Casella CEL CEL-160 - Manual (Page 24)

10.4.5 Repeat Scans
The program may be requested to repeat each
band 1, 2, 4 or 8 times by keying the required
numeral key followed by C. After each band
the average of the scans is printed and again at
the end of the measurement a complete
summary list is produced. The default
condition is 1C.
10.4.6 Excitation Mode
For continuous excitation type measurements
select 1D whilst 2D is necessary for impulse
type excitation. The program will not run
unless one of these selections is made.
10.4.7 Measurement Decay
The RT60 value is extrapolated from either a
30dB or 20dB measurement. OF selects 30 dB
and 1F gives 20 dB. The default condition is 0F.
10.4.8 Initiation
Pressing the E key initiates a measurement
sequence. Further depressions will start a new
measurement with the previously selected
parameter.
Error messages produced on the
print-out are as follows and when an error
condition is detected the calculation of RT60 is
suppressed.
'Over' Produced if the maximum level
is greater than 49 dB or if the
average signal level in the
continuous mode is greater
than 45 dB scale deflection.
'Range' This is produced if there is
insufficient range between the
signal and noise floor to
produce the required RT60
calculation.
'Time' The maximum time permitted
on the selected RT60 decay
range has elapsed without the
signal decaying the required
amount to make the
calculation. The measurement
should be repeated on a higher
range.
10.4.9 Summary
A. Select XXYYA where XX is start band and
YY stop band.
B. Selects RT60 range from 1 to 6 as set
out above.
C. Selects number of averages for each
band. 1, 2, 4 or 8.
D. Selects continuous for 1D or Impulse for
2D.
E. Initiates measurement.
F. Selects dynamic range as 30 dB for 0F
or 20 dB for 1F.
10.4.10 Control Signals For Alternative
Noise Sources
Pin 5 of the remote socket (section 3.2 fig. 2)
is used to control the noise source. It carries a
CMOS logic signal and should not be loaded
with less than 50 KΩ . It will be high (+5 V)
when the source is on or it is ready to receive
the impulse. It reverts to low (0 V) to turn the
signal source off or to show that the impulse
has been detected.
Page 24 - CEL-160 Graphic Recorder