New CHEAP LNA

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milairuk
Posts: 34
Joined: Wed Apr 09, 2014 8:12 pm
Location: Chelmsford, Essex

Re: New CHEAP LNA

Post by milairuk » Wed Aug 20, 2014 2:07 pm

jonfear wrote:Hi John

Just awaiting delivery of some antennas from China via Nic Storey. Hopefully be here for the weekend. From early results, it appears to be outperforming some of the best antennas on the market.

I am not sure that Nic will run a second batch order, perhaps someone else can take that on.

When I have my results I will publish them here. I do have some early screen shots from Nic if anyone is interested.

That will be the limit on my mode-s purchasing for now. I cannot justify a Beast or Cape or for that matter an SBS-3! Dongles are the future!

Jon
Me neither, my RTL and RPi work well enough and I easily get 150nm range. I take my dongles out of their cases and mount them into a diecast box with a layer of Bergquist thermal gap filler to take away the heat into the metal box. Keeps them really cool and stable. Fit a USB cable in place of the socket and a BNC socket on the case with a pigtail lead from China.

Not heard about these Chinese ants from Nic Storey - can you elucidate ?

John

GaryG
Posts: 60
Joined: Wed Jan 30, 2013 1:26 am

Re: New CHEAP LNA

Post by GaryG » Sat Aug 30, 2014 1:16 am

Hi

Received my LNA Wednesday.

Setup is DPD roof mounted antenna to SBS-3 with the 3-pole filter at the SBS-3.

I first tried between the filter and the SBS-3 but the results did not look promising. I tried that setup first as I thought amplified out of band 'stuff' might confuse things. I now have it connected on the antenna side of the filter and like the results.

Using my FlightAware stats as well as a range plot with VRS I see about the same quantity of planes but I am now providing FA with 10%-15% more position reports. The VRS range plot shows I have added almost fifty nm to my previous range in most directions. To the South and West I have now seen planes about 250nm away.

The change of numbers would agree with the flow of traffic I would see in the additional range patterns, most of them would have been seen from this location anyways so that is why the quantity of planes seen did not climb like the quantity of position reports did.

I would say it is a good item for its cost.

Oh yes, the connectors on the LNA - a SMA Male and a SMA Female so if you have SMA already, absolutely no problem connecting it in-line with no adapters required. I also does come with an appropriate SMA to RTL2832 dongle (if it uses the newer connector).

It does require a USB extension cable rather than a 'normal' USB cable for its power, the only sight negative I can think of.

GaryG

CharlieAlpha
Posts: 63
Joined: Sat Mar 15, 2014 6:41 pm

Re: New CHEAP LNA

Post by CharlieAlpha » Sat Sep 06, 2014 4:39 pm

I have just received one of these LNA's. So far it seems pretty good. Like other people I am not really seeing a significant increase in range but that's probably down to antenna / location (ground floor flat so v. limited in what I can do). I do seem to get higher data rates (messages per seconds) and better quality - seems to get call-sign, position etc more often and quicker.

The only downsize so far is I can't get it work with dump1090. Using adbssharp or rtl1090 is fine; data detected in app and forwarded to VRS without a problem. When I try dump1090 I don't get any data feeding to VRS. The command window for dump1090 just shows the column headings with the 'rotating line' in the top right corner but no aircraft listed.

I am assuming this must be something to do with the parameters I have for dump1090 because it works fine without the LNA. My command line is
dump1090.exe --interactive --gain 48 --enable-agc --aggressive --net --net-ro-port 47806 --net-beast --modeac

I guessed it was something to do with the gain setting so I have tried changing (lowering) the --gain setting, having the --gain setting and removing the --enable-agc option, removing the --gain option but having the --enable-agc option, removing both options. Nothing seems to help.

If anybody (Jon ?) is using dump1090 and the LNA what command line options are you using?

Appreciate any suggestions.

Charlie

Bro
Posts: 11
Joined: Sat Sep 06, 2014 7:18 pm
Location: nr Pole Hill VOR-DME (Todmorden,UK)

Re: New CHEAP LNA

Post by Bro » Sat Sep 06, 2014 7:35 pm

Me Too !!!

Same kind of symptoms,
I'm getting sod all using Pi-dump1090-vrs(linux) when the LNA is powered..
yet if I remove the power (unit still inline though)... and I can see aircraft although range severely reduced.
... remove it completely and I see even more aircraft and my normal range.

I've played around with the params of dump1090 (gain, agc) to no avail.

