ANALOG MODULATION MODE
3-90
The other parameter that can be set to control the hopping sequence is the time between steps.
This is done using the command:
SWEEP:HOP:TIME
< t >
where t represents the number of milliseconds.
The 100 frequencies are precalculated and loaded into a software sweep table using the GPIB
command:
SWEEP:CALC
If any of the carrier frequency stores have become corrupt and so result in a checksum
error, the following message will appear in the centre of the screen:
CARRIER STORE < x > CORRUPTED.
RE - ENTER FREQUENCY.
where x is the corrupted store number.
With the frequencies, sequence and step time loaded, the hopping operation is controlled in the
same manner as the ordinary sweeps by using the following commands:
SWEEP:GO
starts the hopping sequence (and will do any
precalculation if required).
SWEEP:HALT
pause the hopping sequence.
SWEEP:UP
go up to the next step while paused.
SWEEP:DN
go down to previous step while paused.
SWEEP:CONT
continue hopping sequence.
SWEEP:RESET
reset sequence to start value.
When paused the carrier store number is displayed on the screen.
There are no markers available and the operation of transferring the paused value to the
main parameter is not permitted..
To enter a new sequence use the HOPSEQ command but the number 255 is inserted at the
beginning of the string.
e.g.
existing sequence
- 0, 6, 53, 72, 43, 96
sequence required
- 22, 16, 7, 41, 59, 66
send GPIB command:
HOPSEQ 255,22,16,7,41,59,66
To add to an existing sequence, use the HOPSEQ command without 255 at the beginning of the
string.
e.g.
existing sequence
- 12, 24, 36, 48
sequence required
- 12, 24, 36, 48, 60, 72, 84
send GPIB command:
HOPSEQ 60,72,84
To determine the length of the hopping sequence the following GPIB command is used:
HOPSEQ?
This returns a value 1 - 1024.