Recent observations at King's College, London, concerning the determination of the propagation constant (attenuation and phase velocity) of electromagnetic waves over the earth's surface are described. The experimental techniques employed include the use of single‐station and two‐station magnetic recording of atmQspherics (sferics) propagated over great distances and the observation of the frequencies and Q factors of Schumann resonances. The experimental results are interpreted in terms of the waveguide mode theory of propagation by assuming various electron and heavy ion density profiles for the ionosphere. The present work agrees well with the observations of other workers made over a limited frequency range, and enables the propagation constant to be determined from 8 c/s to 16 kc/s.

No abstract

No abstract

No abstract

Logic State Imaging (LSI) using Infra-Red Emission Microscopy (IREM) [1-4] has been an indispensable technology for silicon CMOS process development and product debug applications. Its main limitations are relatively poor spatial resolution due to the broadband near-infrared photons emitted, and poor Signal to Noise Ratio (SNR) with low voltage and low leakage processes and products. Continuous-Wave Laser Scanning Microscope (CW-LSM) based Signal Imaging and Probing (CW-SIP) [5-9] technology is also widely used. It features inherently better spatial resolution than IREM, due to the use of monochromatic 1319nm or 1064nm laser light, and high SNR due to its weaker dependence on voltage and leakage, and, for signal imaging applications, the use of narrow band detection to reduce noise. However, CW-SIP can only detect modulating signals, so it couldn’t previously be applied to LSI. In this paper, we introduce an innovative approach that overcomes this limitation to enable Laser Logic State Imaging (LLSI). Actual fault isolation and design debug cases using this technology are presented to show its advantages in terms of resolution (>50% better), SNR (>2X better) and throughput time improvement, especially at low voltages (down to 500mV).