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Betaflight GPS Rescue mode is just like “Return to Residence” on a DJI drone. This characteristic is designed to fly your FPV drone again to its launch level and land it mechanically 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 recommendations on enhancing its efficiency and troubleshooting widespread points.
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Why GPS Rescue is a Sport-Changer
Betaflight’s default failsafe motion is dropping the quad to the bottom. Now, with the most recent GPS Rescue Mode, your drone can return near its launch level and land by itself! That is extremely helpful for long-range flights. Truthfully, I’ve misplaced rely of what number of instances GPS Rescue has saved my drones.
Methods to Select the Greatest GPS?
Listed below are the issues when selecting a very good GPS for Rescue mode:
- M10 GPS is the perfect.
- It Ought to Help UBLOX protocol, keep away from NMEA protocol because it solely helps 1Hz replace price and that’s too gradual.
- Get the most important GPS you may comfortably slot in your drone – larger GPS comes with larger antenna and it’s higher for sign.
- In case your GPS doesn’t reliably provide you with greater than 10 satellites outside, it’s dangerous to make use of.
GPS Suggestions
See my GPS testing right here: https://oscarliang.com/gps-review/
High Performer: GEPRC M1025Q
High Performer: HGLRC M100 5883
Smallest Value Having: GOKU GM10 Nano V3
Smallest Value Having: FlyFishRC M10 Mini
Smallest Value Having: HGLRC M100 Mini
Choosing a smaller GPS module helps save weight, nevertheless it 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 most recent and supply the perfect efficiency, able to connecting concurrently to 4 World GNSS techniques (GPS, Galileo, Glonass, and Beidou). This ends in sooner lock-ons and connections to extra satellites. Regardless of their superior efficiency, the value of M10 GPS is just like M8, making them an economical 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. A majority of these antenna have a nominal tuned frequency, however are sometimes impacted by building, parts location and soldering. Putting small nicks within the centre of the lengthy edges, or corners, can nice tune its frequency.
Is a Barometer Wanted?
A barometer measures altitude utilizing air strain, and whereas many flight controllers include one built-in, e.g. the BMP280 (such because the Speedybee F405 V4 and RushFPV F722 V2). Barometer shouldn’t be needed for Rescue mode, however it may possibly enhance altitude estimations accuracy, ends in higher altitude management and extra dependable landings. Simply keep in mind, for those who’re making use of conformal coating for water resistance, keep away from coating the barometer.
Some GPS modules supply a built-in barometer for an additional value. In case your flight controller doesn’t have one, including a module with a barometer might be helpful.
Is a Compass Crucial?
A compass (as generally known as magnetometer in Betaflight) is for figuring out instructions.
Some GPS modules supply built-in compass, which may 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 possibly work out its path from GPS information.
In actual fact, an improperly calibrated compass may trigger extra points than it solves. In my assessments, Rescue mode labored completely nice with out a compass.
Methods to 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 sort of simple. Merely join it on to any out there 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 price. At 9600 baud, GPS reliability for Rescue Mode is compromised. A {hardware} serial port is the best choice for a steady and dependable connection.
Some flight controllers, just like the Speedybee F405, characteristic 4V5 pads. These are basically the identical as 5V pads however have the additional benefit of drawing energy from USB. That is significantly useful for these instances when the GPS is taking some time looking for satellites. By utilizing the USB for energy, you keep away from the chance of your VTX overheating whereas ready on the bottom with a LiPo battery plugged in. It additionally helps the GPS lock sooner for the reason that VTX isn’t transmitting and inflicting interference. Observe that some FCs may supply 5V pads powered by USB however underneath totally different labels; examine with a multimeter if not sure.
Methods to Setup GPS in Betaflight
GPS Rescue mode in Betaflight is repeatedly evolving, so it’s essential to make use of the most recent firmware model for brand spanking 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 underneath the Different Options part. If GPS all the time deactivates after a reboot, it is perhaps as a result of not choosing GPS within the Cloud Construct choices throughout firmware flashing.
Subsequent, within the Ports tab, assign GPS to the suitable UART underneath “Sensor Enter.” Betaflight helps numerous baud charges: 9600, 19200, 38400, 57600, 115200. If you’re not sure what baudrate your GPS module helps, choosing AUTO often works.
