Patent ID: RE42217

Claim:
An airborne time domain electromagnetic surveying system comprising: (a) A tow assembly for connection to an aircraft, the tow assembly including: (i) A flexible support frame including: (A) A transmitter section having a central axis and including a transmitter means; and (B) A receiver section including a receiver support frame and a sensor means; wherein the receiver section is substantially aligned with the central axis of the transmitter section; and wherein the sensor means is flexibly connected to the receiver support frame for vibration reduction; (b) A transmitter driver linked to the transmitter section in a spaced apart relationship from the transmitter section, such spaced apart relationship being operable to reduce noise, wherein the transmitter driver and transmitter section in cooperation enable the system in an “ON” interval to generate an earthbound electromagnetic field pulse effective for geological surveying, and wherein an earth response to the electromagnetic field pulse is sensed in an “OFF” interval by the sensor means; and (c) A dual-mode gain amplifier linked to the sensor means that enables low linear gain amplification during the “ON” interval and switches to non-bucking high linear gain amplification during the “OFF” interval, wherein the switch is rapidly achieved.