Elad FDM-S2 - Some Thoughts & Questions

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John Faulkner, Skegness
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Elad FDM-S2 - Some Thoughts & Questions

Post by John Faulkner, Skegness » 18 Oct 2014 11:33

I have been looking at band 2 SDRs for some time and have held off buying one until I was sure I could find one which would do exactly what I wanted it to do. Now I wonder if the time has come. The Elad FDM-S2 sounds very appealing. Should I hold on though? Will there be an FDM-S3 in the near future?

To begin with, I will need to sell some other equipment to fund this. Was it all going to be worth it? I thought about meteor scatter. It's a niche area of the hobby and I didn't think there would be any benefits in forking out £500 for this alone.

As things stand, when I search for meteor scatter on band 2, I record a single frequency using the Sony XDR-F1HD, used in conjunction with WaveLab software to process this and my web recordings. There is a big benefit to recording audio from the F1HD. That nice gentle mute which is present when there aren't any signals is extremely useful as I see a very nice waveform on the recording which clearly shows meteor bursts on the timeline. They stand out like a sore thumb against the quieter muted audio. Look at the attached image which shows a waveform of a typical overnight eight hour recording. You can clearly see the meteor bursts against the quieter background.

But ... the recorded waveform looks completely different when I record a frequency from the Kenwood KT6040 as there is no gentle mute. This results in a more solid and compressed waveform, making it less easy to pick out the signal bursts. In fact most of the signals look exactly like the background noise. My concern is that the audio from the Elad FDM-S2 will exhibit the same compressed line as I doubt there is any soft mute. So question number 1 is "Does the Elad FDM-S2 have any kind of optional weak signal mute feature"? I suspect not, but this could actually be useful in this case.

Since the Elad FDM-S2 can record almost half the FM band in one go, I wondered what other benefits it might have over my F1HD, apart from the obvious. Being able to check a large chunk of the band in one go is obviously going to be a big advantage.

So you can feed the audio externally into RDS Spy. Another big advantage as I do not know how the RDS decoding of the FDM-S2 compares to this.

Of course, the Elad FDM-S2 will only be able to do what the software tells it to do, but already I am thinking of some features I would like to see which probably don't currently exist. Or do they?

I would like to be able to get the Elad FDM-S2 to record the whole band. This would only be possible if it could be programmed to record the band in chunks. Let's say it records the bottom of the band, for 30 seconds for instance, then it records the middle chunk, then the upper chunk. If it can be programmed to flip between each chunk of the band at chosen intervals then you would be able to record the whole band. I guess this is not currently possible on the FDM-S2, but something like Hot Keys would surely be able to achieve this.

I would like to see some kind of scanning software which logs the RDS from each frequency, but I suspect this would be pushing it a bit too far. There was an SDR (Italian design I think) which used to do this, but apart from that it was not finely tuned enough for DX purposes.

I am happy to play back recordings, but an automated system like this would be very useful. If only there could be a way to get all RDS displayed, simultaneously, across the band. Could that ever be possible?

You might wonder why I would want something like this. Just consider the HUGE amount of time it will take to play back lengthy recordings of the whole of band 2, then you will see why there is a good case for some level of automation. It's already time-consuming enough checking my nightly medium wave recordings on the Perseus SDR.
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Typical meteor scatter wav file.jpg

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by Julian Hardstone » 18 Oct 2014 13:50

John - On your image of ms bursts, it looks as though you must have to look through 10 or 20 bursts per hour, which sounds like an awful lot of work!
Presumably an FM SDR would allow you to check all the other quiet-ish channels for ms at the times you can see bursts on your logging channel, which could give very rich pickings :)

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by John Faulkner, Skegness » 18 Oct 2014 14:24

That's true enough, but I would need to record more streams than I really can.

I don't know if the computer would collapse under the weight of running an 8 MHz IF spectrum while recording 30 streams. It might even start glowing!

StreamWriter, the software I use for recording multiple streams, has its limitations too. If I record 30 streams I can guarantee two or three of them probably won't have recorded at all. Theoretically, I think StreamWriter can record a maximum of 256 streams simultaneously but that would be taking things to extremes. This is completely over-the-top DXing as it is, but I think it stresses the importance of having some methods of automation along the way.

As for those meteor bursts, there are a huge number of repetitions with the higher powered transmitters each being heard many times. Most of them are unidentifiable too as it's just not possible to record all the streams to compare against.

Meteor scatter is such a fascinating part of the hobby as it can throw up so many surprises. You don't just hear those high powered transmitters, but many low powered sites which you will probably never hear via tropo or Es.

