- Compliant with DVB-C (EN 300 429) and ITU J.83 Annexes A, B and C including DOCSIS 1.1/2.0
- 16, 32, 64, 128 and 256 QAM
- Arbitrary symbol rate up to a quarter of the applied master clock frequency
- Scalable architecture supports from one to four channels per core and multiple cores per FPGA
- Programmable or constant-coefficient channel filter allows trade-off between flexiblity and core size
- Modulation accuracy
- Configurable radio interface supports direct conversion and/or superhet transmitters
- Configurable interleaver operates from either internal or external memory
- Synchronous parallel transport stream interface
Figure 1. CMS0024 Cable (QAM) Modulator Block Diagram
Figure 1 shows a block diagram of this megafunction.
The CMS0024 Cable (QAM) Modulator is fully compliant with the European, US, and Japanese downlink cable standards DVB-C and J.83, providing all the necessary functions between transport stream input and QAM output.
The core can be configured to support from one to four FDM channels with additional (independent) channels accommodated by the instantiation of multiple single or multi-channel cores per FPGA.
Multi-channel J.83B designs can operate either from internal memory (short interleaving modes) or from shared external memory (long interleaving modes) by means of an arbitrating access controller.
A range of synthesis options allows the core to be tailored for any particular application. Commsonic offers transport stream interface cores to perform rate adaptation (NULL packet stuffing) and retiming (PCR restamping).
Typical applications of the CMS0024 include head-end video and broadband data transmissions systems (CMTS), cable modem test equipment and point-to-point (PTP) or point-to-multipoint microwave radio links.
Device Utilization & Performance
Table 1 lists the typical device utilization results for the megafunction.
|Table 1. Typical Device Utilization for Altera Megafunctions|
|Device||Configuration||Logic Elements (LEs)||9x9 Multipliers||M4K RAM|
|EP2C20||1-channel DVB-C||11k, 31%||52, 100%||36, 69%|
|EP2C35||4-channel J.83B (short interleave)||27k, 82%||70, 100%||100, 95%|
|EP2C35||4-channel J.83B (long interleave) external RAM||27k, 82%||70, 100%||36, 34%|
|EP2C70||1-channel J.83B (long interleave)||9k, 13%||84, 28%||161, 37%|
|EP2C70||8-channel J.83B (short interleave)||43k, 64%||288, 96%||192, 76%|
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