The really helpful baud price for 10Hz GPS information price is 38400 or 57600. There may be little to be gained through the use of 115200 with 10hz, however utilizing decrease baud charges cut back the CPU load and are extra immune to electrical noise.
| GPS Information Fee | Baud Fee | CPU Load | Feedback |
| 20Hz | 115200 | Highest | M10 solely; check rigorously! |
| 10Hz | 38400 or increased | Medium | 10Hz and 57600 is really helpful for GPS Rescue |
| 5Hz | 19200 or increased | Medium | Okay settings for basic use |
| 1Hz-2Hz | 9600 or increased | 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 Residence 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 Sort to reinforce positioning accuracy.
- Save and Reboot.
After organising, the GPS indicator on the high of the configurator ought to mild up, indicating communication with the FC. A purple icon means GPS is speaking to the FC however with out a lock, and a yellow icon signifies a profitable GPS lock.
If the GPS indicator stays off, examine for
- GPS shouldn’t be powered? Strive plugging in battery?
- Incorrect parameters, as an illustration, fallacious baud price or protocol.
- Incorrect wiring, strive swapping TX and RX.
Methods to examine 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 trade. Seeing a stream of binary information means communication is occurring.
Run the ‘gpspassthrough‘ command within the CLI can reveal any ongoing information trade between the FC and GPS.
Seeing a stream of hieroglyphic binary information characters means communication is occurring. In case 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 at the least 4 satellites and may take a couple of minutes.
Once you energy up the GPS module for the primary time in a brand new location, it all the time takes longer to seek for satellites, generally known as a “chilly begin”. Subsequent begins are usually faster because the module remembers satellite tv for pc positions (for instance once you change battery).
It’s tougher to get a lock indoor. If you need to check this inside the home, attempt to get near the home windows with the antenna pointing to the sky.
You will note GPS associated info underneath the GPS tab, the place it reveals 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” (often blue) and “PPS” (often purple).
Flashing blue (TX) signifies UART connection. Whether it is off, then the GPS shouldn’t be sending information out. That is additionally an indicator of the refresh price, in 1Hz it ought to flash as soon as per second, whereas in 5Hz it is going to flash 5 instances a second.
Flashing purple (PPS) signifies the 2D/3D repair standing of the GPS. If “PPS” is off then you definitely 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 may show GPS data within the OSD. Take a look at this tutorial about Betaflight OSD if you’re not conversant in it. You may show GPS coordinates, distance and path to dwelling and extra.
To know what number of satellite tv for pc have been acquired, place the gps sats factor in your OSD. 6-8 is the minimal for rescue mode to work, the extra the higher. Your GPS coordinates can even get extra correct once you purchase extra satellites.
It’s also possible to 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 under is good, which might provide you with an accuracy of about 2.5 meters or much less. It is perhaps 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 bought 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 – corresponding to ExpressLRS and Crossfire.
This lets you log GPS coordinates in your radio, it permits you to hold observe of the final identified place of your plane. This may be useful for looking for the misplaced quadcopter for those who 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. Subsequently, 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 may outcome within the drone drifting whereas in Angle mode.
To check Angle mode, strive 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 hold 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 steady. If drifting is noticeable, you may trim the accelerometer within the Configuration tab to attenuate it utilizing stick instructions on the bottom (however unlikely to fully get rid of it so don’t fear).
Additionally, be aware of the throttle place throughout hover (with a half discharged battery). This worth will probably be helpful when organising Rescue mode later.
Disabling Magnetometer
As really helpful by Betaflight Builders, except you’re completely certain that your Magnetometer (aka compass) has been correctly calibrated and is working appropriately, in any other case you must disable it (within the Configuration tab, underneath Accelerometer and Barometer). Betaflight Rescue Mode doesn’t depend upon Magnetometer so it’s nice to disable it.
To examine in case your magnetometer is working, evaluate the compass worth in your cellphone (set to indicate True North, not Magnetic North), with the heading on Configurator’s important opening display, the GPS tab in Configurator, or the Sensors tab debug line 5 in debug mode GPS_RESCUE_HEADING, and examine that each are inside 10 levels of one another. If the heading all the time begins at North, and follows quick actions rapidly however then jumps to another worth, the Magazine shouldn’t be 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 price corresponding to 56700 or increased. Reducing PID looptime will depart 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. In case you can’t discover this tab, be sure to’ve enabled the “Skilled Mode” possibility on the high of the display (subsequent to the Replace Firmware button).
Underneath Stage 2, choose GPS Rescue. Now, in case your drone enters failsafe, it is going to 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 is going to try and return dwelling.
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 carry the quad again.
