FPC1500 Spectrum Analyzer - Review

Table of contents

RoadTest: FPC1500 Spectrum Analyzer

Author: DiligentMinds.com

Creation date:

Evaluation Type: Test Equipment

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: There are no comparable instruments with all of the same features at the same price, in fact even the low-cost vendors can't compete with the price/performance ratio of this unit.

What were the biggest problems encountered?: The only way I could get the WiFi option to work was to use an old router that was configured as an 'open' access point (no passphrase).

Detailed Review:

The FPC1500 is an affordable VNA [Vector Network Analyzer], with a tracking generator that can be used in additional modes.  This is a review of this instrument.  As a disclosure, Element-14 and R&S supplied this instrument for this review, but it is not "free" for me, since I do have to pay income tax for the full retail amount of the instrument and options.  That said, I would not hold back any negative impressions of this instrument (and there are only a few-- hence my high rating).

 

The unit arrived in a surprisingly small box, but inside it was protected quite well with expanded polystyrene molded supports and open-cell foam padding-- and could probably take quite a bit of shipping abuse before the instrument would be damaged. My unit arrived without a scratch on the box or anything inside of it. I was particularly taken aback by the very light weight of the box before I opened it, and I was wondering if they forgot to pack the instrument inside!  But no, there it was-- this instrument is very light weight indeed. For spectrum analyzers, I am used to my old HP unit, which is basically a “boat anchor”-- and at about 100LBS it takes 2 people to safely move it around. I was quite shocked by such a light weight unit-- and that has a lot of advantages (and at least one disadvantage-- see below).

 

The FPC1500 is a 2-port vector network analyzer, that has a frequency range from 5MHz up to 3GHz. The unit supplied to me for this review was configured for a 3GHz maximum frequency.

 

The front panel is well laid out and very intuitive-- I found that I did not need to read the manual much at all, and only for the more esoteric features and tweaks. The buttons have a soft rubbery feel, but with a solid (and satisfying) tactile feel at the end of their travel-- very much reminiscent of the old HP calculators (HP-15C, et. al.). I found that I could do almost everything I needed to do, just by moving around in the menus and getting to know the instrument that way. This instrument is very much easier to use than my old analog HP spectrum analyzer. The screen is absolutely HUGE for what needs to be presented-- and you can directly view even the tiniest signal details without zooming in-- it is a real joy to work with, but you do need to be directly viewing it from the front-- there is not a great vertical or horizontal viewing range on this display. For classroom (or board room) use, an external display can be used with a computer connected to the instrument through the remote interface.

 

With a set of near-field probes and the 3GHz option, this instrument could be used for EMC pre-compliance testing. It is in fact well suited to this task due to the very low noise floor, and fantastic sensitivity.

 

This particular model has some unique characteristics-- the signal generation port can be a (more or less normal) tracking generator, but the frequency of the signal generator can also be controlled independently of the spectrum analyzer’s sweep frequency, as well as locked to center of span, which allows some additional tests over the normal (and expected) frequency response curve.

 

In addition to the special modes of the signal generator, there is also an internal VSWR bridge for additional measurement modes. This can be used to test cables (cable loss vs. frequency and “distance to fault”, much like a TDR), and will measure the frequency response (SWR) of an antenna over any frequency span in the range of the instrument. There are modes to correct for a different characteristic impedance (like 75-ohms)-- or a custom impedance. This came in handy for my TV antenna testing (below).

 

One thing to note though-- the signal generator puts out a square-wave-- not a sine-wave as most people would expect. This is not much of a problem for most measurements because of the super-high performance filters in the spectrum analyzer side of the instrument-- and this square wave will only become an issue in some very rare measurements, so the test engineer will have to be aware of this and take precautions (or use an external generator) if this will be an issue.

 

The only way I could get the WiFi option to work was to use an old router that was configured as an 'open' access point (no passphrase). All other attempts to get the WiFi connection to work with either a very modern access point (using WPA2-PSK-AES) to an older router (using WPA-TKIP) failed. The company took a while to respond, but they were very nice on the phone and promised to send the issue to the R&D group. It is entirely possible that my particular unit simply has a bad WiFi radio, or that radio needs a firmware update (but I don't see any way for me to check and/or update that).

