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[195.171.43.25]) by mx.google.com with ESMTP id p4si22908031wja.141.2013.07.26.22.52.29 for ; Fri, 26 Jul 2013 22:52:30 -0700 (PDT) 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 1V2wtx-0006Nv-5r for rs_out_1@blacksheep.org; Sat, 27 Jul 2013 06:18:45 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1V2wtw-0006Nm-0y for rsgb_lf_group@blacksheep.org; Sat, 27 Jul 2013 06:18:44 +0100 Received: from dub0-omc1-s35.dub0.hotmail.com ([157.55.0.234]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1V2wts-00033s-PU for rsgb_lf_group@blacksheep.org; Sat, 27 Jul 2013 06:18:42 +0100 Received: from DUB114-W110 ([157.55.0.237]) by dub0-omc1-s35.dub0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675); Fri, 26 Jul 2013 22:18:39 -0700 X-TMN: [f0DV0LX4Sq5cUS4VTXa8/AKQWYiaX5He] X-Originating-Email: [bvgbob@hotmail.com] Message-ID: From: Lubos OK2BVG To: _RSGB_LF Date: Sat, 27 Jul 2013 07:18:39 +0200 Importance: Normal In-Reply-To: <51F31086.4080107@iup.uni-heidelberg.de> References: <51D498BD.3050007@iup.uni-heidelberg.de> <005b01ce798a$b0476600$6d01a8c0@DELL4> <20130706131640.GG5246@cs.utwente.nl> <7D6B8CBB38964C9C82487F5D0F3648FC@FMVXD1232> <20130707203537.GA30691@cs.utwente.nl> <51DA00C8.6000600@iup.uni-heidelberg.de> <51DA0212.8020808@iup.uni-heidelberg.de> <51DA03CE.6020508@iup.uni-heidelberg.de> <51DA1680.6030602@iup.uni-heidelberg.de> <51DB6CB3.2080708@iup.uni-heidelberg.de> <001601ce7c95$f235b360$6401a8c0@JAYDELL> <51DBFF7D.9050807@iup.uni-heidelberg.de> <51DC58E9.5030005@iup.uni-heidelberg.de> <51DF1D06.8020208@iup.uni-heidelberg.de> <51DF43E7.8080300@iup.uni-heidelberg.de> <51E125D4.3050804@virginbroadband.com.au> <51F1A6BB.6070805@iup.uni-heidelberg.de>,<51F31086.4080107@iup.uni-heidelberg.de> MIME-Version: 1.0 X-OriginalArrivalTime: 27 Jul 2013 05:18:39.0746 (UTC) FILETIME=[C0EFF620:01CE8A88] X-Spam-Score: -1.5 (-) 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: Hello Stefan and Roelof!Very interesting. Thanks for all technical information! Lubos, OK2BVG Date: Sat, 27 Jul 2013 02:12:54 +0200 From: Re: LF: Re: MiniWhip antenna, fiber optic Hello all, [...] Content analysis details: (-1.5 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [157.55.0.234 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (bvgbob[at]hotmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -1.5 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 16ae5a6b0cd8af8ba18c7df6d1df8b5a Content-Type: multipart/alternative; boundary="_0b8857f7-93e2-40a7-a8e8-a7f5e48b1ae2_" Subject: RE: LF: Re: MiniWhip antenna, fiber optic X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=FORGED_HOTMAIL_RCVD, HTML_MESSAGE 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: 1637 --_0b8857f7-93e2-40a7-a8e8-a7f5e48b1ae2_ Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable Hello Stefan and Roelof!Very interesting. Thanks for all technical informat= ion! Lubos=2C OK2BVG=20 Date: Sat=2C 27 Jul 2013 02:12:54 +0200 From: Stefan.Schaefer@iup.uni-heidelberg.de To: rsgb_lf_group@blacksheep.org Subject: Re: LF: Re: MiniWhip antenna=2C fiber optic =0A= =0A= =0A= =0A= =0A= =0A= Hello all=2C=20 =0A= =0A= There is a real progress again this night with my fiber optic LF/MF/VLF=0A= RX system. =0A= =0A= I am now using a SFH250V photo diode (fast switching) and a different=0A= optical/electrical converter circuit. The design is taken from the link=0A= below. Since there was no LT6200 available this night=2C i took a LT1028=0A= which works too. I will use the LT6200 later. =0A= =0A= This is the schematic and receiver:=0A= https://dl.dropboxusercontent.com/u/19882028/MF/20130727_014150.jpg =0A= The 1 pF C across the 1 MOhm resistor is important. Otherwise there are=0A= self oscillations to the full supply voltage. It is the first time that=0A= i worked with a 1 pF capacitor :-) =0A= =0A= Well=2C there was some lack of sensitivity in the last system=2C even=0A= though the antenna was resonated to 475 kHz. Hence the changes in the=0A= design.