Return-Path: Received: (qmail 29553 invoked from network); 14 Jan 2001 23:57:33 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by 10.226.25.101 with SMTP; 14 Jan 2001 23:57:33 -0000 Received: (qmail 19845 invoked from network); 15 Jan 2001 00:00:57 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 15 Jan 2001 00:00:57 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from majordom by post.thorcom.com with local (Exim 3.16 #1) id 14Hwya-0002yd-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 14 Jan 2001 23:54:20 +0000 Received: from imo-r09.mx.aol.com ([152.163.225.9]) by post.thorcom.com with esmtp (Exim 3.16 #1) id 14HwyZ-0002yY-00 for rsgb_lf_group@blacksheep.org; Sun, 14 Jan 2001 23:54:19 +0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from MarkusVester@aol.com by imo-r09.mx.aol.com (mail_out_v29.5.) id l.cb.d37dde4 (4417); Sun, 14 Jan 2001 18:53:27 -0500 (EST) From: MarkusVester@aol.com Message-ID: Date: Sun, 14 Jan 2001 18:53:26 EST Subject: LF: TX-IM cancellation at RX end To: rsgb_lf_group@blacksheep.org Cc: markus.vester@med.siemens.de MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="------------080304020804090704060606" X-Mailer: AOL 4.0.i for Windows 95 sub 70 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: This is a multi-part message in MIME format. --------------080304020804090704060606 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Dear group, last week I have tried to build a novel intermodulation-cancelling circuit, using a dual-resonant bandfilter for 121.3 and 128.9 kHz, coupled to diodes to locally generate IM and then add it to the signal in antiphase. Basically, this scheme acts as a harmonic mixer driven by 2x 128.93 kHz (=DCF49), linearly converting the DCF42 noise band around 121.3 up to 136.5 kHz. The gif is a circuit diagram, and I could send pictures and spectra directly. The first tests showed a significant improvement in the reception of weak aural CW on 136.5, and in optimal circumstances, the IM-carriers could be reduced by up to 15 dB. Also the noise floor dropped by up to 5 dB, showing that some of my background noise on 136 kHz is actually TX-IM of DCF42 data modulation sidebands. However, I still had no success receiving VE1ZZ yet. The little circuit is not optimized, and the cancellation is narrowband (200 Hz) and quite sensitive to slight variations in received fieldstrength, relative phase and antenna tuning. The concept could probably also be applied to the Rugby problem on 73 kHz. As the frequencies involved are closer together and fit into an audio band, a soundcard software implementation might be quite feasible. And how about the Luxembourg crossmodulation around DBF39 (138.83)? One could think of subtracting the folded-down upper sideband from the offending lower sideband, thus converting AM into pure USB... 73 de Markus, DF6NM --------------080304020804090704060606 Content-Type: image/gif; name="IM_CIRC.GIF" Content-Transfer-Encoding: base64 Content-Disposition: inline; filename="IM_CIRC.GIF" R0lGODdhQAHIAIAAAAAAAP///ywAAAAAQAHIAAAC/oyPqcvtD6OctNqLs968+w+G4kiW5omm 6sq27gvH8kzX9o3n+s73/g8MCofEovGITCqXzKbzCY1Kp9Sq9YrNarfcrvcLDovHYIDZrDij