Modulation mode

These commands allow you to select the modulation mode between amplitude, frequency and phase modulation as well as binary (2-level) and quadrature (4-level) frequency shift keying. Binary FSK results from a logic level digital signal applied to the TRIGGER INPUT socket.

Quadrature FSK is achieved using both the TRIGGER INPUT and PULSE INPUT sockets. Also pulse modulation may be selected from a signal connected to the PULSE INPUT socket. These modulations may be used in the combinations shown in the table below. Additionally, an external signal applied to the EXT MOD INPUT socket can be combined with any selected modulation combination.

MODE

Set modulation mode

Data type : Character Program Data (valid combinations of AM, FM, PM, FSK2L,

FSK4L or PULSE. See table below.)

Allowed suffices : None

Default suffix : None

Examples: MODE AM,FM

MODE FM,PULSE

VALID MODE COMBINATIONS TABLE

AM [,PULSE]

FM [,PULSE]

PM [,PULSE]

AM,FM [,PULSE]

AM,PM [,PULSE]

FSK2L [,PULSE]

FSK4L

Note...

Order is not important, for example AM,FM is equivalent to

FM,AM. PULSE modulation can be used with any of the

AM,FM,PM and FSK2L modes, but not with FSK4L.

FSK2L and FSK4L parameters are controlled using the FM commands. The frequency shifts produced by the applied data are as follows:

2FSK

 

 

4FSK

 

TRIGGER

SHIFT

 

TRIGGER

PULSE

SHIFT

1

+D

 

1

0

+D

0

D

 

1

1

+D/3

 

 

 

0

1

D/3

 

 

0

0

D

Where D is the set deviation value.

MODE?

Prepares message containing information on Modulation Mode in the

 

following format:

 

:MODE <mode>

 

where:

<mode> is character program data indicating the modulation

 

 

mode settings

Example:

:MODE AM,FM

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VXI 3002 manual Modulation mode, Valid Mode Combinations Table, Mode?