# GRC 3.6 / 802.11 a/g test signal **URL:** \ **Category:** GNU Radio\ **Created:** [October 2, 2014, 5:27pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326 "2014-10-02T17:27:18Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [October 2, 2014, 5:27pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/1 "2014-10-02T17:27:18Z")
Greetings engi’s! I’m currently working on my masters (802.11 wlan receiver with MATLAB/USRPN210). After creating all the important stuff ie: -symbol finder -time synchronization -coarse and fine frequency compensation -symbol demodulator -deinterleaver -Viterbi decoder -descrambler etc. -MAC layer decoding i’m looking for any tested 802.11 a/g IQ signal for further research becouse live samples captured by USRP seem to have incorrect result’s (wrong frame type MAC field, random MAC adress, CRC, parity bits etc). And here comes my 1st question. Is there any place where i can get some real, tested IQ wlan signal i a/g standard and full description (rate, coded data, adresses, included MAC fields)? Tried with Agilent Signal Studio but files are saved in .wfm encrypted format ☹ I also found GRC beacon frames transmitter, written in GRC [http://rrsg.ee.uct.ac.za/members/jwamicha/gr-wlan.tar.gz](http://rrsg.ee.uct.ac.za/members/jwamicha/gr-wlan.tar.gz) but due to having GRC 3.7 (where ‘gnuradio-core’ was repleaced with ‘gnurdaio-runtime’) i can’t simply compile this file becouse of an error: * * * checking for GNURADIO\_CORE… configure: error: Package requirements (gnuradio-core \>= 3) were not met: No package ‘gnuradio-core’ found Consider adjusting the PKG\_CONFIG\_PATH environment variable if you installed software in a non-standard prefix. Alternatively, you may set the environment variables GNURADIO\_CORE\_CFLAGS and GNURADIO\_CORE\_LIBS to avoid the need to call pkg-config. * * * It seems that those binaries arent compatible with my GRC version ☹ Any helpful guy to install this library and send me IQ signal of this beacon frame? (in any MATLAB readable format - simple file sink in GRC). Looking forward for any reply. Thanks ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 4, 2014, 11:20am UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/2 "2014-10-04T11:20:07Z")
Hi, you can use gr-ieee802-11 [1] to generate WiFi frames. Just start the TX flow graph and pipe the output to a file. I uploaded a frame (IQ data, no noise) [2] for you that you can use to get started. I dont use Matlab, so i dont know how to import the data, but you can display the IQ samples with od -fw8 frame.bin There is also a GNU Radio script [3] that might be helpful. Hope it helps, Bastian [1] [GitHub - bastibl/gr-ieee802-11: IEEE 802.11 a/g/p Transceiver · GitHub](https://github.com/bastibl/gr-ieee802-11) [2] [Home | Bastian Bloessl](https://www.ccs-labs.org/~bloessl/frame.bin) [3] [gnuradio/gr-utils/octave/read\_complex\_binary.m at master · gnuradio/gnuradio · GitHub](https://github.com/gnuradio/gnuradio/blob/master/gr-utils/octave/read_complex_binary.m) On 02 Oct 2014, at 17:25, Ernest S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > -Viterbi decoder > a/g standard and full description (rate, coded data, adresses, included > > Alternatively, you may set the environment variables > > Thanks > > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) – Dipl.-Inform. Bastian B. Distributed Embedded Systems Group University of Paderborn, Germany > **[Home](https://www.bastibl.net/)** > > I'm Bastian Bloessl, a Research Group Leader at the Secure Mobile Networking Lab, TU Darmstadt. Checkout my blog, projects, publications, and resume; or connect on Github, Twitter, YouTube, or Facebook. ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 5, 2014, 1:39pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/3 "2014-10-05T13:39:22Z")
Greetings, Ok, got this. After some test’s i think that the problem is with my descrambler (de-interleaver and Viterbi seems to be ok). Currently, im using Matlab’s one provided by comm. toolbox. Is it correct to use 127-bit length pre-defined scrambling/descrambling seq? (i found it in 802.11 standard). Or it sould be only implemented as a shift register with poly 1+x4+x7? And last one question: In any of frames generated by your grc script, there sould be 16x"0" in SERVICE field (as it a part of PLCP Header) - becouse a typical wlan card is able to decode it, it is following the 802.11 standard - am I right? Best, Ernest – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50614.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50614.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 6, 2014, 8:13am UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/4 "2014-10-06T08:13:48Z")
