A few words about wireless reception and interference

The transmitter power of the RB02 and RPT1 is .00035 Watts.  By contrast your cell phone can put out 3 Watts or roughly 10,000 times the power.  We are continuously asked about the operating distance of the wireless cab.  There are many factors governing the useful range of wireless products.  The RB02/RPT1 operates in the ISM (Industrial, Scientific and Medical) radio band at 916.5 Megahertz (MHz). Many other DCC systems, cordless phones, wireless computer networks,home automation systems, and wireless security devices also operate in this portion of the radio band and all contribute to radio interference.  Radio waves are like one big telephone ‘party line’ where everyone is talking at once.  A device using these radio waves must attempt to sort out what ‘voices’ are relevant to its operation and which ones are noise.  If there is too much noise it can’t do this successfully and will operate poorly or not at all.

Indoor radio propagation is an issue for special consideration. The human body readily absorbs radio energy in the frequency band used by the cab radios.  Placement of the base station and repeaters can mitigate blocking of the radio signal due to human body absorption. In most indoor situations ‘dead spots’ can be found where reception is very difficult.  These can occur even if there appears to be a direct line of sight between the transmitter and receiver. These dead spots, or ‘nulls’, are the result of multiple radio transmission paths between two points caused by reflections off metal objects such as steel beams, screen wire, concrete rebar, metal door and window frames, ceiling tile frames, model railroad track, etc. Nulls occur where the path lengths differ by an odd ½ wavelength (about 6 inches at 900 MHz).  Deep nulls are usually very localized and can be avoided by moving slightly, usually only a few inches. We suggest adding one or more RPT1 repeaters if you experience severe null areas on your layout.

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