User's Manual
Table Of Contents
- 1 System Overview
- 2 Features Summary
- 3 EXACT-V2 Rack
- 3.1 EXACT-V2 mechanics
- 3.2 Interface characteristics
- 3.3 Front Panel signalization (LEDs description)
- 3.4 Power requirements
- 3.5 Performances and technical characteristics
- 3.5.1 General characteristics
- 3.5.2 Control and data Ethernet interfaces
- 3.5.3 Serial control interfaces
- 3.5.4 ASI inputs / output and MPEG-TS processing
- 3.5.5 Digital modulation
- 3.5.6 Clock synchronization
- 3.5.7 RF and monitoring outputs
- 3.5.8 Digital precorrection
- 3.5.9 Power level measurement inputs and AGC
- 3.5.10 Dry contacts
- 3.6 Conformity with EC Directive
- 4 EXACT-V2 Installation
- 5 Operation
- 6 Maintenance & Troubleshooting
- Appendix A GPS Installation Recommendations
- Appendix B Example of GPS Antenna
USER
MANUAL
MPD-1611291-A
EXACT-V2 High End Rack Modulator / Exciter
3/10/2017
MPD-1611291-A
Page 22/94
2.6.1 Digital Adaptive Precorrection
The Digital Adaptive Precorrection (DAP) block is illustrated here below.
Figure 6: DAP integration block diagram
The DAP function is composed of Non-Linear and Linear Precorrection and a dedicated
down-converter. The down-converter receives the signal feedback after the external
amplifier (FBA_In) and after the RF filter (FBF_In). Then, a particular algorithm
processes the digital IQ samples to reduce the signal distortions at the transmitter
output.
To monitor the DAP process several statuses are available:
MER indicative measure
PAPR indicative measure
Measured left and right shoulder levels
DAP elapsed time
DAP status: Active, Stopped by user, Stopped by timer, Failed
2.6.1.1 Non-Linear Adaptive Precorrection
EXACT-V2 performs non-linear precorrection over a 75 MHz bandwidth. The purpose of
non-linear precorrection is to correct the distortion from the power amplifier. With the
feedback from the output amplifier, an adaptive non-linear precorrection should
automatically find the best precorrection and follow the variations of the amplifier
characteristics.
Four operating modes are available:
• STATIC (EDIT) mode: The DAP is disabled. The user can load a previous DAP
configuration to be applied to the modulator.