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by Jim (Bournemouth) » 18 Oct 2014 21:45

Hi John.....

Should I hold on though? Will there be an FDM-S3 in the near future?

I doubt it. the S2 only appeared in February and they have just brought out the Duo, a tranciever.

Does the Elad FDM-S2 have any kind of optional weak signal mute feature?

There is a squelch function on the Elad software, but having just checked, it is not operational on Broadcast FM. The Elad team are very receptive to suggestions, so perhaps this could be enabled in future.

So you can feed the audio externally into RDS Spy. Another big advantage as I do not know how the RDS decoding of the FDM-S2 compares to this.

Yes, this can be done. Each VFO has two configurable sound outputs, so that you can send one audio to the PC soundcard and the other to VAC and onto RDS Spy in mux form.

As things stand, when I search for meteor scatter on band 2, I record a single frequency using the Sony XDR-F1HD, used in conjunction with WaveLab software to process this and my web recordings. There is a big benefit to recording audio from the F1HD. That nice gentle mute which is present when there aren't any signals is extremely useful as I see a very nice waveform on the recording which clearly shows meteor bursts on the timeline. They stand out like a sore thumb against the quieter muted audio. Look at the attached image which shows a waveform of a typical overnight eight hour recording. You can clearly see the meteor bursts against the quieter background.


If you used SDR-Radio, you could record audio of up to 6 frequencies at once within a 6.144Mhz span. Only issue is the lack of a mute or squelch. Don't think you could do this with ELADs own software though.
An alternative would be to use the SDR File Analyser (as long as you recorded the whole spectrum span in IQ format on SDR Radio) and you would see meteor bursts on the spectrum, and play them back to hear them. I do this with 2m MS.
One big drawback with that is that for example, 6.144Mhz of bandwidth would cost 1GB of disk space every 40 seconds!!
You could use smaller spans and use less space, a matter of choosing the best freq span.

I would like to be able to get the Elad FDM-S2 to record the whole band. This would only be possible if it could be programmed to record the band in chunks. Let's say it records the bottom of the band, for 30 seconds for instance, then it records the middle chunk, then the upper chunk.


I don't know of any software that would do this at the moment, or any that would do the automation/read RDS in the whole spectrum that you mention in the rest of your post. The latter in particular would need a very meaty machine to do all the processing!!

Any more questions, please ask!
Jim, Bournemouth, Dorset. IO90BR.

Elad FDM-S2, Perseus/FM+ and Funcube Dongle SDR Recievers 8-element OP-DES for Band 2, 12-ele ZL Special for 2m, plus wideband vertical
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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by John Faulkner, Skegness » 18 Oct 2014 22:52

Thanks Jim.

I guess the squelch could perform the task in a similar way, responding to stronger signals. A squelch mutes the audio in the absence of a signal. What I am referring to above is an audio mute. The F1HD mutes the audio in the absence of a signal. The KT6040 doesn't mute anything and so the waveform appears flat, making it almost impossible to see the spikes you can see on my attached screen grab.

It looks like the ability to record up to six channels of audio with the SDR-Radio software would be extremely useful.

So with the SDR File Analyser you can see the meteor bursts and jump straight to them without having to sit through lots of audio. That sounds excellent.

Regarding my suggestion of using Hot Keys, I don't know how this works as I have never used any kind of software like that. If you look at the function keys on a computer keyboard, they are hot keys. A single key which is programmed to perform a task or series of tasks. What I was thinking was software which records your mouse movements as a macro and can run that automatically while I am out. It would be as if I am sat at the computer myself, selecting which chunk to record, etc. So I believe that is 'doable' even if there is no FDM-S2 control software which can do that.

I am sure it might be possible at some point for software to decode RDS on multiple frequencies at the same time. How much processor power that would use I have no idea. As I said, that software already exists but I have not seen it used for DXing. The easiest I can describe it would be to call it an RDS spectrum analyser. We have such software which shows the signals across a given spectrum. To scan the RDS data across the same should definitely be possible.

Thanks again for your detailed reply Jim. Very good of you.

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by Jim (Bournemouth) » 19 Oct 2014 13:05

You're welcome, John.

At some point I'll have to get you hooked up on here via Teamviewer and show you how I use the spectrum analyser to hunt for signals in a recording
Jim, Bournemouth, Dorset. IO90BR.

Elad FDM-S2, Perseus/FM+ and Funcube Dongle SDR Recievers 8-element OP-DES for Band 2, 12-ele ZL Special for 2m, plus wideband vertical
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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by John Faulkner, Skegness » 19 Oct 2014 16:29

That will be great. Thanks.

