UM400a/UM450 v1.3

Added support for blocks 470 and 19.

UM400a/UM450 v1.2

Adjusted subsonic filter to meet specification for frequency response at 35 Hz.

UM400a/UM450 v1.1

Added support for new 944 MHz block. Also replaced subsonic filter with a quieter one, for a slight improvement in noise performance.

UM400a/UM450 v1.0

First production release.