EXTERNAL CLOCK
An external clock can be applied to the BPM module to drive the input multiplexer.
It must be applied to CLK* (See “Connector Pins Allocation”, this manual).
Amplitude
≥
6Vp-p, or
≥
3 V positive-going, pulse length
≥
10µs.
It overrides the internal clock after a few milliseconds.
The BPM module operates properly up to an external frequency of 40 kHz, therefore the sampling
of each button input can be made in 25µs, the four buttons can be sampled in 100µs. As a result,
the beam position can be effectively sampled up to a frequency of 10 kHz.
The use of an external clock –and faster beam position sampling– may be required to eliminate
aliasing of certain beam motions.
The performance of the BPM module is not affected by a higher sampling frequency:
• The X/Y output noise increase is not noticeable
• The X/Y zero (on-center) dc values are slightly shifted, but stable at each particular frequency.
ALGORITHM & POLARITY CONVENTION
45° buttons
V
A
+ V
B
+ V
C
+V
D
V
A
+ V
B
- V
C
- V
D
K
y
X
=
V
A
- V
B
- V
C
+ V
D
V
A
+ V
B
+ V
C
+V
D
K
x
Y =
Y
X
A
B
C
D
Orthogonal buttons
B
C
D
A
X
Y
K
y
Y =
V
A
+ V
B
+ V
C
+V
D
V
B
- V
D
X
=
V
A
- V
C
V
A
+ V
B
+ V
C
+V
D
K
x
BERGOZ Instrumentation
Multiplexed
01630 Saint Genis Pouilly, France
Beam Position Monitor
Tel. +33-450.426.642
Fax +33-450.426.643
Page 8
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
