Prearm: Need Position Estimate

Helo i am configuring a matek OPTICAL FLOW & LIDAR SENSOR 3901-L0X, I already have the rangefinder working and now i am configuring optical flow sensor, i followed all steps on Optical Flow Sensor Testing and Setup — Copter documentation
i receive data from the sensor and i already calibrated it, but the problem comes on the Second flight step

Because when i try to arm in loiter mode mode it shows me this error

I can succesfully arm in stab or althold mode, but it dont let me arm in loiter mode.

MatekH743 001B0031 33305118 36353839
ChibiOS: 66e5de0d
ArduCopter V4.3.1 (22f45675)

It’s looking for a proper GPS fix still. Have you power cycled the flight controller after you set the EK3 parameters mentioned in the Wiki?

If the vehicle appearing on the ground station map? If not then the issue could be that the “Set Origin Here” hasn’t worked for some reason.

My next guess is that the rangefinder isn’t happy.

Probably best to provide an onboard log. To produce a log while the vehicle is disarmed you might need to set LOG_DISARMED = 1.

kindly tell me how to solve an error of Pre arm: AHRS waiting for home ???

Notice the message GPS:No GPS. You need to sort that out. If you are indoors then the GPS may not be getting enough signal to get a position. Or if you are powered by USB the GPS may not be powered up and needs battery to be working (depends on your flight controller)

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But I’m not using the GPS with pixhawk 2.4.8 flight controller and when i armed it gives an error of AHRS waiting for home…! or with GPS it shows green light and not armed and error of GPS not fix…

You’ll need to give the AHRS some kind of position information.

Look at Non-GPS Navigation — Copter documentation

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using gps, it also give an error of waiting for home.can u suggest me a proper documentation ???

You need to be outside with a clear view of the sky. Especially if the GPS module hasn’t had a full lock recently it will be a “cold” start and that just takes time.