Bruker NMR AV4 BSMS System, Руководство пользователя

Страница: 97 / 234

L-TRX/L-19F
H172203_1_001 97 / 234
11.2.1 Function Description
The architecture of the L-TRX / L-19F units is significantly different to the design of the former
L-TX and L-RX units. The individual signal processing and amplifier control stages are as
much as possible shifted into the digital domain.
Signal processing
The transmitter consists of a direct digital synthesizer. The output power range is fully
implemented with D/A-converters, which eliminates the need of real-time controlled analog
attenuators.
The receiver consists of a mostly direct digital system. The receiver gain is mainly
implemented in the digital section.
Deuterium Power Amplifier with Active Quiescent Current Control
The operating point of the on-board 5W power amplifier for 2H gradient shimming is matched
to the different operating modes in order to reduce power dissipation. The individual
quiescent current values are stored in the calibration data memory of each unit. In
2H Lock
mode the quiescent current is actively regulated.
Gradient Shimming
Together with the L-19F unit, the on-board 5W power amplifier should not be used for
gradient shimming on 2H. In spectrometer configurations with the L-19F unit a high power 2H
amplifier is anyway mandatory for 2H observe experiments. In this configuration the same
high power 2H amplifier is used for gradient shimming.
The L-TRX / L-19F units do not support gradient shimming on 19F.
Reference Clock
The L-TRX / L-19F units requires a reference frequency mixture produced by the AV4
REFERENCE board. The former 10 MHz system clock is not required anymore.
SSRB Communication Interface with ELCB
The L-TRX / L-19F units use a dedicated SSRB (Synchronous Serial Rack Bus) interface for
control and data transfer to the ELCB.
Real-Time Pulses via Backplane
The L-TRX is able to receive and transmit real-time control pulses via backplane to reduce
external wiring. This feature is currently only used in the NanoBay console (BLNKTR_2H~).
Other pulses and/or consoles may follow in the future.
2H-TR Power Amplifier Output Connector
The output connector is a N-type instead of SMA to avoid the risk of unintentional wrong
wiring. E.g. low power RF-boards could be permanently damaged if wrongfully connected to
the 5W power output of the L-TRX.