Electronics > Projects, Designs, and Technical Stuff
Radio Direction Finding
katzohki:
Wow, really cool!
PA3BNX:
Hello Everybody,
I have the new updated version SoundDoppler146All on our PI4WAG site.
It has now switchable driver 8, 12 or 16 bits SoundCard inputs
Improved Noise Squelch
And Fieldlogger102 that is a GPS-RSSI FT817 FT840 logging program.
The log files can be played in MyMapping.exe
So have fun !
PA3BNX:
Hello Every Body,
New Idea!
5x Antenna SuperSimpleSoundDoppler VHF/UHF
--------------------------------------------
My wish is an optimal doppler system for VHF/UHF
without the need to change the antenna array.
Normally you have to exchange the whips and change the antenna
circle width.
I propose to create a VHF/UHF antenna by switching the length
of the antenna.
The diameter of the antenna circle must be as large as possible
for the highest frequency.
By giving the antenna the length of 17 and 50 cm.
For that is needed a re-tour conductor so a monopole
that consist off two parallel conductors.
The switches are ordinary 1n4148 diodes.
Maybe it can be build by twisting wires in a
standard PVC electricity tube.
(No idea of a twisted isolated wire functions as stiff antenna in this
construction method)
The antenna plug must consist of two contacts that cannot be turned around
5x monopole antennas instead of 4 because bigger capture area but also
for VHF a bigger base width.
(By adjacent monopoles may by 430 MHz maximal 17 cm)
So more monopoles means bigger circle diameter possible.
See also my SoundDoppler program the 'Doppler antenna array calculator'
5 antenna maybe possible without to complicated control cable.
The control cable needs 5 antenna control lines a VHF/UHF line and mass
There are 7 pin Din connectors but also of course cheap db9.
The antenna plate must be for 430 MHz about 60 cm diameter and the antenna
circle diameter about 26 cm.
that gives with 600 Hz Doppler about 2.8 kHz bandwidth.
Same measures for VHF 145 MHz about 1.7 kHz bandwidth.
Only needed an extra switch to serve for antenna VHF or UHF.
Remark:
---------
If you take a bearing on VHF and the station becomes very strong
you can attenuate by switching to UHF so to short and attenuates.
Why not us a dual band VHF/UHF antenna
because on UHF a VHF/UHF antenna resonates
and with the doppler you don't want to disturb RF field
by absorption or reflection.
The coax cables do still need good earth at each antenna feet.
5x big magnet glue feet with much capacity between
feet and car roof is possible wit feet that have space for the components.
I am curious to see the performance of an antenna-array with antenna at 5 x 72 degrees angles
and if this differences with errors at 4 x 90 degrees angles
73's
PA3BNX
PA3BNX:
Hello Everybody,
I did build a small audio pre-amp with galvanic separation transformers
for connecting de Doppler hardware to the soundcard of the PC.
So enjoy !
PA3BNX:
Hello Every Body,
New version SoundDoppler148All.zip on the site PI4WAG
ManualSend Button option.
en bugs fixed in logging all the audio wav files in 8 bits 8000 samples/sec PCM
http://www.pi4wag.nl/projecten/doppler-peiler-radio-direction-finder
73's
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