H Heuer Instruments UMDT51A, Руководство пользователя

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Configuring the Tester
LT51 User Manual 31
LT51 Frequency Bandwidth
Frequency span

Press the key and then [f1] to select Span.

Turn the knob clockwise to increase, or anti-clockwise to reduce, the Span

Press the key (or any key) to clear the dialog box.

The frequency span is updated on the frequency axis (in spectral mode) or
in the results area if in DMM mode.

The Span automatically sets the Resolution BW (see Resolution BW below)

Where the centre frequency is less than half the span selected, the start
frequency is set to 0 Hz and the measurement is baseband. Otherwise the
start, centre and stop frequencies are adjusted with the centre frequency.
NOTE: if the span selected together with the current centre frequency, would
cause the Stop frequency to exceed 2.4 MHz, the span is limited.
NOTE: For all measurement modes where the Interface is set to RTX, and the
LT51 Transmitter is ON sourcing a tone (eg. Return Loss, NEXT/Loss,
Balance etc.), the span will be automatically set to receive the current
Transmit Frequency. This does not apply when making selective
measurements or when sweeping.
The following table describes the relationship between frequency spans, marker
resolution and bandwidths used to measure signals in the LT51. The Res BW is
displayed in the centre of the CONFIG bar along the bottom of the display. The
LT51 uses the Hanning for numerical displays and Flattop for spectral displays.
Span Marker Res BW / ENBW (Hz)
(kHz) Resolution (Hz) Hanning FlatTop
2,400.0 10,000 15,000 38,750
1,200.0 5,000 7,500 19,375
600.0 2,500 3,750 9,687
300.0 1,250 1,875 4,843
150.0 625 937 2,421
75.0 312.5 468 1,210
37.5 156.25 234 605
18.75 78.125 117 302
9.375 39.0625 58 151
4.6875 19.53125 29 75
Centre Frequency / Selective Level Meter

Press the key and then [f2] to select Centre Frq.

Turn the knob clockwise to increase, or anti-clockwise to reduce, the centre
frequency.

Press the key (or any key) to clear the dialog box.