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Satellite DMB(Digital Multimedia Broadcasting) derives from satellite DAB(Digital Audio Broadcasting), but recent development of digital condensation technology widened the multimedia contents covering audio and simple video clips. Satellite DMB is a service receiving diverse multimedia contents through personal portable terminal or automobile terminal utilizing satellites. Satellite DMB has a unique trait of providing moving service distinguished from existing fixed satellite broadcasts.
For the service in shadow area such as urban areas, basement, and building inside, utilizing satellites for moving service is basis, and ground relay instrument called gap filler should be performed.
Types of gap filler include Frequency Conversion Gap Filler, Direct Amplifying Gap Filler, and Spotlight Gap Filler.
Board performing the main function of gap filler system is TCCU(TDM to CDM Converter Unit).
TCCU is gap filler receiving TDM signal (18.432MHz) of 11GHz span through Frequency Conversion Gap Filler, converting it into CDM signal (16.384MHz) of 2.6GHz span, and re-transmitting it.
Thus, TCCU is comprised of TDM receptor that can receive TDM signal, signal processor that can divide CDM signal per channel from received TDM signal, CDM transmitter that combine separated CDM signal and transmit it, and CPU that regulates TCCU.
| NO | Function | Specifications | Comments |
|---|---|---|---|
| 1 | RF Input Frequency Range | 950 MHz ~ 2,150 MHz | |
| 2 | Input Range | -70 dBm ~ -20 dBm | |
| 3 | Input Connector Type | F - Female | |
| 4 | Modulation Type | QPSK | |
| 5 | Number of Channel | 32 Chs (Pilot 1Ch, including spare 1Ch) | |
| 6 | Symbol Rate | 18.432 MHz (Convolutional encoder1/2) | |
| 7 | Error Correction | RS (204,188) | |
| 8 | Interleave | 12 Cycle Convolution | |
| 9 | Error correction Inside Code | Covolutional Encoder 1/2 | |
| 10 | Roll-OFF Filter | Roll-Off Factor 0.35 RRC | |
| 11 | BER | 210E-4 Max (After Viterbi-decode Eb/No4.5 dB, 18.432 MHz |
|
| 12 | Impedance | 75 Ohm (VSWR < 2.5) | |
| 13 | LNB Frequency Error | Provided by Tuner | |
| 14 | Storage Temperature | -40 ~ +75 | |
| 15 | Operation Temperature | -30 ~ +70 |
| NO | Function | Specifications | Comments |
|---|---|---|---|
| 1 | Walsh Code Channel | 32 Chs. (Pilot 1Ch, including spare 1Ch) | |
| 2 | Spread Ratio | 64 | |
| 3 | Short Code | Walsh | |
| 4 | Long Code | PN 12, 2048 chip x 2 | |
| 5 | Frame Length | 12.75 ms | |
| 6 | Roll-OFF Filter | over sampling 0.22 1:4 Interpolation18.432 |
|
| 7 | Filter Window | Hanning | |
| 8 | Modulation Type | DS-CDMQPSK | |
| 9 | Output Terminal | SMA Type Female | |
| 10 | Output Impedance | 50 | |
| 11 | Gap Filler ID Method | Message Type |
