http://groups.yahoo.com/group/Optical_DX/ Australian Optical DX Group Wed, 28 Oct 2009 12:27:06 GMT Robo L http://groups.yahoo.com/group/Optical_DX/message/429 http://groups.yahoo.com/group/Optical_DX/message/429 Congratulations boys! Good works! Justin, please downlaod and fill my form for publish world record on my pages Please edit the form with Notpad (or similiar) Wed, 28 Oct 2009 11:55:07 GMT vk7tangledwhiskers http://groups.yahoo.com/group/Optical_DX/message/428 http://groups.yahoo.com/group/Optical_DX/message/428 On the night of October 27th 2009, Rex VK7MO and Joe VK7JG assisted by Paul VK7KPG set a new one way NLOS Optical record of 288km across Bass Strait using red Sat, 10 Oct 2009 21:33:41 GMT om2zz http://groups.yahoo.com/group/Optical_DX/message/427 http://groups.yahoo.com/group/Optical_DX/message/427 Our next succesful optical contact in Slovakia over 94km. SOme photoes, audio and short story you can find here: www.foton.sk radosan.ic.cz 73, Rado om2zz Tue, 01 Sep 2009 22:34:41 GMT Rex Moncur http://groups.yahoo.com/group/Optical_DX/message/426 http://groups.yahoo.com/group/Optical_DX/message/426 Hi Rado Congratulations to your team - good work. 73 Rex VK7MO _____ From: Optical_DX@yahoogroups.com [mailto:Optical_DX@yahoogroups.com] On Behalf Of om2zz Tue, 01 Sep 2009 22:03:09 GMT om2zz http://groups.yahoo.com/group/Optical_DX/message/425 http://groups.yahoo.com/group/Optical_DX/message/425 I would like to inform you about our next successful optical contact here in Europe. On August 31-st 2009 we made radioamateur optical contact on red line Sun, 16 Aug 2009 20:55:53 GMT Tom Becker http://groups.yahoo.com/group/Optical_DX/message/424 http://groups.yahoo.com/group/Optical_DX/message/424 ... That's sadly true - and I used none of those terms. There are, nevertheless, surplus filters that pop up from time to time and, if he's working in red or Sun, 16 Aug 2009 20:32:32 GMT ryersong http://groups.yahoo.com/group/Optical_DX/message/423 http://groups.yahoo.com/group/Optical_DX/message/423 The terms inexpensive, low loss and narrowband are not tightly coupled to the term optical filter...... Sun, 16 Aug 2009 18:41:22 GMT Tom Becker http://groups.yahoo.com/group/Optical_DX/message/422 http://groups.yahoo.com/group/Optical_DX/message/422 ... Optical filters can selectively allow your laser return to pass while blocking most ambient light. Match the filter passband or cutoff to the laser Sun, 16 Aug 2009 18:12:37 GMT ryersong http://groups.yahoo.com/group/Optical_DX/message/421 http://groups.yahoo.com/group/Optical_DX/message/421 It's quite possible that the 50Hz energy will saturate your photodiode making sensitive measurements in the 3 KHz range difficult. The K3PZP optical front end Sun, 16 Aug 2009 15:25:33 GMT Bernhard http://groups.yahoo.com/group/Optical_DX/message/420 http://groups.yahoo.com/group/Optical_DX/message/420 Hi, 50 Hz to 3000 Hz is quite a distance, it should be possible to use a high pass filter. You can use fixed inductors. Those are cheap, easy to use and make a Sun, 16 Aug 2009 09:56:44 GMT lb3hc http://groups.yahoo.com/group/Optical_DX/message/419 http://groups.yahoo.com/group/Optical_DX/message/419 Hello again. I am going to do some PD amplifier chain experiments inside my house (with AC lighting installed). There will likely be strong 50Hz (Europe) Thu, 13 Aug 2009 20:16:21 GMT lb3hc http://groups.yahoo.com/group/Optical_DX/message/418 http://groups.yahoo.com/group/Optical_DX/message/418 Hello optical dx'ers. I am planning a new experiment where I would like to detect where a laser beam with amplitude modulation of 2-5 Khz hits a matrix of Mon, 13 Jul 2009 21:52:55 GMT lb3hc http://groups.yahoo.com/group/Optical_DX/message/417 http://groups.yahoo.com/group/Optical_DX/message/417 Hi. OK I understand what you mean when I see the graph. The near IR reflectance for dense grass is approx 5 times higher than for the visual range. That Mon, 13 Jul 2009 10:31:39 GMT Garnier Yves http://groups.yahoo.com/group/Optical_DX/message/416 http://groups.yahoo.com/group/Optical_DX/message/416 Have a look on the grass spectrum and compare the green reflectance with the near IR one... http://www.aai.ee/bgf/ger2600/d_grass.png 73 Yves F1AVY Mon, 13 Jul 2009 09:30:18 GMT lb3hc http://groups.yahoo.com/group/Optical_DX/message/415 http://groups.yahoo.com/group/Optical_DX/message/415 To continue on the range finder discussion: What about using a green laser pointer? It will give better reflection from the clorofyl of the green vegetation.