=20 =0A= =0A= Now=2C the antenna is not resonated and covers VLF/LF/MF=2C at least! This= =0A= will make performance measurements in the field more accurate. It is=0A= preferred to have a wideband antenna anyway. =0A= =0A= I took a spectrum graph of the old system 0...1MHz:=0A= https://dl.dropboxusercontent.com/u/19882028/MF/SFH350V%2BSFH750V.png=20 =0A= And this is the new one:=0A= https://dl.dropboxusercontent.com/u/19882028/MF/SFH250V%2BSFH750V.png =0A= which shows a much better frequency response.=20 =0A= =0A= Compared to the old system the gain on 475 kHz is 24 dB=2C on 137 kHz it=0A= is 23 dB. The coupling of the signal generator to the floating antenna=0A= is the same=2C so there is always an attenuation. =0A= =0A= All in all this looks much more promising now and i will do a new /p=0A= test on the band soon. BTW the DC working point of the OP at 12V supply=0A= voltage is (of course) 6V when the LED transmitter is OFF and it rises=0A= to 8V when it is ON. So there is some room for further system gain. =0A= And BTW=2C the OP can be loaded with 50 Ohm directly... =0A= =0A= 73=2C Stefan/DK7FC =0A= =0A= =0A= Am 26.07.2013 00:29=2C schrieb Stefan Sch=E4fer:=0A= =0A= =0A= Hello Roelof=2C=20 =0A= =20 =0A= Is there some progress on your side? I may have some useful=0A= informations for you.=20 =0A= =20 =0A= In the last test i found that i need more gain and in the end i want to=0A= have a fiber optic antenna that covers LF and MF=2C maybe even VLF.=0A= Furthermore a resonated antenna is not suitable when the antenna is=0A= sometimes grounded or floating in the tests.=20 =0A= In my circuit the problem is the low rise- and fall- time of the=0A= SFH350V. I saw the problem years ago and ordered a few SFH250V photo=0A= diodes which should work well. The LED transmitter is suitable i think=2C= =0A= although the SFH757 is faster of course. But i'm always looking below 1=0A= MHz. =0A= Now i seareched for some additional ideas for a the optical/electrical=0A= converter. Some time ago i built a transimpedance converter but i was=0A= sceptic about OP AMPs at 475 kHz. But i think i learned something and=0A= got some new ideas on these pages:=20 =0A= http://circuits.linear.com/all--Photodiode_Interface_*_Transimpedance_Amp= s-53 =0A= Seems that these frequencies are no problem at all=2C even if a high gain= =0A= is desired. The LT6200=0A= is available at RS=2C 4.56 EUR here. Quite expensive but worth to play=0A= with :-) OK=2C some may say it is overkill and the device can cause VHF=0A= oscillations=2C but anyway... =0A= =20 =0A= I guess it will be no problem to get the needed gain to go on with the=0A= experiments=2C even if no resonated antenna is used... BTW the output=0A= current of the device is even 60 mA. So maybe it is even suitable to=0A= drive the LED... =0A= =20 =0A= What do you think? =0A= =20 =0A= 73=2C Stefan/DK7FC =0A= =20 =0A= =20 =0A= =20 =0A= Am 13.07.2013 12:55=2C schrieb Roelof Bakker:=0A= Hello=0A= Edgar=2C=20 =0A= =20 =0A= I don't know how linear these devices are=2C but that will show up in=0A= actual use.=20 =0A= =20 =0A= The SFH756V and SFH350V are housed in a moulded plastic casing with a=0A= cable clamp:=20 =0A= =20 =0A= http://www.avagotech.com/pages/en/fiber_optics/general_purpose_industri= al_control_data_link_650nm/sfh756v/=0A= =20 =0A= =20 =0A= I also found that for a wider bandwidth the SFH 757V / SFH 250V are=0A= more suitable.=20 =0A= These are rated at 100 MBd.=20 =0A= I will order them in the near future.=20 =0A= =20 =0A= 73=2C=20 =0A= Roelof Bakker=2C pa0rdt=20 =0A= =0A= = --_0b8857f7-93e2-40a7-a8e8-a7f5e48b1ae2_ Content-Type: text/html; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable
Hello Stefan and Roelof!
Ver= y interesting. Thanks for all technical information!

Lubos=2C OK2BVG =3B

Date: Sat=2C= 27 Jul 2013 02:12:54 +0200
From: Stefan.Schaefer@iup.uni-heidelberg.de<= br>To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Re: MiniWhip antenn= a=2C fiber optic

=0A= =0A= =0A= =0A= =0A= =0A= Hello all=2C
=0A=
=0A= There is a real progress again this night with my fiber optic LF/MF/VLF=0A= RX system.