On 10/05/2014 01:37 PM, Ernest S. wrote: > Greetings, > > Ok, got this. After some test’s i think that the problem is with my > descrambler (de-interleaver and Viterbi seems to be ok). Currently, im using > Matlab’s one provided by comm. toolbox. > > Is it correct to use 127-bit length pre-defined scrambling/descrambling seq? No, this is an example output if you initialize the scrambler with 0b1111111. > (i found it in 802.11 standard). Or it sould be only implemented as a shift > register with poly 1+x4+x7? yes. > And last one question: > > In any of frames generated by your grc script, there sould be 16x"0" in > SERVICE field (as it a part of PLCP Header) yes. > - becouse a typical wlan card is > able to decode it, it is following the 802.11 standard - am I right? No. It’s following the standard and, thus, a normal card can decode it 🙂 Best, Bastian ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 6, 2014, 4:34pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/5 "2014-10-06T16:34:02Z")
Hi, On 06 Oct 2014, at 10:33, Ernest S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Could you please check my methodology?? > > - OFDM demodulation (to get 48 complex data points) > - BPSK demodulation (to get 48 coded bits) > - de-interleaving (1st and 2nd permutation) > - Viterbi decoding ([133 171 poly] to get 24 uncoded bits) > - descrambling > > and if its correct way, i should get 24 bits of data (16x0 and 8 bits > depending on FRAME CONTROL paylaod) right? The payload is scrambled (as opposed to the signal field). So maybe your scrambler has a bug. Did you try to generate the example sequence from the standard? Do not try to decode the next OFDM symbol on its own, but the rest of the frame. The decoder is not reset with a zero sequence as with the signal tail bits. So it might not work with the same decoding function that you used for the first symbol. Best, Bastian ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 6, 2014, 10:22pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/6 "2014-10-06T22:22:05Z")
Ok, so i decoded all of the payload (123 data symbols, de-interleaving every one in receiver’s loop). After Viterbi and descrambling it gives some strange results: 7 of SERVICE bits are random - OK (i read in standard that those 7 bits are 0’s at the transmitter, and will set receivers descrambler to correct initial state). 9x0’s in RESERVED field - OK. and now: FRAME CONTROL - !incorrect! TAIL bit’s looks fine (11x0’s - 6 zeros from TAIL field and probably 5 PAD bits). I also checked autocorelation function of received data bits. It indicates that there is some cyclicness in payload (every 96 bits function shows a simple peak). Assuming that your frame consist of text:Hello world! - its 12 characters, 8 bits each - together 96 bits repeating sequence, but cant find Hello world text. Its rather imposible, that those results are correct. You have mentioned that i should try with some test sequence (dont have any one). If i will try to generate it on my own, i wouldnt be sure that its following the standard ☹ PS. I was also searching for 48x"1" bit broadcast adress. Found only 43x"1" in row. Close but not the same 😃 Best, Ernest – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50639.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50639.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 6, 2014, 10:35am UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/7 "2014-10-06T10:35:05Z")
Hi, much appreciate for your reply Bastian. I have succefully found your frame.bin signal, forwarded by my USRP (generated in MATLAB, received with Windows Network Monitor and wlan card). You were right. It is Data frame, 232323:232323 Source MAC and FFFFFF:FFFFFF Destination MAC. Still dunno what’s wrong. Could you please check my methodology?? 1st OFDM symbol is carrying a SIGNAL field - it is decoded correctly (i checked all rates with your grc wlan script) - no problem here. 2nd OFDM symbol is carrying Data. Assuming BPSK 1/2, it should carry 16 bit SERVICE field, and 8 bits from FRAME CONTROL field (together - 24 uncoded bits). And my algorythm goes as follows (for 2nd OFDM symbol): - OFDM demodulation (to get 48 complex data points) - BPSK demodulation (to get 48 coded bits) - de-interleaving (1st and 2nd permutation) - Viterbi decoding ([133 171 poly] to get 24 uncoded bits) - descrambling and if its correct way, i should get 24 bits of data (16x0 and 8 bits depending on FRAME CONTROL paylaod) right? Best, Ernest – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50621.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50621.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 7, 2014, 12:12pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/8 "2014-10-07T12:12:47Z")
