Typical Application Circuit; Power For Receiver And Active Antenna; Grounding; Figure 2-1: Jupiter 32 Mechanical Layout - Navman Jupiter 32 Integrator's Manual

Miniature 20-channel gps receiver module

Table of Contents

2.2 Typical application circuit

The schematic in Figure 2-2 (next page) represents a very basic application circuit, with simple

interfaces to the module. It is subject to variations depending on application requirements.

The receiver power connection requires a clean 3.3 VDC. Noise on this line may affect the

performance of the GPS receiver.

When an active antenna is used, the DC power is fed to it through the antenna coax. This

requires the user to apply the antenna DC voltage to pad A4 of the module.

A 2.85 V 30 mA supply is made available on pad F3 if the chosen antenna can accept that

voltage. This supply is under the command of the TricklePower energy control.

The source impedance of the power supply must be kept sufficiently low. The capacitance of

the power supply and PCB track width determine the overall source impedance. If a passive

antenna is used, the supply must be able to provide a minimum of 100mA continuously with

minimal ripple as measured at the power input pin. This ripple requirement must be adhered

to for a larger current flow when an active antenna is used. In-rush current for some active

antennas have been measured as high as 70mA and may cause a dip in voltage or ripple.

Therefore, a low source impedance is important since the power to the Jupiter 32 must be

able to accommodate instantaneous currents in excess of 200mA.

Separate analogue and digital grounds are not used. However, the antenna signal ground

uses a particular layout for optimum results. See Figure 2-3 (next page) and Section 2.3.5

for ground plane recommendations and for design considerations involving the antenna input

and the 50 ohm microstrip connection.

All dimensions in mm

Table of Contents