Whereas setting GPS Rescue as your failsafe technique is helpful, it’s not suited to all environments. As an example, it’s not advisable in bando, forests, stadiums, or indoors. Dropping management underneath a tree or inside a constructing might outcome within the drone crashing into obstacles when Rescue mode engages.
When you have 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 entails 5 phases:
- Self Stage: 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 path.
- Fly Residence: The drone begins its journey again to the launch level. The flight may not be a clean cruise, because the drone may pitch forth and again attempting to regulate its pace.
- Descend: As soon as close to the launch level, it begins descending slowly. The descent is perhaps uneven, with the motors making pulsating sounds because the drone tries to decelerate.
- Land: Upon touching the bottom, the drone mechanically disarms, with motors terminating based mostly on impression, not based mostly on altitude.
Methods to 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 need to tweak the GPS Rescue settings in Betaflight to your particular setup and setting. I extremely suggest visiting the Betaflight wiki to understand a full understanding of what every parameter entails: https://github.com/betaflight/betaflight/pull/11579. The default settings supply a strong place to begin, particularly for five″ freestyle drones.
Right here, I’ll stroll you thru the settings, sharing the values I take advantage of on my 5″ freestyle drone and the reasoning behind every selection.
Accessing all settings is simple by way of CLI—simply enter get gps_rescue for a complete listing 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 dwelling.
- Most altitude is the very 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
Your best option varies with every flight’s context and setting. Most altitude could be a secure possibility, nevertheless it’s not all the time the suitable possibility. As an example, for those who was diving a mountain in that flight, you may be losing power climbing again to the max altitude when Rescue mode is activated. When flying over ocean the place there’s no obstructions, mounted altitude might be a very good possibility. Use widespread sense, be adaptive to the totally different setting and missions.
Preliminary Climb (meters): The space 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 needs to be excessive sufficient to clear any obstacles like bushes and buildings however not so excessive that it excessively consumes battery throughout ascent. For my flying spots, which options tall bushes 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 properly. If utilizing Li-ion packs or low C-rating LiPo, think about a decrease ascend price.
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 path can be extra correct and replace sooner in increased pace (within the absence of a compass). Don’t set it to decrease than 2m/s or orientation received’t work. Observe when coming into this worth in GUI, the unit is totally different than CLI (which is cm/s).
Most Pitch Angle: This setting caps the drone’s tilt angle. A better 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 is perhaps needed for sustaining pace, particularly for smaller quads. Nonetheless, with an excessively steep angle the drone might lose altitude and crash. Not sure of what to set? Beginning with the default worth of 40 levels is a secure wager—it’s labored properly for my 4inch and 5inch setup.
Descend Distance (meters): That is the distance from dwelling our drone begins to descend. I persist with the default right here.
Throttle minimal, Throttle most, Throttle hover – these are the min, max and hover throttle values you need to use throughout Rescue mode. Set most so the quad isn’t too quick/jerky (it needs to be above your hover level), set min to maintain the props spinning at an inexpensive price (it needs to be decrease than your hover level). I left Throttle Min/Max at default.
To set Throttle Hover, it’s worthwhile to decide an correct worth. Take a look at fly your quad and see at what throttle it hovers (simply sufficient throttle to maintain the quad afloat). Use the “Throttle %” OSD factor to get the precise worth as an alternative of simply guessing. Ideas, the perfect 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 totally different is determined by battery voltage, so that you may surprise, what throttle worth ought to I take advantage of? Nicely you bought to ask your self, at what battery voltage you’re almost definitely going to get a failsafe? It’s bought to be when the drone is the fartherest from you proper? And you’re in all probability simply earlier than half means by way of the battery, round 3.8V to three.9V. So use the hover throttle worth at this voltage.
Minimal Distance to Residence (meters): If Rescue begins too near dwelling (inside this minimal distance), the drone will fly away on its present heading till this distance from dwelling, and begin the conventional Rescue behaviour. I depart this on the default 15 meters.
Minimal Satellites: A minimal of 8 satellites ensures dependable Rescue mode operation. In case you take off earlier than the GPS attain the minimal quantity of satellites, it received’t know the precise dwelling location. Extra satellites imply higher accuracy. I depart this on the default, 8.
Enable Arming With out Repair: This selection supplies flexibility by permitting arming with out a GPS lock. I allow this for the comfort of check flights, however make sure you get a GPS lock for once you intend to make use of GPS Rescue Mode.
Beware that GPS Rescue WILL NOT work for that flight for those who arm earlier than getting a satellite tv for pc lock (as a result of it doesn’t know the house place).
