A null direction control method allows optimum antenna weights forming designated null beam directions without calculating an inverse matrix. The system comprises the endoscopic accessory with a working end to be placed at the distal end of the endoscope, a control sheath extending proximally external to the endoscope and a control handle joined to the proximal end of the control sheath. The session credentials themselves may include metadata that may be used in determining whether to fulfill requests to access the one or more computing resources. When assembling, the drive bracket stays in the chassis, the confining patch is engaging in the confining hole, the elastic patch presses the baffle; when disassembling the drive bracket is pushed outwardly by the elastic patch pressing the baffle.