The centerpiece of the PDAudio system is PDAudio-CF, a Type I (extended) Compact Flash S/PDIF interface with optical and coaxial inputs. PDAudio-CF can be mounted in PDA hosts that run Windows Mobile/Windows CE/PocketPC 2002/PocketPC 2003, or used with laptop and desktop computers running Linux, Windows 2000 or Windows XP.

Here's PDAudio-CF in the very small HP iPAQ h2215. (The iPAQ is running Gidluck Mastering's Live2496 software, and the PDAudio-CF card is partly pulled out of its slot so that it's more visible.)

It fits very comfortably in one hand. Provided with a digital input, it is a complete 24/96 digital recording system.

Using PDAudio-CF, PDAudio records in both single-channel and dual-channel modes, with eight, sixteen, twenty or twenty-four bit word widths, and data rates from 32 KiloSamples/second up to 192 KS/s (32, 44.1, 48, 88.2, 96, 176.4 and 192 KS/s). (Note that even though the PDAudio-CF supports sampling rates to 192 KS/s, some PDAs currently only support sampling rates to 96 KS/s. Almost all desktop and laptop PCs will support 192 KS/s.)

At 96 KS/s PDAudio-CF draws only 45 mA and so has minimal impact on your PDA's operating time per battery charge. (Various models of iPAQs are available with 1000, 1400 and 2200 mAh battery packs, and some of the CF/PC Card expansion packs provide still more battery capacity).

It has two LED indicators, both under software control. One is typically used to indicate that it's seeing a valid S/PDIF data stream and the other to indicate other record system status. Both LEDs can be flashed at various rates to signal sample rate, media-fullness warnings and other information.

PDAudio-CF will accept digital audio data from a wide variety of outboard units, essentially any device that uses an S/PDIF coaxial or optical interface. These include microphone pre-amplifiers/A-to-D convertors (e.g., our Mic2496, Lunatec's V3, M-Audio's Duo), CD players/recorders, DAT players/recorders, hard disk recorders (like the Alesis Masterlink), and digital PC & Mac sound cards. Input is via a 3.5mm (1/8-inch) jack for both optical and coaxial S/PDIF input, selectable via software.

In a laptop/desktop-based recorder, PDAudio-CF will provide a bit-for-bit accurate S/PDIF interface at up to 192 KS/s for use with most popular audio software applications including Adobe Audition (formerly know as Cool Edit Pro), Sonic Foundry Sound Forge and Vegas, and Steinberg WaveLab. A WDM driver for Windows XP (SP1 with DirectX 9.x) and Windows 2000 is now available for download here (see the "Downloads" section below).

PDAudio-CF can also accept other IEC-60958 compliant data formats including DTS, AC-3 and MP3 data streams. It's up to the software recording application to use this capability. This means that with the right software and front-end processors, you could do surround sound recordings with PDAudio-CF.

PDAudio-CF is for input only; it does not have a digital output.

Since the PDAudio-CF driver source code, user guide and programming guide are freely available to third-party audio software developers, we expect to see many software applications become available. We welcome inquiries from audio software developers.

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