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by daveB » 22 Oct 2014 13:47

I've been unable to contribute to the discussion until now due to the effects of a Hospital Acquired Infection following the successful removal of a small kidney stone. I've got enough energy now to type at the keyboard!

John - I've been thinking along the same lines- how long should one wait to get something that is 'perfect'? How much am I willing to invest in my hobby?

I think it would be quite possible to buy an Elad FDM-S2 and be disappointed because my computer isn't man enough for it. You can get an idea of how good one's computer is by looking up what process chip it uses and then entering into Google followed by the word "benchmark" i.e. my laptop has Core i3 M330 and has a benchmark of just over 1800. Is that number helpful?

Well I know that I can happily run my RTL-Dongle at 1.048 MBps in HDSDR and it needs 5-10% process power. Double the bandwidth and it still works but samples are dropped and RDS decoding isn't so good. Go to 2.8Mps and it all falls over.

The conclusion is that I would not be able to run the Elad properly. Laptops are under-powered compared to desktops on a £ for £ basis so I'm looking at small form desktops and need to spend a £400-£450 to replace. A couple of examples - an i3-4150 chip has a benchmark of 5004, an i5-4590 has a benchmark of 7229. The latter if 4 x that of my current lapptop - and at least suggest it could cope with a 5MHz bandwidth. Dell Optiplex 3020 look interesting.

"Fortunately" my laptop is now 4 years old - so has done pretty well and I can justify retiring it as my back up PC and ditching my 12yr old pentium 4. When my energy levels are improved(!) I will get round to doing it as the first move.

As for SDR performance and capability - it's down to personal affordabilty. Ettus do stuff that will handle the full 20MHZ but getting the information back and extracting it is another thing! Earlier in the year I recorded a 1MHz chunk during a SpE opening and played back each frequency to make an individual RDSSpy log and that gave a few extra stations. During a tropo opening I would record say 10 minutes straddling the hour or half-hour marks - then play back and see what I can hear - in order to max the chances of getting station announcements.

So just a couple of thoughts

Rgds

David
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SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by John Faulkner, Skegness » 22 Oct 2014 14:26

Sorry to hear about your hospital issues. I hope you are fully recovered now.

So it's not just me who likes to maximise the potential and grab as much DX as I can. :D So many people argue about the quantity over quality issue. I have always said it's not about that, it's about being ready and not missing that rare DX catch when it eventually does come through.

As for computers, my desktop was future-proofed when I was able to afford something decent three years ago and it still holds up well today. Just checked the spec and I see it is an Intel Quad Core i7-2600K 3.40GHz with an 8586 rating. There is 8GB of RAM in there too and it flies pretty well. I am shocked to see modern day computers up as high as 21123 in the spec range. Wow! How things have come along.

My i7 allows me to record the full spectrum (2MHz) bandwidth on Perseus, running the GTK software to control the XDR, recording 30 web streams on StreamWriter and using WaveLab to record the audio from the XDR.

But my laptops - they are all old and feeble. Probably four or five years old at least and capable of recording about 2 channels on band 2 with the RTL dongle. Great for mobile work just to tune around, but forget about recording large IFs.

I had no idea that SDRs had come on so much that we could now record the full 20 MHz spectrum. That is quite amazing!

I have not heard of the Ettus SDRs, but at £3500 I will probably buy two. Er, not really. It would be cheaper to buy two Elads and two computers!

Being able to afford the FDM-S2 is going to be a challenge in itself. As I mentioned, I have to sell a few bits and pieces to fund this and I haven't been successful so far. My current SDR savings amount to £70 and I will no doubt have to keep dipping into that.

Hopefully other members will give us their computer specs and tell us what SDRs they are capable of supporting.

Jeez! It used to be simple at one time. All we needed was a radio. Now we need other expensive hi-tech kit to support it.

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by John Faulkner, Skegness » 04 Nov 2014 00:02

Well, I need to start looking at this again as I am suddenly not far off my target figure and, with a bit of luck, I might be in a position to order the FDM-S2 next week. Nothing is 100% certain yet but I think it's time to start looking closely at some files.

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by Jim (Bournemouth) » 04 Nov 2014 08:55

Just catching up with this thread.

Dave (hope your health continues to improver!) - I run my Elad on an i5 with 4gb RAM and it works fine on the full 6.144 bandwidth with both the Elad software and with SDR-Radio.

You should find it works fine when set with a 1.5Mhz bandwidth (you're not stuck with 6.144Mhs or nothing... you can use 192, 384, 768khz, 1.5, 3 and 6Mhz approx) so I wouldnt let worries about processing power stop you as you can always mitigate that with lower bandwidths if necessary until you get a more powerful PC.
Jim, Bournemouth, Dorset. IO90BR.

