NASA DWPR 2015-07-30 Interference @ 50 MHz

NASA Form to report reception of this sort of interference

These two video's show the NASA KSC DWPR very strong into the 50 MHz Amateur Radio Spectrum allocation.  These video's show 2.5 MHz of spectrum starting about 49.000 MHz. 

To view more like this back as far as 2011 visit this YOUTUBE Playlist

The following is what the DWPR might look like if you only have a limited spectrum display.
Note the ON/OFF nature of it.  Also the Spacing between carriers changes as the pattern changes.  Sometimes they'll be closer (more of them) sometimes less.

Click to Zoom

This Radar's location is at about EL99pp Maidenhead Grid Square.

• Work Begins to upgrade drwp @ NASA
• KSC writeup on DRWP
• Some detail about the system
• More in-depth Detail
• ITU M.2013 mentioning WPR @ 50 MHz
• 50 Mhz Doppler Radar Wind Profiler Filters

HackRF One - EXTIO DLL - HDSDR (WORKS!)

I've been searching for an EXTIO DLL for the HackRF One that will work with HDSDR for years now.

https://github.com/jocover/ExtIO_HackRF

Finally came across this today!  AND BONUS!  IT WORKS!

I contacted the author and asked him to add some smaller sample rates of 4 and 2 MSPS.  He did that and posted the new release in just about 1-2 hours.  This is useful for weak-signal stuff I most do.  It allows the ability to get HDSDR's "Resolution Bandwidth" down to 7.6 hz when MSPS is @ 2.  Which in my experience shows weak CW signals up very well!

A little about how I use HDSDR. 

I use the 9 MHz IF OUTPUT from my Yaesu FTDX-5000 as the input source to whatever SDR I'm using to feed HDSDR.   I've been using a TCXO based Nooelec RTL and an OCXO upconverter I built myself.  Even with all that 'stability' the TCXO RTL drifts all the time.  Which is a total pain in the butt for CW over the coarse of a day.

After swapping out the EXTIO for RTL in my HDSDR install I fired it up with HackRF.   Although the HackRF has advertised a low range of 30 MHz or my experience has been that it works just fine down as far as 3.5 MHz in it's stock config.  Mine is about 1.5 years old now with recent firmware installed.

Anyway I setup HDSDR initially to use 9,000,000 hz.  HDSDR has a nifty option to display the VFO frequency of the Yaesu FTDX-5000 as it's frequency regardless of what input you're really using (9 MHz in my case).

There is also a way to automatically remove the DC Spike that would show up in the middle of the display if left as noted above.  To accomplish this I set the OPTIONS > RF Front-end Frequency "IF frequency" to 9098000 and the Global Offset to 98067.  This pushes the DC Spike well below my normal viewing area, and then the 'Auto RX DC Removal' notches it down to nothing.

In this way the DC spike goes away but everything stays lined up PERFECTLY for CW.

I also connected a GPSDO I've had around for a long time that I use with my Apache Labs "Hermes" SDR.  Tee GPSDO emits a super stable 10 MHz signal that Hermes and now the HackRF lock onto.  

In a 24 hour test just completed there was 0 hz drift noted on the HackRF.  Which is what I had expected (and hoped for).  This has been my experience with the GPSDO and Hermes so I didn't expect any difference.

------------

So all of this Eliminates use of an RTL (which are drifty little bastards, but VERY VERY useful I've used them for over 5 years now with very good success), and because the RTL's are limited to 24 MHz I have always used an Upconverter which has the potential to add noise from it's OSC, and add drift to the resulting signal input to the RTL.

I'm using the HackRF because it's what I have currently and because this EXTIO is now FINALLY available.

I plan to also buy and test the AirSpy and SDRPlay at some point since I've read they hear better than the HackRF.  BUT at this point I think I can actually relax after years of muxing around with RTL's that drift like crazy and spending way to much to make a $8 device do something it doesn't really wanna do LOL.

Time will tell, but for now I'm setting my upconverters and RTL's to the side to collect some MUCH NEEDED DUST.

Double Conversion Frequency Upconverter

The 100 MHz upconverter I've built seems to work VERY well.  I don't have any complaints as it is right now.

For the sake of experimenting, and trying to learn I've decided to try to increase the distance between the LO and the Pass Band.

In the 100 MHz upconverter there's only 9 MHz between the LO and the final pass band.  I want to try to increase that distance to have as much reduction of the LO in the final pass band as possible.  (I don't think this is required to be honest, which is why I already mentioned this is for the sake of experimenting).

I enjoy working with RF Filters so I thought this would be a chance to build two of my own (and spend some more money on an already completed project LOL).

So the idea I'm going to try looks something like this block diagram below including the filter designs to reduce the LO(s) as much as possible.

This is all subject to change, but I just wanted to post the idea I'm playing around with at this point.  I will also have available a MK-3 by mini-circuits which is a frequency (doubler) Multiplier.  I may play around with that, and then rework the filters again.  But that's just something I was kicking around with.  I could (I think) use it at the 19 MHz Mixer on the 10 MHz LO and end up with 29 MHz out of that mixer (I think), which would make it even easier to build the second LO BPF since there would then be 29 MHz from the 100 MHz second LO and the final pass band.  That's just something I've been toying with in the back of my mind.  Again I don't really thing any of this is needed at this point.  My 100 MHz upconverter is working great (so far) even in the face of some very strong signals.  I just want to learn more is the bottom line.  

