The current analog vs. digital scene is fraught with misconceptions and disinformation in the form of marketing hype. For example, digitally generated frequencies do not vary, which many say implies that they do not have overtones and undertones. This would only be true if the frequencies remained digital. That is why digital frequencies from DDS (Direct Digital Synthesis) and DSP (Digital Signal Processing) are converted to analog before they are output from the GB-4000 and all other analog frequency generators. These Digital-to-Analog Converters are called a DAC for short.
You can see in the diagram above that a frequency comes out of a DDS or a DSP looking like stairs. The signal then goes through a DAC or Digital-to-Analog Converter. Then it goes through a Low-Pass or Bandpass Filter to finish the analog conversion. Now the frequency that you have is a very accurate analog frequency with all the overtones and undertones of that analog frequency. The analog frequency produced by a digital chip can be swept up or down with more accuracy than any of the old tube based analog instruments. The most important thing to remember is the frequency has to be converted to analog before it is output from the frequency generator.
Digitally produced frequencies converted to analog are far superior to any signal that comes from an antique tube type analog frequency generator. Antique tube type generators are very limited. If we want a frequency of 2128.5, an old tube analog generator would not be accurate enough to give you that frequency to use. It could only give you 2128. Also digitally converted frequencies allow you to sweep with far more accuracy than old analog tube type instruments. Even a thousandth or millionth of a frequency is possible even though this kind of accuracy is not needed.
This frequency selection and sweep capability is something that a purely analog instrument could not do as accurately. Digitally produced frequencies when converted to analog can accurately produce minute details. These analog frequencies when converted to a square wave waveform produce square wave harmonics. Some claim that their instruments which output analog frequencies produce advanced analog harmonics, but this is just sales hype. All the digital to analog frequency generators on the market today that we have tested with a spectrum analyzer produce the same analog harmonics. Anyone claiming to have some form of superior advanced square wave harmonics is just giving the consumer lots of sales hype. So when it comes to Analog Vs. Digital frequencies make sure that the person you talk to knows the facts.
The GB4000 uses a crystal controlled oscillator and a Digital signal processor to produce accurate frequencies and sweep functions. The resulting frequencies are then processed through a Digital to Analog converter and a filter circuit to give you accurate and reliable frequency outputs. You can
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