Abstract:
A stencil printer apparatus for depositing a solder paste onto the surfac e of the electronic substrate, comprising a frame, a stencil coupled to the frame, the stencil having a plurality of apertures, a dispenser coupled to t he frame, the stencil and the dispenser being configured to deposit the sold er paste onto the electronic substrate, an imaging system (121) constructed and arranged to capture an image of the electronic substrate, and a controll er coupled to the imaging- system and configured to control movement of the imaging system to capture the image. The imaging system (121) comprises a ca mera element (201, 203) configured to capture the image of at least the port ion of the surface of the electronic substrate (111), and a first illuminati on element (209) comprising a long-wavelength light source configured to ill uminate at least the portion of the surface of the electronic substrate by g enerating long-wavelength light. Other embodiments and methods are disclosed .
Abstract:
To detect the number of transmit antennas, a fast Fourier transform operation is performed on the received samples of the transmitted long training symbols of a preamble. Next, each of the Fourier transformed results is multiplied with the reference frequency-domain representation of the long training symbol so as to remove the effect of the symbols and to maintain the channel information. Next, inverse Fourier transform or least squares operations is performed on the multiplied values to compute channel impulse response. The number of shifted impulse response in the channel impulse response represents the detected number of transmit antennas. Packets containing preambles of the present invention may be received by extended devices as well as by legacy receivers that are not configured to receive and interpret these preambles. The training symbols may be cyclically-shifted and transmitted on different transmit antennas.
Abstract:
A stencil printer apparatus for depositing a solder paste onto the surface of the electronic substrate, comprising a frame, a stencil coupled to the frame, the stencil having a plurality of apertures, a dispenser coupled to the frame, the stencil and the dispenser being configured to deposit the solder paste onto the electronic substrate, an imaging system (121) constructed and arranged to capture an image of the electronic substrate, and a controller coupled to the imaging- system and configured to control movement of the imaging system to capture the image. The imaging system (121) comprises a camera element (201, 203) configured to capture the image of at least the portion of the surface of the electronic substrate (111), and a first illumination element (209) comprising a long-wavelength light source configured to illuminate at least the portion of the surface of the electronic substrate by generating long-wavelength light. Other embodiments and methods are disclosed.