 

There has already been a tear-down and review on “The Signal Path” YouTube channel, and on that channel the presenter provides a great deal of information on the functionality of the instrument. I particularly like that he discovered that there is a lot of space inside (in the back of the unit), and the unit runs on a 12V supply. This opens up the possibility that a battery can be installed for use in locations that have no AC power-- (like the top of a tower, etc.-- a lot like a “Field Fox”). It is certainly light enough for this-- in fact so light that I have to hold onto it with my other hand to push the front panel buttons when the unit is sitting on a slippery lab bench. The “fix” for this is to put a rubber pad underneath the unit when on your bench.

 

As far as the spectrum analyzer function goes-- this unit has one of the lowest DANL specs I have seen-- even compared to my ancient HP spectrum analyzer that uses “old school” YIG filters and oscillators. In fact, in one of my tests, I set the RBW and VBW to 1Hz, and the number of sweep (trace) averages to 100, and was able to achieve a noise floor of -195dBm (with the LN preamp turned on). The small "blip" at the center of span appears to be an artifact of the signal chain-- and it appears no matter the span or center frequency.  This setting takes a ridiculously long time to take a measurement, but I did it as an exercise to see just how low we can go.

 

The spectrum analyzer also has an AM/FM/ASK/FSK demodulator option, that I was unable to test at this time (but will post back later in the forum as I use these obscure functions)-- this feature would be very handy if you need it.

 

Of particular interest, is the ability to connect a filter in the traditional tracking-generator/spectrum-analyzer (insertion loss) mode (S21), and then the response of the filter can be monitored as the filter is tuned. If you are doing this kind of work, there is no better tool to help you with this task. You can also use this mode to get a fairly good idea of the frequency response for a cable.

 

In the single-port (return loss) mode (S11), there are some additional tests that can be done to test a cable-- even when you don’t have access to the other end of the cable (though it’s better when you do). This mode is also magnificent in determining the frequency response of an antenna. After reading some scientific papers on wide-band disc antennas from MIT, I made a UHF TV antenna out of (2) 12-inch pizza pans (88 cents each at Walmart) and a standard 4:1 balun. I mounted this antenna right on the wall-- very crude! Since I’m only 17 miles from the major TV broadcast stations, I was able to pull in all of the prime channels, with the exception of the one channel that is broadcasting on physical channel 2 (low end of the VHF TV spectrum-- 54MHz..60MHz)-- the pizza-pan dipole was just too small to get a good signal and so this channel is very marginal. It was interesting to see the frequency response and SWR curve of this “weird” antenna. It has an SWR of below 4.0 over the entire upper VHF and lower UHF TV bands-- which would probably be a lot lower if I could find a 1:1 balun to test it with-- (the characteristic impedance is closer to 75-ohms than 300-ohms).

 

Enhancements I would like to see:

  1. I would like a way to see the version information of the WiFi radio firmware and be able to update it in the same way the instrument can be updated through the USB port (by using a thumb drive). Additionally, it would be nice to be able to TEST this radio (somehow)-- and to know if it is set to USA standards or some other standard (which is usually just a setting in the radio’s configuration memory).
  2. There was little support for a keyboard-- when plugged in, it only replicated the front panel buttons, making signal labeling (and entering a WiFi passphrase) tedious. It should be easy to add HID support to the application-- since the hardware seems to support this, it most likely would be a firmware-only upgrade.
  3. As the 5.8GHz (ISM) band is becoming increasingly important-- it would be nice to see a version of this instrument with a 6GHz bandwidth option.

 

Conclusions:

The size, weight, and price of this instrument, along with it’s “Swiss Army Knife” feature set, makes this a “must have” instrument for anyone engaged in even very rudimentary RF work. Even someone that only manufactures (or installs or aligns) antennas could use one of these, and would save countless hours of fussing around with lesser instruments. Designing, and adjusting filters is made much easier with this instrument-- it would easily pay for itself rapidly if you make a living doing these things. If you already have a high-end oscilloscope in your lab, this should be the next instrument you buy if you are doing any work that needs RF testing or EMC pre-compliance testing (embedded systems, etc.). The price from R&S is very reasonable for the performance and features offered-- and is an even better bargain than some of the lower cost alternatives out there (like company ‘R’ for example).

