  In this work, targeting, e.g., future generation cellular, microwave-links,
or optical fiber systems, we propose a new geometric shaping design for golden
angle modulation (GAM) based on a (double) truncated Gaussian input
distribution. The design improves the mutual information (MI), and the
peak-to-average power ratio, over the full signal-to-noise ratio (SNR) range
relative to two key GAM schemes introduced in [1],[2]. Inspired by the proposed
geometric shaping, a simpler, SNR-dependent, design is also suggested. The
performance is numerically evaluated with respect to MI and compared with
classical modulation schemes. With the proposed design, the SNR can be
decreased relative to classical quadrature amplitude modulation, even for
relatively modest target spectral efficiencies. As the GAM design can approach
the Gaussian channel capacity, the power/energy efficiency is expected to
improve.
