1.9 Architectural Overview
The Astral ARX32 builds upon the existing Astral-RX16’ new approach to professional audio receiver design, allowing tuning from 169MHz all the way to
1525MHz, with some significant additions.
The first thing to note about the Astral ARX32 architecture is there are six independent RF signal paths – one for each antenna input – which all operate
simultaneously. This allows for several significant advances over the existing Astral-RX16' two antenna paths. Now, up to three antenna pairs can be
routed to different tuning bands. For example, four Astral transmitters could be operating in the 174-198 MHz VHF band, twelve in the 512-536 MHz UHF
band, and sixteen in the 940-960 MHz band – all with full, true-diversity operation. Alternatively, all six antennas could be simultaneously assigned to one
tuning band (“HexVersity”) for up to 32 transmitters, providing the ultimate in robust reception for all transmitters. The six antenna inputs can also be
configured in many other modes.
The architecture of the Astral ARX32 is as follows: the antenna inputs first route through fail-safe bypass relays, followed by pre-select filters. The fail-safe
relays switch the incoming antennas directly to the cascade outputs in the event of a power loss. Antenna bias power can pass through the fail-safe relays.
The pre-select filters reduce any out-of-band interference. The RF signals then pass through a versatile antenna matrix splitter/combiner. This matrix
allows for many configurations, including traditional Diversity (1 antenna pair), 4Versity (2 antenna pairs), HexVersity (3 antenna pairs), as well as zone
combining. Following this antenna matrix are the main receiver sections.
The section that immediately follows the matrix splitter/combiner is the first SAW filter array. These filter ranges are a key element of our unique
SpectraBand technology. They allow for a tuning range from 169 MHz - 1525 MHz to be divided into multiple, tightly filtered tuning bands. The extremely
sharp attenuation at either end of a tuning band’s filter range significantly reduces unwanted interference outside the selected tuning band, resulting in
excellent range performance. Filter ranges can vary in width but tend to be around 24 MHz wide. The next section is the Low-Noise Amplifier (LNA), which
is one of the most important stages in the design. This section has been specially designed for very low noise and high dynamic range, which results in
long-range reception and high overload capability. This LNA stage exhibits a noise figure of only 0.35 dB, one of the very best on the market currently.
This is followed by yet another SAW filter array. This array further attenuates out-of-band signals, ensuring reliable reception, and greatly suppressing any
image frequencies.
A Local Oscillator and Mixer perform the traditional function of a single down-conversion superheterodyne radio. This section has been meticulously
designed and is the other key element of our unique SpectraBand technology. This section exhibits extremely low phase noise and wide dynamic range to
accurately down-convert the RF to a lower Intermediate Frequency (IF) for conversion into the digital domain. Before conversion into the digital domain,
the signal passes through a final array of SAW filters, rejecting any extraneous energy not wanted in the down-conversion, as well as providing anti-
aliasing before the Analog-to-Digital (A/D) converter. The A/D converter is a wideband, extremely high dynamic range part which accurately captures 24
MHz of IF energy into a digital version of that signal.
The real magic of the entire Astral ARX32 happens within the Field-Programmable Gate Array (FPGA). An FPGA is essentially a giant custom, massively
parallel processor programmed in house. The FPGA can perform filtering, frequency conversion, and demodulation in the digital domain which far exceeds
anything that can be done via analog or traditional digital circuitry. The FPGA can perform demodulation of 32 channels simultaneously. The FPGA also