Maximizar Senal Maxiprox

Application Note 010

INSTALLING THE HID MAXIPROX

FOR OPTIMUM READ RANGE

POWER SUPPLY
The HID MaxiProx has become the reader of choice for passive long range reader applications. In some placements, read range performance is critical to customer satisfaction. These installation guidelines will help planners and installers maximize read range.

HID has introduced a new version ofthe MaxiProx called the DFM. Please note the differences:
• The DFM has two terminal strips. The NT has one.
• The DFM can operate on 12vdc or 24vdc. The NT is 24vdc only. Warning: P2 jumper must be on pins 2-3 for 24vdc!
• The DFM tunes itself automatically, so ignore the tuning comments. They apply only to the NT.
• The DFM can be configured for serial output.
• The DFM DIPswitches are not the same as NT.

The MaxiProx DFM reader requires a linear power supply with a rating of 12 or 24 Volts DC at a minimum of 1.2 Amps per reader. A linear power supply aids maximum reader performance. HID recommends against using switched supplies, as switching type supplies often interfere with effective reader operation.

HID does not specify a single brand or model linear supply.There are many companies that make them.

REASONS FOR USING A LINEAR POWER SUPPLY
MaxiProx readers cycle through low, medium, and high power modes. Whenever the MaxiProx switches into high power mode it demands up to one Amp of instantaneous current. Switching supplies monitor the output voltage and adjust by rapidly switching current “on” and “off”. As a result, current supply can lagbehind the demand of the load. This also causes fluctuations in the voltage of the power supply, compounding the problem. The result is a reduced read range.

In contrast, linear power supplies are always on, ready to supply constant voltage and current.

Switching power supplies can generate electrical “noise” that is radiated or conducted. This inherent electrical noise can interfere withcard data transmission to the reader, reducing read range.

METAL
MaxiProx readers surround themselves with a radio frequency excite field. This RF energy field provides power to HID Proximity cards. The field is elliptical in shape and extends about three feet in front of and behind the reader. The field also extends about 8” from the edges of the reader.

Metal of any type (aluminum,copper, lead…) should be avoided when mounting a MaxiProx. Even non-ferrous metal within the field can affect reader performance in two ways:

1. Metal absorbs the excite energy that is meant to power the card.
2. Metal de-tunes the reader’s antennas.

Reduced read range is the result. The degree to which the read range is affected is dependent on how much and how close the metal isto the reader. If metal is unavoidable, then absorption loss will be likely. But the de-tuning effect can be somewhat compensated by re-tuning the reader. Some tips on mounting and tuning are included later in this document.

RF NOISE
Since all RFID (Radio Frequency Identification) readers are radio frequency devices, care should be taken to avoid Radio Frequency Interference (RFI) in themounting area.

Some electronic equipment can generate RFI at a frequency that interferes with the card data transmission to the reader. As an analogy, when a vacuum cleaner is plugged into the same power line as a television, the TV’s reception becomes very poor, but the picture quality returns to normal once the vacuum is turned off. There is nothing wrong with the TV; the vacuum motorgenerates “noise” (unwanted electrical frequencies) on the power line. Some computer monitors, vehicle detect loops, and industrial equipment can emit RFI that causes interference with the card data transmission to the reader. Most equipment does not emit an interfering frequency. But it is best to plan the placement of readers away from equipment that generates RFI.

MaxiProx readers can also...