When you have bother getting these many sats (or it takes a very long time), take a look at my tutorial on the right way to increase your GPS receiver efficiency. Get a brand new GPS for those who should, they solely value $15, an important funding for shielding 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 a very good variety of satellite tv for pc locks?
- Are we at the least 20 meters away from dwelling?
- Are we getting nearer to the house, and we didn’t hit an impediment?
If any of those situations will not be met, it is going to abort rescue mode and your quad will simply disarm and drop to the bottom. So yea, it’s not ideally suited if you’re flying over unrecoverable locations like ocean or mountains, however typically, it needs to be on for security causes.
The Betaflight wiki additionally recommends setting Sanity Checks to “Failsafe Solely” if you’re having bother 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 possibility.
It’s dangerous to show off Sanity Verify fully, you may get an indefinite flyaway. In Betaflight 4.4, there’s 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.
Methods to Manually Activate GPS Rescue?
Moreover failsafe, you may have the choice to manually set off GPS Rescue by flipping a change in your radio transmitter. This characteristic is useful throughout emergencies, corresponding to dropping your means or encountering points together with your FPV system, permitting your drone to autonomously return dwelling.
Go to the Modes tab in Betaflight Configurator and assign an AUX channel particularly for GPS Rescue Mode. In case you’re new to configuring modes, take a look at 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 sensible to evaluate 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 throughout the guard time. This interruption might destabilize the drone earlier than GPS Rescue kicks in, probably failing a sanity examine and inflicting the drone to drop to the bottom.
One answer 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 favor 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!
Methods to Take a look at GPS Rescue
Testing GPS Rescue is an important step earlier than counting on it in real-world situations. Right here’s my method to making sure it really works as anticipated.
The Setup
First, assign a change in your radio to GPS Rescue to substantiate it may possibly certainly carry your drone dwelling. Ought to something not go in keeping 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, identical to dropping RC sign, however in a a lot safer method since you may exit the mode every time needed 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 probably be momentarily locked out. Confirm for those who 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 price mode, and “Angle” in angle mode.
Discipline Testing
For an precise check, select an open space free from obstacles and other people, with smooth grass. Guarantee you may have a sound dwelling level earlier than taking off – ideally the OSD ought to present at the least 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 dwelling, when pointing down means you’re flying away. Initially, the arrow may level within the fallacious path if you’re not utilizing a magnetometer, which is regular because it takes 5 to 10 seconds for Betaflight to work out which path it’s heading—simply make sure the drone isn’t flying the exact opposite path after 10 seconds.
You may give up failsafe mode at any time by flipping the change, regaining full management instantly.
In case you select to not disengage, the drone will proceed flying again to the launch level. Upon arrival, it is going to hover briefly earlier than beginning a gradual descent, throughout which the motors might pulsate, till it safely lands and disarms mechanically.
You might need to repeat this course of a number of instances, till you’re assured within the system’s reliability. After thorough testing, don’t overlook to take away Failsafe from the Modes tab.
Ideas and Troubleshooting
Greatest 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 overlaying it, significantly conductive supplies like carbon fiber, electrical wires, or steel, can considerably weaken the GPS sign.
Avoiding EMI
Electromagnetic interference (EMI) from different electrical parts in your quad can even have an effect on GPS efficiency. Notable sources of RF interference embody HD cameras and video transmitters. To mitigate this, mount your GPS as distant from these gadgets as attainable.
Correct Mounting Orientation
A typical error is mounting the GPS the wrong way up. The receiver antenna, identifiable by its flat sq. form with a small steel round half within the middle, ought to all the time face upwards. Guarantee no parts 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 issues when mounting your GPS on a quad:
- Tthere’s nothing blocking the GPS unit
- The ceramic antenna is pointing to the sky
- Perfect mounting spots embody the highest of your quad, distant from VTX and RX antennas
- Steer clear of potential radiation sources like HD cameras which may lack correct EMI shielding
Listed below are a number of mounting concepts:
On high of your GoPro/HD digital camera.
On high 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.
Considered one 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 constantly takes lengthy to lock, examine if its battery is depleted utilizing a multimeter. Reduce interference as a lot as attainable—as an illustration, by relocating a robust VTX, particularly for those who’re on a 1.3GHz FPV setup. Climate situations like cloudy days can even impression GPS sign high quality.
For extra recommendations on optimizing BN220 for elevated satellite tv for pc locks, take a look at my devoted tutorial: https://oscarliang.com/gps-settings-u-center/
Recommendations straight from Betaflight Builders
I like to recommend 10 satellites. [And] Anticipate 30s after [you have] 10 satellites for altitude to stabilise [before taking off].
