Agilent Built-In Signal Generator? - Page 1
Forum section: electronics / testgear

author: Digibin
author_rank: Regular Contributor
timestamp: March 12, 2014, 10:46:31 pm
content: Hey guys. I've decided that I need a signal generator to progress on a project I'm working on. I have an Agilent InfiniiVision 2000X scope so I'm considering enabling the built in sig-gen on that.Agilent site:http://www.home.agilent.com/en/pd-1952364-pn-DSOX2WAVEGEN/built-in-function-generator-option-for-infiniivision-2000-x-series-oscilloscopes?cc=GB&lc=engDatasheet (page 18):http://cp.literature.agilent.com/litweb/pdf/5990-6618EN.pdfThing is it's over £400. I'll certainly be using the free 30 day trial to test it out and base a decision on that. But I wanted to probe the communities opinion on the value for money of this as compared to other sig-gens I could potentially grab off eBay. I know it ultimately comes down to how much I expect to use it, and for what purpose etc. The application I need it for at this point in time is very simple - just generating sine waves at different amplitudes across a low frequency range. I've no idea what I'll need it for in the future, but I imagine once I have it I'll probably use it on most projects since it's such a versatile tool.I've had a look on eBay and it appears that I'd be spending in the region of £200 anyway to get a decent sig-gen. However I really don't know my sig-gens so that might be rubbish. For what it is, is the Agilent one a decent sig-gen for the money? Or does the built in nature of it come at a price premium? I'm always keen to spend a bit more and buy something that'll last and is reliable, which I'm sure I'll get from the Agilent brand - but more so than the makes and models on eBay or elsewhere?Please share thoughts and comments - I'm curious to see what you think.Cheers.

author: plesa
author_rank: Frequent Contributor
timestamp: March 12, 2014, 11:07:24 pm
content: Check this threadhttps://www.eevblog.com/forum/testgear/dsox2000-and-3000-series-licence-have-anyone-tried-to-hack-that-scope/

author: Rigby
author_rank: Super Contributor
timestamp: March 12, 2014, 11:57:33 pm
content: yes, have a good read of that thread.what are your requirements for the signals? waveforms required, and what frequencies?

author: KD0RC
author_rank: Regular Contributor
timestamp: March 13, 2014, 12:52:13 am
content: I have it enabled on trial license and am not overly impressed. It only has a single channel and does not have a swept output or arbitrary waveforms. On the other hand, I will probably do the $500 USD deal in April to turn on all options to get the I2C and UART decode and memory upgrade, and will get the wave gen in the bargain. I don't think I would spend the money just to get this particular wave gen. If I needed it, I would probably spend under $400 for a new Rigol and get two channels, arbitrary waveforms and a sweep generator or perhaps a bit more to get better stability and functionality.Since I said all of that, I will probably find it indispensible and be glad I got it...So, if you want all the other goodies for $500 (after April 1), you may not need another wave gen. If that is the only reason you are getting it, I would go for a separate unit.

author: Hypernova
author_rank: Unknown
timestamp: March 13, 2014, 05:00:08 am
content: Quote from: KD0RC on March 13, 2014, 12:52:13 amI got a 3000X and it's got modulation and arb wave forms (including copy from scope input). The data sheet linked by OP even says so on page 19. Did you update your firmware?

author: KD0RC
author_rank: Regular Contributor
timestamp: March 14, 2014, 12:41:02 am
content: Quote from: Hypernova on March 13, 2014, 05:00:08 amThe 2000X does AM, FM and FSK modulation, but no arbitrary waveforms and no sweep. Page 19 does not mention arb waveform, but does leave out several of the standard waveforms. It will do Sine, Square, Ramp Pulse, DC and Noise. The sweep seems kind of fundamental, so I am surprised (and disappointed) it is not in there. Maybe someday...Mine came with version 2.36 of the FW, but the Agilent support site only has 2.35 available. I am not sure if they just haven't updated it yet or if there is a problem with 2.36 that they do not want to propagate...

author: Rigby
author_rank: Super Contributor
timestamp: March 14, 2014, 02:07:37 am
content: unpublished firmware updates are often only copyright changes (such as 'Agilent' -> 'Keysight' or whatever) and don't warrant a published release.

author: KD0RC
author_rank: Regular Contributor
timestamp: March 14, 2014, 02:22:39 am
content: Not sure if I am missing something here... The 10 MHz square wave from the wave gen has a rise time of arount 18 nS. That does not seem real 'square'... I moved the frequency down to 100 KHz and it stays at 18 or so nS. Moving down to 100 Hz it is still around 16 or 17 nS. I have the DSOX 2022A, so I don't think the scope bandwidth is the culprit. I get the same poor looking square(ish) wave on 50 ohm or high impenence output and it does not matter if I am using a 50 ohm cable or the 10:1 probe. I also do not have the BW limit set.So what would a typical $500 USD class wave generator be expected to do in terms of square wave rise time? I was expecting 3 or so nS rise times, but not being an engineer, I don't know if that is an unreasonable expectation. Am I falling into any of Dave's traps for young players?

