NOIZ White & Pink Noise Generator

PRODUCT INDEX

• Notice
• Introduction
• Features and Specifications
• Physical
• Outputs
• Design, Operation and Test
• Design
• Operation
• Test
• Power
• Polarity
• Connections
• Voltage
• Current
• Dissipation
• Parts List
• Revision Summary

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Notice

The NOIZ module has been superseded by the AGEN module. The documentation in this section is primarily intended for customers who have previously purchased NOIZ modules. The AGEN module produces both white and pink noise using the same algorithm as the NOIZ module. The AGEN module also generates other audio tones and test sounds. The photos in this section showing the white and pink noise outputs and spectrum are identical to those produced by AGEN. Refer to the AGEN documentation for AGEN specifications and a summary of the differences between NOIZ and AGEN.

Introduction

The following describes the design, construction, operation and use of the NOIZ White and Pink Noise Generator module. The primary use of the module is to generate simultaneous white and pink noise signals for audio testing.

As shown in Photo 1, the white noise signal is at logic levels. Photo 2 shows a narrow spectrum (25 kHz per horizontal division) view of the white noise output. The wide spectrum (250 kHz per horizontal division) output of the white noise is shown in Photo 3.

As shown in Photo 4, the pink noise is at a level of a few tens of millivolts for input to an audio system. Photo 5 shows a wide spectrum (250 kHz per horizontal division) view of the pink noise output.

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Features and Specifications

For the following, refer to Schematic 1 titled "NOIZ WHITE AND PINK NOISE GENERATOR." The schematic shows the components, circuitry and pinouts for the module. User's with older NOIZ modules with only 6 I/O pins please refer to the Schematic 2. You can download both NOIZ schematics as a zip file.

The Parts List provides additional information about the components used to assemble the module.

The module's header pins are spaced on tenth inch apart. However, the module is not intended for use with a solderless breadboard; insertion of the module into such a breadboard will short some of the pin rows and may damage the module.

The white noise output, available on J3/4, is directly connected to one of the microprocessor's port pins and is capable of sourcing or sinking up to 100 milliamperes (also reference the Power section). The pink noize output is at a level of a few tens of millivolts and is at a relatively high impedance level (it is driven through a 6.8K resistor from a microprocessor output).

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Design, Operation and Test

The pink noise output is also derived from the same software generator as the white noise signal but the white noise is first filtered by a "pinking" network before it is routed to the module's pink noise output (see the section labeled PINKING NETWORK on the schematic.)

To set up the module for operation, it is necessary only to supply it with power. Once supplied with power in the range of 5.2 to 16 Volts, white and pink outputs are continuously available (also see the PIN/PORT MAPPING table on the schematic).

The following sections describe power connection and verification procedures.

All module outputs are verified on a test fixture before shipment. Outputs are checked for waveform integrity and level with a Tektronix TDS 2014 oscilloscope. The pink noise output is also visually checked by observing correct frequency rolloff with the oscilloscope's FFT display.

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Power

The module is not protected against input voltage reversal. Take care to verify that the correct voltage polarity is applied to the power input pins.

Once the proper input voltage is applied to pins J1, the operation of the regulator can be verified by measuring the voltage between ground and the output pad for the regulator. This pad is labeled "out" on the module. The power can also be verified by carefully probing the voltage on pin 3 of the microprocessor. The measured regulator output voltage should be close to 3.3 Volts.

Note that the module may operate with an input voltage as low as 5 Volts, but the worst-case dropout specification for the regulator is 5.5 Volts. because modules are tested with a supply that measures just below 5.2 Volts, the module will operate at this lower voltage but operation at voltages lower than this test voltage is not guaranteed.

Revision Summary