Meteor Detection via GRAVES - Trying to get it to work...

[wxsatuser]

Well done, glad you could hear it.

[PhotoGav]

My next questions are going to be all about what the waterfall display tells us... pictures and questions to follow soon!

[Tomatobro]

When I started I used some software called Bandicam. It was about $30 as I recall. I set it up to record the screen and audio in half hour periods. It has a delayed start feature that is useful for meteor recording.

Next day I would revue each AVI for recordings of interest. Fast forwarding I would look for signals then reverse and watch and listen to the event.

I could also take screen shots of interesting events.  With twenty in the class you could give them one half hour AVI each for analysis. Just a thought.

[PhotoGav]

1 hour ago, Tomatobro said:

When I started I used some software called Bandicam. It was about $30 as I recall. I set it up to record the screen and audio in half hour periods. It has a delayed start feature that is useful for meteor recording.

Next day I would revue each AVI for recordings of interest. Fast forwarding I would look for signals then reverse and watch and listen to the event.

I could also take screen shots of interesting events.  With twenty in the class you could give them one half hour AVI each for analysis. Just a thought.

I like that idea very much, thank you! You might have seen that I have also started another thread about decoding the waterfall to understand what the reflections tell us about the meteors that caused them. Your thoughts would be most welcome!

[PhotoGav]

Here’s a general question regarding the aerial: does the elevation angle of the aerial really matter? The theoretical elevation from my location is 17°, but if it is basically horizontal, will it make a significant difference? I am struggling to devise a good method of getting the 17° angle on the antenna when I am mounting the system outside on a big tripod and 3m mast. I bought an adjustable elevation bracket, but it is a bit flimsy and I don’t have the correct hardware to attach the aerial to it anyway! I’m wondering if I can not worry about this 17° angle for now and still get good data?

[Tomatobro]

From Shropshire I point my Yagi  so the element support beam is 20 degrees up from horizontal. and slightly East of South. A degree or two out I don't think matters

 

[wxsatuser]

4 hours ago, PhotoGav said:

Here’s a general question regarding the aerial: does the elevation angle of the aerial really matter? The theoretical elevation from my location is 17°, but if it is basically horizontal, will it make a significant difference? I am struggling to devise a good method of getting the 17° angle on the antenna when I am mounting the system outside on a big tripod and 3m mast. I bought an adjustable elevation bracket, but it is a bit flimsy and I don’t have the correct hardware to attach the aerial to it anyway! I’m wondering if I can not worry about this 17° angle for now and still get good data?

My logperiodic has no elevation and does ok.

In my 144MHz meteorscatter days my setup had about 5degrees of elevation.
I worked all over Europe and as far south as Tunisia..

Here is a nice Leonid from this year.
Screen capture only so two shots cover this one, the tick marks are 10secs.

 

[PhotoGav]

@Tomatobro & @wxsatuser - thank you both. I think I will give ‘no elevation’ a go and see how it fares while I make a bespoke bracket. 

[wxsatuser]

Another long one from the Leonids, this one at least 100secs, spread over three screen shots.

 

 

[PhotoGav]

Mike, I caught that one too, logged at 64.4 seconds!

 

Edited December 7, 2020 by PhotoGav
pictures

[wxsatuser]

cannot see images.

[The Admiral]

On 05/12/2020 at 17:35, PhotoGav said:

@Tomatobro & @wxsatuser - thank you both. I think I will give ‘no elevation’ a go and see how it fares while I make a bespoke bracket. 

I think it'll be fine.

In the dim and distant past I did some antenna plotting with a 6m high S@N Yagi, horizontal and with 10° up elevation. There was hardly any difference in the response plots.

10° up elevation

Horizontal

These response lobes are a result of the antenna picking up the direct wave and the wave reflected off the earth, an interference effect if you will. There appears to be a slight loss of forward gain. That's my understanding of it anyway. In reality I suspect that local obstructions will have a greater impact. My antenna is horizontal in the loft space, and goodness knows what response I'm getting .

Ian

 

Edited December 7, 2020 by The Admiral

[PhotoGav]

3 hours ago, wxsatuser said:

cannot see images.

Hopefully you can seen an image on that post now.

[wxsatuser]

6 minutes ago, PhotoGav said:

Hopefully you can seen an image on that post now.

Yes, now visible.

Looks like the same event, nice.

[PhotoGav]

The continuing story:

I moved the aerial from the Warm Room to outside yesterday and the radio sky has exploded into life... and it was pretty busy before! I am finding that it is regularly detecting an almost continuous stream around events. Is this just lingering ionisation or might it be the direct GRAVES signal itself? I can't belief it is the direct signal as geography suggests that is not possible. My best interpretation is that the system is now massively more sensitive. I have reduced the Gain right down and altered the SNR threshold up slightly. I will see if that calms things down to just the more significant meteor events - though the first screenshot would suggest that that hasn't happened.

Here are a selection of screenshots, including what I can only imagine is a pass of multiple Starlink satellites:

[PhotoGav]

Could the intermittent line be occasional reflection off the ionosphere?

[andrew s]

@PhotoGav it a high gain arial optimised for Garves so I am not surprised. 

If you're worried rig up a simple dipole and compare the results. 

Glad it's working so well.

Regards Andrew 

[wxsatuser]

Looks mighty good to me, I would be well pleased with that once your fixed outside.

My view towards GRAVES is restricted by the South Downs so I do not always see everything.

I do get a direct signal on and off but it must be the back lobes as they would need to be close
for me to hear them.
I do get the odd satellite but I'm sure that must be off the back lobe as again I believe I cannot hear
the main beam from here.

[The Admiral]

19 hours ago, PhotoGav said:

The continuing story

That's a nice series of events you've captured there Gav. Putting the antenna outside has made all the difference. How high off the ground have you mounted it?

Ian

[PhotoGav]

1 hour ago, The Admiral said:

That's a nice series of events you've captured there Gav. Putting the antenna outside has made all the difference. How high off the ground have you mounted it?

Ian

Thanks Ian, yes, the kit is glowing! The aerial is on a 3 metre mast. It is at an elevation angle of only about 10° as the ground is uneven. I will do a bit of gardening to drop the back foot of the tripod to raise the elevation of the aerial a few degrees. I have reduced the gain and upped the SNR threshold; the system is now registering proper meteor events only. I’m ready for the Quadrantids!

[The Admiral]

4 hours ago, PhotoGav said:

to raise the elevation of the aerial a few degrees

Personally I'm not convinced it needs to be angled upwards, but it won't do any harm. As it is, 10° should be fine I would have thought.

Cheers, Ian