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[195.171.43.25]) by mx.google.com with ESMTP id bi10si453316wib.6.2013.12.05.19.35.24 for ; Thu, 05 Dec 2013 19:35:24 -0800 (PST) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1VoleS-0002Oe-Tr for rs_out_1@blacksheep.org; Fri, 06 Dec 2013 03:00:24 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1VoleR-0002OT-Uo for rsgb_lf_group@blacksheep.org; Fri, 06 Dec 2013 03:00:23 +0000 Received: from blu0-omc1-s2.blu0.hotmail.com ([65.55.116.13]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1VoleO-0001sP-Ba for rsgb_lf_group@blacksheep.org; Fri, 06 Dec 2013 03:00:22 +0000 Received: from BLU180-W87 ([65.55.116.9]) by blu0-omc1-s2.blu0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675); Thu, 5 Dec 2013 19:00:18 -0800 X-TMN: [JkOd3rNeRF0J7t3d+/lsvGucvxjesn6P] X-Originating-Email: [rjraide@hotmail.com] Message-ID: From: Bob Raide To: "rsgb_lf_group@blacksheep.org" Date: Thu, 5 Dec 2013 22:00:17 -0500 Importance: Normal In-Reply-To: <5FBCFC1F826C434E94FBACF3D24866DB@White> References: <5FBCFC1F826C434E94FBACF3D24866DB@White> MIME-Version: 1.0 X-OriginalArrivalTime: 06 Dec 2013 03:00:18.0293 (UTC) FILETIME=[4B69C250:01CEF22F] X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Markus; That could most certainly improve things for 73 band use. Especially for those close, as you are to the offending emissions. I am ready to go back to 74 tomorrow anyway. Will continue with QRSS 60 and 74.5495. Let me know when you might be ready I can also summon Dex for his signal one hertz away. The interference was not the reason for requesting other modes but was to introduce something in the way of a new emission for the band. QRSS has proven it's worth and just wanted to try something else. To do so with a clearer freq would only help matters-Bob [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [65.55.116.13 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (rjraide[at]hotmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: ae2896ef8313eee6ed442f2e390e76bb Content-Type: multipart/alternative; boundary="_3dcc5b5b-ee93-4fe1-9ac2-eb2eb9013aeb_" Subject: RE: LF: Cleaning up DCF77 junk around 74.55 kHz X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=FORGED_HOTMAIL_RCVD,HTML_40_50, HTML_MESSAGE,TO_ADDRESS_EQ_REAL autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false Status: O X-Status: X-Keywords: X-UID: 1485 --_3dcc5b5b-ee93-4fe1-9ac2-eb2eb9013aeb_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Markus=3B That could most certainly improve things for 73 band use. Especially for t= hose close=2C as you are to the offending emissions. I am ready to go back to 74 tomorrow anyway. Will continue with QRSS 60 an= d 74.5495. =20 Let me know when you might be ready I can also summon Dex for his signal on= e hertz away. The interference was not the reason for requesting other modes but was to i= ntroduce something in the way of a new emission for the band. QRSS has pro= ven it's worth and just wanted to try something else. To do so with a clea= rer freq would only help matters-Bob =20 From: markusvester@aol.com To: rsgb_lf_group@blacksheep.org=3B rsgb_lf_group@yahoogroups.co.uk Date: Fri=2C 6 Dec 2013 00:57:47 +0100 Subject: LF: Cleaning up DCF77 junk around 74.55 kHz =0A= =0A= =0A= =0A= =0A= =0A= =0A= I think I have found a way =0A= to eliminate interference from the DCF77 pseudonoise modulation =0A= in 74.55 kHz spectrograms.