PDAudio is a system of inexpensive hardware and software components you can select among to assemble a very compact recorder that meets your needs.
The centerpiece of the 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 CE/Pocket PC 2002 or Linux (such as HP/Compaq's iPAQ), or used with laptop and desktop computers running Linux, Windows 2000 or Windows XP.
The PDA-based PDAudio will operate on rechargeable batteries for more than enough time to record a concert, and be able to quickly transfer audio data to a computer (PC or Mac) via removable solid-state memory cards (currently available in sizes up to 4 GB from Lexar), removable PC Card (currently up to 5 GB from Toshiba) and CF Card (currently 1 GB and up to 4 GB from Hitachi/IBM come Fall '03) hard disk drives, high capacity 2.5" hard drives (40 GB or more) using the PC Card interface, and via wired and wireless local area networks.
The PDA, PDAudio-CF interface, CF storage cards all fit together in one compact package, using a dual CF (or PC Card) expansion pack.
The recorder is be able to record in both single channel and dual channel modes, with sixteen, eighteen, 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: one to indicate that it's seeing a valid S/PDIF data stream and another under the software application's control. The second LED flashed at various rates and can be used 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. A WDM driver for Windows XP and Windows 2000 is included.
The PDAudio-CF driver source code, user guide and programming is freely available to third-party audio software developers.