User`s guide

72 53220A/53230A User’s Guide
3 53220A/53230A Measurements
CONTinuous - configures the counter for continuous, resolution-enhanced,
gap-free measurements. These measurements are used by the counter's Allan
Deviation feature when estimating stability.
In CONTinuous mode a trigger count of ‘1’ is the only value allowed, and all
samples (readings) per trigger are taken within a single (hardware) gate
open/gate close sequence and computed back-to-back. There is no lag (dead
time) between readings that otherwise occurs with the per-sample gate
open/gate close sequence of the AUTO and RECiprocal modes.
Figure 3-1 and the following paragraphs describe continuous, gap-free mea-
surements with an example one second gate time.
Figure 3-1. 53230A Continuous, Gap-Free Measurement Sequence.
gate open
Reading #1
Reading #2
Reading n
start
2341
stop
5
1
start
234
5
stop
start
1
234
5
stop
gate closed
gap-free
‘stop’ edge of previous reading
is ‘start’ edge of next reading
subsequent readings based on number
of edges for first reading
e
dges required for reading
d
etermined by gate time
gap-free
Gate In/Out BNC:
OUTput:STATe ON
OUTput:POLarity NORMal
CONFigure:FREQuency [<expected value>, <resolution>, <channel
>]
TRIGger:COUNt 1
SAMPle:COUNt <count>
SENSe:FREQuency:MODE CONTinuous
SENSe:FREQuency:GATE:SOURce TIME
SENSe:FREQuency:GATE:TIME 1
...
...
gate time (1s) gate time (1s) gate time (1s)
firmware controlled – will see fluctuations
on the output BNC but readings are continuous (gap free)