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E2730A VXI RF TUNER
3.4.2 MANUAL CONTROL
FREQUENCY OPERATIONS
OPERATION
When the tuner is in the manual operating mode, the operating frequency
and tuner attenuation parameters may be controlled. Frequency and tuner
attenuation operations are described in the following paragraphs.
The E2730A supports a frequency range query (FRG?) that returns the
upper and lower frequency limits of the tuner. This query allows an
application to configure itself based on the current frequency limits.
While all of the E2730A tuners currently respond with the same limits,
future units could potentially have extended capabilities. The frequency
range query will respond with a lower frequency limit of 2 MHz and an
upper frequency limit of 2700 MHz. The specified RF performance of the
E2730A is however guaranteed between 20 MHz and 2700 MHz.
A frequency command (FRQ) is available for setting the tuner's tuned
frequency. The limit of the command is 0 MHz to 2700 MHz. The
frequency query (FRQ?) is always valid and will return the current tuner
frequency.
The E2730A supports two combinations of tuning speed and tuning
resolution. These tuning modes are selected by the tuning speed command
(TSP). This allows the tuner tuning to be optimized for either speed or
resolution. Tuning speed one (TSP 1) offers 100 Hz resolution and a
worst case tuning time of less than 8 ms. Tuning speed two (TSP 2) offers
1 kHz resolution and a typical tuning time of less than 3 ms for 25 kHz
steps. The worst case tuning time for TSP 2 is less than 6 ms. When TSP
2 is active, the tuner always accepts the frequency inputs with a resolution
of 100 Hz and then internally rounds the value to the nearest 1 kHz before
tuning the second LO. A query response will retain the originally input
100 Hz value. The default tuning speed setting is TSP 2 (1 kHz).
The frequency operations commands (frequency range query, frequency
and tuning resolution commands) are listed in Table 3-6.
3-11
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