Looking for PRBS PN9, PN11 or PN15 bit sequences - Page 1
Forum section: electronics / testgear

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: August 13, 2023, 06:18:09 am
content: Hello!For a Bit Error Rate Test (BERT) i’m looking for PRBS data. Does someone happen to have a bit sequence based on PN9, PN11 and/or PN15 lying around, or a reference to a source where I can find one?So I’m really looking for a series of 0s and 1s (with a length of 511 resp 32,767 bits). If possible with relevant information (like seed, numbers of run, or code that generated it).I know they are defined by the ITU-T 0.150 (05/96) standard and can be generated with computer code - or hardware! - with shift registers and feedback loops (e.g., for PN9 a 9 registers with feedbacks after register 4 and 0). But jut having the string of bits would be helpful for me.Thanks, RudiRudi’s Electronics Labs (YouTube)

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: September 03, 2023, 09:21:59 am
content: Should anyone in the future be looking for such a code: I eventually sampled the PN9 output of a Rohde & Schwarz SMIQ3 vector signal generator. The procedure was as follows:- I defined a trigger output indicating the start of a new PN9 sequence,- I used a parallel bus decode on an oscilloscope to sample the PRBS code as well as the trigger output,- I captured a total of eight 511-bit sequences to ensure they were each time identical to each other (and they were).So, the sequence I found is:0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,1,1,0,0,0,0,1,0,0,1,1,1,0,0,1,0,1,0,1,0,1,1,0,0,0,0,1,1,0,1,1,1,1,0,1,0,0,1,1,0,1,1,1,0,0,1,0,0,0,1,0,1,0,0,0,0,1,0,1,0,1,1,0,1,0,0,1,1,1,1,1,1,0,1,1,0,0,1,0,0,1,0,0,1,0,1,1,0,1,1,1,1,1,1,0,0,1,0,0,1,1,0,1,0,1,0,0,1,1,0,0,1,1,0,0,0,0,0,0,0,1,1,0,0,0,1,1,0,0,1,0,1,0,0,0,1,1,0,1,0,0,1,0,1,1,1,1,1,1,1,0,1,0,0,0,1,0,1,1,0,0,0,1,1,1,0,1,0,1,1,0,0,1,0,1,1,0,0,1,1,1,1,0,0,0,1,1,1,1,1,0,1,1,1,0,1,0,0,0,0,0,1,1,0,1,0,1,1,0,1,1,0,1,1,1,0,1,1,0,0,0,0,0,1,0,1,1,0,1,0,1,1,1,1,1,0,1,0,1,0,1,0,1,0,0,0,0,0,0,1,0,1,0,0,1,0,1,0,1,1,1,1,0,0,1,0,1,1,1,0,1,1,1,0,0,0,0,0,0,1,1,1,0,0,1,1,1,0,1,0,0,1,0,0,1,1,1,1,0,1,0,1,1,1,0,1,0,1,0,0,0,1,0,0,1,0,0,0,0,1,1,0,0,1,1,1,0,0,0,0,1,0,1,1,1,1,0,1,1,0,1,1,0,0,1,1,0,1,0,0,0,0,1,1,1,0,1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1,1,0,0,0,0,0,1,1,1,1,0,1,1,1,1,1,0,0,0,1,0,1,1,1,0,0,1,1,0,0,1,0,0,0,0,0,1,0,0,1,0,1,0,0,1,1,1,0,1,1,0,1,0,0,0,1,1,1,1,0,0,1,1,1,1,1,0,0,1,1,0,1,1,0,0,0,1,0,1,0,1,0,0,1,0,0,0,1,1,1,0,0,0,1,1,0,1,1,0,1,0,1,0,1,1,1,0,0,0,1,0,0,1,1,0,0,0,1,0The found PN9 code features a maximum of 8 subsequent 0’s and a maximum of 9 subsequent 1’s.Note that I show the code as individual bits, not hex codes. The reason is that the PN codes repeat themselves in 2^n-1 bits, so the PN9 code repeats itself in 2^9-1=511 bits. That does not translate nicely into a discrete number of hex codes. In other words, should you express, say, 10 subsequent PN9 sequences into HEX values, you do not see the HEX code repeating itself.

