AF Signal Function Generator





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Characteristics:





updownswitchgroup

With the upper switches arbitrary values can be adjust (frequency, phase, level, etc.). The values are set at the upper and at the lower notice on the limit value. With the lower switches once round the value to the respective digit, or reseting to the default value.



choice of channels

The selection of the channel which can be edited takes place again by means of keys. Mean:


Main

Frequency-normally generator, frequency reference for other channels, modulator and output channels can run on this frequency by means of a factor phasesynchronously
Parameter: frequency


Measure

channel for signals with an instrumentation character such as sine sweep or MLS noise signal, with sweep signal is showed the current frequency
Parameter: Level, classification of signals


M1, M2, M3, M4 - modulators

The modulator channels affect the forward channels in phase, frequency or amplitude.
Parameter: classification of signals, frequency, level, phase, synchrony of phase


C1, C2, C3, C4 - output channels

The types of modulation can be combined at will. The signals of different modulators are summed up however same type of modulation.
Parameter: Classification of signals, frequency, level, phase, balance, DCOffset, synchrony of phase, classification of modulation


Modulator switch

Choice of type of modulation in form of a matrix circuit. Signals of a line are summed up. Attitudes are individually adjustable for each output channel. In the example above the output channel with the sum of modulator of channel 1 and 2 frequency-modulated and with modulator channel 2 amplitude-modulated.


Sync switch

If channels have to run synchronously at phase, this is possible with this attitude. Individually for output and modulator channels. The frequency of a channel forms from the product of frequency normal and frequency factor of the respective channel.


Classification of signals choice

At the time the following classifications of signals are selectable:

  • Sine
  • Triangle
  • Square
  • Pulse
  • Sawtooth
  • Random Square
  • Random Pulse
  • Whitenoise
  • Pinknoise

  • Extended options

    Second window for further options opens.



    Further options


    Generally

    In this window all options are again adjustable by a updownswitchgroup, in addition the values can be entered in addition, directly.
    As important parameters is considered the sampling frequency (8000Hz-96000Hz). Then the unit for the level attitudes is selectable (FS or Volts, and additionally logarithmically dB). FS stands for Full Sample, the value 1.0 means the maximum level that produce the DAC (digitally to analog converter). For the calibration with Volt-based output, the calibration factor and the maximum value are to be entered here. For the digital synthesis 3 different algorithms stand to the selection. The effects of the choice show follow pictures.

    Rectangle 360 Hz, sampling frequency 44100 Hz, Virtual audio Cable,
    Above: simplest approximation, down best approximation


    Filtering for output channel 1

    For the output channel 1 a FIR or a IIR filter of 2nd order can to be inserted. For the FIR filter (finite impulses Response) can be selected order, the beginning and the final frequency and type (band-pass filter or band suppressor). For the IIR filter can be edited type (low-pass, high-pass, band-pass filter, band-stop (notch)), frequency and damping ratio factor.


    Sweep

    For the Sweep the parameters are initial frequency, final frequency, flow velocity, out time in seconds, character (exponentially, linear) and direction to be adjusted. The velocity of sweep is indicated as octaves per second in the exponential range and in the linear range as Hz per second.


    wavefile

    For the storage of wav - files the values time length in seconds, name of the file (storage in the work listing) without ending and the channel dispatching are the main parameters. With the switch 32 bits stores it at the 32 bit resolution format. With the switch dithering/bluring will result spectral noise floor by the digital synthesis from uniform distributed noise. The effect shows the following diagram.


    1 kHz without additional noise

    1 kHz with spectral bluring

    Sound card device parameter

    Here the choice of the sound card (if only dump for file is desired, takes place here "off" selects). In addition again alising dithering/bluring can be selected here. For the calibration of Volt adjusted output, the generator mixer attitudes can be changed here. The calibration procedure is further below described. The mixer parameters appear in a tree opinion the values can be adjust with the updownswitch and the mute with the checkbox.


    Calibration

    Those in the following described calibration procedure was not practically tested yet. If this cannot be practically reconstructed, then they send please a mail to the author. 1. Maximum value determine. In addition all values are to be stopped to maximum. This concerns the mixer attitudes waveout and sumout and the calibration factor (= 1). Then a channel is to be adjusted to the classification of signals sine and level=1. As frequency 50 Hz is recommended. The measured rms is to be multiplied by the factor 1.41. This value to a desired value without decimal place reduce and then into the text field "trunced max volume days" register. 2. Now the values waveout and sumout and calibration factor adjust that in such a way the registered tension at the measuring instrument are indicated (again by 1.41 to multiply, rms announcement is supported shortly). As large a value for the calibration factor as possible select there otherwise the output section of the DACs one limits. 3. Try different values out for levels for the examination simply times. If the switch "V" was pressed should this always with that measured value agree.