Hacker Measurement and Computing FreeVIEW sound (download here)

Sound card driver with FreeVIEW software

Nearly every today's PC and notebook is equipped with an additional or on-board sound card. Iit can be turned into a 2 channel audio measurement system because not only the driver, also the analyzing software is included!

The 32 bit sound card driver and the accompanying FreeVIEW plus application software turns a PC or notebook into a long-time data logger, a chart recorder, a storage oscilloscope, spectrum analyzer and much more.

The driver supports popular programming languages and applications.

Hacker offers this software package free of charge.

Basic features

The free of charge version of the sound card driver called "FreeVIEW sound" works with Microsoft® Windows® 95/98/ME and can be used for recording with sample rates up to 48kHz per channel. One or both input channels of the sound card can be used.

The full version called "FreeVIEW sound pro" has A/D and D/A capability (recording and playing), also simultaneously. In addition the operating systems Microsoft® Windows NT® and Windows® 2000 are supported. The sample rate is limited to that supported by the sound card. For example sound cards with 96kHz sample rate per channel can be used.
Also technical support for the driver and the programming language interfaces is included. A bundle containing a high-quality 96kHz sound card and driver software will be available too. For further information, contact hacker directly.

Both versions share the following basic features:

	For writing applications, the driver can be used directly with Borland Delphi 5, Agilent VEE / HP VEE / DT VEE, Microsoft® Visual Basic® 6 and Microsoft® Visual C++® 6.
	Example programs are included in the software package.
	FreeVIEW plus data logger / scope recorder software, in a special version for sound cards only, is included!

FreeVIEW plus for sound cards

Highlights

	32 bit driver on top of Microsoft® Windows® multimedia API.
	The driver uses an additional FIFO buffer for intermediate storage. Sampled data can be retrieved in arbitrary length. The synchronous data capture is decoupled from block-like data processing. No data gets lost! This is a significant enhancement over the double buffer principle enforced by the original multimedia interface.
	Scaled data is returned in volts unit.
	Simple programming interface using only a few functions open(), close(), read(), write() and ioctl().
	Full error handling.
	Shares the features, the interfaces, the style and the experience of ines data acquisition card drivers.
	FreeVIEW plus data acquisition software, version for sound cards, is included in package. No programming required. Immediate data capture and data analyzing capability including Fourier transform and many other functions. See here for a description of FreeVIEW plus.
	Ready to run example programs and Online help for Borland Delphi 5, Agilent VEE / HP VEE / DT VEE, Microsoft® Visual Basic® 6 and Microsoft® Visual C++® 6.

Sound card properties

Not every measurement that can be performed using a full-featured data acquisition card can be also done by a sound card. There are major differences that one should know:

Sound cards limitations

	DC voltage measurements are not possible. Sound cards use capacitors in the signal path, so any DC level is removed. This means also that there is a lower frequency limit because of the high-pass characteristic of the capacitor in line. The lower cutoff frequency is card dependent.
	The input impedance is low. Measurements are done using the line input. Real data acquisition cards have impedances of 1 to 10MOhm. In general sound cards have a much lower impedance, ranging from 600 Ohm to 47kOhm. One could use the microphone input for better sensitivity, but the noise floor is higher, and many cards output a voltage for microphone supply. If that input is used, a capacitor for blocking this voltage is necessary!
	Data acquisition cards can measure voltages with high accuracy (+/-1% or better). Furthermore they provide different measurement ranges. In contrast the sound cards recording level is set by a slider. There's no initial calibration; it must be performed by the user.
	The input voltage range used for sensor input is +/-10V in general. Sound cards with line input provide an input range of about +/- 400mV. The microphone input is much more sensitive. Only sensors with low voltage AC output and low output impedance are suitable!
	No trigger facilities. Data acquisition cards usually can wait for a so-called trigger event that starts the data capture. Common trigger events include "input voltage above or below level" or "rising edge" or "falling edge at level" detected. To some degree this limitation can be overcome by software. The calibration problem remains, so the trigger level will not be very accurate.
	Only two single-ended channels are available. Most data acquisition cards provide 8 or 16 channels that can be switched to single ended "non-symmetric" or differential "symmetric" inputs if signals differ in ground level.

Sound cards advantages

	A clear advantage of sound cards in comparison to most data acquisition cards is that two channels are captured at the same time using two A/D converters or at least two sample and hold devices. Data acquisition cards usually use one A/D converter and a multiplexer. For that reason multiple channels are scanned one after another and not in parallel. Phase shifts can be caused, such cards are not suitable for vibration analysis or phase measurements.
	Notebook or desktop PC with built-in 16 bit sound card or sound system. A line input is preferable in comparison to a microphone input. Pentium class CPU and 32MB RAM minimum recommended.
	FreeVIEW sound

Additional information

FreeVIEW sound (free of charge) includes:

	The driver supporting A/D conversion (recording only) with 16 bit resolution
	Sample rates up to 48kHz per channel, 2 channels maximum (stereo input)
	For operating systems Microsoft® Windows® 95/98/ME (note: Windows NT/2000/XP are not supported)
	Interfaces for the supported programming languages and applications
	Example programs for these interfaces
	FreeVIEW plus for sound cards
	No support (bug and test reports welcome)

FreeVIEW sound pro (full version) includes:

	The driver supporting A/D and D/A conversion (recording and playing) with 16 bt resolution.
	Simultaneous A/D and D/A possible. A sound card capable of "full duplex" mode is required.
	No sample rate limitation, all conversion rates that cards offer can be set. 96kHz cards can be used.
	For operating systems Microsoft® Windows® 95/98/ME, Windows NT® and Windows® 2000
	Interfaces for the supported programming languages and applications
	Example programs for these interfaces
	FreeVIEW plus for sound cards
	Technical support