| Electronics > Projects, Designs, and Technical Stuff |
| Radio Direction Finding |
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| jackdev23:
Hello everybody, thank for this good thread. I made a ARDF with Arduino Nano. Check the prototype here http://youtu.be/jm0Q4p4GudA?list=UU17SR_h8OR9WCBrsh_ak_sQ PCB READY :) 73 IW2NDH |
| PA3BNX:
Hello Every Body, I see some have a problem with the max232 do not connect or tap the internal voltages from the pins 2 and 6 from the max232 Nice to see the Arduino experiments IW2NDH. I have done now a simple ne555 circuit to drive manually the AMPlate antenna So easy only adjust the 4 stands turn switch NSEW and a scanner or portofoon with S-meter while drving in a car So no more stopping and using a Yagi or HB9CV for the balloon fox hunt. Nice experimenting |
| PA3BNX:
Hello everybody, Subject: Doppler RDF on the 100 MHz 3 metres FM broadcast band The problem with RDF on a FM broadcast TX with about 150 kHz bandwidth is in the fact that the standard doppler rotation tone is 500 Hz With my standard SuperSimpleSoundDoppler 4017 generator (about .5-.6 kHz) That's compared to modulated audio from the TX 150 kHz undetectable. If I use mono FM TX with 150 kHz bandwidth: At 100 MHz and a 500 Hz doppler tone. With my 8 bits sound-card channel there is almost no doppler tone to detect. A 8 bit sound card has 256 samples so maximum amplitude contains 127 bits (This is also true for a conventional doppler with classic 8 caps SCF) (They have also a problem with the low pass filters in hardware) 150 kHz / .5 kHz = 300x if I take just one bit for doppler tone then I still have 256 - 300 = -44 bits short. I do not have enough bits to process undistorted FM audio by the soundcard and detect the doppler tone. This works better I think Higher doppler rotation frequency and bigger antenna plate diameter. There is a maximum diameter with 4 antenna (Of course it may not become unhandy large) (See: SoundDoppler.exe menu Info>Doppler antenna array calc) Larger Doppler tone deviation by higher rotation frequency I found that 4 dipoles and a doppler tone rotation frequency of 3 kHz gives 12 kHz doppler deviation on 100 MHz Antenna diameter for 100 MHz about .93 metres and optimal antenna plate diameter for monopoles 2.43 metres 150 kHz / 12 kHz = 13 steps 256 / 13 = 19x This is possible with a 8 bit sound-channel. (You must set the sample rate higher or the same as 22050 samples per second) It's simple to set the multivibrator on about 4 x 3 = 12 kHz by change the 15nF by 2n2 (Divide all by 3 kHz /.5 kHz = 6x) In the SuperSimpleSoundDoppler de Luxe also change the 1n5 by 220 pF Also change the 3x 100nF lowpass filter cap's for the reference frequency output in 3x 10nF With the AM-Plate and Correlation detector mode this is different. If I create on a FM broad cast RX a broadband AM detector just before the AM limiter then I have excellent AM detected modulation. This demands a broadband AM detector added to the WFM detector Hint: Maybe it's handy to modify an 'old' mono 12v car-radio with an extra AM broadband detector because car radio's are well shielded and have a coax antenna plug. 73's |
| YD2WPE:
Hi,..PA3BNX,...i search a sound doppler program,...where could i found.,.? thanks before |
| PA3BNX:
Hello EveryBody My software can be found on: http://www.pi4wag.nl/projecten/doppler-peiler-radio-direction-finder Download button at bottom of page |
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