Hi, I cant help you much without the code, but did you see the example frame in Annex L of the standard? Maybe it helps you to debug your scripts. Bastian ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 8, 2014, 10:39am UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/9 "2014-10-08T10:39:09Z")
On 10/07/2014 04:57 PM, Ernest S. wrote: > Nope, > > Any way to get it? Is it downloadable? > > Should be helpfull indeed. As far as I know it is not downloadable. You would have to extract (copy - paste) the data from the pdf. Bastian ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 7, 2014, 5:00pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/10 "2014-10-07T17:00:12Z")
Nope, Any way to get it? Is it downloadable? Should be helpfull indeed. – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50661.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50661.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 8, 2014, 12:05pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/11 "2014-10-08T12:05:35Z")
On 10/08/2014 11:54 AM, Ernest S. wrote: > Ok. After couple of days trying to decode your frame i decided to check my > receiver with real samples. > Could it be possible that after demodulation (de-interleaving, > de-convolutional, de-scrambling) im getting over 40x0’s in correct positions > (9 reserved bits, 16x0s in duration, correct pads) and still cant work out > your frames? Such amount of correct data couldnt be a coincidence ☹ As I already mentioned, it is very hard to help you without the code… > That test frame from Annex L is fully coded (scrambled, interleaved and conv > coded)? Yes, it is. And it’s clearly stated. But for your convenience I can copy paste from the standard. The encoding illustration goes through the following stages: a) Generating the short training sequence section of the preamble; b) Generating the long preamble sequence section of the preamble; c) Generating the SIGNAL field bits; d) Coding and interleaving the SIGNAL field bits; e) Mapping the SIGNAL field into frequency domain; f) Pilot insertion; g) Transforming into time domain; h) Delineating the data octet stream into a bit stream; i) Prepending the SERVICE field and adding the pad bits, thus forming the DATA; j) Scrambling and zeroing the tail bits; k) Encoding the DATA with a convolutional encoder and puncturing; l) Mapping into complex 16-QAM symbols; m) Pilot insertion; n) Transforming from frequency to time and adding a circular prefix; o) Concatenating the OFDM symbols into a single, time-domain signal. Bastian ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 8, 2014, 11:57am UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/12 "2014-10-08T11:57:24Z")
Ok. After couple of days trying to decode your frame i decided to check my receiver with real samples. Could it be possible that after demodulation (de-interleaving, de-convolutional, de-scrambling) im getting over 40x0’s in correct positions (9 reserved bits, 16x0s in duration, correct pads) and still cant work out your frames? Such amount of correct data couldnt be a coincidence ☹ That test frame from Annex L is fully coded (scrambled, interleaved and conv coded)? Best, Ernest – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50672.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50672.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 8, 2014, 12:20pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/13 "2014-10-08T12:20:47Z")
Got the pilot sequence but ill check it once more. I also got Annex L so not neccesary to post it but thanks. Ill check everything once more, according to L. – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50678.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50678.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 8, 2014, 12:16pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/14 "2014-10-08T12:16:41Z")
On 10/08/2014 11:54 AM, Ernest S. wrote: > Ok. After couple of days trying to decode your frame i decided to check my > receiver with real samples. > Could it be possible that after demodulation (de-interleaving, > de-convolutional, de-scrambling) im getting over 40x0’s in correct positions > (9 reserved bits, 16x0s in duration, correct pads) and still cant work out > your frames? Such amount of correct data couldnt be a coincidence ☹ > One last idea: If groups of bits are correct, then most likely you > forgot to invert the pilot patter according to the sequence given in > Equation 18-25 of the standard. Bastian ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 8, 2014, 2:25pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/15 "2014-10-08T14:25:46Z")