Anonymous
  • Hi David,

     

    Thank you so much for your comments and suggestions-- the content of which I will take into consideration, along with the spirit and demeanor in which they were presented.

     

    Regards,

    Ken

  • You don't work for any of us, Ken. You have however made a commitment to E14 to road test this and have failed to live up to it. You know what I'd like to see - your application for the road test. If you've fulfilled a fair proportion of what you've promised then that's fair enough, you've done what you said you would. I suspect you may have promised a fair bit more than screwing two pizza pans to the wall under duress.

     

    Fair's fair - if you do show us your application, then I'll also show my application for the RTM3004 road test that I just completed and you can let me know if I fulfilled what I promised for that.

  • Hi Rachael,

     

    Fortunately for me, I don't work for you.  That said, I will still take your comments into consideration.  Thank you for your insight.

     

    Regards,

    Ken

  •   wrote:

     

    I've heard from a few of you how you don't think my review has enough content, but I see no calls for specific tests to be done. 

     

    I thought I was quite specific. You should redo the testing you said you did but "lost" due to your "computer failures". I also suggested you should hook the instrument up using the LAN point and do the remote control testing you said you couldn't do because you couldn't get the WiFi working.

     

      wrote:

     

    I'm being taxed (as income, and a "use tax") on the value of this instrument (plus options), and so it is not free to me (discounted yes, but not free).

     

    Ok fair enough, but you still obtained a very good instrument which was heavily discounted, and you aren't the only US based reviewer of high value items like this I don't believe so not the only person who was taxed on it, yet your review is the only one (for a big ticket item) which several people have commented as lacking.

     

      wrote:

     

    Please describe in colorful detail, the specific tests that you would like to see, or features that you would like me to explore that are not already covered by the other reviews.

     

    Ignore what other people have done. There is nothing wrong with covering a feature in your own way with your own viewpoints. You may discover something somebody else had missed on help enlighten somebody regarding a subtle detail they didn't understand from other reviews. Variety in the different viewpoints is very useful.

     

      wrote:

     

    When I have a list of specific tests that you would like to have done, I will consider covering them.

     

    Statements like this don't help. If you do everything you claim you were originally going to do but couldn't then nobody would be complaining. Or was there actually no more in your original road test plan then you have already produced?

     

    Regards,

     

    Rachael

  • I'm being taxed (as income, and a "use tax") on the value of this instrument (plus options), and so it is not free to me (discounted yes, but not free).  I've heard from a few of you how you don't think my review has enough content, but I see no calls for specific tests to be done.  I have read the reviews on the FPC1000 and the FPC1500, and I have had the same experience as the other reviewers describe in them, and I agree with their perspective on this instrument-- I see no reason to fill up a review with "fluff" just to make it look good.  I have provided *MY* take on this instrument, in *MY* way.  The features and functions that I have reviewed are from the perspective of an embedded systems engineer (with an occasional need for RF testing)-- and not from the perspective of an RF engineer that spends 100% of their time on RF design.  That said, I'm not insensitive to the curiosity and need for answers from others.  Please describe in colorful detail, the specific tests that you would like to see, or features that you would like me to explore that are not already covered by the other reviews.  When I have a list of specific tests that you would like to have done, I will consider covering them.

     

    Regards,

    Ken

  • OK

     

    For future reference add a line at the top saying this is a preliminary review with more to follow.

    That way we can bound our expectations.

     

    DAB

  • If I were to get serious about a proper TV antenna, it would be better done outdoors (to increase signal and reduce interference), as high as I could get it (while hiding it as much as possible from the neighbors and the HOA).  Probably I would have a dual bi-quad antenna (with a screen reflector) for the UHF channels, and a 2-element beam for the VHF channels, mixed with an RCA amplifier (these have a built-in VHF/UHF diplexer)-- then run a coax all the way to the central splitter that feeds the entire house-- then all of the TVs in the house would simply connect to where the cable used to go.  My cable modem would be the only thing connected to the cable company in that case-- (and I'm looking for alternatives to that-- perhaps a wireless link from LV.net).

