Appendix C
Application Information Notes
Note 1: Special Considerations for Slow and Narrow Sweeps
When using narrow frequency sweeps in combination with long ramp times it is possible
that the magnitude of the frequency increment can become so small with respect to the
magnitude of the sweep start frequency that the internal mathematical precision of the
TG1010 is exceeded. As the ramp time is increased for a given frequency span there is a
progressive loss of accuracy of the calculated sweep stop frequency until a point is
reached where a linear sweep will not function at all and a log sweep will reverse in
direction.
The points at which these effects occur depend on the numerical values involved and
cannot be defined precisely, but the following serves as a guide.
if F
INC
<
6
START
10
F
stop frequency accuracy will be affected.
if F
INC
<
7
START
10
F
the sweep may not function at all.
In the above, F
START
and F
STOP
are the actual frequencies of sweep start and stop; F
START
will be
BEG FREQ
if
MODE
is
BEG-END
, F
START
will be
END FREQ
if
MODE
is
END-BEG
, etc.
F
INC
is calculated as follows:
For linear sweeps
=
INC
F
(
)
RAMPTIME
START
STOP
t
F
F
×
−
For log sweeps
=
INC
F
( )
START
STOP
RAMPTIME
t
F
F
⎟
⎠
⎞
⎜
⎝
⎛
where t = 5e
-3
(5 ms) for ramp times above 200 ms,
C-1
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