=0A= =0A= As explained before=2C the problem =0A= is that the phase-modulating PRN sequence carries the timecode of =0A= DCF77=2C sending an inverted sequence with every "1" bit. =0A= Thus what would otherwise be a comb spectrum of discrete 1 Hz lines is =0A= being spread out=2C contaminating the space between the lines with noise-li= ke =0A= patterns.=0A= =0A= The idea is now to =0A= unspread the lines=2C based on the known time bits=2C which are also =0A= communicated by prolonged second gaps (0.2 s for a "1" bit). Multiplying = =0A= the 74.5 kHz stream by the 1=2C 1=2C -1... data will fold all =0A= the interference energy back to discrete 1 Hz multiples. =0A= These can then be notched out. Finally the despeading has to be undone =0A= with the same data=2C restoring the desired spectral features (amateur =0A= signals or Loran lines)=2C but without the interference. =0A= =0A= Example results and zipped =0A= MathCad and data files are in =0A= df6nm.bplaced.net/LF/74kHz/DCF77_PRN_cancellation/ =0A= and a comparison of =0A= unprocessed and processed spectrograms from the night November 7 / =0A= 8:=0A= df6nm.bplaced.net/LF/74kHz/DCF77_PRN_cancellation/sp_2e.png =0A= (spectrogram as received)=2C=0A= df6nm.bplaced.net/LF/74kHz/DCF77_PRN_cancellation/spr_2e.png =0A= (spectrogram with DCF77 sidebands removed).=0A= =0A= Unfortunately there was no =0A= signal from Bob or Dex during the night of the recording. All you can see a= re a =0A= few Loran lines=2C eg. on 74556.6076=2C 74550.5868=2C 74549.9400 Hz. I want= =0A= to try this again=2C but not today as the big antenna which is needed for 7= 4 kHz =0A= is currently retracted due to heavy winds.=0A= =0A= For anyone interested in =0A= the postprocessing=2C here are the steps in detail:=0A= =0A= 1. Using =0A= SpecLab=2C VAC and SndInput=2C I took a narrowband IQ recording=2C =0A= with decimation of 768 down to 15.625 Hz samplerate. There =0A= are two audio channels=2C one centered on the desired band around 74.550 kH= z=2C and =0A= the other on 77.5 kHz for reference. In the example=2C the overnight =0A= recording started 13-11-07 16:38=2C and ended next morning =0A= 6:24. The 6 MB .tmp file was preceded by a dummy .bmp =0A= header to be able to read it with the old MathCad =0A= version 6.0. =0A= =0A= 2. In the MathCad script=2C the =0A= second dips were identified and the bits extracted from therir duration. Th= e =0A= first 15 bits which carry encrypted weather information are not included in= the =0A= phase modulation=2C and have to be substituted by a fixed =0A= 111111111100000 sequence. In principle=2C the time telegrams are completely= =0A= predictable (except possible leap seconds)=2C so with accurate time informa= tion =0A= one could do without the 77.5 kHz channel and the bit =0A= decoding.=0A= =0A= 3. The time domain data =0A= is split into overlapping 2048 sample chunks=2C allowing to generate =0A= spectrograms at 7.63 mHz resolution. For each chunk=2C a windowed FFT is = =0A= generated=2C leading to the unprocessed spectrogram (sp_2e.png)=0A= =0A= 4. In time domain=2C =0A= the samples during each second with a preceding "1" bit are multiplied =0A= by -1=2C despreading the interference. =0A= =0A= 5. These data chunks =0A= are also Fourier transformed=2C producing spectra with discrete 1 Hz peaks.= =0A= =0A= =0A= 6. The bins on and =0A= near integer Hz frequencies are nulled=2C notching out the =0A= interference.=0A= =0A= 7. The data is brought back =0A= to time domain with an inverse FFT.=0A= =0A= 8. The polarity inversion =0A= of the "1" periods is undone=2C applying the same procedure as in step 4 = =0A= again.=0A= =0A= 9. Finally data is Fourier =0A= transformed again=2C producing the clean spectrogram result =0A= (spr_2e.png).