# Difficult to achieve RTK fix with ZED-F9P

**URL:** <https://community.sparkfun.com/t/difficult-to-achieve-rtk-fix-with-zed-f9p/44818>\
**Category:** Development Boards\
**Created:** [December 2, 2022, 5:02pm UTC](https://community.sparkfun.com/t/difficult-to-achieve-rtk-fix-with-zed-f9p/44818 "2022-12-02T17:02:17Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![maridimimoniqui](https://avatars.discourse-cdn.com/v4/letter/m/a5b964/32.png) [@maridimimoniqui](https://community.sparkfun.com/u/maridimimoniqui)\
**Post date:** [December 2, 2022, 5:02pm UTC](https://community.sparkfun.com/t/difficult-to-achieve-rtk-fix-with-zed-f9p/44818/1 "2022-12-02T17:02:17Z")

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Hello.

I have a Sparkfun GPS-RTK-SMA Breakout with u-blox ZED-F9P connected to an Arduino Mega in a rover.

A Raspberry Pi send RTCM Corrections to the USB port of the GPS-RTK-SMA Breakout.

I am using the SparkFun\_u-blox\_GNSS\_Arduino\_Library in order to configure the device and to receive data in Arduino board thought the UART1 port of the GPS-RTK-SMA Breakout.

But the behavior of the device is very strange:

- Sometimes, it retrieves very incorrect data while RTK solution returns RTK fixed.
  
- RTK led rarely agrees with RTK solution read with _getCarrierSolutionType_ function.
  
- Sometimes, getCarrierSolutionType function even returns 3, when the expected values are between 0 and 2.

Could be that behavior caused by a deficient power supply of the GPS-RTK-SMA Breakout?

I am feeding it trough the 3.3V of the Arduino Mega. In the Hookup Guide I have read:

“Note that if you’re provide the board with 3.3V directly it should be a clean supply with minimal noise (less than 50mV VPP ripple is ideal for precision locating)”

If that is the case, if I feed the GPS-RTK-SMA Breakout through the 5V pin, the 3.3V regulator will reduce the 5V down to 3.3V the module requires?

Thank you.

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<div class="post-metadata">

**Author:** ![bidrohini](https://avatars.discourse-cdn.com/v4/letter/b/ecae2f/32.png) [@bidrohini](https://community.sparkfun.com/u/bidrohini)\
**Post date:** [December 3, 2022, 3:49pm UTC](https://community.sparkfun.com/t/difficult-to-achieve-rtk-fix-with-zed-f9p/44818/2 "2022-12-03T15:49:25Z")

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I believe, the Arduino mega cannot supply sufficient current to the Sparkfun GPS-RTK-SMA Breakout with u-blox ZED-F9P. You have to use a separate power supply. From the specifications, it looks like you can power up the module with 5V. The in-built voltage regulator will maintain 3.3V.