Method and apparatus for reducing the effects of impulse noise in Loran-C receivers

Apparatus for reducing the effects of impulse noise on the operation of a navigation receiver of the type that provides navigation information by receiving signals periodically transmitted by each of a plurality of navigation transmitters and measuring the difference in time of arrival of said signals from pairs of said navigation transmitters, the receiver having filter and amplifier means for filtering/amplifying the appropriate bandwidth of received signals, and acquisition/tracking means and microprocessor means for generating appropriately timed pulse output signals upon receiving the passed signals, and providing the navigation information from the time difference between the generation of said pulse signals, said apparatus comprising:

• means associated with the microprocessor means for generating a time gate signal which defines a time period of selected duration that preceeds the time of arrival at said receiver of said periodically transmitted signals, and
• means in the front end of said receiver responsive to said time gate signal for attenuating signals received by said receiver prior to where the received signals are filtered and amplified during the time periods defined by said time gate signal.