DS335 Synthesized Function Generator
DS335 Synthesized Function Generator
DS335 Synthesized Function Generator
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2-14 Sweeps & FSK<br />
Sweep/FSK RATE<br />
Sweep/FSK FREQUENCIES<br />
Start and Stop Frequencies<br />
Sweep/FSK OUTPUT<br />
The duration of the sweep is set by [RATE], and the value is entered or<br />
modified with the keypad. The sweep rate may be set over the range of<br />
0.01 Hz to1 kHz. The sweep rate is the inverse of the sweep time, a 0.01 Hz<br />
rate is equal to a 100s sweep time, and a1 kHz rate is equal to a 1 ms sweep<br />
time. For a TRIANGLE sweep the sweep time is the total time to sweep up<br />
and down. If FSK is selected from the UNI/BI menu, then the "Sweep Rate"<br />
button sets the FSK Rate. If the rate is set to 0 Hz then the rear panel FSK<br />
BNC input toggles between the two preset frequencies. For any non zero<br />
rate the <strong>DS335</strong> will toggle between the two preset frequencies at the<br />
specified rate. The maximum internal FSK rate is 50 kHz.<br />
The <strong>DS335</strong> may sweep over any portion of its frequency range: 1 µHz to<br />
3.1 MHz for sine and square waves, 1 µHz to 100 kHz for triangle and ramp<br />
waves. The sweep span is limited to six decades for logarithmic sweeps.<br />
The <strong>DS335</strong>'s sweep range is set by entering the start and stop frequencies.<br />
In FSK mode, the <strong>DS335</strong> will toggle between any two frequencies: 1µHz to<br />
3.1 MHz for sine and square waves, and 1 µHz to 100 kHz for triangle and<br />
ramp waves. There are no restrictions on the values of the start and stop<br />
frequencies for linear sweeps.<br />
To enter the start and stop frequency press the [START FREQ] and [STOP<br />
FREQ] keys. The span value is restricted to sweep frequencies greater than<br />
zero and less than or equal to the maximum allowed frequency. If the stop<br />
frequency is greater than the start frequency, the <strong>DS335</strong> will sweep up. If the<br />
start frequency is larger the <strong>DS335</strong> will sweep down. If FSK is enabled the<br />
<strong>DS335</strong> toggles between the Start and Stop frequencies at the Sweep/FSK<br />
Rate. If the rate has been set to zero then the rear panel FSK input is active.<br />
A TTL low level activates the start frequency and a TTL high level activates<br />
the stop frequency.<br />
The rear-panel SWP/FSK output is synchronous with the sweep rate. This<br />
output emits a TTL pulse at the beginning of every sweep cycle and can be<br />
used to trigger an oscilloscope. When the start frequency is selected, the<br />
Sweep output is at 0 Volts, and when the Stop frequency is selected the<br />
Sweep level is at 5 Volts. The Sweep output is synchronous with the<br />
frequency shifts.<br />
FSK Input<br />
The FSK input accepts TTL level signals. When enabled (FSK mode with<br />
0 Hz rate), it is sampled at a 10 MHz frequency by the <strong>DS335</strong>. A low TTL<br />
level selects the start frequency, and a high TTL level selects the stop<br />
frequency (see example below). When the FSK Input is being used, the<br />
Sweep output is disabled and stays at 0 Volts.<br />
<strong>DS335</strong> <strong>Synthesized</strong> <strong>Function</strong> <strong>Generator</strong>