Detecting meteor scatter with an icom R7000 receiver

[Gazabone]

Hi,

I've been trying to get this to work now for about 18 months and despite what looks like some "hits" on my software, I have yet to hear the 'ping' from the receiver (I do see some of the "hits" being made but the sound is more of a snap than a ping with the trace on the waterfall lasting less than a second). I can only think that I have the receiver set up wrong. This is;

icom R7000 tuned to 143.048 and set to SSB

7 element Yagi Ariel set horizontally in the loft pointing SE. 

Any ideas anyone please?

[Ibbo!]

I will have a look at my settings whn i fire the old PC up.

 

If I do not reply in the next couple of days pm to remind me.

 

[Gazabone]

Thanks, will do. ??

[The Admiral]

Well, I'm a little rusty on the details now, but tuned to 143.048MHz will give you 2kHz difference frequency from Graves, so I don't see why it shouldn't work. Outside meteor showers I would not expect a high proportion of lengthy trails, and so you don't always get a ping. Antenna should give you good sensitivity, as long as it is pointing close to the horizon. I use a Funcube dongle and SpectrumLab though.

There must be a lot of info around on using the Icom I should have thought. Have you Googled?

Ian

[Gazabone]

Thanks Admiral,

i have a feeling I'm not far off. I'm using SpectraVue and it does show definite blips which I'm assuming are meteors but I think the whole thing could work better. It might be worth shortening the aerial lead, I do have quite a bit to spare. 

[The Admiral]

I would have thought that with a 7-element Yagi you'd have more than enough signal, unless you've got very lossy feeder. Most basic setups manage with a 2 or 3 element Yagi and just a dongle. Are you able to get some screen dumps of the waterfall trace and post them up? One thought though is that with a multi-element antenna the beam width is narrow, whereas the meteor reflections can come from a large volume of sky South of roughly Dijon, so you might just be picking up a small fraction. The rate is quite low outside showers. Also, do you have a low horizon without obstruction in that direction? Have a look at this thread https://stargazerslounge.com/topic/279836-meteor-detection/

Have you seen the rather long thread https://stargazerslounge.com/topic/220150-new-to-meteor-detecting/. That might have a few clues.

Good luck, Ian

PS. You might find this paper by Dr D Morgan worth a read. He used an ICOM R7000 but doesn't really give any settings.

Detection_of_meteors_by_RADAR.pdf

[Gazabone]

1 hour ago, The Admiral said:

I would have thought that with a 7-element Yagi you'd have more than enough signal, unless you've got very lossy feeder. Most basic setups manage with a 2 or 3 element Yagi and just a dongle. Are you able to get some screen dumps of the waterfall trace and post them up? One thought though is that with a multi-element antenna the beam width is narrow, whereas the meteor reflections can come from a large volume of sky South of roughly Dijon, so you might just be picking up a small fraction. The rate is quite low outside showers. Also, do you have a low horizon without obstruction in that direction? Have a look at this thread https://stargazerslounge.com/topic/279836-meteor-detection/

Have you seen the rather long thread https://stargazerslounge.com/topic/220150-new-to-meteor-detecting/. That might have a few clues.

Good luck, Ian

PS. You might find this paper by Dr D Morgan worth a read. He used an ICOM R7000 but doesn't really give any settings.

Detection_of_meteors_by_RADAR.pdf

Many thanks for this, yes, some interesting reading. 

This is the sort of "click" I'm getting (far right hand side at 21:24:54

and again at 22:15:40.

These are not the only examples from a couple nights ago but this is about the full extant of what I'm getting.  The software is Spectravue.

[The Admiral]

Grief, I find it hard to see what's going on here! I'm not familiar with Spectravue. I'm assuming that the figures along the y-axis represent frequency. Am I correct in saying that it shows both the signal and it's image? Otherwise I don't understand why it's symmetrical. So what's all the hash? Is it just noise? I may be wrong, but those two events would seem to represent a reduction in noise, rather than a pulse? I can't work it out to be honest. Anyone else like to contribute on this?

I did spot some note elsewhere that the receiver doesn't allow you to switch off the automatic gain control, so may be that is having some influence, or may be there is a noise limiter having an impact. Of course, the ICOM is an advanced communications receiver with lots of 'twiddles' that I am not at all familiar with. As a matter of interest, are you able to receive GB3VHF where you are, and if so, what sort of trace do you get with that?

Sorry, I can't be much help here.

Ian

Edit. Another thing puzzles me, the signal should be coming in at a few kHz, and tailing off to 2kHz. So why is the frequency scale at ~10.5kHz, if indeed it is in kHz? Are you sure that you are not looking at a conventional signal on a different (i.e. wrong) frequency? Graves transmissions aren't normally observed as they are 'over the horizon' and beamed towards the South. My guess is that trace represents the wrong signal.

[Gazabone]

Thanks Ian, the numbers are time stamps but you've stated my problem exactly. The audible signal seems more of a click, certainly not a ping. I'll see if I can tune to the signal you suggest. I've also just checked and the aerial is pointing pretty much directly at Dijion. 

Does the aerial need to be outdoors? It's in the loft at the moment. 

I do have an funcube dongle so I'll try uninstalling the software and downloading the software mentioned in the other post. 

Cheers

Gareth

[The Admiral]

Mine's in the loft, not a problem.

I didn't mean the numbers across the top, the ones up the side. If they are kHz, then you need to be looking around 2, not 10.5.

What software is that?

