Avance II

From NMR Wiki

Avance II is series of Bruker BioSpin Group produced Avance NMR spectrometers (consoles) with up to 8 (?) RF (Radio Frequency) channels, plus lock channel. This console has a improved version Avance II+ also. It is/was produced for NMR spectrometers from 200 to 900 (950) MHz. Around 2008 it was replaced with Avance III series of consoles. The main difference of Avance II from earlier Avance series of spectrometer consoles is introduction of the DRU (Digital Receiving Unit) and the more extensive integration of different spectrometer functions into one physical block (device). Avance II uses oversampling for the signal analog-digital conversion, and the digital lock system working on the same referencing frequency with which quadrature detector is feeded. This allows to get spectrum reference frequency on the basis of lock signal and get correct chemical shifts scale automatically. The console is controlled by the Bruker TopSpin software.

Accuracy of frequency generation is <0.005 Hz and <0.01 deg for its phase. Timing resolution for operations (system clock?) is 12.5 ns.

Avance II console can be implemented in three different chassies: MicroBay (only 200-400 MHz and up to 3-channel configuration), OneBay (up to 600 MHz?) and TwoBay (Up to 900 MHz and for MAS). The main parts of the Avance II console are AQS (AQuisition System) or newer version AQS/2 and BSMS/2 (Bruker Smart Magnet System). In TwoBay configuration two AQS-s modules can be installed simultaneously which is used for additional RF channels.

Internal architecture

In AQS/2 are located the (main) devices (blocks): ACB (Aquisition Control Board), DRU, RXAD (receiver with integrated analog to digital converter), REF or REF/2 (REference Unit), SGU (Signal Generation Unit), FCU4 (Frequency Control Unit), TCU3 (Timing Control Unit), GCU (Gradient Control Unit), CCU (Communication Control Unit), PSM1 or 2 (Power Supply Module). AQS/2 can also contain internal amplifiers (BLA2BB, BLAX300), preamplifiers (PREAMP XBB and PREAMP 1H2H), and Router(s). AQS/2 can contain more then one of each of those units.

BSMS/2 contains: ELCB (Extended Lock Control Board) or CPU/3 (Central Processing Unit) plus LCB (Lock Control Board), SLCB (Sample Level Control Board), GAB (Gradient Amplifier Board), PSB (Power Supply Board), SCB13 or SCB20 (Shim Control Board), BVT (Bruker Variable Temperature), L-TX (Lock Transmitter), L-RX (Lock Receiver), 2H-TX (Lockswitch), PNK (console pneumatics).

Additionally, depending on configuration, Avance II console chassis can be configured with various power amplifiers, differnt VTU (Variable Temberature Unit), MAS devices, etc.

To the console external devices, like HPPR (High Power Preamplifier) or HPPR/2, KBC (keyboard), PC (computer) and others, are and can be connected.

Maintenance

Bugs

1) There are observed problems with locking and lock signal displaing, when the system is up a long time. The BSMS or console reboot solves this problem.

2) In the case of longtime experiments with rapid pulsing, there are observed problems with the communication with AQS. During of the aquisition the realtime FID and spectrum can't be monitored on screen after some time (after around 1-2 million scans). The AQS or Console reboot solves this problem.