So… After going deep into Annex L i found that my scrambler fails. Also MATLAB built-in scrambler gives wrong results. Could you pls check this code fragment? Asumme that we have 20 data bits to scramble. Initial scrambler state is [1 0 1 1 1 0 1] (bit nr 7 left side). scrambler\_register=[1 0 1 1 1 0 1]; % scrambler seed data\_bits=randi([0 1],1,20); % data to be scrambled for i=1:20 temp=xor(scrambler\_register(1),scrambler\_register(4)); % x7 and x4 xor operation data\_scrambled(i)=xor(data\_bits(i),temp); % output bit register=circshift(scrambler\_register’,-1,1)'; % shift left register register(7)=data\_scrambled(i); % insert data to register end To clarify, left side of register has index (1), right side has index (7). Best, Ernest – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50685.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50685.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 8, 2014, 2:36pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/16 "2014-10-08T14:36:17Z")
On 08 Oct 2014, at 14:23, Ernest S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > data to be scrambled > > for i=1:20 > temp=xor(scrambler\_register(1),scrambler\_register(4)); % x7 and x4 xor > operation > data\_scrambled(i)=xor(data\_bits(i),temp); % output > bit > register=circshift(scrambler\_register’,-1,1)'; % shift > left register > register(7)=data\_scrambled(i); the scrambler is independent from the data. you want to feedback temp and not data\_scrambled. Maybe you want to have a look at Figure 1 in > **[Literature Database Entry - Distributed Embedded Systems](https://www.ccs-labs.org/bib/bloessl2015scrambler/)** Bastian > View this message in context: > [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50685.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50685.html) > Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). > > * * * > > Discuss-gnuradio mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) – Dipl.-Inform. Bastian B. Distributed Embedded Systems Group University of Paderborn, Germany > **[Home](https://www.bastibl.net/)** > > I'm Bastian Bloessl, a Research Group Leader at the Secure Mobile Networking Lab, TU Darmstadt. Checkout my blog, projects, publications, and resume; or connect on Github, Twitter, YouTube, or Facebook. ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 9, 2014, 10:43am UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/17 "2014-10-09T10:43:02Z")
Greetings, finnaly got it working 😃 Problem was with descrambler. Now it gives results as follows: ``` Service: 'ok' Duration: '0000' Source_MAC_Adress: '232323232323' ``` Destination\_MAC\_Adress: ‘FFFFFFFFFFFF’ Protocol\_version: ‘Supported’ Type: ‘Data’ Subtype: ‘Data’ To\_DS: ‘False’ From\_DS: ‘False’ More\_fragments: ‘No’ Power\_menagement: ‘Active’ More\_data: ‘No’ Protected: ‘No’ Order: ‘Random’ But I still dunno how to estimate initial descrambler state (checked all and found correct one this time). Descrambler graph sould be the same as the scrambler from you paper right? Best, Ernest – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50709.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50709.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 8, 2014, 3:12pm UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/18 "2014-10-08T15:12:30Z")
Ok fixed. Now giving correct results 🙂 Ill try with your frame once more and hit you up later. Thanks for your amazing feedback Bastian. Best, Ernest – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50690.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50690.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 10, 2014, 1:34am UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/19 "2014-10-10T01:34:56Z")
Ok. All working fine 😃 – View this message in context: [http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50731.html](http://gnuradio.4.n7.nabble.com/GRC-3-6-802-11-a-g-test-signal-tp50585p50731.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![ernest\_s](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/779978/32.png) [@ernest\_s](https://www.ruby-forum.com/u/ernest_s)\ **Post date:** [October 9, 2014, 11:28am UTC](https://www.ruby-forum.com/t/grc-3-6-802-11-a-g-test-signal/232326/20 "2014-10-09T11:28:00Z")
On 10/09/2014 10:40 AM, Ernest S. wrote: > ``` > Type: 'Data' > Subtype: 'Data' > To_DS: 'False' > From_DS: 'False' > More_fragments: 'No' > Power_menagement: 'Active' > More_data: 'No' > Protected: 'No' > Order: 'Random' > > ``` Great > But I still dunno how to estimate initial descrambler state (checked all and > found correct one this time). > Descrambler graph sould be the same as the scrambler from you paper right? > On the receiving side, take the first 7 bits, put them in the scrambler > register, and use the very same algorithm on as on TX side. (Since the > output of the scrambler is fed back the first seven bits are also the > internal state of the scrambler). Bastian