Agilent Technologies E1441A Frequency-Shift Keying FSK Modulation, •“FSK “Hop” Frequency” on page

Frequency-Shift

Keying (FSK)

Modulation

Use the following command to set the burst phase:

BM:PHASe <degrees>MINimumMAXimum

You can configure the function generator to “shift” its output frequency between two preset values using FSK modulation. The rate at which the output shifts between the two frequencies (called the “carrier frequency” and the “hop frequency”) is determined by the internal rate generator or the signal level on the"Ext Trig/FSK/Burst terminal". The function generator can produce an FSK waveform using sine, square, triangle, ramp, and arbitrary waveforms. Topics covered on frequency-shift keying modulation are:

•“FSK Carrier Frequency” on page 40

•“FSK “Hop” Frequency” on page 41

•“FSK Rate” on page 41

•“FSK "Hop" Source” on page 42

--“Internal Hop Source” on page 42

--“External Hop Source” on page 42

Only one modulation mode can be enabled at a time. When you enable FSK, the previous modulation mode is turned off.

Use the following command to enable frequency-shift keying: To ensure proper operation, you should enable FSK after you have set up the other modulation parameters.

FSKey:STATe OFFON

FSK Carrier Frequency FSK Carrier frequency: 10 mHz to 15 MHz (100 kHz for triangle

and ramp). The default is 1 kHz. You can use sine, square, ramp, triangle, or arbitrary waveforms for the carrier waveform.

For arbitrary waveforms, the maximum carrier frequency depends on the number of points specified in the waveform. The five built-in arbitrary waveforms can be output at a maximum of 5 MHz.

Table 2-8.

Number of Arb Points	Minimum Frequency	Maximum Frequency
8 to 8,192 (8k)	100 mHz	5 MHz
8,193 to 12,287 (12k)	100 mHz	2.5 MHz
12,288 to 16,000	100 mHz	200 kHz

For an externally-controlled FSK waveform, the carrier frequency is output when a "low" TTL level is applied to the source selected by the TRIG:SOUR command. The hop frequency is output when a “high” TTL level is applied.

For FSK, the sync signal is referenced to the FSK “hop” signal (not the carrier). A momentary TTL “high” pulse (> 200 ns) is output on the transition to the “hop” frequency. The signal is output from the front- panel Sync terminal.

40 Agilent E1441A Application Information Chapter 2