FIRST TURN CAPABILITY
When the Single Button Sampling option (BPM-SBS) is installed on the BPM module board, the
BPM module has a limited capability of monitoring the first turn(s) after beam injection.
The BPM-SBS option consists of a small piggy-back plug-in board which installs on the BPM
main board.
The first turn capability offered when BPM-SBS is installed consists of measuring four successive
injections, first with button A, second with button B, third with button C and fourth with button D.
The value of each button is given by the BPM module on the X analog output XOUT. It
corresponds to the highest signal received by the selected button, until it is reset by the user. A
peak and hold (P/H) circuit on the BPM-SBS piggy-back board implements it.
The value of each button must be measured and the position must be calculated by an external
computer.
When the SBS mode is enabled, the Automatic Gain Control (AGC) is disabled. The amplifiers
gain is controlled by a 20-turn potentiometer “Gain Adjust” located on the BPM module front panel.
The potentiometer must be roughly adjusted so that the amplifiers gain is sufficient in relation to the
injected charge and the pickups sensitivity. Note: The gain may be different among BPM modules.
The Single Button Sampling mode is enabled by pulling down:
SBS*
Single Button Sampling mode. TTL input.
The button is designated by a 2-bit address:
BADD0*
Button addresses. TTL input. Active only when SBS mode is enabled.
BADD1*
BADD1
BADD0
Button A
high
low
Button B
low
low
Button C
high
high
Button D
low
high
Default value: Button C
The output is obtained on:
XOUT
Analog output value of button addressed, from P/H circuit
Voltage range: 0…+5V, pedestal
≈
0.5V.
Settling time < 1 ms
Signal droop negligible up to 100 ms.
The Peak and Hold circuit is reset by pulling down:
PHRESET*
Peak and Hold Reset. TTL input.
This input has no internal pull-up.
Pull up to reset (min 5 ms).
Pull down to measure bunch, at least 1 ms before bunch. Keep down to hold.
But don’t pull down too early, or SBS will measure peak ambiant noise !
BERGOZ Instrumentation
Multiplexed
01630 Saint Genis Pouilly, France
Beam Position Monitor
Tel. +33-450.426.642
Fax +33-450.426.643
Page 14
User’s manual
BERGOZ Instrumentation - 01630 Saint Genis Pouilly, France - Tel.: +33-450.426.642 - Fax: +33-450.426.643
TVA-VAT-IVA-USt. Nº FR88414997130 - Sàrl. capital 152K - Siren 414 997 130 R.C.S. Bourg - APE 332B
