I found the manual to be clear concise and complete. It was of immense assistance when removing the unit as the unit was over 22 years old and the wiring diagram was unobtainable from the manufacturer. The exploded drawings were clear as were the instructions and labels.
This manual was very good & was very helpful with repairs.
Always great & fast service from Owner's manual.
Text excerpt from page 56 (click to view)
GEX-P900DAB
3) Guard interval The time 25% more than the sampling time required for processing DAB signals by FFT is called "guard interval." For multipath within the time of guard interval, errors can be corrected in most cases, regardless of the D/U ratio. Mode 1 2048 points (1 ms): Number of samples required for FFT 512 points (250 µs): Guard interval
Delayed multipath wave S1 S2 Actual DAB signal S1 S2 Direct wave (OFDM wave)
Interference between different symbols (effect of delay) Time required for FFT (1 ms)
Guard interval (250 µs)
S1
S2 Received DAB signal
Time required for FFT for every symbol
The time of guard interval depends on modes. Different time of guide interval is used for transmitting frequency, receiving speed (vehicle speed), etc.