Optimize GPS reception

Reading time 3 minutes

Updated – October 17, 2023

Optimizing GPS reception for navigation via cell phone, tablet or navigation device is a good option, especially in alcove or fully integrated motorhomes, in order to prevent reception problems and thus bumpy navigation. The reception usually stops shortly before an announced turn and you then find yourself quite deserted in unknown territory.

Fortunately, there is a 5V USB powered one GPS signal amplifier ANT-1573 in unity with the GPS antenna ANT-1575R. The convenience for an untroubled navigation experience in the future costs less than 20 euros.

function

How it works is quickly explained: the flat antenna, which is glued near the top edge in the middle of the windshield (for fully integrated models) and to the edge of the roof/front window for alcoves, receives the satellites from this position undisturbed and passes the data on to the amplifier via the antenna cable. This is placed near the device used for navigation purposes. The amplifier, in turn, sends the signals supplied by the GPS antenna to the respective navigation device with sufficient strength.

Installation location

The GPS antenna should actually be installed outside and the antenna cable should be routed inside through the outer skin. Why? If the transmitter and receiver are too close to each other, feedback occurs, as with the microphone and loudspeaker. There is no whistle here, but the signals are superimposed and therefore unusable. Anyone who has no knowledge of this can easily come to the mistaken conclusion that the signal amplifier is “no good”.
The metal roof that is common in cars shields the antenna from the receiver and thus prevents feedback from occurring.

However, mobile homes rarely have a sheet metal roof, instead they have an aluminum or GRP roof. Therefore, it is almost irrelevant whether the antenna is installed inside or outside. In order to effectively prevent possible feedback, it helps to use your bag of tricks.

Measurements

With a free app Commander Compass Go (iOS) you can easily check the reception quality with and without the signal amplifier activated.

Tests have shown that shielding may be unnecessary if the distance from antenna to amplifier is greater than around 100 cm AND the amplifier has no line of sight to the antenna, i.e. other materials (dashboard, cabinet, etc.) are in between. If you still use shielding, the gain drops from, for example, 42 dB to 35 dB or worse.

The solution from the 'box of tricks'

If a line of sight cannot be avoided, this can be done copper-clad GRP circuit boards a quick housing construction can be easily realized.
For this purpose, two small sections of approximately 4.7 x 1.3 cm and 8 x 1.3 cm are sufficient for the side walls, as well as a base plate of 5 x 8 cm.
To the right and left of the narrow side of the base plate, the 4.7 x 1.3 cm sections are positioned at an angle of 90° and soldered vertically to the base plate at around 450 .. 500 °C (place a soldering point at each end, ensuring parallelism to the base plate). Pay attention to the edge of the base plate, check the verticality, correct if necessary and then fill the entire distance with plumb line).
Insert the long sides and connect them vertically in the same way (with the side strips and the base plate).
A cutout for the antenna cable is made in the middle of one long side.

The result is a perfect shielding housing. The outer edges can be rounded off (sanded) and the housing can then be embellished with matt black spray paint or a leather cover.
The enclosed 3M adhesive pad is applied to the center of the bottom, which is used to connect the housing to the antenna housing to reduce vibration.

If the positioning accuracy is reduced after attaching the cover, removing the copper coating on the side and above the GPS antenna using a Dremel or similar will help.