Receivers & Decoders

WHAT WILL CAUSE A DECREASE IN RANGE?
There are three possible reasons why the range would not be normal.

1. Obstructions by metal or radio absorbent materials which either absorb the radio energy from the transmitter or reflect the energy to another direction preventing the signal from reaching the receiver. Reflections also cause multi-path effects where there will be areas of poor reception within a few feet of each other. Multi-path effects can be substantially eliminated by using two receivers a few feet apart.
   
   Location of the receiver is also important. In general the higher elevation the better. For instance, it is better to locate the receiver in an upstairs room than in a basement if it is desired to have reception outside the home. Obstructions such as aluminium siding or foil insulation/wall paper will block 90% or more of signal. In commercial installations place the receiver away from metal partitions and below suspended ceilings.
2. EMI/RFI electro-magnetic interference and radio frequency interference. Electrical or radio interference will not cause false alarms but may cause a substantial decrease in range. Typical sources are alarm panels with high clock rate micro-processor controls, radio scanners, local high power radio stations, defective dimmer controls, etc. For maximum immunity to EMI/RFI use the extended range receivers 811LX, 902L, 904L, 800LX which are superheterodyne receivers with good shielding and helical resonator antenna pre-filters.
3. A defective receiver or transmitter can result in poor range. This can be eliminated most easily by trying a different transmitter and then a different receiver. If the results are consistently poor range, then the most likely problems are with items 1 and 2 or both.
   If you are installing the receiver inside a control panel, there are two things that must be considered.
   1. There will be some decrease in range if all of the antenna is not outside the metal box.
      
   2. Some control panels generate considerable RF interference (noise) inside the panels due to the use of micro processors in the controls. This may severely limit range because the noise masks the desired signal. It may be necessary to mount the receiver outside and away from the panel.

WHEN THE TRANSMITTER DOES NOT ACTIVATE THE RECEIVER OR DECODER EVEN AT CLOSE RANGE.
Load the key code into memory. The receivers or decoders will not recognize any transmitter unless the key code is stored in memory. All the receiver have "teach" buttons to perform this function. On the 902L it is also necessary to program the operating mode.