Crown SMX-6, MPX-6, AMB-5 6.2.3 D/A Converter, Log Amp and A/D Converter, Auxiliary Port

IQ Mixer / Multiplexer Hardware Installation

6.2.3 D/A Converter

To set channel gain levels, a digital-to-analog con- verter continuously converts all gain settings to control voltages. An analog demultiplexer sends the appropriate control voltages to each of the twelve VCAs.

6.2.4 Log Amp and A/D Converter

The A/D converter scans through an eight-channel multiplexer to read the input and output signal lev- els. When a channel is selected, the signal is sent through a logarithmic amplifier for increased dy- namic range. This analog voltage is then converted to a binary number that the microprocessor can read. The processor can then mathematically in- crease detector time constants, perform averaging or other response functions.

6.2.5 Auxiliary Port

Auxiliary devices such as supplemental cooling fans can be remotely controlled via the AUX output on the unit. When the auxiliary control feature is turned on by the host computer, 10 VDC is supplied across pin 3 and pin 1 (ground) of the male 3-pin AUX connector. This port can control solid state relays, and since it has a current-limit resistor (16 mA max.), it can directly drive an LED or opto- coupler.

The AUX input function is used by applying a 5-30 VDC signal to pin 2 (with pin 1 as ground). A high or low signal here will be communicated to the host computer. A logic low can be less than 0 volts (negative); the signal is internally clamped for cir- cuit protection.

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