Clients often ask me what they'd need for pre-compliance. My default answer is the Hameg 5510, around $2k, probably more after the $ decline. Fits the bill, gets the job done, but it's hard to document your work. The Atten AT5011 costs half that but I don't know it, haven't used it.
The problem with most of these: You can't easily dump the screen onto a PC, let alone memory stick. My new DSO does that very nicely but that company's analyzers are too expensive for this kind of job.
Any other contenders? Ideally not a handheld but something that gets plopped onto the benchs and plugs into mains. And no, I am not asking again about USB analyzers as they don't seem to exist (I still think somone could become rich if they made one).
I use HP859x series of spectrum analyzers, particularly 8591EM if available. For an interface, I use Nat'l Instruments ENET, which converts the GPIB port to 10BaseT. The spectrum analyzer then has a LAN address, and relatively simple commands sent via the NI GPIB layer suffice to control the instrument and exchange data. Instead of using LabView, for example, I wrote a VB6 app to make it easier to store and compare traces, subtract baselines, etc. Not a straightforward approach, I'll admit, but it does the job. I'm quite fond of these old HP SAs. Paul Mathews
Why not try photographing the screen with a digital camera? I've done this many times on gear that doesn't have output capability. Results have ranged from crappy but usable to excellent. Never as good as a direct screen dump to a USB stick, but good enough for most documentation purposes. A slow shutter speed is the go to avoid screen refresh problems etc. A mini tripod or Farnell catalog or two works a treat to keep it steady.
Check if your SA has a plotter output. There are PC based HPGL plotter emulators available:
I've used a digital camera for grabbing scope traces. My black cardboard "scope camera" is ugly but functional.
One device just wouldn't cooperate. I found where the X-Y signals to the scope section could be found and attached scope probes from a DSO (digital storage oscillosope) to grab the trace. Many scopes that have an external display or perhaps "HP storage normalizer" have external X-Y signals available on a connector.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
I know that company a little (and their chip designer). They do not have any units suitable for the pre-compliance frequency range. Supposedly coming but right now you'd have to buy two units and that becomes expensive and cumbersome. And some clients need this capability now, not next year or so.
Well, there are spectrum analyzers that have the tradition mess of BNC connectors on the back, which usually include something to drive a pen plotter. They're usually labelled X, Y, and pen lift. You can probably do something useful with that. XY pen plotters can still be found, or just use your DSO.
You're lazy, but such laziness has been the inspiration behind some of my best ideas. Don't let it bother you (much).
How about a compromise? Instead of a USB stick, one of the ever growing variety of memory cards that are being used in digital cameras will probably suffice. Build a cardboard or foam board hood and mount the camera at the correct location. Make it fairly long (about 0.8 meters) so that you don't have a depth of field problem, where the focus is different in the display center and at the edges. Pre-focus and set the zoom. Paint the hood black inside. When the display has something that's worth capturing, push the shutter button. Clean up the picture with Photoshop or Irfanview.
If dealing with the memory card is too much for you, run a USB cable to the camera, and capture the image directly on your PC. The only problem with this approach is that the "video" mode on most cheap digital cameras is 320x240 or 640x480 at best. That may not be enough for a detailed photo. However, I've seen spectrum analyzer photos on FCC type certification documents that look like they were frame grabbed from a video camera, so this method is probably suitable for pre-certification.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
The pen lift thing would present a wee problem with the DSO. Other than that it could do it since mine and probably most others are capable of X-Y plots.
That's how I do it now. Would be nice if I didn't have to ;-)
But it's not so much me, it's for clients. Most young engineers are not very familiar with spectrum analysis, much less with vintage equipment. It would be great if I could tell them "Press this, then that and later the other button and shoot it over via email attachment". Then I could look at the plot and tell them "Place 220uH between D17 and C45, then do the spectrum again."
Connect it to the Z axis input (trace inhibit) of your DSO.
You don't have to. You can hire someone to do it for you.