=0A= =0A= Best 73=2C=0A= Markus (DF6NM)=0A= =0A= =0A= =0A= From: =0A= Markus Vester =0A= Sent: Tuesday=2C October 01=2C 2013 7:35 =0A= AM=0A= To: rsgb_lf_group@blacksheep.org =0A= =0A= Subject: Re: LF: 74.550kHz Sep =0A= 29/30=0A= =0A= Here are clearer shots of the DCF77 =0A= sidebands from the morning:=0A= http://dl.dropboxusercontent.com/u/26404526/dcf77_prn_sidebands_131001_0605= .png=0A= http://dl.dropboxusercontent.com/u/26404526/74k_131001_0600.png=0A= =0A= Notes:=0A= - the RX antenna is resonant around 75 kHz=2C =0A= which emphasizes the PRN sidebands below the DCF77 carrier. The fifth and = =0A= sixth lobe are still visible. In reality=2C the upper sidebands are slightl= y =0A= stronger. This is probably due to an offset (or a 75 kHz notch) in the =0A= transmitter antenna matching=2C which happens to help us now.=0A= - the Swiss time signal HBG on 75 kHz is no =0A= longer on air.=0A= - there is an RTTY signal at 73.6 kHz which =0A= could be CFH. =0A= - the 1 Hz lines are surrounded by a somewhat =0A= regular fine structure=2C consisting of 16.6 mHz spaced sub-lines. This is = =0A= probably due to parts of the BCD timecode and weather =0A= information data which are repeating or similar in consecutive =0A= minutes.=0A= =0A= Best 73=2C=0A= Markus (DF6NM)=0A= =0A= From: =0A= Markus Vester =0A= Sent: Monday=2C September 30=2C 2013 11:26 =0A= PM=0A= To: rsgb_lf_group@blacksheep.org =0A= Subject: Re: LF: 74.550kHz Sep =0A= 29/30=0A= =0A= Hi Bob=2C LF=2C=0A= =0A= last night my improvised grabber http://dl.dropboxusercontent.com/u/2640452= 6/df6nm_74kHz.jpg indeed showed weak and slightly fuzzy traces on both =0A= your QRG's=2C and on all other integer Hz frequencies as well. =0A= =0A= These are presumably artifacts from DCF77 which is =0A= only about 160 km from here. In addition to the well known =0A= AM timecode=2C it also carries pseudorandom phase modulation=2C =0A= which has been proposed in the 80ies to provide higher resolution timing = =0A= (albeit orders of magnitude worse than Loran or GPS). The resulting sideban= ds =0A= extend a couple of kHz on either side of the carrier=2C with pronounced min= ima =0A= around multiples of the chip rate 77500/120 =3D 645.833 Hz=2C see =0A= http://www.ptb.de/cms/fileadmin/internet/fachabteilungen/abteilung_4/4.4_ze= it_und_frequenz/pdf/5_1988_Hetzel_-_Proc_EFTF_88.pdf (page 358). The same c= ode sequence is repeated every =0A= second=2C so in theory the spectrum would consist of sharp 1 Hz spaced line= s. =0A= However=2C additionally the sign of the sequence is alternated with the =0A= disseminated timecode bits=2C producing some widening or "fuzzyness" of the= =0A= lines.=0A= =0A= Attached is a spectrogram which was taken =0A= tonight on the resonant antenna. Between statics=2C you can still =0A= see the fourth sideband lobe which is centered near 74.6 kHz. The =0A= spectral gaps are on =0A= 74916.666 Hz=2C =0A= 74270.833 Hz=2C =0A= 73625.000 Hz=2C =0A= with small and sharp central lines=2C presumably =0A= caused by slight inbalances or nonlinearities in the =0A= transmitter.=0A= =0A= By these criteria=2C if you have the choice I =0A= would recommend to operate somewhere near these gaps=2C but not exactly in = =0A= their middle=2C and also preferably not exactly on integer Hz =0A= frequencies =3B-)=0A= =0A= Best 73=2C=0A= Markus (DF6NM)=0A= ... = --_3dcc5b5b-ee93-4fe1-9ac2-eb2eb9013aeb_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Markus=3B
That could most cer= tainly improve things for 73 band use. =3B Especially for those close= =2C as =3Byou are to the =3Boffending emissions.
