. This choice instantly influences how precisely you possibly can pinpoint a location on a map based mostly on the GPS information.
The “Decimal Levels” Wikipedia web page gives an in depth desk evaluating diploma precision to bodily distance:
decimal locations levels distance ------- ------- -------- 0 1 111 km 1 0.1 11.1 km 2 0.01 1.11 km 3 0.001 111 m 4 0.0001 11.1 m 5 0.00001 1.11 m 6 0.000001 11.1 cm 7 0.0000001 1.11 cm 8 0.00000001 1.11 mm
It’s essential to distinguish between accuracy and precision on this context. The GPS could show a excessive diploma of precision (variety of digits), however not all decimal locations could replicate true accuracy. Because of this whereas your GPS can report coordinates to a really tremendous decision, the precise accuracy—how shut these coordinates are to the true location—could fluctuate.
Edit Historical past
- Oct 2018: Tutorial creation.
- Aug 2020: Updates for GUI and CLI parameter adjustments, addition of throttle settings.
- Feb 2023: BF4.4 replace with auto-landing characteristic.
- Mar 2024: BF4.5 replace.
- Apr 2025: up to date
