The Sonifex PC-FM24 is a 24-channel FM radio-capture PCIe card designed for simultaneous recording of 24 radio stations on a Windows computer. The frequency of each station is set in software and its audio appears as a standard Windows audio input device. RDS decoding is also supported. To capture the required signal, connect an antenna to the BNC connector.
The card uses a high-speed A/D converter to digitize the entire FM band (87.5 to 108.5 MHz), with 24 individual tuners. The card achieves exceptionally low audio distortion through the use of linear phase filtering and mathematically precise FM demodulation and stereo decoding. FM demodulation, stereo decoding, and RDS decoding (if enabled) are all performed in FPGA fabric. The card is factory-configured for 24 stations, but may be expanded up to 32 stations with an additional upgrade key (available separately).
- Drivers have been fully implemented for Windows and Linux, with RDS being available on both platforms now.
- A 64-bit WDM driver for Windows 10, Windows Server 2016, 2019, and Windows 11 is supplied as well as software for setting the tuner frequencies and monitoring the received audio.
- A programming API and DLL for software control and monitoring are also supplied.
- The Linux driver is Alsa-based and supports Kernels from version 3.8 and later.
- The card can be configured to operate in stereo, mono, or paired mono (two mono stations combined on a 2-channel audio stream) modes.
- Multiple cards can be used in a single PC, subject to available CPU bandwidth.
- The audio de-emphasis may also be set to either 50 or 75us. In Australia, New Zealand, and Europe, 50us is used, while in the USA and Canada, 75us is used.
- A Windows utility called FMSpectrum is supplied. This displays the RF spectrum from 85 to 111 MHz (using data from the card’s front-end 256-point FFT) and may be useful in selecting the best location for the antenna or resolving interference problems.