11 April, 2016

Improved GPS reception with a ground plane

My poor-man's 10 MHz reference based on the Ublox Neo-7M GPS module didn't always receive GPS satellites. Since I rely on reception indoors, conditions were sometimes too marginal to lock the oscillator output to 10 MHz. Inspired by the QRPlabs GPS module of Hans Summers (G0UPL) with its large 6 x 6 cm PCB groundplane, I therefore decided to do something similar.

The first picture shows the unit with the 8.5 x 6.5 cm single-sided PCB ground plane attached with double-sided tape. It definitely helped make indoors reception in my shack much more reliable. In addition to the improved conditions for the patch antenna, it probably helps too that the antenna now is shielded from the digital circuitry of the GPS module, the 10 MHz pulse shaper, and the USB interface. I also added a small LED to the right so that I could see from the outside whether the GPS locks properly.

The second picture shows the interior prior to adding the ground plane.

This post is a continuation of these other posts about the 10 MHz reference:
  1. Just good enough 10 MHz reference (3 Oct 2015)
  2. Better with SMA (15 Oct 2015)
  3. Curing amnesia in the 10 MHz GPS reference (19 Nov 2015)


  1. Excellent article Just down loaded the UBLOX PROGRAM AND HAVE ATTEMPTED to get the 10Mhz output so far not measurable with frequency counter .
    Is the 10 Mhz at a very low level ? or do I need a Crow to take measurements , I need the 10 mhz for a frequency locking a transceiver

  2. The output is 3.3 V square, as far as I remember, so it should be simple to measure. It’s been some time since I did this, but the setup I used in the Ublox program is near the end of this post. https://la3za.blogspot.com/2015/10/just-good-enough-10-mhz-reference.html

  3. Please also be aware that this 10 MHz reference has lots of sideband noise, https://la3za.blogspot.com/2019/05/more-spurs-than-i-had-hoped-for.html

    Therefore I have moved on to a GPS-corrected reference now, https://la3za.blogspot.com/2020/09/gps-corrected-10-mhz-reference.html