advanced audio recording
Realtime Signal Sampler with Cyclone 4
  Cyclone IV

48kHz /

200 MHz
sample rate

Base Hardware Unit

Altera Cyclone IV + ADC/DAC board

Altera DE-115 base board
Altera base board with Cyclone 4

The Altera Cyclone 4 DE2-115 from Terasic is used to implement a high resolution sampler and signal generator for technical signal tests to be used for connections in between PCBs. The test data is stored in block RAMs and can be continously driven out with any given frequency. A 150Msps - DAC is used here to shape signals typically used for audio data transmission like TDM and S/PDIF. In the example, shaping is performed with 8 dots per clock, leading to almost 100MHz to define the analog behaviour of the 12,288MHz BMC clock for 96kHz Audio in terms of rising and overshot behaviour.

Altera DE-115 base board with ADc + DAC
Terasic DAC-ADC-board for Cyclone 4

The incoming signal is sampled with twice the driver clock using 4 different angles of PLL-outputs settings (0°, 90°, 180°, 270°) to statically oversample the signal. This leads to 64 positions for each sample of the S/PDIF clock. Together with the programable output delays of the driving Pin in the FPGA, 640 postions are possible altogether. An area of 640x400 dots is used to store the accumulated number of crossings of the signal for this combination of voltage and time leading to a common eye pattern. The received and reconstructed S/PDIF signal is monitored at the line out ports of the Terassic DAC board.

250 Msps High Speed Signal Analyser with Altera DE-115
Eye Pattern of a 192kHz S/PDIF signal

Click here for details of the signal generation with the multi rate clock resampler and the pulse shaper.

Get the VHDL code here: sa_2012_os.zip

Click here to see the Sampler



© Dipl.-Ing. Jürgen Schuhmacher 2012