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RE: (meteorobs) Radio Orionids - 15th to 27th
>Can you provide a little information on the radio setup and the interface?
>What type of receiver are you using? Where is the transmitter? What type of
>signal are you detecting (CW?)? What frequency are you using? How did you
>calibrate your system?
>
>Are you using an analog to digital converter coming out of the receiver? 4 ,
>8 or 16 bit?
>
>I would like to look at the computer program you are using if possible.
>Where can it be obtained?
>
Hello Dick
Here are some details of my system using the type of info usually
supplied in the Radio Meteor Observation Bulletins.
Observer: Bruce Young
Location: Deception Bay, Queensland, Australia (27 30' E, 153 10' S)
Frequencies: 103.1 MHz
Transmitter: 103.1 Townsville, Queensland (1,100 km)
Location 103.1 Rockhampton, Queensland (550 km)
Both stations are almost in a straight line from here.
Antenna: 3-element Yagi FM, horizontally polarised.
azimuth NW, elevation 15 deg.
Amplifier: TV masthead amplifier 15 dB gain
Receiver: Samsung domestic type FM radio, digitial tunning
Observing: Electronic interface on LINE output audio signal is fed in
method COM2: of PC IBM 486 DX2 66 MHz.
METEOR v 4.0 version processes the signal and records on
floppy disk the time of the events.
METEOR parameters: THRESHOLD = 8
I'll currently building up an old 60 MHz Pentium as the final system.
It will use an FM receiver on an ISA card in the computer.
http://www.redsword.com/tjacobs/geeb/fmcard.htm I've not tested this
yet. I will continue to use Pierre's system at this stage. If I have
time I might be able to get it ready for the Leonids but at this
stage it might be better to use what I have. I have FM two cards and
I'll work with a friend to modify one to try out some other ideas.
Pierre's site is: http://radio.meteor.free.fr/us/
He has provided schematics for a circuit that acts as an audio
limiter/integrator and which is read by your PC Com port. He has a
program that then detects the peaks, logs the detection and can also,
if required, write all the raw data to disk. I'm just running mine
from a bootable DOS floppy at the moment so I'm not recording all the
raw data, just the detections. He also has another program to take
the detection data and produce a University of Ghent format
visualisation of the data and spit out a observation report. I've not
be able to get that to run yet as one of the modules seems to be
corrupted.
I do have an 8-bit a/d converter (parallel port) but I'd planned to
use that in a radio astronomy project.
The Meteor progam analyses the initial output from his circuit and
sets some parametes so it makes a nice graph on the screen. You can
see detections as peaks on that graph. I don't exactly know what he's
doing but I think I get the idea and there are a few limitations on
the way he does it... I will email him and discuss it when I get a
chancce. I'm sure all systems have limitations, assumptions and
"issues". Don't get me wrong here, I am grateful that he has made his
system avalable for us all to use.
After listening to the system and watching the graph and noting what
it was counting, I have chosen a certain threshold detection
parameter that minimises false positives but still has a resonable
sensitivity. The long period of checking the data in this way has
shown that it works very well for signals of low to medium strength
and up to a few seconds duration. It has problems with very strong
reflections and ones that last more than about 5 seconds. It also
can't cope with more than one detection per 10 sec "sweep". Thus it
can be "saturated" at higher rates. As I said, I don't know exactly
how other systems work and I'm sure that on close analysis, they all
have "issues".
My comments should not be taken as an indication that Pierre's system
is of no use... exactly the opposite, I think it's great... I'm just
saying that I've noted a few areas that either I've misunderstood or
that may need some more work. I'm not a "radio ham" and aren't that
keen on making circuits (I can if pushed but i'ts not my area of
expertise).
As I mentioned last time, my system appears to be working as well as
could be expected. It is clearly picking up the daily meteor cycle
and I suspect that it is also picking up some radiant position
effects. I do have a possible problem with direct reception from the
closer station (550 km) on occasion. I'll look at what I can do to
minimise that when I get the system working with the FM card.
thanks for your interest
Bruce
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