ALEXIARES
ALEXIARES
Alexiares (or Alex for short) is an RF Preselector for use with Mercury or any other SDR. The project leader for Alex is Graham, KE9H, who is also laying out the PCB. The purpose for Alex is to reduce the level of out-of-band signals at the input of a receiver.
It has three filter sections, a continuously tunable 1.8 to 30 MHz bandbass filter, a 50 to 54 MHz bandpass filter, and provision for a user defined filter. In addition, a bypass function is provided. An on-board noise generator is provided for alignment of the continuously tunable filter.
Protection from potentially damaging high signal levels is provided in the form of a transient suppressor (details TBD) at the antenna socket.
Alex has provision to be switched between two paths; either in the path from the antenna to the receiver, or to filter a low level transmitter signal.
A CPLD is used to interface the filter selection and routing to the Atlas bus to provide maximum flexibility in Alex’s configuration.
A block diagram of Alex is shown below.
Why Alexiares? Alexiares and his twin brother Anicetus - were the Greek Gods of Defense, in particular the defense of fortified towns and citadels.
Both were sons of Herakles (Hercules), born after the hero's ascension to Olympus and his marriage to the goddess Hebe. The pair likely served as the gatekeepers of Olympus, assisting their father in a role which was commonly assigned to Herakles.
