MC92307 Datasheet, PDF (8/10 Pages) Motorola, Inc – 2K - Samples FFT-Processor

Application Information
As already mentioned the FFT device is especially suit-
ed to be combined with Motorola’s OFDM device
MC92308 to form the complete digital part of a frontend
for a 2K DVB-T receiver. Refer to Figure 6 for the func-
tional blocks of a terrestrial DVB receiver. Further de-
tails of the blocks are given in reference [2].
One of the key signals for the successful reception of an
OFDM signal is the correct timing synchronization, that
means that the synchronization circuitry chooses the
correct starting point to trigger the FFT operation.
Therefore the OFDM demodulator MC92308 provides
the FFTSTART signal to the FFT device. If 2048 com-
plex time domain samples have been read into the input
buffer the FFT operation starts. Its result is flagged with
the SYMSYNC line and the calculated frequency do-
main samples are output to the OFDM device that con-
tinues with the demodulation process.
MC92307
2k-FFT
Tuner
Core
Tuner
8
12
I ²C
A
n _D 8
atio ^1/2
FFTDO FFT
RESB
START
SYMSYNC FFTDI
MBUS
ADCDATA
MC92308
uP IF
16
CLKEN18
OFDM
DVALID
FECCLK
G1DATA
CLK
CLK CLK AGC AGC
3
CTLP CTLN CTLP CTLN
G2DATA
3
HC05
uC
MC92309
FEC
~ _{form VCO}
Preliminary ^{In Figure 6. Application Example for the OFDM and FFT Devices}
8
MPEG Clock
MPEG-2
Transport
Stream
MOTOROLA
8
MC92307_DS - 8/12/97