Claims that a 48-turbine wind farm would interfere with military radar have been contested at a public inquiry in the Scottish Borders.
It has been claimed the turbines could affect nearby radar
Chartered engineer Michael Watson said the North British Windpower proposal would not affect national security.
However, the Ministry of Defence has claimed most of the turbines would have an impact on a nearby radar station.
The inquiry into the development in the Lammermuir Hills near Duns is scheduled to continue until 22 February.
Scottish Borders Council rejected the scheme originally but developers appealed against that decision.
Opposition has also been lodged by East Lothian Council and Scottish Natural Heritage.
The MoD has told the inquiry of its fears over the proposal.
They believe air defence could be unacceptably compromised because 35 of the turbines would be in the line of sight of a nationally important radar station near Alnwick in Northumberland.
However, Mr Watson said his studies in the area had shown they would have little impact.
A final decision on the proposal will be given by a Scottish Government Reporter.