Design of an FPGA based bit error rate tester

[Altera_Forum]

Hello. I am looking into making an FPGA based BERT for some lab testing based on this article http://www.physics.smu.edu/web/research/preprints/smu-hep-11-14.pdf I found on the web. I am not an FPGA person but I was hoping I could purchase a development board and some software in order to create a "relatively" inexpensive Bit Error Rate Tester that would operate from around 1.25Gbps to 10.3125Gbps. Does anyone know what opensource software the author is talking about in this paper? Could you use the Transceiver Toolkit provided by Altera to create a BERT. Any other help suggestions would be greatly appreciated.

[Altera_Forum]

Yes, the transceiver toolkit can be used for bit-error-rate tests of transceiver links. 

 I'm currently using the transceivers on several development kits, so if you can describe your application, I might be able to suggest an appropriate kit.  Cheers, Dave

[Altera_Forum]

Dave , 

Thank you. It would be very helpful if you could offer suggestions to me for this application. My application would be bit error rate testing of what are essentially SFP / SFP+ modules operating from 1.25Gbps to 10.3125Gbps. I need an electrical transmit and receive channel (SMA connections), an optical transmit and receive channel (SFP module), and a trigger output (SMA connection) for a scope. I certainly wouldn't argue with the option of having more I/O channels for future expansion but that is all I need at the moment. Ideally it would be able to run PRBS patterns and short user defined patterns (4-8 bits is enough to just basically do a 0001 pattern as a sanity check for proper data polarity). Is the transceiver toolkit user friendly? I have little experience with FPGA programming so that is why I was looking for some type of open source software or at least an interface that I could learn without needing years of FPGA experience. I have some Labview experience that allows me to toy with programs but again I am not an expert by any stretch of the word.  Thanks

[Altera_Forum]

--- Quote Start ---   My application would be bit error rate testing of what are essentially SFP / SFP+ modules operating from 1.25Gbps to 10.3125Gbps. I need an electrical transmit and receive channel (SMA connections), an optical transmit and receive channel (SFP module), and a trigger output (SMA connection) for a scope. I certainly wouldn't argue with the option of having more I/O channels for future expansion but that is all I need at the moment.   --- Quote End ---   The need for 10.3125Gbps pushes you into the higher-end and therefore higher cost devices.  To test SFP/SFP+ modules at 10Gbps you want a board with one or more SFP/SFP+ connectors, so that your signals are not distorted by adapter/connector transitions.  To test a transceiver via SMA connectors, you do not need the SMA connectors on the PCB, you just need an SFP/SFP+ to SMA breakout cable, eg., I use QSFP+ breakout cables from Elpeus (yes, they are $600 each, but your time is worth money too ...)  http://www.elpeus.com/categories/sma-test-cables.html  I do not have a kit with SFP/SFP+ connectors. I am using a kit with FMC connectors and an FMC-to-QSFP+ adapter board (not an ideal setup for 10Gbps).  Browsing through the list of Altera kits  http://www.altera.com/products/devkits/kit-dev_platforms.jsp  I see ...  http://www.altera.com/products/devkits/altera/kit-stratix-v-dsp.html http://www.altera.com/products/devkits/altera/kit-sv-gx-host.html   * both have a QSFP+ connector (you can use a QSFP-to-SFP breakout cable)  http://www.altera.com/products/devkits/altera/kit-sv-gt-si.html http://www.altera.com/products/devkits/altera/kit-transceiver-si-stratix-v.html http://www.altera.com/products/devkits/altera/kit-stratix-v-gx-100g.html    * transceivers and SMA connectors  * I tend to avoid these boards as they are expensive and not too  useful for anything but looking at transceivers (no DDR etc).  http://www.nallatech.com/pci-express-fpga-cards/pcie-385n-altera-stratix-v-fpga-computing-card.html http://gidel.com/procev.html   * SFP/SFP+ ports  http://www.bittware.com/products-services-fpga-cots-hardware/a5-pcie-l-a5pl http://www.bittware.com/products-services-fpga-cots-hardware/s5-pcie-hq http://www.bittware.com/products-services-fpga-cots-hardware/s5-pcie-ds   * QSFP+ ports  * Bitware has several other products like this too  http://www.terasic.com.tw/cgi-bin/page/archive.pl?language=english&categoryno=13&no=&~123   * Terasic have several boards with QSFP+ or SFP+ connectors too  Browse through these options and check out pricing. Terasic and Bittware make nice hardware and have good support.  If you are considering "software development" using your FPGA, then you might want to consider buying a board that is already supported by Altera's OpenCL (you can do a little more research to check which boards are supported).  Cheers, Dave

[Altera_Forum]

--- Quote Start ---   I have little experience with FPGA programming so that is why I was looking for some type of open source software or at least an interface that I could learn without needing years of FPGA experience.  --- Quote End ---    Determine whether any of the boards are within your price-range, and then I'll create a 10Gbps transceiver example for it to confirm it can meet your requirements. That will ensure that the device on the board you order has the appropriate speed grade to support the lane rates you are interested in.  Cheers, Dave

[Altera_Forum]

Dave, 

Thanks. This board http://www.altera.com/products/devkits/altera/kit-transceiver-si-stratix-v.html (http://www.altera.com/products/devkits/altera/kit-transceiver-si-stratix-v.html) would certainly be within my price range if I had confidence the application was going to work how I envision. I would prefer to have SMA connections since I will be interfacing with scopes and evaluation boards that use SMA connections and I am not a big fan using cable adapters. I'm not actually testing SFP modules but optical transceivers that are identical in functionality but are packaged different. The SFP module on the BERT will be used as a source to drive an optical receiver. I have attached a simple block diagram of my test application. I test both transmit and receive simultaneously. I use the BERT to drive the electrical input of an optical transciever and I view the output of the optical transmitter on a scope. I use an optical master (SFP module) to drive the optical input of the transceiver and measure the BER of the electrical output. If you think this application lends itself well to an FPGA based BERT please let me know. Do you know if Altera has demo boards to tryout an application without requiring purchase? I can't justify spending this type of money unless I am sure it is going to work.  Thanks

[Altera_Forum]

Hi,  

since your last post is a bit older, did you realized the BERT in FPGA? Did you get the VHDL sources you mentioned in your first post of these thread?

[Altera_Forum]

--- Quote Start ---   since your last post is a bit older, did you realized the BERT in FPGA?   --- Quote End ---   If I recall correctly, the BERT function in the Stratix IV series is hard-coded, i.e., you synthesize for the BERT or you synthesize for a design that uses the transceivers. The idea of using a BERT created in the fabric is that you can dynamically switch to it and then over to your transcieiver logic.     --- Quote Start ---   Did you get the VHDL sources you mentioned in your first post of these thread?  --- Quote End ---   I wrote up a couple of articles on how to use the Altera Transceiver Toolkit ... it is quite buggy, so the articles are useful for figuring out that you are not going crazy, that in fact Altera provides broken software :)  The articles are near the top of this page: https://www.ovro.caltech.edu/~dwh/correlator/cobra_docs.html  Cheers, Dave