2
The Xplorer is a completely unique nearfield test receiver. It is not a single frequency radio receiver in the conventional sense, or a high
speed scanner. It is actually a frequency sweeper using multiple swept harmonic LO frequencies that enable the Xplorer to lock on to virtu-
ally any two-way FM signal in less than one second. Its unique frequency conversion system allows it to search for and acquire new fre-
quencies much more quickly than a conventional receiver.
Nearfield refers to the relative strength of a transmitter as compared with the background RF floor. The nearfield refers to an approximate
distance where the signal strength radiating from an antenna is relatively strong. As you approach an antenna, the observed signal strength
increases to a point where its amplitude becomes greater than any other signal sources. At this point you are in the nearfield of the trans-
mitter. The Xplorer will pick up signals in the nearfield of a transmitter.
Because of its high rate of sweeping, the Xplorer is essentially a self tuning receiver. The primary reason for a nearfield receiver is to trade
distance for speed. A conventional scanning receiver will receive signals from greater distances than the Xplorer but suffers from being able
to scan only 25 to 100 frequencies per second. It could take several minutes to several hours to tune an unknown frequency using a scan-
ner. (An FCC data base search shows over 5,000 licensed transmitters within 5 miles of the Optoelectronics facility.)
The self tuning feature along with its measurement and decoding capabilities makes the Xplorer valuable for testing two-way radios. The
Xplorer is also able to locate strong RF signals located nearby in order to evaluate interference. The Xplorer is useful for checking com-
mercial FM wireless microphones and other low power transmitters, as well as commercial two way radios.
INTRODUCTION