I am ready to g= o back to 74 tomorrow anyway. =3B Will continue with QRSS 60 and 74.549= 5. =3B
Let me know when you =3Bmight be ready I can also summon= Dex for his signal one =3Bhertz =3Baway.
The interference was n= ot the reason for requesting other modes but was to introduce something in = the way of a new emission for the band. =3B QRSS has proven it's worth = and just wanted to try something else. =3B To do so with a clearer freq= would only help matters-Bob
 =3B
Fr= om: markusvester@aol.com
To: rsgb_lf_group@blacksheep.org=3B rsgb_lf_gro= up@yahoogroups.co.uk
Date: Fri=2C 6 Dec 2013 00:57:47 +0100
Subject: = LF: Cleaning up DCF77 junk around 74.55 kHz

=0A= =0A= =0A= =0A= =0A= =0A= =0A=
I think I have found a way =0A= to =3Beliminate =3Binterference from the DCF77 =3Bpseudonoise m= odulation =0A= in 74.55 kHz spectrograms.
=0A=
 =3B
=0A=
As explained before=2C the problem = =0A= is that =3Bthe =3Bphase-modulating PRN sequence carries the timecod= e of =0A= DCF77=2C =3Bsending an inverted sequence =3Bwith =3Bevery "1" b= it. =0A= Thus =3Bwhat =3Bwould otherwise be a comb spectrum of discrete 1 Hz= lines is =0A= being spread out=2C contaminating the space =3Bbetween the lines with n= oise-like =0A= patterns.
=0A=
&= nbsp=3B
=0A=
The idea is =3Bnow to =0A= unspread =3Bthe lines=2C based on the known =3Btime bits=2C =3B= which are also =0A= communicated by prolonged second gaps (0.2 s for a "1" bit). =3BMultipl= ying =0A= the 74.5 kHz stream =3Bby =3Bthe 1=2C 1=2C -1... =3Bdata will&n= bsp=3Bfold all =0A= the interference energy =3Bback to =3Bdiscrete 1 Hz multiples. =0A= These =3Bcan then be =3Bnotched out. Finally the despeading has to = be undone =0A= with the same data=2C =3Brestoring the desired spectral features (amate= ur =0A= signals or Loran lines)=2C but without the interference. =3B=0A=
&= nbsp=3B
=0A=
Example results and zipped =0A= MathCad and data =3Bfiles are in =3B
=0A=
 =3Bdf6nm.bplaced.net/LF/74kHz/D= CF77_PRN_cancellation/ =3B
=0A=
and =3Ba comparison of =0A= unprocessed and processed spectrograms =3Bfrom the night November 7 / = =0A= 8:
=0A=
 =3Bdf6nm.bplaced.net/LF/74kHz/D= CF77_PRN_cancellation/sp_2e.png =0A=  =3B(spectrogram as received)=2C
=0A=
 =3Bdf6nm.bplaced.net/LF/74kHz/D= CF77_PRN_cancellation/spr_2e.png =0A=  =3B(spectrogram with DCF77 sidebands removed).
=0A=
&= nbsp=3B
=0A=
Unfortunately there was no =0A= signal from Bob or Dex during the night of the recording. All you can see a= re a =0A= few Loran lines=2C eg. =3Bon 74556.6076=2C 74550.5868=2C 74549.9400 Hz. =3BI want =0A= to try this again=2C but not today as the big antenna which is needed for 7= 4 kHz =0A= is currently retracted due to heavy winds.
