8 Bit Mode for Data Saving

The 8 bit data mode is available on digitizers of the 33xx and 44xx series. This mode is available on all platforms of these two series. The mode has been implemented with a firmware update after the initial release of the product. Please update to the latest firmware to use this mode.

As standard these digitizers store each sample in two bytes. Activating the 8-bit mode the resolution of the ADC is reduced from the native resolution down to 8 bit and each sample is stored in one byte only. By reducing the resolution the least significant bits of the ADC samples are cut-off, sacrificing some of the signal quality for storage reason.

Using the 8 bit mode has two advantages:

Storage

By reducing the resolution to 8 bit, double the number of samples can be stored in the on-board memory:

• 44xx Series: these digitizers have an on-board memory of 2 GSamples (4 GBytes). Using the fastes model M4i.4451-x8 (4 x 500 MS/s, 14 bit), one can store 1 second of data in the on-board memory. When operated in 8-bit mode, one can store 2 seconds of data in the on-board memory
• 33xx Series: these digitizers have an on-board memory of 2 GSamples (4 GBytes) as standard and optionally 8 GSamples (16 GBytes). Using the fastes model M5i.3360-x8 (1 x 10 GS/s, 12 bit), one can store 200 milli seconds (ms) of data in the standard on-board memory or 800 ms with optional memory extension. When operated in 8-bit mode, one can store 400 ms of data in the standard on-board memory or 1.6 seconds with the optional memory extension.

Streaming (FIFO) mode

All products have a limited data throughput based on their interface. Switching to 8-bit mode a much faster sampling speed is possible for continuous streaming. A second advantage is the reduced need for storage space and data throughput need on the storage device (SSD array).

Below are some examples with the maximum available streaming speed with native resolution in contrast to 8-bot mode:

• M4i.4451-x8 (4 x 500 MS/s, 14 Bit, PCIe x8): Streaming speed is limited to 3.4 GByte/s. In native resolution that allows to stream data continuously with 4 x 400 MS/s. Using 8-bit mode one can run with full streaming speed of 4 x 500 MS/s
• M4x.4451-x4 (4 x 500 MS/s, 14 Bit, PXIe x4): Streaming speed is limited to 1.7 GByte/s. In native resolution that allows to stream data continuously with 4 x 200 MS/s. Using 8-bit mode one can run with full streaming speed of 4 x 400 MS/s
• DN2.445-04 (4 x 500 MS/s, 14 Bit, Ethernet): Streaming speed is limited to 100 MByte/s. In native resolution that allows to stream data continuously with 4 x 10 MS/s. Using 8-bit mode one can run with full streaming speed of 4 x 20 MS/s
• M5i.3360-x16 (1 x 10 GS/s, 12 Bit, PCIe x16): Streaming speed is limited to 12.8 GByte/s. In native resolution that allows to stream data continuously with 1 x 6.4 GS/s. Using 8-bit mode one can run with full streaming speed of 1 x 10 GS/s