GPS-unit RFI Problem Solving


RFI noise occurs in a range of frequencies. In fact equipment may only be prone to problems within a specific frequency range. In many cases you will have multiple noise sources that overlay each other.

This will result in a gradual degradation of the electronics components and when the cumulative effects reach a critical point the devices will subsequently fail. Solve noise and interference on your GPS-product, GPS-unit, gps-receiver, gps-navigation-system, weather-radio and save on radio-repair costs


These are repetitive spikes that are caused by electric motor commutators and the sparking of brushes. For example the brushes on an alternator, particularly if dirty can cause this sparking and radio noise. This is common in charging systems where loose connections may exist. The most common cause is usually loose or poor engine return paths for alternators, when the negative path arcs across points of poor electrical contact. It pays to regularly check and tighten your negative terminals.

Another cause is that of noise on ignition systems from distributors and spark plugs being impressed onto a DC system, and frequently this is through radiation any adjacent cables. When troubleshooting the first step is always to determine what is operating at the time. Solve noise and interference on your GPS-product, GPS-unit and save on radio-repair costs.


Electrical wires that are installed in parallel with other wires can suffer from what is termed inductive coupling interference. The symptom is buzzes and humming sounds on the radios-marine. This happens due to a transformer effect with a single turn primary and secondary coil, with the magnetic effects creating the induction.

Low ground impedances and unbalanced circuits are the greatest source of problems with serial data, multi-cable control and co-axial cables being the most susceptible to noise. Again the best measure is to keep all signal cables installed separately so you don’t have parallel runs with the main power wiring.

The first step in troubleshooting RFI is to determine what equipment is operating at the time as this will directly affect the cables involved and will aid in fault localization. Solve noise and interference on your GPS-product, GPS-unit and save on radio-repair costs.


Ripple is an affect created in rectifier bridges (such as the diode or SCR bridge). These are found in charging alternators, battery chargers, fluorescent lights and AC inverters. It usually presents as a high-pitched whine sound on radios-marine. Most good quality equipment will have suppressed electronics. Ripple will cause severe communications audio quality degradation on radios. As before always determine which lights are operating, whether charger is on, and whether the engine is running. It is often a sign that an alternator diode has blown. Solve noise and interference on your GPS-product, GPS-unit and save on radio-repair costs.


Static charges have several sources. External charge interference appears usually due to static build-ups in sailboat rigging. The static charge will attain a certain voltage level, before it discharges to ground which causes the interference on radios. Another very common source is when dry offshore winds occur, and this causes a high net static charge to build up on GRP deck surfaces. This problem is more prevalent on larger GRP vessels such as catamarans with relatively large deck surface areas.

A lightning protection system does serve this purpose well and can ground out these static charges. The engine and propeller shaft can also accumulate charges when rotating, and interference is caused when the accumulated charges ground out. These charges arise due to static build-ups, both induced and due to the interaction of moving parts within the engine. The static charge will discharge to ground when it gets high enough and will also cause RFI interference. Solve noise and interference on your GPS-product, GPS-unit and save on radio-repair costs.

WHAT IS SURGE? (Electromagnetic Pulse)

This interference is caused by local lightning activity. The pulses are generally induced into electrical wiring supplying your gps-unit, gps-receiver, gps-navigation-system, weather-radio and radios-marine or other aerials.


A common cause is the turn-on spike which results from the initial charging of power supply input filters on power supplies. Turn-off spikes happen when reactive loads are switched, and the magnetic fields collapse on inductive loads. These are usually on transformers, relay or contactor coils, solenoid coils, pump motors etc. A common suppression method is the use of MOV suppressors which are connected across the coils. Solve noise and interference on your GPS-product and save on radio-repair costs.


This source is from activity and changes within the ionosphere and solar or sun spot activity. The main result is signal losses or major data corruption. A good basic check is to verify that there is no current major activity. Solve noise and interference on your GPS-product, GPS-unit and save on radio-repair costs.

Part 3 of this 3 Part Series on RFI and Interference problem solving on your GPS and radios. Click on this link to find out more about. Part 3 RFI and Interference and all you need to know.


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