=0A=
 =3B
=0A=
For anyone =3Binterested in =0A= the =3Bpostprocessing=2C =3Bhere are the steps in detail:=0A=
&= nbsp=3B
=0A=
1. Using =0A= SpecLab=2C =3BVAC =3Band SndInput=2C I =3Btook a =3Bnarrowb= and IQ recording=2C =0A= with decimation of 768 =3Bdown to =3B15.625 =3BHz samplerate.&n= bsp=3BThere =0A= are two audio channels=2C one centered on the desired band around 74.550 kH= z=2C and =0A= the other on =3B77.5 kHz for reference. In the example=2C =3Bthe ov= ernight =0A= recording =3Bstarted =3B13-11-07 =3B16:38=2C and ended =3Bn= ext morning =0A= 6:24. =3BThe 6 MB .tmp file was =3Bpreceded by a dummy .bmp =0A= header =3Bto =3Bbe able to read =3Bit =3Bwith =3Bthe ol= d MathCad =0A= version 6.0. =3B
=0A=
&= nbsp=3B
=0A=
2. In the MathCad script=2C the =0A= second dips were identified and the bits extracted from therir duration. Th= e =0A= first 15 bits which carry encrypted weather information are not included in= the =0A= phase modulation=2C and =3Bhave to be =3Bsubstituted by a fixed =0A= 111111111100000 sequence. In principle=2C the time telegrams are completely= =0A= predictable (except possible leap seconds)=2C so with accurate time informa= tion =0A= one could do without the =3B77.5 kHz =3Bchannel and the bit =0A= decoding.
=0A=
&= nbsp=3B
=0A=
3. The time domain data =0A= is =3Bsplit into overlapping 2048 sample chunks=2C allowing to generate= =0A= spectrograms at 7.63 mHz resolution. For each chunk=2C a windowed FFT is = =0A= generated=2C leading to the unprocessed spectrogram (sp_2e.png)=0A=
 =3B
=0A=
4. In time domain=2C =0A= the =3Bsamples =3Bduring each second with a preceding "1" bit are m= ultiplied =0A= by -1=2C despreading the interference.
=0A=
&= nbsp=3B
=0A=
5. =3BThese data chunks =0A= are =3Balso Fourier transformed=2C producing spectra with discrete 1 Hz= peaks. =0A=
=0A=
&= nbsp=3B
=0A=
6. The =3Bbins =3Bon and =0A= near integer Hz frequencies are nulled=2C notching out the =0A= interference.
=0A=
&= nbsp=3B
=0A=
7. The data is =3Bbrought back = =0A= to time domain with an inverse FFT.
=0A=
&= nbsp=3B
=0A=
8. =3BThe polarity inversion =0A= of the "1" =3Bperiods is undone=2C applying the same procedure as in st= ep 4 =0A= again.
=0A=
&= nbsp=3B
=0A=
9. Finally =3Bdata is Fourier = =0A= transformed again=2C producing the =3Bclean spectrogram result =0A= (spr_2e.png).
=0A=
&= nbsp=3B
=0A=
Best 73=2C
=0A=
Markus (DF6NM)
=0A=
&= nbsp=3B
=0A=
 =3B
=0A=
<= font face=3D"Arial">
=0A=
From: =0A= Markus Vester
=0A=
Sent: Tuesday=2C October = 01=2C 2013 7:35 =0A= AM
=0A= =0A=
Subject: Re: LF: 74.550kH= z Sep =0A= 29/30
=0A=

=0A=
Here are clearer shots of the DCF77 = =0A= sidebands =3Bfrom the morning:
=0A=
http://dl.dropboxuse= rcontent.com/u/26404526/dcf77_prn_sidebands_131001_0605.png=0A= =0A=
 =3B
=0A=
Notes:
=0A=
- the RX antenna is resonant =3Bar= ound 75 kHz=2C =0A= which emphasizes the =3BPRN sidebands below the DCF77 carrier. The fift= h and =0A= sixth =3Blobe are still visible. In reality=2C the upper sidebands are = slightly =0A= stronger. This is probably due to =3Ban offset (or a 75 kHz notch) in t= he =0A= transmitter antenna matching=2C which happens to =3Bhelp us now.=
=0A=
- the Swiss time signal HBG on 75 kHz = is no =0A= longer =3Bon air.