A+q1wa1OAA7w82Jtf7tb+Dn5z+a3VxfI0KeH4Fe4uIcYqJjncghIRrgop5g4CUfXeNmphxb3 MkkpZun52SnISrealukYN4pZRzgYSVuqG2kqhRrrmMjY+mbcmHo4txysDPpIjLhZPO1rBXzX dgw5CvnZ+yzKpkr+SF0cfi6Lbv3LLawpBy9r/B28Ps4Mu1+t2qZurlS7KNj2aaJFLyA7TNJE NYvVTyC5fvEGuoN36160/nEcK6ZKB82TMoDVIpLUaFGJtloSn0Gr53FlzHrJcnVDx6ugOZcp e/r8CTSo0KFEixo9ihQESkMI/4XyNqxj1IPcaiJjejUpl6V3pjaLOmhe1mNTYXZM5pWrVoIV IJp9S5YmRLeulmYSJNWV3mVrt+iD+RVsmq5Q+cbVe7gr4rxm7/bVggfwYLDdXnLEm6+uPM3g pDqe3PhxFqiZQdM0ePl0asyL/+b9DNdzWdFUSBvevNc0a8N4WYeGHXpx69m0fyG+Pdt3cG+Y eeMu/Rb4PenFrw1XLPm578jZhwOXLTx47OpOEDJ++v2p8N3hc9oGB9u82i95OpuaT55I/Y+A /vDnF7Kff13w998RARaIYA0HJljcPw4+CGGEEt4kIINAVfgcBwFOyGGHHhJo4Q8YEqfBgh6M iF2IRaA4HgYmdsBihioCWKJSfcRoWo0zrqjjiTcqdeKOPGaAYy2hAAmjkPr1GESRLSqpQ4xO rjDllFCiIOWSSV4JRJZDVMlll0xqKOMGYIbpg5cw3mXlkxS0iaYIapp5Vp0gPnBmnDvMSWZa bjqQp5458EmnV+FNECgErLwo6JhtIXncoRIkCihdpDVKpKNjvnPepEFGgFxqZN2JaY6PfkBX PoS66Gl8dSlXKp6ajuAkpYq5ehicO65K65YWdAhLfYZeGqusmfYw/iGiHDZwKXOwFmvIrDYk O+my0UYXGaladbYhSp/xOq2Eg1rY7HXXqsYqsuLioOtP6Z1WWW7H8kAttCYg08s7va0EroLr gmqtvbpFqhpyzyKa5r+KBixwWYUJBp2o6dKrMJ4M21suuqIa/CegCUc4Lx9lvlnVKyxVBBK7 nFj2bWIHe6ouyBPz8a6yrTjkz0MMlWNdyFFW/CYMuRAJn2sozzSSfVD0W6lGJTPrMNAIkyIs q7ioRxVDN+bbLrvSegwXd52Ch56DPlM5i5lzFRKWPTppqxLJUpuqmZ07ka2QUzOzYHaJa+OM WkD48MyWzTJbLNJZzqja1Nyg+vhh5Erj/oNz5UYDPhJkch8ONnjsNYd3vb9+anioKaJm0zlr s32zeU04DimbdjAHb9Scn9qn4X923Q7sqB76ee2t+d55oTZLSiJ5vl/M7MqAcdeb7RCevffC yV/f4O3Bai+D6LgbDzPy4tO2vPczmD917iXwbg3xI4fLfbWSP4glufFDHfP01e8fwvz+yzSg +51rT+4b4NeKZ6zH+SqA+ksfAQWYQPAVD27+sdVouOetjzVwdAvs3OToZkDqXXCDyGOfhgp4 OhFOxnX4U6D6thI/pw1QdibMGwC/d8BXffB9IOSgF4CmtOlwqmOQI2HQOti8GyJwifzDwr+G ZirnEMtoqEJh/g/b8r8POTCHtQEZWmTEMayJrYoQZOK99NY/0jHQiAjcDmHGdwH0hU8FzNhh E3HolzJmSCbTqVP/rMjDXt0tjUiEjB6ThytVEXFz9LujIC0DKQnmkY1mlE622iXHbADSh4Tj ogtheEg4RlBOKGTeCTCpxgva0I6BVNQZQ2lKI1jQHVVp5BYHtUkO8gtuKZjlE0QSykVSLZhx tJQo6ZhKgjiNmDX0GzEfZcxRzQU+yRmeDAs5QlvO8WewNF8Y7eTGSE1RGIV55jFpqc1PiqmY FQun3cTzzuzcppyUVOck0+nKL7nIe/waljWHlkg/XsacwlwaM7X0wha6aowt+412/rqFRk6a jGW85CY+RymiZJ5rmtvQDnqGkSrK1DOf/sxVEgDZzN9hU4SOCWlg/JjLJ7mFdhU930H1uVL+ 9dNhurHFRbfJE7H9JaVrGmkK06RRA8WQpKebp0C7dFMa5VQ/9+OKXeRBu4J2L6pNSqosq4rR rEJnqF/i6joTioS5fVCIT3sJFUVk1oxOtaxGHOMVgdqkuCJ1rgDi3Fjuas+8GhWwXuOrYBtZ UaLiMouMbaxjHwvZyEp2bGZs2FoyiVHL9iWmlNXsUTirWM8acrAtFO1m9Ri59pkWYKRN7X1q ijH3ubY/LFytQ0ibFLXYYqK8XU9bJ4KvncG2rKv4qWis/po5wDWkp607UjyuNpMp4Au3SLFL 0Vj3XJdet7bQxVwdhzuu7fUNccCihBI7GpO/uTRnigwcdhVyNGW2VotffWywLIa0aYYUI2xi StYG10kmyJa+Q5LfRXU7ROXGV2diWSZVTnIF0P6SkRElGX+xq2AhziMaGR5qc7uXorUmh6Cd RShrjYtfwbl1UWXaGqd+lN+GsJKUqCvhiKlLWKkaeLxQCpXpMhMvbOG4lTjdcYWF9OM+ioNx RRsy9gp8Yh4jOTaBAd13JFweCp9XRUpMlZVvjOLMplXLtd1ViCH2zbJtObBjLt2RlWSb4jon YvqV8hFfR+YZr1a8b8Zrm428/uY9Ny3MlZVlnsFrWizj2c2BFjRWCF3aJbAotHpStIBV6Ogo 95nNBsJ0pslr51ue1NOfTqJkKb0+Upe6KJNedYNU7WqhtDrWj5k1rS8L61ufurFRyjWtOduf WwO6zBcStqYb7RNUownYJwXRfJQdpl0j2qbW5bSxT5lWD8/OjtCeUTMreJMNn3EjCo60sfWc 68wF+I/kfutRf01sw7Z72ljUhrrFrOteKoucoc3Icpl67RLLG4D0xiIoKGLuc+u7WpeIt1wD jmxJNu/fBRdawHv7SOuJsdsSF/a3J+zIi8sJ5HEUOd/+1+t9SnvlLG+5yyMbbJPbCNKjkfnM Q00fZJuTEec/1HkRNz0gnxeV50EXutpo7kSjH53oW1G6M5nuF6cTDekRlrrKoa45q//KybXR +tap3jOvMxrd13i52c+O9rTbV+xsb7vb3w73uMt97nSvu93vjve8633vfO+73xtVAAAAOw== --------------080304020804090704060606--