=0A=
=0A= I am now using a SFH250V photo diode (fast switching) and a different=0A= optical/electrical converter circuit. The design is taken from the link=0A= below. Since there was no LT6200 available this night=2C i took a LT1028=0A= which works too. I will use the LT6200 later.
=0A=
=0A= This is the schematic and receiver:=0A= https://dl.dropbo= xusercontent.com/u/19882028/MF/20130727_014150.jpg =3B=0A= The 1 pF C across the 1 MOhm resistor is important. Otherwise there are=0A= self oscillations to the full supply voltage. It is the first time that=0A= i worked with a 1 pF capacitor :-)
=0A=
=0A= Well=2C there was some lack of sensitivity in the last system=2C even=0A= though the antenna was resonated to 475 kHz. Hence the changes in the=0A= design.
=0A=
=0A= Now=2C the antenna is not resonated and covers VLF/LF/MF=2C at least! This= =0A= will make performance measurements in the field more accurate. It is=0A= preferred to have a wideband antenna anyway.
=0A=
=0A= I took a spectrum graph of the old system 0...1MHz:=0A= https://dl.drop= boxusercontent.com/u/19882028/MF/SFH350V%2BSFH750V.png
=0A= And this is the new one:=0A= https://dl.drop= boxusercontent.com/u/19882028/MF/SFH250V%2BSFH750V.png =3B=0A= which shows a much better frequency response.
=0A=
=0A= Compared to the old system the gain on 475 kHz is 24 dB=2C on 137 kHz it=0A= is 23 dB. The coupling of the signal generator to the floating antenna=0A= is the same=2C so there is always an attenuation.
=0A=
=0A= All in all this looks much more promising now and i will do a new /p=0A= test on the band soon. BTW the DC working point of the OP at 12V supply=0A= voltage is (of course) 6V when the LED transmitter is OFF and it rises=0A= to 8V when it is ON. So there is some room for further system gain.
=0A= And BTW=2C the OP can be loaded with 50 Ohm directly...
=0A=
=0A= 73=2C Stefan/DK7FC
=0A=
=0A=
=0A= Am 26.07.2013 00:29=2C schrieb Stefan Sch=E4fer:=0A=
=0A= =0A= Hello Roelof=2C
=0A=
=0A= Is there some progress on your side? I may have some useful=0A= informations for you.
=0A=
=0A= In the last test i found that i need more gain and in the end i want to=0A= have a fiber optic antenna that covers LF and MF=2C maybe even VLF.=0A= Furthermore a resonated antenna is not suitable when the antenna is=0A= sometimes grounded or floating in the tests.
=0A= In my circuit the problem is the low rise- and fall- time of the=0A= SFH350V. I saw the problem years ago and ordered a few SFH250V photo=0A= diodes which should work well. The LED transmitter is suitable i think=2C= =0A= although the SFH757 is faster of course. But i'm always looking below 1=0A= MHz.
=0A= Now i seareched for some additional ideas for a the optical/electrical=0A= converter. Some time ago i built a transimpedance converter but i was=0A= sceptic about OP AMPs at 475 kHz. But i think i learned something and=0A= got some new ideas on these pages:
=0A= htt= p://circuits.linear.com/all--Photodiode_Interface_*_Transimpedance_Amps-53<= /a>
=0A= Seems that these frequencies are no problem at all=2C even if a high gain= =0A= is desired. The LT6200=0A= is available at RS=2C 4.56 EUR here. Quite expensive but worth to play=0A= with :-) OK=2C some may say it is overkill and the device can cause VHF=0A= oscillations=2C but anyway...
=0A=
=0A= I guess it will be no problem to get the needed gain to go on with the=0A= experiments=2C even if no resonated antenna is used... BTW the output=0A= current of the device is even 60 mA. So maybe it is even suitable to=0A= drive the LED...
=0A=
=0A= What do you think?
=0A=
=0A= 73=2C Stefan/DK7FC
=0A=
=0A=
=0A=
=0A= Am 13.07.2013 12:55=2C schrieb Roelof Bakker:=0A=
Hello=0A= Edgar=2C
=0A=
=0A= I don't know how linear these devices are=2C but that will show up in=0A= actual use.
=0A=
=0A= The SFH756V and SFH350V are housed in a moulded plastic casing with a=0A= cable clamp:
=0A=
=0A= http://www.avagotech.com/pages/en/fiber_optics/ge= neral_purpose_industrial_control_data_link_650nm/sfh756v/=0A=
=0A=
=0A= I also found that for a wider bandwidth the SFH 757V / SFH 250V are=0A= more suitable.
=0A= These are rated at 100 MBd.
=0A= I will order them in the near future.
=0A=
=0A= 73=2C
=0A= Roelof Bakker=2C pa0rdt
=0A=
=0A=
= --_0b8857f7-93e2-40a7-a8e8-a7f5e48b1ae2_--