author: sorenkir
author_rank: Regular Contributor
timestamp: February 24, 2024, 05:26:48 pm
content: Hello,Rudi, I have watched your series of videos about BER tests and PRBS generation.I have an old Wandel & Goltermann SF-60 SDH/PDH Transmission Analyser. It can generate PRBS patterns, from PRBS6 to PRBS31, with variants, insert errors, add jitter, etc.I have acquired the bit series for PRBS9 with my scope. It is the exact same series than you, except that the start pulse is not at the same position (see Excel file).Regards,Michel.Also, PRBS11 bit stream is in the txt file, if anyone is interested...

author: RAPo
author_rank: Super Contributor
timestamp: February 24, 2024, 06:00:52 pm
content: What a wonderful video you´ve made.

author: Njk
author_rank: Frequent Contributor
timestamp: February 24, 2024, 07:35:15 pm
content: Many function gens can generate PRBS waveforms. Check that of Rigol, Siglent, Hantek, Owon (and FNIRSI, of course) brands

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: February 25, 2024, 03:11:34 pm
content: Dear sorenkir,>> I have an old Wandel & Goltermann SF-60 SDH/PDH Transmission Analyser. It can generate PRBS patterns, from PRBS6 to PRBS31, with variants, insert errors, add jitter, etc.I have acquired the bit series for PRBS9 with my scope. It is the exact same series than you, except that the start pulse is not at the same position (see Excel file).Interesting! That Wandel & Goltermann SF-60 looks like an interesting piece of kit!I see in the XLS that we indeed have the same sequence. I guess that, in theory, there are more PN9 code sequences possible that meet the PRBS requirements, but I have only come across this one up to now, and it works, so it satisfies me.The beginning point is arbitrary, I'd say. As long as it always begins at that point ;-)

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: February 01, 2025, 05:53:35 pm
content: Hi there!For those following this threat: In the threat below, I posted a manual how to run the above code as an ARB wave file in any Siglent SDG waveform generator:https://www.eevblog.com/forum/testgear/upgraded-sdg1000x-plus-awgs-coming/50/

author: RBBVNL9
author_rank: Frequent Contributor
timestamp: February 02, 2025, 09:45:17 am
content: @sorenkir, thanks again for sharing the PN9 and PN11 code generated by the Wandel & Goltermann SF-60.Our codes are identical but have different start positions. As a matter of fact, I do not know how surprising that is as I do not know whether there are different codes possible that meet the PN9 requirements (see below); perhaps there is just one 511-bit code that complies, perhaps several that do. Do not know that for PN11, PN15, PN23, etc., either.Anyway, there is an interesting thing, though, with both the R&S SMIQ code and the Wandel & Goltermann SF-60 code. As I just wrote in the other threat on the not working PRBS code on the new Siglent 1000X Plus (https://www.eevblog.com/forum/testgear/upgraded-sdg1000x-plus-awgs-coming/50/):Normally, generators that generate or analyse PRBS patterns are designed to comply with international standards such as ITU/CCITT Rec. O.151, O.152 and O. 153 (some instruments’ documentation refer to CCITT V.52, but this one was replaced by CCITT Rec O. 153). Indeed, my R&S SMIQ and my TTC FIREBERD6000A, in their documentation, refer to compliance with the above standards.CCITT Rec O. 153 includes specifications for a PN9 code and notes that the pattern may be generated in a nine-stage shift-register whose 5th and 9th stage outputs are added in a modulo-two addition stage, and the result is fed back to the input of the first stage. (See an example of such a design attached, from the SMIQ manual). The standard requires, among other things, that the pattern includes one sequence of 9 consecutive ones and that the longest sequence of zeros is 8 (in a non-converted signal version).These nine consecutive ones are useful for several things, I guess. They help to stress test the proper working of equipment- for instance, with some line characteristics or AC coupling, the test may fail. Secondly, they can help an analyser to synchronise to the start of the pattern (assuming that such a sequence of nine ones only appears once in each pattern, as is the case in both our codes). You could also use an oscilloscope to trigger on a positive pulse width with a length of just above 8 times the 1/f of the clock to detect the repetition point in a pattern.But there is one more thing the relevant standard for PN9 specifies: "The patternbeginswith the first ONE of 9 consecutive ONES." (CCITT Rec O. 153 (10/92), page 1).Now here is the curious thing:neitherR&S SMIQ code nor the W&G SF-60 START with the nine consecutive ones, as the standard requires!!!Not a big deal, I guess, because once the pattern is running and repeating, the analyzer will find its way, but still, it surprises me, to be honest.Best, Rudi