12-41
Module I/O Specifications
A19 Measurement
Counter Inputs
AUDIO1_CNT J1(6) - FM Audio Analyzer 1 A3
RI_CNT J1(8)
IN_CNT J1(5) - From Input Section A23
IF_CNT J1(9) - From Global Board A9
TIME BASE REF 20 MHz J3(29)
MIXED_IF Internal
STRIG Internal
GND Internal
20 MHz Time Base Standard The 20 MHz Sine wave drives a divide by 2 circuit
which provides the 10 MHz reference for the counter.
Input Impedance 50Ω
Input Level > +5 dBm Sinewave
2nd Harmonics < -25 dBc
IN_CNT Input module prescaler count signal
Input Z 2.35 kΩ — .1 uF AC Coupling
Minimum input 100 mV Peak
Freq Range 10 kHz to 4 MHz
IF_CNT Receiver Module I.F. Count
Input Z 2.35 kΩ — 100 pF AC Coupling
Minimum input 100 mV Peak
Freq 10.7 MHz
AUD1_CNT HCMOS Vih > 4 V, Vil < 1 V
RI_CNT HCMOS Vih > 4 V, Vil < 1 V
Maximum Count Time 25.6 µS x 216 = 1.6777216 S
Minimum Count Time 25.6 µS
Count time step size 25.6µS
Accuracy same as 10 MHz Ref
Gate Time Jitter < ± 10 nS 100 mV Input
Resolution 0.01 ppm/gate time