User`s manual

Doppler MPT Users Manual

Revision A

The Series 7000 is a high performance radio direction finding system that operates using the

synthetic Doppler principle in which a circular array of antennas are combined in a way that

simulates a single element rotating in a circular path. As the simulated element approaches

the wave front of an RF signal, the frequency increases due to the Doppler effect, and as it

recedes from the transmitted source, the frequency decreases. The amount of frequency

change (deviation) is related to the speed of rotation and the diameter of the antenna array,

while the modulation frequency is equal to the frequency of rotation (the antenna sweep

frequency). When connected to a narrow band communication receiver, the sweep frequency

is present on the audio output. To obtain the bearing angle, the direction finder processes

this audio output.

Many features are present in the Series 7000:

• The system may be used with either an 8-element high accuracy fixed site antenna or

a 4-element magnetic mount antenna for mobile operation.

• The sweep frequency may be set to 250, 500, 1000 or 2000 Hz to avoid tone

frequencies that may be present in the signal modulation.

• Advanced signal processing is used to detect the signal with the receiver either

squelched or unsquelched. Signals as short as 80 msec can be detected.

• The sweep direction automatically reverses from clockwise to counterclockwise to

compensate for asymmetries in the receiver.

• An internal audio amplifier and loudspeaker are provided for monitoring the signal,

and a sharp notch filter removes the sweep frequency for clarity.

• Two host USB ports allow for direct connection of USB receivers and other USB

devices.

• An Ethernet connection allows the direction finder to be easily networked via the

Internet or an Intranet.

• Sturdy antenna construction will survive wind loads up to 120 mph (60 mph with ½

inch of ice buildup)

Chapter

INTRODUCTION