     

    Probably, it would be much better if the pizza-pans were on a proper mount (edge-on board, or PVC pipe) and moved away from the wall-- Yeah, I thought about the rock-board attenuating the signal.  I *did* do a test where the 2 pizza-pans were mounted on cardboard, and in rotating the antenna, there was very little variation in signal-- maybe +/-1dBm broadside, and -2dBm at the edges of the antenna-- so this antenna is (weirdly) very omnidirectional.  I did not try vertical polarization though.  I might re-test all of this with proper mounting-- and move it to a proper thread (since this thread is about the instrument review).

     

    That said, with the FPC1500, you can actually SEE what you are doing, and what is happening with the SWR and the signal levels-- in real-time...  I have absolutely no idea how I managed to get by in years past without one of these instruments!

     

    -Ken

  • TV transmitters are required to support horizontally polarized antennas.

    Thats the bit that confused me as well. ...

     

    When you're talking about a dipole, it is essentially a donut. ... Its the best way to picture it.

    From what I read and your statement "...there ARE nulls at the edges ....", this tells me you have the 'donut' rotated 90 degs.

     

    I suspect the responder was suggesting that if the wall the pizza pans were on, was in line with the signal, it would be in the null.

     

    I also suspect that your SWR will improve by rotating it.

    You have a large lump of earth stopping the signal from freely transferring into a magnetic field, and this would have an effect on the antenna tuning at those frequencies.

     

     

    Be interesting to re-run the test if you have a chance.

     

    Mark

  • Hi Ken,

     

      wrote:

     

    I had done a lot more testing (with more photos and screenshots) than this before the computer crash.  This was all I was able to put together by the deadline. 

     

    You didn't need to stop just because you'd reached the deadline and published an incomplete review. Now your computers are back up and running you should be able to redo all the things you had done and lost and it should be a lot easier second time around. There is nothing stopping you updating your review in order to add what is missing.

     

      wrote:

     

    I also realized that many of the features this instrument have already been covered by multiple reviewers (and also the FPC1000 reviews, as the spectrum analyzer is the same)-- so I focused on those aspects of the instrument that were not covered by other reviewers. 

     

    Just because others have covered things doesn't mean you shouldn't too. Multiple different perspectives on how things work help others to understand better. I've enjoyed reading the reviews of all the other reviewers of the FPC-1x00 units as they all have a different take on various aspects of the unit and it adds to my understanding of how it works.

     

      wrote:

     

    In addition, there are some features that require some DUT or piece of test gear that I don't have.

     

    We all had issues relating to requiring additional gear to test out features and we purchased additional items or designed and built them to enable us to do our reviews. I personally have paid out an extra £300 for the pieces I needed so far and this will rise another £200-300 when I have completed the equipment needed for the additional detailed blogs on the two remaining features I need to test further. One of the questions on the road test application is about whether you have any other equipment you will need in order to be able to complete the road test.

     

      wrote:

     

    It's a shame that I could not get it to work on my access point, because I could have shown the remote control capabilities on a Win-8.1 machine-- R&S customer service has not got back with me (yet) on that issue-- I suspect it will be fixed in the next release.

     

    If R&S do fix the issue you are seeing in their next release are you planning to do additional testing and update your review?

     

    However, your wireless access point issues should not have stopped you reviewing the remote control capabilities of the unit. It also has a LAN port and I find it hard to believe you have no way of even plugging it into regular network with a regular RJ45 cable. Nobody else had these issues with the unit.

     

      wrote:

     

    Thanks much for your input!  Sorry my review did not meet your expectations

     

    You've received approximately $5k-6k of equipment here and for that a lot more effort is expected. This should not be put off for "next time", you should go back and complete the review you say you intended to produce all along. If not then I would question your sincerity in your justifications above for not having finished the review already.

     

      wrote:

     

    I will try to do better next time.

     

    I really hope you do. Maybe next time you apply for a road test you go for something less complex which requires a lot less effort in order to do a good review.

     

    Regards,

     

    Rachael