Section 4: Software Commands
NetClock/GTP Instruction Manual
Page 4-3
4.1
ANTENNA CABLE DELAY
The command,
ACD
, reads or sets the antenna cable delay value expressed in
microseconds. The on-time point is offset by the delay value entered to compensate for
antenna cable and in-line amplifier delays. The expected cable and amplifier delays are
typically negligible. The
ACD
command is intended for advanced user setup. The
advanced user can calculate the delay based upon the cable manufacturer’s
specifications.
Range:
0.000 to 999.999 microseconds
Default Value:
0.000 microseconds
Resolution:
1
nanosecond
To read the antenna cable delay, issue the
ACD
command as shown below:
Type:
ACD <ent>
Response:
ANT CABLE DELAY = XXXXXX.XXX MICROSECONDS
Where:
XXXXXX.XXX
= 000000.000 to 000999.999 microseconds.
To enter a cable delay, place the clock in
Set
Mode
operation, issue the
ACD
command
as follows:
Type:
ACD XXXXXX.XXX <ent>
Where:
XXXXXX.XXX
= 000000.000 to 000999.999 microseconds.
NOTE: It is not necessary to fill every digit space when entering a
delay value. The delay value can range from 1 to 9 digits long.
The clock then responds with the antenna cable delay value entered.
Example, the calculated cable delay for 140 feet of RG-213 cable is 216 nanoseconds.
Follow the example below to compensate the on-time point by the antenna cable delay.
Type:
SM ON <ent>
Response:
SET MODE ON
Type:
ACD 0.216 <ent>
Response:
ANT CABLE DELAY = 000000.216 MICROSECONDS
Cable delay can be calculated using the formula:
D = LxC
Where: D = Cable delay in nanoseconds.
V
L = Cable length in feet.
C = Constant derived from velocity of light; 1.016.
V = Nominal velocity of propagation expressed as a decimal,
i.e. 66% = .66, value is provided by cable manufacturer.