Elad FDM-S2, Perseus/FM+ and Funcube Dongle SDR Recievers 8-element OP-DES for Band 2, 12-ele ZL Special for 2m, plus wideband vertical
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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by daveB » 04 Nov 2014 14:45

Hi Jim,

Thanks for the additional comments. Helathwise the nifection came back - another course of anti-biotics and tomorrow (Weds) a visit to hospitsl to have the last bit done and hopefully everything will be fine.

I should think a 1.5MHz bandwidth would be more than adequate - so when everything settles down and I catch up on other things (basically I've 'lost' over two months) I'll take the plunge - maybe in time for the December meteor showers?.

Rgds

David
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by simbeav » 05 Nov 2014 15:49

John,

Don't do it !

I got an FDM-S2 just before the Sporadic-E season and it has ruined my life ;)

I'm STILL going through TBs of recordings from the summer. I only have an indoor 5 element and my location isn't ideal for FM DX, but with the Elad I have already ID'd hundreds of stations that I have not heard before (and I mean ID'd - Add in the RDS IDs and I'm swimming in new stations. Being full time in work there is no way I would have got more than a mere fraction of what I have without the Elad.

Being line of sight and just a few miles from Wenvoe, I was really worried about overloading, but not one spurious signal on the whole band.

It's lucky the Medium Wave DX has been poor so far this year or I would be tearing my hair out :D

Simon

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by John Faulkner, Skegness » 05 Nov 2014 18:13

I won't get one then Simon. ;) Nothing like being able to tune just the one frequency and miss everything else ;) Are we just greedy?

Thanks to the help from Jim Smith, who got my RTL dongle working in SDR Console, I have had a taste of things to come, so to speak. Being able to record a range of frequencies simultaneously and play them back at my leisure is quite something, but I have already been doing that with the Perseus.

I have often said I will dread the amount of extra listening time which will come with all this. This is why some kind of fully automated, auto-logging, etc., system will be necessary, otherwise there just won't be enough hours in the day.

Imagine having software which auto-logs for you when you are out, then submits each logging to FM List, etc. I know it's not what some would like to call DXing, but it means you need never miss anything again. Perseus has given me this much and I have been able to catch rare DX which I simply wouldn't have had, had I just had a single channel recording.

I remember, years ago, somebody wrote an article for the Medium Wave Circle (or was it Contact?) called "DXing Without Sitting in Front of the Receiver". The following month, there were complaints that this was NOT DXing, but CHEATING! :) I wonder what those people would make of all this?

My funds currently stand at £410. Providing everything sells satisfactorily at the weekend, I will be able to place my order. Best of it is, Jane, my wife, wants me to get this SDR. I had just better make sure I don't devote too much time on it. :|

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by daveB » 05 Nov 2014 22:04

Hi Simon,

The obvious answer is play back the recordings when you aren't home :lol:

On the slightly more serious side - it's a case of deciding what you want out of the hobby. For example - with MS reception I've decided I will only concentrate on the peaks of meteor showers and only on RDS Logs. Others will decide to specialise in identifying weak audio bursts.

If you have terrabytes of SpE recordings from the summer you have at least got something to work on during the winter months and it will be fascinating to see just what has come through. My crude set up using as ST-311 to scan 30 preset frequencies has certainly thrown up some interesting stuff - and going through the RDS log to match stations to frequencies is also time consuming.

As for JF's wish to have a receiver that will log everything on every channel I would say it may be DX'ing "but not as we know it [Jim]" - it moves much more into a serious science project. Maybe it could be emulated with a WebSDR covering all or a good part of the band and a whole bunch of DXers who would be willing to remotely monitor one specified frequency each it woul need to be able to use RDSSpy to log. Then pool the results for analysis.

Rgds

David
Sittingbourne
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

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Re: Elad FDM-S2 - Some Thoughts & Questions

Post by simbeav » 07 Nov 2014 22:07

Dave,

I think (hope) it is something I will "grow" out of. When I first got the Perseus I was obsessively listening to every top of the hour, every frequency, every night on medium wave. I was getting weeks behind and I realised that I wasn't achieving anything and it was becoming a chore, not a pleasure. Now I'm more adept at deciding which recordings are worth listening to.

Obviously Band II is more difficult because in an opening there is always the chance of something new just appearing from nowhere, but I'm sure I'll find a compromise before I sink under the weight.......or by another 4tb or so.....

Simon

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