Bedienungsanleitung Yaesu FT-991 (Seite 3 von 154) (Englisch)

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T-991

OperaTing Manual

General Description

Built-in high-brightness TFT full-color

display with touch-panel functionality

The FT-991 is equipped with a 3.5 inch full-color TFT

display. Functions, including the receiving band, the noise

and signal interference reduction tools are graphically

displayed. Even while performing rigorous operations,

during DX pditions or contests, the operator may instantly

grasp the status of each function.

Equipped with C4FM digital mode

This transceiver C4FM mode provides good error cor-

rection performance, and supports the V/D mode (voice/

data simultaneous transmission mode) which makes the

transceiver suitable for mobile communication, and the

Voice FR mode (voice full rate mode) which allows the

transceiver to transmit high quality digital audio. The AMS

function recognizes the contacting stations transmission

method and automatically switches the transceiver to the

same C4FM digital or analog (FM) communications mode

as the received signal.

GM (Group Monitor) function allows

registering frequently communicating

stations to a memory group. The group

members may then automatically

exchange (send/receive) station location

information.

The transceiver automatically checks the channel fre-

quency for registered member stations that are within com-

municating range. The distance and direction information

of the call sign members of the group may be shown on

the TFT display.

Comes equipped with two types of

roong lters

This transceiver is equipped with two types of roong

lters for 3kHz and 15kHz bandwidths. These narrow band

lters are especially useful on a very crowded band during

contests, because they can dramatically attenuate powerful

out-of-band signals in the rst IF stage and reduce their

impact in the second stage to further optimizing the excel-

lent dynamic range and IP3 characteristics for processing

signals ranging from faint to powerful.

Two selectable RF ampliers provide the

optimal receiver gain for each low-to high

HF band (see page 46.)

Congure the front end RF circuitry for the precise gain and

performance to suit the conditions of each HF band.Select

the IPO (Intercept Point Optimization) feature to optimize

the proximal multi-signal and mutual modulation character-

istics in order to minimize the effects of powerful broadcast

stations, especially in the low-band so that even the faintest

signals can be received. When higher gain is advantageous,

select the single low noise RF amplier AMP1. In the high

bands, adding AMP2 provides maximum useful gain.

High stability built-in TCXO

The 30.225 MHz standard oscillator provides exceptional

frequency stability. It is temperature compensated and

boasts an enhanced ±0.5 ppm stability from −10°C to

+50°C.

WIDTH feature and continuously variable

bandwidth SHIFT feature. Optimal wide to

narrow bandwidth switching (see pages

49, 50.)

The SHIFT feature, can eliminate interference in one side

of the passband. The WIDTH feature allows the bandwidth

to be narrowed by rotating the WIDTH knob. The moment

weak signals disappear due to interfering signals (includ-

ing pile-ups), you can eliminate the interfering signals and

extract only the desired signal, thanks to the unique DSP

sharp ltering characteristic.

CONTOUR feature is renowned for

effective noise control (see page 48.)

Rather than using the DSP extremely sharp attenuation

characteristics, the CONTOUR circuit provides gentle

shaping of the DSP passband lter and can thus attenuate

or peak bandwidth components in segments. The interfer-

ing signal can be naturally shaped without having part of

the signal suddenly interrupted. The contour function is

very effective in making the desired signal rise out of the

interference.

DNR (Digital Noise Reduction) by DSP

digital processing (see page 54.)

The incorporated digital noise reduction circuit may be

set to the optimal working point by varying the 15 step

parameters according to the noise type.

NOTCH feature that significantly

eliminates unwanted beat signals; and

DNF feature that instantly attenuates

multiple beat signals (see page 54.)

When interfering beat signals are present in the receiver

passband, the IF NOTCH feature can signicantly elimi-

nate a part of the passband and remove the beat signal.

Moreover, the function is equipped with an Automatic

Tracking System DNF (Digital Notch Filter) that can

be engaged by DSP when there are multiple interfering

signals, even when the frequency is changing.

Reliable High-output Final Amplifier

Stage

In the HF/50MHz frequency range, a pair of RD100HHF1

transistors in a push-pull RF amplier arrangement deliv-

ers 100 watts of low-distortion, high-quality transmitter

power. The nal amplier for the 144 MHz/430 MHz

bands uses the high-output RDH70HUF2 device, provid-

ing ample output power of 50 watts.

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