Q. What frequency should I use for data transfer? A. Per FCC Part 15 regulations, the 300 and 400 MHz bands may only be used for periodic data transmissions, such as keyless entry type applications. See FCC Part 15 rules for requirements. For continuous or regular transmission intervals, the 900 MHz band must be used. The 900 MHz band can be used for periodic data transmissions as well. Within the 300 and 400 MHz band the choice is yours, and may be limited by your RF environment. For instance, if you will be designing for an application where the environment already has 315 MHz, you can choose to use a 303 MHz or a 400 MHz frequency.
Q. Is a preamble necessary preceding each transmission? A. A preamble is very helpful for establishing the correct slicing level of the received signal. It can also guarantee that the first transmitted data bit will be correct, because when the receiver is idling, the data output may toggle randomly until a transmission is received.
Q. How should the loop antennas be oriented with respect to each other? A. They should be oriented horizontally to produce a vertically polarized omni-directional electric field. Because nulls appear along a line perpendicular to the PC board, avoid situations where the antennas are directly above or below each other.
Q. Will the signal of your wireless products penetrate walls, floors, shrubbery, and fences? A. In most cases the signal will pass through wood and stucco construction with little attenuation. Tightly welded metal construction will attenuate the signal to a much greater degree. Chain link fences will attenuate the signal if the fence height is high. Shrubbery will have little effect on the signal.
Q. Can two or more wireless transmitters operate at the same frequency at the same time in the same area? A. If the transmissions are for a short duration and redundant transmissions are sent, multiple transmitters can operate at the same frequency.
Q. Will your wireless products interfere with other radios, TV’s or wireless systems? A. This is very unlikely due to the very low power level of the transmitter and the excellent internal filtering of the harmonics.
Q. Can the receiver operate near other high power radio transmitters such as cellular telephones, two-way radios, cordless telephones, amateur radio or CB transmitters? A. Yes. The wireless receivers incorporate a very selective front-end SAW filter which rejects out-of-band energy that could potentially desensitize or interfere with the receiver. The receiver is superheterodyne with excellent selectivity. It will perform far better than the typical low-cost regenerative receiver found in toys and some car alarms.
Q. Are the receiver and transmitter modules FCC approved? A. The KTX303A keyfob and RCR receiver are FCC certified. Our other wireless products, such as modules and evaluation boards are designed to comply with FCC requirements but are not certified. The FCC will certify only complete products, not individual components. All Applied Wireless receivers and transmitters can be used for prototype, design and experimental purposes without FCC certification. Applied Wireless can provide application assistance with obtaining FCC certification for your finished product (see application note AN-101).
Q. How can I reduce the receiver current consumption for the battery-powered applications? A. The receiver may be operated in a sampled mode by periodically switching on the power and testing for valid incoming data. Another solution is to use a step-down switching regulator, which can lower the receiver current to about 3.5 mA or less from a 12 Volt battery.
Q. Are Applied Wireless products RoHS compliant? A. Applied Wireless products that are manufactured exclusively for export to the EU and which fall within the scope of Directive 2002/95/EC of the European Parliament and of the Council of 27 January 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment (the “RoHS Directive”), as amended by the Commission Decision of 18 August 2005 (the “Commission Decision”) are marked with a “-RC” suffix appended to the product’s base part number. As such, the products so marked meet the requirements and the threshold limits of the six hazardous substances specified in the RoHS Directive and the Commission Decision. The maximum allowable concentration values of the six hazardous substances in homogeneous materials specified in the Commission Decision is 0.1% by weight for lead, mercury, hexavalent chromium, polybrominated buphenyls (PBB), and polybrominated diphenyl ethers (PBDE), and 0.01% by weight for cadmium.