At all times verify regular GPS Rescue behaviour in the beginning of a essential flight by testing with the failsafe change. Set the change to instantly enter Stage 2. You may enter and depart GPS Rescue by way of the change with speedy on and off impact. Verify that the quad rotates and flies in the direction of dwelling and does the suitable issues earlier than you’re so distant {that a} true failsafe might happen.
ALWAYS CHECK that the Residence Arrow factors straight again in the direction of dwelling after takeoff! Typically, for those who take off and spin round throughout arming or instantly on takeoff, the quad’s angle info can develop into corrupted, and the Residence Arrow can level the fallacious means. It’s greatest to arm cleanly and fly away from Residence in a straight line at an inexpensive pace instantly after takeoff. Watch the Residence Arrow rigorously to make sure it rapidly factors again to Residence. If the Residence Arrow factors the fallacious means when a failsafe happens, the GPS Rescue will initially fly off within the fallacious path, and in some circumstances, it’s possible you’ll lose the quad.
Fallacious Route in Rescue Mode?
With no compass, rescue mode ought to nonetheless work because the quads calculate path by way of GPS information comparability.
In the beginning, your quad is perhaps wandering round and even flying in the direction of the fallacious path however ultimately it ought to self-correct. With weak GPS connection, it may possibly take longer to right.
If you’re utilizing a compass and it’s flying the fallacious path, then perhaps there’s one thing fallacious with the compass, or perhaps it’s not calibrated correctly. On this case strive 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 is perhaps 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 totally 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 may show PDOP in Betaflight OSD by coming into set osd_gps_sats_show_hdop = ON within the CLI. Here’s what the worth means:
- 1.0 to 1.5: Glorious accuracy, very steady GPS lock.
- 1.5 to 2.0: Acceptable, minor drifting may happen.
- 2.0 to three.0+: Poor accuracy, important place drift is widespread.
Extra satellites usually decrease your PDOP/HDOP, enhancing GPS accuracy. Digital interference, particularly from gadgets 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. You might use it to show GPS associated data on the OSD, nevertheless it’s merely not dependable sufficient for GPS Rescue. It’s greatest to make use of a {hardware} serial port (any TX and RX pins on the FC), and set baudrate to at the least 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 potential to lock onto satellites. In case you’re dealing with difficulties reaching a GPS lock, think about the next steps:
- Energy the Flight Controller (FC) by way of USB to examine if it powers the GPS module. If not, transfer the GPS module’s energy connection to a distinct 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 can assist you get a faster GPS lock. However, it’s advisable to mount your GPS so far as attainable from each the VTX and RX antennas to attenuate potential interference.
- Shielding Electrical Wires: shielding wires that conduct important present can mitigate interference. These wires can act like antennas, probably disrupting GPS indicators.
GPS satellites function on two frequencies, L1 1575.42MHz and L2 1227.60MHz. Consequently, a 1.3GHz FPV setup may intervene together with your GPS. The vast majority of pilots use 5.8GHz, which typically avoids this downside. Nonetheless, given the weak GPS sign—originating from satellites in area—even sturdy close by indicators may cause interference. Thus, positioning the GPS module away from any transmission sources is essential.
Operating GPS wires underneath the VTX may cause points, significantly if the VTX lacks ample RF shielding. This RF noise can compromise GPS performance. For instance, the Avatar VTX V1 was identified to trigger GPS issues when wires are routed beneath it. A possible repair entails grounding the VTX’s shielding. Alternatively, shielding the wires between the GPS and FC—and guaranteeing they’re grounded—may supply an answer.
I attempted to defend wires with foil in one in every of 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 seen minimal enchancment. Whereas some have reported constructive outcomes with this modification, it’s price exploring if different simple options are unavailable.
Did not Activate GPS After Updating Betaflight
In case you’re unable to allow GPS after flashing the most recent Betaflight model, it’s attainable 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 out there,” 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 possibility 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—presently, solely 4 and seven decimal choices can be found. This choice straight influences how precisely you may pinpoint a location on a map based mostly on the GPS information.
The “Decimal Levels” Wikipedia web page supplies 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 might show a excessive diploma of precision (variety of digits), however not all decimal locations might replicate true accuracy. Which means that whereas your GPS can report coordinates to a really nice decision, the precise accuracy—how shut these coordinates are to the true location—might 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
