Spectrum Brands MC.31XX - Manual (Page 83)

Option Timestamp General information
(c) Spectrum GmbH 83
Option Timestamp
General information
The timestamp function is used to record trigger events relative to the beginning of the measurement, relative to a fixed time-zero point or
synchronized to an external radio clock. This is done by a wide resetable counter that is incremented with every sample rate. With every
detected trigger event the actual counter value is stored in a seperate timestamp memory.
This function is designed as an enhancement to the Multiple Recording and the Gated Sampling mode but can also be used without these
options. If Gated Sampling mode is used, then both the start and end of a recorded segment are timestamped.
The timestamp memory is designed as a FIFO buffer so that it can be read out even while the Spectrum board is recording data continuously
to the PC in the FIFO mode. This extra memory is 64 K Timestamps in size.
Each recorded timestamp consists of the number of samples that has been counted since the last
counter reset has been done. The actual time from the point since the last reset has been done so
can easily be calculated by the formular besides.
If you want to know the time between two timestamps, you can simply calculate this by the for-
mular besides.
Limits
The timestamp counter is running with the sampling clock on the base card. Some card types (like 2030 and 3025) use an interlace mode
to double the sampling speed. In this case the timestamp counter is only running with the non-interlaced sampling rate. Therefore the maximum
counting frequency of the timestamp option is limited to 125 MS/s.
Timestamp modes
Standard mode
In standard mode the timestamp counter is set to zero
once by writing the TS_RESET commando to the com-
mand register. After that command the counter counts
continuously.
The timestamps of all recorded trigger events are refer-
enced to this common zero time. With this mode you
can calculate the exact time difference between differ-
ent recordings.
The following table shows the valid values that can be
written to the timestamp command register.
StartReset mode
In StartReset mode the timestamp counter is set to zero
on every start of the board. After starting the board the
counter counts continuously.
The timestamps of one recording are referenced to the
start of the recording. This mode is very useful for Multi-
ple Recording and Gated Sampling (see according
chapters for detailed information on these two optional
modes).
The following table shows the valid values that can be
written to the timestamp command register.
Register Value Direction Description
SPC_TIMESTAMP_CMD 47000 w Writes a command to the timestamp command register.
SPC_TIMESTAMP_CMD 47000 r Reads out the actual timestamp mode.
TS_RESET 0 Resets the counter of the timestamp module to zero.
TS_MODE_DISABLE 10 Disables the timestamp module. No timestamps are recorded.
TS_MODE_STANDARD 12 Must be written to enable the Standard timestamp mode. The counter must be manually reset by writing the command
TS_RESET to the command register. The timestamps values will be relative to this reset time.
Register Value Direction Description
SPC_TIMESTAMP_CMD 47000 w Writes a command to the timestamp command register.
SPC_TIMESTAMP_CMD 47000 r Reads out the actual timestamp mode.
TS_RESET 0 Resets the counter of the timestamp module to zero.
TS_MODE_DISABLE 10 Disables the timestamp module. No timestamps are recorded.
t
Timestamp
Sample rate
-------------------------------------------------- =
t
∆
Timestampn 1
+
Timestampn –
Sample rate
----------------------------------------------------------------------------------------------------------------------------- =