Kenwood TS-990S User Manual

Page 10

Band Elimination Filter

-1,000

-80

-60

-40

-20

-500

500

1,000

litu

e (

)

Frequency (Hz)

For main IF DSP, transmission unit
ADSP-21363 clock @333 MHz

For sub IF DSP, every kind of signal processing
ADSP-21369 clock @260 MHz

For band scope
ADSP-21363 clock @333 MHz

Advanced AGC control, fusing together digital and analogue

The sound quality of the built-in speakers is largely determined by
the chassis structure. With the TS-990S, we have been able to mini-
mize unnecessary chassis vibration through multiple simulations
from the conceptual phase. The Kenwood tone is supported not only
by circuits and DSP but also by exact chassis design.

Exacting chassis design for realizing quality sound

77 mm

Built-in speaker

Top plate oscillation
simulation example

You can vary DSP filter bandwidth and eliminate ex-
tensive interference depending on use and condition.
You can operate it as a HI CUT/LOW CUT function
in SSB/AM/FM mode, and WIDTH/SHIFT function
in CW/FSK/SSB-DATA transmission mode.

The filter is capable of varying the stopband band-
width and the amount of loss. When signals that
interfere with the target signal multiply, this is a
convenient func-
tion for operations
such as dampen-
ing interference
signals, even if it
cuts down some of
the target signal.

IF filter bandwidth variability

Band elimination filter function

Extensive interference elimination
and noise reduction functions

You can eliminate overpowering interference signals
with a notch filter and catch intended weak signals.
You can switch between the IF auto notch and the
manual notch that
can be changed
manually, depend-
ing on the state of
interference.

It is possible to preset a maximum of three IF filter
switch and switch instantly at any time. Set for
narrow or wide,
such a function is
convenient for com-
petitions requiring
quick operations.

WIDTH

If the interference is on one side only,
you can shift the central frequency
without changing bandwidth.

You can avoid neighbouring
signals by varying the
bandpass width.

Target

signal

Intended

signal

SHIFT

WIDTH

IF filter A/B/C one-touch switch instantly

IF notch

IF Manual Notch

BW 400 Hz / 800 Hz

litu

e (

)

Frequency (Hz)

-1,000

-80

-60

-40

-20

-500

500

1,000

Equipped with an analogue noise blanker (NB1)
which is considered being effective against weak
noise, and a digital noise blanker (NB2). Choose the
NB1 or NB2 based on noise type and reception con-
dition. With NB1, stable noise reduction is possible
without depending on reception bandwidth. NB2 is
effective against noise that cannot be tracked by an
analogue noise blanker. Plus, both the NB1 and NB2
can be used simultaneously with the TS-990S.

The noise blanker function (NB1/NB2) is

equipped with digital/analogue 2 format

Other extensive interference elimination and noise

reduction functions

Beat cancel function (BC1/BC2)

The beat cancel function is effective against relatively weak, multiple beats,
whereas the IF auto notch is effective against strong beats.

Audio peak filter

You can vary bandpass width of pitch tone when there are carrier receptions
like CW and FSK. FSK is compatible with mark and space frequencies.

Kenwood continues to provide quality sound trans-
mission that is unattainable through analog circuits.
By loading the world-premiere DSP on the TS-950
and achieving IF AGC control on the TS-870 by
using DSP for the first time for amateur wireless
devices. As a culmination of the foregoing develop-

ments, three DSP units are used, one on each major
block of the TS-990S. By distributing the signal pro-
cessing of the main IF, band scope, and sub-IF, we
have realized ample digital signal processing. (FM
mode is AF DSP processing.)

Equipped with dedicated DSP for the main receiver, sub-receiver,
and band scope

The reception sound quality of SSB and CW is not
solely determined by audio frequency and filter
delay properties. AGC characteristics play a very

significant role as well. The opinion of many of our
fans that “even for long periods of time they never
get tired of listening” is due to the characteristics

of Kenwood’s AGC. The
TS-990S goes a long way
in helping further refine the
Kenwood tone by innovating
not only the AGC control al-
gorithm on the DSP but also
the analog AGC unit as well.

IF AGC control block diagram

RX IF

AGC DET

RX Audio

IF Filter
AutoManual Notch
Band Elimination Filter

OUT Band
ATK/REL
Manager

AGCV DAC

Analog
AGCV

IF ADC

Digital NB

AGC DET

Demod

SOFT-ATK

CONT

The device is also equipped with two types of noise
reduction format—NR1 and NR2. An optimal noise
reduction format is applied to each reception mode
for NR1. And for NR2, SPAC method is applied
which is more effective in CW operation.

DSP-based noise reduction function (NR1/NR2)

HF/50MHz TRANSCEIVER TS-990S

DSP / IF filter