Kenwood TS 2000 TS 2000 X Service Manual

Page 2

TS-2000/X

CIRCUIT DESCRIPTION

Overview of the Operation

The TS2000/X basically consists of an allamode-receiver
incorporating an IF/AF DSP for satellite communication with
an independent FM/AM subreceiver for the VHF and UHF
bands.

I Overview of the operation of the all-mode trans-
ceiver unit (main hand side) with an IF/AF DSP
for satellite communication
The receiver unit has an independent front end for each

of the HF, 50MHz, 144MHz, 430MHz and 1.26Hz bands

(some products do not support the 1.2GHz band). The cir-

cuits following the 10.695MHz IF stage are common to all

the bands. (Thus, it cannot receive two SSB signals at the
same time.)

The IF frequency of the transmitter unit is shifted from
the IF frequency of the receiver unit by IOOkHz to enable
satellite operation (full duplex operation). The final section is
independent of the HF, 50MHz, 144MHz, 430MHz and
1.2GHz bands. Consequently, you can select a combination
of bands permitting satellite communication from the HF,
50MHz, 144MHz, 430MHz and 1.26Hz bands.

The transmitter unit and receiver unit on the main band
side operate simultaneously during satellite transmission.
The receiver unit on the sub-band side does not work. (The
sub-band receiver is not used during satellite operation.)

Two 16-bit DSP ICs are used; one performs IF processing
(main band side) and the other carries out AF processing
(main and sub bands). Although the DSP IC is a 16-bit unit, it
carries out double-precision operations" for critical parts of
IF processing to perform 32-bit equivalent processing. In
addition, the DSP IC uses a 100MHz highAspeed internal
clock. The conversion from an analog signal to a digital sig-
nal (A/D conversion) is performed with 24 bits at high preci~
sion.

The DSP circuit for IF operates in any mode other than
FM mode for both transmission and reception. FM modula4
tion, detection and squelch processing are conventional anal
log processes. (The processing prior to modulation and af-
ter demodulation in FM is performed by the DSP.)

In the mode in which the IF DSP circuit operates, it car-
ries out modulation and demodulation, digital IF filtering,
digital AGC, and CW waveform processing during transmis-
sion, as in the T's-870. All these functions are operated in all
the bands on the main hand side, including satellite opera-
tion.

The AF unit is processed by the DSP in all modes. The
operating range of the DSP circuit depends on the mode,
but it performs beat cancellation, noise reduction, AF DSP
filtering, etc.

I Overview of the operation of the independent
FM/AM sub-receiver unit (sub-band side) for the
VHF and UHF bands
The local oscillator system and lF/AF signal system of the

sub-receiver unit are independent of the main band side.

Therefore, the sub-band receiver can receive signals while

the main band receiver is sending a signal. (Except when

reception is impossible due to harmonics of the transmit fre
quency and when the main band and sub-band are on the
same frequency band.)

The sub-band receive signal is branched from the RF unit
on the main band side. It is, therefore, not necessary to
install a dedicated antenna for sub-band reception.

Transmission can be performed with the sub receive fre
quency by shifting the "PTT band" to the sub-band side. It
is made possible by internally using the transmission func
tion on the main hand side.

AF processing is also carried out by the DSP on the sub
band side and the noise reduction function works.

The sub-band reception function, including display, can
be turned off.

Frequency Configuration (Fig. 1)

This transceiver utilizes double conversion in FM mode
and triple conversion in non-FM modes during transmission.

It utilizes triple conversion in FM mode and quadruple
conversion in nonAFM modes during reception. The fourth
12kHz IF signal is converted from analog to digital and conA
nected to the DSP.

When the carrier point frequency of the signal input from
the antenna is fIN, the relationship between these signals
when demodulating this signal is expressed by the following
equations:

HF MAIN fIN =fL01 - fLoz 4 fLoa +fL04~12kHz

VHF MAIN fIN =fL01-fLOZ A fLoa + fLo4 ~12kHz

UHF MAIN fIN =fL01 + fLoz + fLoa ~fLo4 +12kHz

1.26 MAIN fIN = fLOI x 2 + fLoz + fLoa-fLOA +12kHz

Reference Signal Generation Circuit

The 15.6MHz reference frequency fstd for PLL frequency
control is generated by the TCXO (X400). The signal passes
through a buffer amplifier (0420) and is used as the refer,
ence signal for the second local oscillator (HFLO2) for HF
band reception and the first local oscillator (SLO1) subband
reception.

The reference signal is doubled by 0412, and the result
ing 31 .2MHz signal is used as the reference signal for DDSs
(|C406, |C407, K3408, |C601, |C602, |C603).

The 31.2MHz signal is supplied to the TXRX2 unit (X57A
606 A/11) as L02 for VHF and UHF bands.