ALV-LinCorr, Fast Linear Tau Digital Correlator

Technical Data

Fastest realtime STC No. of Correlation Channels Computes Lags 25 ns 128 + 32 0 ... 127 + 2016 ... 2047 37,5 ns 256 + 32 0 ... 255 + 2016 ... 2047 75 ns 512 + 32 0 ... 511 + 2016 ... 2047 137,5 ns 1024 + 32 0 ... 1023 + 2016 ... 2047 250 ns 2048 2 x (1024 + 32) 0 ... 2047 2 x (0 ... 1023 + 2016 ... 2047)

 

High speed, 100% real time linear correlator supporting the following modes

DUAL Channel Mode

two independent correlation functions (independently AUTO or CROSS from 4 counting inputs), 1024 linear channels each + 32 delayed channels each at lag times 2016 ... 2047 x STC, fastest realtime STC 250 ns, STC range 250 ns ... 812,9 µs in 12,5 ns steps, counting inputs with up to 9 bit input data per STC, individual random preset scaler (for count rate / STC combinations exceeding the 9 bit format) with 1:2/4/8/16/32/64/128 pre-scale level for each input.

SINGLE Channel Realtime Mode

single correlation function (AUTO or CROSS), sampling time dependent number of correlation channels,

2048 linear channels, fastest realtime STC 225 ns, STC range 225 ns ... 812,9 µs in 12,5 ns steps, counting inputs with up to 9 bit input data per STC, individual random preset scaler (for count rate / STC combinations exceeding the 9 bit format) with 1:2/4/8/16/32/64/128 pre-scale level for each input..

1024 linear channels + 32 delayed channels each at lag times 2016 ... 2047 x STC, fastest realtime STC 137,5 ns, STC range 137,5 ns ... 237,5 ns 12,5 ns steps.

512 linear channels + 32 delayed channels each at lag times 2016 ... 2047 x STC, fastest realtime STC 75 ns, STC range 75 ns ... 125 ns in 12,5 ns steps.

256 linear channels + 32 delayed channels each at lag times 2016 ... 2047 x STC, fastest realtime STC 37,5 ns, STC range 37,5 ns ... 62,5 ns in 12,5 ns steps.

128 linear channels + 32 delayed channels each at lag times 2016 ... 2047 x STC, fastest realtime STC 25 ns

 

SINGLE Channel Batch Mode

single correlation function (AUTO or CROSS) with 2048 linear correlation channels in batch mode for all sampling times below 250 ns. The correlation function is computed from batches (8k samples each) of data. Sampling is halted until the full block processing is completed. The maximum achievable efficiency is sampling time dependent and can reach nearly 75% for 237.5 ns sampling time.

For the smallest possible sampling time of 25 ns the efficiency is still slightly larger than 10%.

Pre-Delay of the Direct Channel

for all real and batch modes the direct channel can be pre-delayed in steps of 12,5 ns from 0 (default) to max. 1,5875 µs. This allows to compensate for propagation times on direct and delayed channel as well as allowing the access of “negative lag times” by purposely introducing such a pre-delay in the direct channel.

Note for current users of the ALV-LinCorr:

Both features, batch mode as well as pre-delay can be retrofitted to your ALV-LinCorr via a special online firmware update. Please contact ALV for details.

4 x TTL at 50 Ohm counting input with up to 160 MHz input count rate (80 MHz with pre-delay active)
EPP/PCI interface, inbuilt advanced test generator, WINDOWS-NT/2000/2003/XP/VISTA compatible software

Application

General high speed correlation application involving periodic correlation functions (surface scattering, modulated heterodyne detection, LDA, LDV ...)