Knowledge-Base
12 Bit Packed Mode for Data Saving
The 12 bit packed data mode is available on digitizers of the 33xxseries. This mode is available on all platforms of this 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. The 12-bit packed mode is a standard feature and available to all customers without further cost.
As standard these digitizers store each sample in two bytes. Storing a 12-bit digitizer value in 16 bit leaves 4 bit unused. Activating the 12-bit packed mode, these 4 empty bits are used to store data. Each two 12-bit samples are stored in 3 bytes instead of 4 bytes. This reduces the needed data transfer bandwidth significantly.
After transfering data to the PC, the packed data needs to be unpacked in software to perform algorithms ony it.
12-bit packed mode compared to 8-bit mode
The M5i.33xx series also features an 8-bit mode. While data throughput is even less, the ADC resolution is reduced when using the 8-bit mode. The 12-bit Packed Mode allows higher throughput withotu sacrificing analog resolution.
Streaming (FIFO) mode advantages
All products have a limited data throughput based on their interface. Switching to 12-bit packed 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 12-bit mode:
- M5i.3321, M5i.3330, M5i.3337:
- Standard Mode: streaming of 2 x 3.2 GS/s or 1 x 6.4 GS/s, data throughput 12.8 GByte/s. This throughput is possible on powerful dedicated systems
- 12-Bit Packed Mode: streaming of 2 x 3.2 GS/s or 1 x 6.4 GS/s, reduced data throughput of 9.6 GByte/s. This throughput is possible on nearly all systems on the market that have a matching PCIe interface
- M5i.3350, M5i.3357, M5i.3360, M5i.3367:
- Standard Mode: streaming of 2 x 3.2 GS/s or 1 x 6.4 GS/s, data throughput 12.8 GByte/s. This throughput is possible on powerful dedicated systems
- 12-Bit Packed Mode: streaming of 2 x 4.0 GS/s or 1 x 8.0 GS/s, reduced data throughput of 12.0 GByte/s. Fastest streaming speed with full 12-bit resolution
- 8 Bit Mode: streaming of 2 x 5.0 GS/s or 1 x 10.0 GS/s, reduced data throughput of 10.0 GByte/s. Fastest streaming speed with reduced 8-bit resolution
- SSD Storage and Throughput
- 12-Bit Packed Mode: reduces data storage and throughput need by 25%