=0A=
- there is an RTTY signal at 73.6 kHz = which =0A= could =3Bbe CFH. =3B
=0A=
- the 1 Hz lines are surrounded = =3Bby a somewhat =0A= regular fine structure=2C consisting of 16.6 mHz spaced sub-lines. This&nbs= p=3Bis =0A= probably due =3Bto =3Bparts of the =3BBCD timecode and =3Bw= eather =0A= information data which are repeating or similar in consecutive =0A= minutes.
=0A=
 =3B
=0A=
Best 73=2C
=0A=
Markus (DF6NM)
=0A=

=0A=
From: =0A= Markus Vester
=0A=
Sent: Monday=2C September= 30=2C 2013 11:26 =0A= PM
=0A= =0A=
Subject: Re: LF: 74.550kH= z Sep =0A= 29/30
=0A=

=0A=
Hi Bob=2C LF=2C
=0A=
 =3B
=0A=
last night my improvised grabber = =3Bhttp://dl.dropbo= xusercontent.com/u/26404526/df6nm_74kHz.jpg indeed showed =3Bweak and slightly fuzzy traces on both =0A= your QRG's=2C and on all other integer Hz frequencies as well. =0A=
 =3B
=0A=
These are presumably artifacts from DC= F77 which is =0A= only about 160 km from here. =3BIn addition to the well known =0A= AM =3Btimecode=2C it also =3Bcarries =3B =3Bpseudorandom ph= ase modulation=2C =0A= which has =3Bbeen proposed in the 80ies to provide higher resolution ti= ming =0A= (albeit orders of magnitude worse than Loran or GPS). The resulting sideban= ds =0A= extend a couple of kHz on either side of the carrier=2C with pronounced min= ima =0A= around multiples of the chip rate 77500/120 =3D 645.833 Hz=2C see =0A=
http://www.ptb.de/cms/fileadmin/internet/fa= chabteilungen/abteilung_4/4.4_zeit_und_frequenz/pdf/5_1988_Hetzel_-_Proc_EF= TF_88.pdf =3B(page 358). The= same code sequence is repeated every =0A= second=2C so in theory the spectrum would consist of sharp 1 Hz spaced line= s. =0A= However=2C additionally the =3Bsign of the sequence is alternated with = the =0A= disseminated timecode bits=2C =3Bproducing some widening or "fuzzyness"= of the =0A= lines.
=0A=
 =3B
=0A=
Attached is a spectrogram =3Bwhich= was =3Btaken =0A= tonight on =3Bthe resonant antenna. Between statics=2C =3Byou can&n= bsp=3Bstill =0A= see the =3Bfourth sideband lobe which is =3Bcentered near 74.6 kHz.= The =0A= spectral gaps are on =3B
= =0A=
 =3B74916.666 Hz=2C
= =0A=
 =3B74270.833 Hz=2C
= =0A=
 =3B73625.000 Hz=2C
<= /font>=0A=
with small and sharp central lines=2C = presumably =0A= caused by slight inbalances or nonlinearities =3Bin the =0A= transmitter.
=0A=
 =3B
=0A=
By these criteria=2C =3Bif you hav= e the choice I =0A= would recommend to operate somewhere =3Bnear these gaps=2C but not exac= tly in =0A= their middle=2C and also preferably not exactly on integer Hz =0A= frequencies =3B=3B-)
=0A=
 =3B
=0A=
Best 73=2C
=0A=
Markus (DF6NM)
=0A=

...=
= --_3dcc5b5b-ee93-4fe1-9ac2-eb2eb9013aeb_--