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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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