Ian

[Gazabone]

Ah, sorry, yes the numbers up the side are kHz but it think on the plot, it's not relevant to detecting something (please tell me if I'm wrong). I did have it showing centered on 143.048 but I had some problems with the laptop and can't seem to get it back to that (to be fair, haven't given it my best effort yet as more interested in getting the receiver to ping and then sort out the waterfall). 

[The Admiral]

Hi Gareth,

Well, if you accept that I'm straying into unknown territory here, here's my two pennyworth. I'm not familiar with the Icom, but having looked at the specifications let me think this through. Let's start with the receiver.

Graves transmits a plain carrier wave on 143.050MHz. Ordinarily this isn't detectable, unless the signal is scattered by a meteor in its beam (or the ISS for that matter). So if you set the Icom to SSB and tuned to 143.050MHz, you'd hear nothing, even if it was possible to detect the carrier. Therefore, tune to say 143.049 or .048 MHz (as you've done), and any carrier that you do receive, through meteor scatter etc, will give you a tone of 1kHz or 2kHz respectively. You can switch between USB and LSB; to be honest I'm not sure which one. May be it won't make any difference so far as the audio signal is concerned, not sure about that. I would switch 'squelch' off. Likewise noise blanker (NB). A weak meteor signal will just give a short 'beep'. With a stronger signal you will hear the initial strike and you may get a changing pitch, ultimately becoming the 1kHz (or 2kHz). For 'over-developed' trails the signal upon reaching the 1kHz (or 2kHz) continues, sometimes for many seconds. These are much easier to detect during meteor showers. The receiver bandwidth I see is set to ±1.4kHz when on SSB, which I would think is a little on the narrow side because some of the initial strikes can be many kHz different from the carrier frequency. But you are stuck with that. Thinking about that, I wonder that if you set your tuning to 143.048MHz, then the signal will actually be outside the passband.* Perhaps try tuning to 143.049MHz or even 143.0495MHz. I wouldn't expect there to be a strong background 'sharsh', just an audible hiss. I would imagine AGC could be a problem because it will reduce the gain of your receiver on receipt of the signal. How much of a problem I don't know. See here.

If you want to analyse the frequency spectrum you'll need to feed the audio O/P into your PC. I can't interpret the Spectravue trace. Most folk ultimately use Spectrum Lab. This will require a little setting up, making sure that your sound card is set up correctly in the first instance. There should be information in the long thread I linked to.

If those receiver settings don't get you up and running, then I am at a loss, as you should be detecting meteors. Have you checked through the antenna connections just to make sure there isn't a faulty connection somewhere? As I said before, it might be worth tuning to VHF beacon GB3VHF, which transmits precisely on 144.430 MHz. If you are able to detect it then it will at least confirm that your antenna and feed are OK, and double check the accuracy of your tuning.

Good luck

Ian

* Then again, for SSB mode perhaps it depends on whether the 'tuned in' frequency is offset to the side of the passband, rather than in the centre of it, which would make sense as it is trying to replicate the carrier. So maybe the passband is tuned frequency +2.8kHz, or -2.8kHz, depending on whether it is set to USB or LSB. In that event, I can see that if you choose the wrong setting you might find the passband totally excludes the wanted signal, rather than encompasses it. If you catch my drift. I can't see anything in the manual which clarifies that. It need someone familiar with the receiver to answer that.

[The Admiral]

Just to clarify what I mean by the sideband issue.

If the so-called 'tuned' frequency is actually off-set from the passband, as shown above, rather than being centred within it, then by incorrectly selecting either USB or LSB might dictate that the signal produced by the meteors is missed. That's my thinking anyway - I'm not saying it is correct .

Ian

[Gazabone]

Ah, sorry, yes the numbers up the side are kHz but it think on the plot, it's not relevant to detecting something (please tell me if I'm wrong). I did have it showing centered on 143.048 but I had some problems S effort yet as more interested in getting the receiver to ping and then sort out the waterfall). 

 

 

Many many many thanks Ian, you've given a lot for me to thonk about and I think I set the squelch quite close so I'll take that off as a first step. I'll go through all your thoughts tonight when I get home and see if I can make progress. I do wonder from what you've said if my squelch setting is what's cutting the sinlgnal off. 

Once I am detecting stuff I'll explore the mysteries of  Spectrum Lab, I will get there eventually, thanks once again for all your help and advice. 

 

Brst wishes

Gareth

[The Admiral]

You're more than welcome Gareth. I don't know how well you can expect to receive the VHF beacon as it's in Kent and beamed towards Gloucester, and also you presumably have a quite narrow beam width on your Yagi. I see that there are other beacons to be found in France which might be useful though.

Ian

[Gazabone]

Best success to date, swapped the Icom over to a Funcube dongle and am now hearing the pings. Using SDRsharp software to run the dongle but I think I have to uninstall that and install the alternative software mentioned in the other thread. That will be another adventure again, but at least I know I'm now getting some pings ??

[7170]

On 10/08/2017 at 19:09, Gazabone said:

Best success to date, swapped the Icom over to a Funcube dongle and am now hearing the pings.

Great to hear you are now having success Gareth. I'm late to the party but my guess would have been AGC (which I don't think you can turn off) or too small a pass band, and to check how accoutre the tuning actually is by comparing to a known beacon. The advantage of dongles like the Funcube is that you can turn AGC off and define the filter bandwidth you want etc.

For what it is worth I never had much luck with my Icom handheld scanner with meteor detection or picking up weather satellites for that matter, for both my RTL-SDR dongle works better despite being technically less sensitive as you have more control of all the settings.