Perhaps hire an artist have have them sketch the display?
You'll be amazed at how quickly they learn after you explain that their job, life, future, and salary depend on their ability to operate the device. No rush, take all night if you need to.
I have a camcorder for such exercises. I've video taped how I setup a rather messy rack full of acronyms before it was shipped. On arrival, the techs followed the video religiously, including purchasing a trash can to match the one I accidentally left in the video. Immitation works amazingly well, even with little thinking involved.
Incidentally, I intentionally delayed the shipment of the manuals so that they had to follow the video and could not get creative. The problems started immediately after the manuals arrived, when the tweaks, adjustments, and "calibration" began.
You really are lazy. Pry yourself out of your overstuffed easy chair, get up, and go look at the spectrum analzyer display. Then tell the tech to make the changes. Think paperless office or save a tree. When you're happy, say "print it" and do the photographic ordeal process.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
I am afraid it doesn't have that function. Unless it's thoroughly hidden somewhere.
Hmm, I might not even have to, my wife is pretty good at pencil drawings. Now I'd just have to cajole that pulse noise into sitting still for 10 minutes or so.
:-)
There remains a wee problem though: I am a consultant and the engineers I am talking to are anywhere from 25 miles to 6000 miles from here. We do have a runway right in town and my office is next to it but I haven't found the matching LearJet on EBay yet.
I second the recommendation for the 809x analyzers. I bought one several years ago and sobbed when they sent it and the calibrated antennas out to scrap a year later. :-( ' ' -- Keith
My clients typically pay about $1000/day or more for EMI test lab time. I've come into situations where they've already spend $50K or more on repeated trips to the labs, so they are sometimes ready to discuss spending $20K on some pre-compliance gear. The engineers ALWAYS need training, although I agree that it would be a little easier if the equipment was easier to use, and we can hope that we won't have to wait much longer. In the meantime, anyone can learn a lot by sniffing around with near field probes, particularly B-field probes, and the controls of most portable spectrum analyzers are really pretty simple: Start Freq, Stop Freq, BW, Sweep Time, Level/ Attenuation are the main ones to know about. They need to understand how Sweep Time needs to be long enough to capture sufficient energy to measure at each frequency. A good broadband preamp is a necessity, but the Ramsey SA7 is available for $20 in a kit or about $70 assembled. You can pick up an older Anritsu, HP, Advantest, Marconi, Tektronix or other brand portable spectrum analyzer for under $2K with GPIB. It's not too difficult to get any of these to respond to remote commands. If anyone wants to use it as a starting point, I'll share my VB sourcecode for an app that controls the SA, uploads and downloads traces, overlays EMI compliance limit lines, compares traces before and after mods and setup changes, sets up the SA in various default configurations, etc, etc. I have HP959x and Anritsu MS420 versions. No support beyond commented sourcecode. Here's some articles that teach about building your own near field probes and LISN and how to use them:
formatting link
EMI sniffer probes:
formatting link
buy from Bruce or use his design (see link on page)
formatting link
formatting link
(see middle of page and get ready to be overwhelmed)
The link above gets you to more info than you'll ever need to build and use your own pre-compliance probes.
Wideband Preamplifiers:
Search ebay for HP 8447A/B/C/D and pay a few hundred $ or
formatting link
this looks interesting, too:
formatting link
other good sites:
formatting link
(first of a series of 7 excellent articles by Sanjaya Maniktala)
Don't know them either but from the spec sheet it doesn't look too encouraging. -60dBc for two sigs 10dB below ref level could be a problem out here, at least in the Bay Area. And you only get two BW settings that don't seem to quite fit the quasi-peak checks one has to do for EMC. But this is indeed an interesting approach, to have a PalmPilot in there. However, it seems those little organizers are on the way out and people got back to the old paper booklets. I never had a PalmPilot.
That gets old. The main impediment is that you can't tell the digital camera to correct for the antenna gain versus frequency before taking the picture.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.