author: Mark_O
author_rank: Frequent Contributor
timestamp: March 14, 2014, 08:31:43 am
content: Quote from: KD0RC on March 14, 2014, 02:22:39 amYes, that is unreasonable, for this class of instrument.You're in the ballbark for dedicated pulse generators. My (old) HP8082A pulse generator will go as low as 1 ns (rise time is one of many controllable parameters). But these are multi-purpose devices, and their strength is their flexibility... not absolute performance in any one characteristic.I can give you an overview of Rigol multi-function generators, just for one data point, and some perspective: the $500 class devices are <20 ns, $700 gets you <10 ns. The DG4000 series goes from <12 to <8 ns ($900-1,500).

author: jpb
author_rank: Super Contributor
timestamp: March 14, 2014, 11:04:11 am
content: Quote from: Mark_O on March 14, 2014, 08:31:43 amThe figures given for the Rigol are correct, but the Rigol does allow faster pulses via arbitrary waveforms. The speed depends on the amplitude in that the Rigol switches between two gains at 4Vpp so for amplitudes below that it is much wider bandwidth and the rise time is in the range of 3 to 4 nsecs. Above 4Vpp the bandwidth is around 60MHz and the rise times are around 6 nsecs.The latest Agilent 33622 has a similiar amplitude dependent rise time switching at 4Vpp (the output amplifier has approximately fixed gain-bandwidth product so if you decrease the gain you can increase the bandwidth).A rise time of 3 nsecs corresponds roughly to 120MHz bandwidth and Signal generators going up to 120MHz are generally much more expensive than those going to around 30MHz. This is certainly true if you want large amplitudes. For small signal Rigol (DG4162) Siglent (SDG5162) and now Agilent (33622) give you the option - though it should be pointed out that the Agilent is around $7000 for the top end model so is not exactly cheap.

author: Mark_O
author_rank: Frequent Contributor
timestamp: March 14, 2014, 01:30:50 pm
content: Quote from: jpb on March 14, 2014, 11:04:11 amThanks, jpb. That's good to know.

author: KD0RC
author_rank: Regular Contributor
timestamp: March 14, 2014, 03:26:16 pm
content: jpb and Mark_O - Thanks for the perspective! I don't have a need for superfast risetime square waves, I was just surprised at what I was seeing. It sounds like the 2000x wave gen is not a bargain at $500 USD, but it is not a rip off either. Getting it thrown in with all the other features makes it a good deal, so I will take Agilent up on that offer in a couple of weeks. So far, I am quite happy with the scope and used it to find a problem in a radio that I have been struggling with for quite a while.

author: jpb
author_rank: Super Contributor
timestamp: March 14, 2014, 03:28:44 pm
content: Quote from: Mark_O on March 14, 2014, 01:30:50 pmAs a caveat, I should add that I don't have one myself (I'm still deciding) but what I've said is based on results published on this site from various owners such as on this thread:https://www.eevblog.com/forum/reviews/rigol-dg4062-8679/15/And the fact that the Rigol manual has a change of allowed Voltage at the output at 4Vpp and deducing what the gain must be from the allowed Voltage at the output vs the around 1V that the DAC can produce shows that the gain switches between 4.5 and 11.25.Also the thread below shows the actual bandwidth which switches between around 60MHz and nearer 140MHz which are consistent with a Gain x Bandwidth product of about 650MHz (i.e. when the gain is switched to 11.25 the BW is down at around 60MHz and the rise time is around 6nsecs when the gain is switched to 4.5 the BW is right up close to the 150MHz Image Reject Filter corresponding to approx 1/3 of the 500MS/s DAC used and the rise time is nearer 3 nsecs (spec is < 5nsecs for arb).https://www.eevblog.com/forum/testgear/250-mhz-out-of-a-rigol-dg4102-a-100-mhz-waveform-generator/msg220649/#msg220649

author: jpb
author_rank: Super Contributor
timestamp: March 14, 2014, 03:34:19 pm
content: Quote from: KD0RC on March 14, 2014, 03:26:16 pmRise time is certainly not everything, or perhaps even that important - it is just something you have to pay for if you want it (like bandwidth in scopes). The Agilent 33500 series have quite slow rise time (8.4 nsecs) but are nice generators with very little jitter, sequencing, etc and their TruForm techniques seems to get around the problem of missed points. I don't know how much of this makes it into their built-in solutions.

author: Digibin
author_rank: Regular Contributor
timestamp: March 15, 2014, 08:01:06 pm
content: Quote from: KD0RC on March 13, 2014, 12:52:13 amCould you provide a link with more detail on this deal? Is it available to the UK? Sounds like a decent deal, certainly worth considering.Also a good point about the single channel. Two channels would be much better. Also sweeping capability would be really useful. I'll take a look at the Rigol as that seems like a decent choice for an entry level sig gen. The main issue with it appears to be the less than satisfactory software, which by the sound of it has been more or less fixed.

author: AndyC_772
author_rank: Super Contributor
timestamp: March 15, 2014, 08:11:47 pm
content: Quote from: graymp89 on March 15, 2014, 08:01:06 pmHere:http://www.agilent.aspen-electronics.com/dsox2appbndl