another question about function generator... - Page 1
Forum section: electronics / general

author: SnakeBite
author_rank: Regular Contributor
timestamp: August 19, 2011, 12:59:35 pm
content: in the description of the FG it's says that it's "Synthesized Function Generator" is that mean that it's analog ?for example the Hp 3325b is it analog or digital FG?thanksIdoaricha

author: amspire
author_rank: Super Contributor
timestamp: August 19, 2011, 02:16:24 pm
content: I don't think "Synthesized" has to mean Digital, but it does in the case of the 3325B. Definitely digital.The HP 3325 was a wonderful device, but by today's standards, it is very big, involves a huge number of components, and it had custom output attenuators that had great performance, but were easy to damage and very expensive to repair. No arbitrary waveforms - just sine, square and a few triangular waveforms with modulation available.HP used the word to indicate the waveforms were not generated from a traditional oscillator circuit.I don't think anyone would use the term much now for Function Generators.Richard

author: SnakeBite
author_rank: Regular Contributor
timestamp: August 19, 2011, 03:09:34 pm
content: does arbitrary waveform capability important? don't we use normally only sin ,square and triangular?

author: amspire
author_rank: Super Contributor
timestamp: August 19, 2011, 03:35:02 pm
content: Quote from: SnakeBite on August 19, 2011, 03:09:34 pmMost people use the standard waveforms most of the time.However, occasionally the arbitrary waveform is very useful. For example, to simulate a problem, you can capture a waveform on a digital oscilloscope and load the waveform into the generator, and then use the generator to make the waveform that caused the problem.If you don't know that you need an arbitrary waveform generator, then you don't need it.Richard

author: ejeffrey
author_rank: Super Contributor
timestamp: August 19, 2011, 04:11:44 pm
content: Yeah, I have used many arbitrary waveform generators but never actually used the arbitrary waveform feature. The rare occasion when I need something other than the standard waveforms I generally find that the AWG is not up to the task and have to use a computerized DAQ card -- for something like very long digital pattern output or weird tone bursts that don't fit in the sample memory of most AWGs.

author: saturation
author_rank: Super Contributor
timestamp: August 20, 2011, 02:48:49 pm
content: Today DDS is a popular way to make high quality synthesized waveforms.http://en.wikipedia.org/wiki/Direct_digital_synthesizerIn ye old days, people could invent their own, and generically, digital approaches were labeled waveform synthesis or digitally synthesized as they were 'synthetic' rather than as the result of natural electronic phenomena, like oscillations. Analog FG began with a basic sine wave oscillator and shaped it through various means to get square, triangle, ramp etc.,

author: ejeffrey
author_rank: Super Contributor
timestamp: August 20, 2011, 03:16:15 pm
content: Quote from: saturation on August 20, 2011, 02:48:49 pmThat is true, but your typical 'DDS function generator' like the aglient 33220A series are pretty much terrible spectrally speaking.

author: saturation
author_rank: Super Contributor
timestamp: August 20, 2011, 04:22:16 pm
content: Yes, I don't have 1st hand experience with that arb generator, but generally, spectral purity is the illness of digital synthesis. OTAH, frequency stability is the illness of analog generators; you can get the best of both in each method, digital or analog, but at high costs.Quote from: ejeffrey on August 20, 2011, 03:16:15 pm

author: Unknown
author_rank: Unknown
timestamp: August 20, 2011, 05:10:29 pm
content: Quote from: ejeffrey on August 20, 2011, 03:16:15 pmCompared to an analog function generator or signal generator? Compared to analog function generators they're a lot a better (don't have experience with the 33220A, but do have experience with similar models). But you won't mistake them for an RF signal generator.

author: SnakeBite
author_rank: Regular Contributor
timestamp: August 27, 2011, 10:48:47 pm
content: what do you think about wavetek 278 FG?? is it good?what is more important in general use FG - a large signal possibilities (square , ramp , triangle, sin , dc , pulse ,Sawtooth) or signal accuracy/integrity?i don't know what to decide a have two FG one with more signal (writen above) option but not very accurate but the other has only the basic signals (square , traingle , sin , pulse ,dc) and a lot more signal accuracy/integrity which one is a beter pick?

author: saturation
author_rank: Super Contributor
timestamp: August 28, 2011, 06:23:03 pm
content: Its very good, but as mentioned earlier, its an early form of digital synthesizer and the harmonics of its waveforms are noisier. Check the spec sheets.Precision is better. Without it you won't know if any instability in your design or testing is due to instability from within the DUT or your test signal. For general design, different waveshapes are need, but most work today use sine, square and pulse; rather than rely on an analog FG to have various waveforms available through analog waveshaping circuitry [ for rarely used waves like ramp, or sawtooth, popular during analog days], an arb in a DDS like device can make anything you want when you need it.The Hantek 3x25, see the thread on eevblog, is a DDS-like generator, but it has rudimentary arb capability, which makes for a versatile generator that rivals analog versions. Its stability is better than most analog generators, but worse than low cost digital ones. I've tested its arb capability to 100kHz. Its largest drawback compared to analog generators is its lack of VCO and sweep capability; mechatrommer, marmad and others forum members are trying to improve functionality through hacking the its PC software, you can read the long thread of developments. Its still for sale from China.Quote from: SnakeBite on August 27, 2011, 10:48:47 pm

author: nquantum
author_rank: Regular Contributor
timestamp: July 22, 2013, 01:43:52 pm
content: i found simply circuit here u may interest:http://www.overunity.com/6857/diy-simple-signal-generator/

author: TerraHertz
author_rank: Super Contributor
timestamp: July 23, 2013, 12:08:31 pm
content: Quote from: nquantum on July 22, 2013, 01:43:52 pmhttp://www.overunity.comOh, that's a goldmine. Of... ah... entertaining stuff.