Screen Display

the scan length is only meaningful is parameters are being swept. Once the trace buffer has looped around, the oldest point (at any time) is at bin#0 and the most recent point is at bin#k where k is the buffer length (minus 1).

The default mode is Loop.

Default Scan

Upon reset, all four traces are stored for a maxi- mum of 16000 points. The sample rate is 1 Hz, the scan length is 16000 seconds and the scan mode is Loop. The trace definitions are X, Y, R and θ for Traces 1-4.

Starting and Stopping a Scan

The [START/CONT] and [PAUSE/RESET] keys are used to control data acquisition. Basically, the [START/CONT] key starts a scan or continues a paused scan and the [PAUSE/RESET] key pauses a scan or resets a finished scan. See the discus- sion of keypad operation later in this section for details. Scans can also be controlled via the com- puter interfaces. See the programming section for an explanation.

In addition, the rear panel Trigger input can be used to start a scan. To select this mode, set the Trigger Starts option in the AUX menu. In this mode, a rising TTL trigger will act the same as the [START/CONT] key. The sample rate can be either internal or Triggered. In the first case, the trigger starts the scan and data is sampled at the programmed sample rate (up to 512 Hz). In the latter case, the first trigger will start the scan and data will be sampled at every subsequent trigger.

Aliasing Effects

In any sampled data stream, it is possible to sample a high frequency signal such that it will appear to be a much lower frequency. This is called aliasing.

For example, suppose the lock-in is detecting a signal near 1 Hz with a relatively short time con- stant. The X output will have a DC component and a 2 Hz component (2xf). If the sample rate is 2 Hz, then the samples may be taken as illustrated below.

1 second

The samples represent a sine wave much slower than 2 Hz that isn't actually present in the output! The chart display of this trace will show a sine wave at a very low frequency and will be rather misleading. In this case, a much higher sampling rate will solve the problem.

Aliasing occurs whenever the output signal being sampled contains signals at frequencies greater than 1/2 the sample rate. The effect is most noticeable when trying to sample an output frequency at an integer multiple of the sample rate (as above). The above aliasing problem will be the same for a 1 kHz output (500 times the sample rate) as for the 2 Hz output.

Generally, the highest possible sample rate should be used given the desired scan length and number of stored traces. The lock-in time constant and filter slope should be chosen to attenuate signals at frequencies higher than 1/2 the sample rate as much as possible.

Aliasing can occur with the polar and bar graph displays as well. These displays sample the output signal at a fixed rate.

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SRS Labs SR850 manual Default Scan, Starting and Stopping a Scan, Aliasing Effects
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SR850 specifications

The SRS Labs SR850 is a high-performance audio processor designed to enhance the listening experience across a variety of applications. With its advanced technologies, the SR850 delivers superior sound quality that is particularly noticeable in environments where audio clarity and fidelity are paramount. This device caters to audio professionals, audiophiles, and casual listeners who demand exceptional performance from their audio systems.

One of the standout features of the SR850 is its proprietary SRS 3D Audio technology. This innovative feature creates a more immersive soundstage, allowing users to experience audio as if they were in a live performance setting. By adding depth and dimension, it elevates the listening experience, making music, movies, and games far more engaging.

Additionally, the SR850 incorporates SRS dialog clarity technology, which enhances speech intelligibility in dialogues and vocals. This is particularly beneficial in film and television viewing, where dialogue can sometimes be drowned out by background music or sound effects. With dialog clarity, users can enjoy crystal-clear conversation tracks without adjusting volume levels continuously.

The device also supports various audio formats, ensuring compatibility with a broad range of media. It boasts inputs for both digital and analog sources, allowing connections to various devices such as TVs, laptops, gaming consoles, and more. The versatility of inputs makes the SR850 a convenient addition to any home entertainment system.

Another impressive characteristic of the SR850 is its compact and user-friendly design. The intuitive interface makes it easy for users to adjust settings to their preference, whether they are a novice or an audio expert. The device is equipped with programmable presets, enabling users to store their favorite sound profiles, making switching between settings quick and hassle-free.

Furthermore, the SR850 features advanced EQ capabilities, granting users the ability to tailor the audio output to their specific tastes. This personalized approach to sound adjustment enhances the overall experience, allowing users to get the most out of their audio content.

In summary, the SRS Labs SR850 is a sophisticated audio processor packed with features designed to significantly uplift sound quality and listening pleasure. With its cutting-edge technologies such as SRS 3D Audio and dialog clarity, an array of connectivity options, and customizable EQ settings, the SR850 stands out as an outstanding option for anyone looking to enhance their audio experience. Whether for professional use in sound engineering or personal enjoyment in home entertainment, the SR850 proves to be a valuable asset.
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