Powered it from a usb hub incase of power issue... no result.

If I connect using sdr# I'm getting clearer "pulses" without lna... the total opposite of what I expect???

Spent most of today "playing" .. It's frustrated me enough to register on your site! :)

Hope someone can work it out and share the secret.

GaryG
Posts: 60
Joined: Wed Jan 30, 2013 1:26 am

Re: New CHEAP LNA

Post by GaryG » Sat Sep 06, 2014 11:10 pm

A thought re the RTL not seeming to work problem.

The LNA is a broadband amplifier and I am now thinking the gain at 1090 is not very high in comparison to lower frequencies. What you are describing and what I saw when I connected my LNA between the 1090 filter and my SBS-3, I'm now wondering if the LNA is creating a lot of low frequency noise that's overloading the receivers thus causing 1090 reception deterioration. When I put the 1090 filter between the LNA and the SBS-3 it works fine but perhaps part of the improvement is caused by the 1090 filter blocking all the lower frequency signals from reaching my SBS-3.

The only way I can think of to test this theory is to put a 1090 pass filter between the LNA and the RTL. It's beyond my skill level but that could account for why, with my setup, that it works better before the filter where in theory it should have worked better after the filter. I guess a Spectrum Analyzer could answer this question and I'm sure lots of us have one to check if this thought is correct ;-)

GaryG

jonfear
Posts: 365
Joined: Sat Feb 09, 2013 12:15 pm
Location: Wick St Lawrence
Contact:

Re: New CHEAP LNA

Post by jonfear » Sun Sep 07, 2014 7:23 pm

Just bought one of these:

http://www.minicircuits.com/MCLStore/Mo ... 7714151058

I too have been having trouble with the RPi seeing the signal though the LNA and decent antenna. Works fine with the GSM antenna which is badly out of band so I suspect far too much gain swamping the front end...I will let everyone know.

Jon
http://www.360radar.co.uk, the new name for MLAT Radar in the UK and Western Europe.

Former PP feeder Bm. No longer feeding. I do not have time to sort out imaginary problems with NTP
when it has been working fine for 2+ Years.

milairuk
Posts: 34
Joined: Wed Apr 09, 2014 8:12 pm
Location: Chelmsford, Essex

Re: New CHEAP LNA

Post by milairuk » Mon Sep 08, 2014 8:28 pm

jonfear wrote:Just bought one of these:

http://www.minicircuits.com/MCLStore/Mo ... 7714151058

I too have been having trouble with the RPi seeing the signal though the LNA and decent antenna. Works fine with the GSM antenna which is badly out of band so I suspect far too much gain swamping the front end...I will let everyone know.

Jon
Here's one I made with single sided PCB and a sharp Stanley knife !!
CIMG0400.jpg
CIMG0400.jpg (37.27 KiB) Viewed 3945 times

jonfear
Posts: 365
Joined: Sat Feb 09, 2013 12:15 pm
Location: Wick St Lawrence
Contact:

Re: New CHEAP LNA

Post by jonfear » Tue Sep 09, 2014 7:54 pm

Ok John

That got my attention! Please tell us more, parts list etc? Looks like double sided FR4 sub-strait. I do love to fiddle with this like this...

Jon
http://www.360radar.co.uk, the new name for MLAT Radar in the UK and Western Europe.

Former PP feeder Bm. No longer feeding. I do not have time to sort out imaginary problems with NTP
when it has been working fine for 2+ Years.

vincem
Posts: 1
Joined: Sat Jun 14, 2014 5:54 pm

Re: New CHEAP LNA

Post by vincem » Tue Sep 16, 2014 6:00 pm

I've just fitted one of the CosyCave amplifiers to my setup and the results are very good - I have gone from around 25 aircraft tracked to 65-70 now so money very well spent there.

jonfear
Posts: 365
Joined: Sat Feb 09, 2013 12:15 pm
Location: Wick St Lawrence
Contact:

Re: New CHEAP LNA

Post by jonfear » Tue Sep 16, 2014 9:05 pm

All

I found that I had to install a 1090 filter, this really cleaned up the signal. I think that would be a good modification for what seems a reasonable bit of kit.

If Cosycave can persuade the designer to fit a 1090 filter, they will sell an awful lot of these!

Just added our 26th feed to VRS World!

Jon
http://www.360radar.co.uk, the new name for MLAT Radar in the UK and Western Europe.

Former PP feeder Bm. No longer feeding. I do not have time to sort out imaginary problems with NTP
when it has been working fine for 2+ Years.

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