An Ultra-stable Event Timer

Etienne SAMAIN

Observatoire de la Côte d’Azur CERGA2130 route de l’Observatoire

06460 CAUSSOLSFrance

etienne.samain@obs-azur.fr

Characteristics

Resolution: 1 psDynamic: 64 bitsExternal Clock Frequency: 10 or 100 MHzPrecision < 3 psLinearity: 1 ps rms ( +/- 1.5 ps)Dead time: 10 µs2 independent channels2 inputs per channel

Characteristics

Automatic internal calibrationInternal memory: 10 000 measurementsInterface: RS 422 @ 1 MBitsSize: 19 inches rack 3U x 280 mm

OCA Event timer synoptic

2 vernier cards

Frequency: 50 MHzResolution: 1 psDead time: 10 µs

Frequency Synthesis card

Ultra low noise local oscillator @ 100 MHz» Phase noise: 100 Hz : -130 dBc, 10 kHz : -165 dBc

Digital phase lock loop: 20 bitsInput frequency: 10 MHzOutput frequency: 100 MHz and 10 MHzThermal sensitivity < 100 fs/°C (10 to 30 °C)Calibration events

3 programmable cards

Digital timer: 10 ns resolution

Frequency synthesis control (20 bits)

Global control» Memory (10 000 events)» 16 bits Analog to digital converter» RS 422 serial interface

OCA Event TimerGround design

OCA Event Timer Preliminary Space Design (EREMS)

Mass: 7 kgSize: 250×240×130 mm3

Power: 40 W

Asynchronous Test Bench

Thales Event timers

2 event timers (5 & 2 ps rms)200 MHz frequency synthesisGlobal control» Memory (10 000 events)» 16 bits Analog to digital converter» RS 422 serial interface

Spectral density of the vernierlinearity error

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1.00E+07 1.00E+08 1.00E+09 1.00E+10 1.00E+11

Frequency (Hz)

Sp

ectr

al d

ensi

ty (

ps/

Hz1

/2)

Linearity: 1 ps rms, +/- 1.5 ps

Synchronous Test Bench

Time stability

0.001

0.01

0.1

1

10

0.001 0.01 0.1 1 10 100 1000 10000ττττ (s)

σσσσx (

ps)

Thermal sensitivity

8

10

12

14

16

18

20

18 19 20 21 22 23 24

Temperature (°C)

Tim

e w

alk

(ps)

Events

Reference

Vernier linearity

Linearity : 1 ps rms, +/- 1.5 ps

-5-4-3-2-1012345

0 5000 10000 15000 20000

t vernier (ps)

x(p

s)