Parts for this modification have already been ordered.  So this is the next revision based on my 100 MHz up-converter noted previous on this blog.

HF Upconverter - Assembly and Initial Testing

SUCCESS!

After a few days or working on my new HF Upconverter I got it working!  I'd been waiting for some Buck type DC-DC converters.  So I could connect the OCXO (3.3vdc) up to the 13.8vdc from my primary Astron RS-35M.  One of the Buck converters drops 13.8vdc to 12.0 vdc, then a second one drops it again from 12vdc to 3.3vdc.  They seem to be working fine.  The 12vdc is variable.  The 3.3vdc is not which is kind of a bummer, but it's at idle on my Fluke meter 3.29vdc. (probably close enough although if I'm going to the trouble of an OCXO I'd like the PS's to be adjustable).  I'll probably hunt around for a Buck DC-DC 12-3.3vdc that is adjustable.  These things are CHEAP on ebay.  Total spent on both was around $15.00 combined including shipping.  Which beats spending hours building them at this point.

I am running the OCXO HF upconverter right now as I type this, and it seems to be rock solid so far.  No FM Bcast interference (which I didn't think I'd have with all the shielding).

I have a fair amount of work to do yet on this.  However, the fact that the SBL-1+ Mixer and the OCXO work as expected is definitely encouraging.

I am listening right now to 14 Mhz Morse Code on the FTDX-5000 and also on SDR# at 109 Mhz.  (remember the FTDX-5000 uses a 9Mhz IF Output that I'm tapped into, so the actual VFO frequency is irrelevant since all signals are sent out in the 9 Mhz realm.

Anyway...I just wanted to post that as simple as this is right now and working as well as it is, I can't wait to add the Lo and Hi pass filters to my Homebrew HF Upconverter that is accurate to within 200ppb (that's parts per BILLION)!  NO DRIFTING has been noted in my testing thus far.

Tomorrow I'll start it up from cold, and see if there is any noticeable.  I'll also post some updated pictures of where the project is now.

Things are subject to change until I setting on a mixer.  While the SBL-1+ works fine I'm curious how well the the other two I ordered from Minicircuits will work.  The are supposed to be better, and certainly should be at 4-7x the cost of the SBL-1+ (which was only $9.95).

This is FUN STUFF!

100 Mhz OCXO 200ppb For Home Brew Upconverter

I still have some work to do on this.  The closest (bottom left) (pin 1) large pad get +1.15-2.15vdc via resistor network voltage divider that bridges over from the large pad behind it  (pin 14) that is the +3.3vdc Power Supply pin.

The SMA is the 100Mhz @ 200ppb output from the OCXO which comes off pin 8.

The resistor network I was talking about is a voltage divider in the standard configuration of R1 and R2 except that I've slightly modified it to include a 1-turn 1000 Ohm Potentiometer which should allow fine tuning the OCXO by as much as -500hz and +500hz.  Hopefully this won't be needed much as that the point of having the OCXO to start with, but it simplifies retouching tuning quite a bit and seemed simple enough to add (as long as my design holds up!).

There will be a KNOB on the front of this which allows easy access for tuning the OCXO to mate up with the signals on the 9 Mhz output of the FTDX-5000.  INSTEAD OF having to go into HDSDR software's option menu and extio menu to adjust things (WHICH DRIVES ME NUTS!).

I hadn't realized that I had to provide a Vcc for pin 1 initially, and at first when I discovered this I didn't really like the idea.  Still not sure I do frankly, BUT since it adds a feature I hadn't thought of to start with I figured why not make it something I can make use of, instead of simply setting pin 1's voltage to 1.65vdc which SHOULD place the OCXO at 0pmm/0hz offset from 100 Mhz.

This "feature" provides a much as 1 full Khz adjustment (I think, according to the doc's I've read).

HF Upconverter - Home Brew (sort of)

(smoke testing components)

(Partially built, still working on final placement)

The TOP SHP-100A+ which is a HP Filter feeding the RTL Dongle is going to get replaced with a High Pass Filter I'm going to build.  My own filter will be VERY sharp and drop the 100 Mhz Carrier from the Oscillator down about 53db from where it is now, while leaving 107+ Mhz open.  My Filter will have about 5db insertion loss at 109 Mhz, but I'm also planning to add a LNA after the filter which will allow me to overcome that loss somewhat.

The Empty space top LEFT will contain a +20vdc DC-DC boost converter as well as a LM117 voltage variable regulator +17vdc to 1.2vdc to power a 41db voltage variable Attenuator and a pot will be added with a second knob to control it.

I'm also planning to add a PTT actuated RF Relay to switch out the RF input when my primary radio (and FTDX-5000 transmits) as I don't like the output of my Transmit via the 9Mhz IF output showing up in my Pan Adapter output.

The only dismal be at this point is that the Nooelec 0.5ppm RTL Dongle doesn't really seem to be living up to what I'd expected.  From a cold start it takes 15-30 minutes to (mostly) stop drifting.  But I suppose that's what you get with a TCXO (I don't really know).  I do know at cold start up it drifts in excess of 700 Khz, before it's really starts to settle down.

This is NOT the fault of the FTDX-5000 or the featured 100 Mhz upconverter I've built.  The upconverter after about 45 seconds basically doesn't drift.  It's pretty amazing and well worth the $74.00 I paid for it (for my needs, it's worth it anyway).

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I've started to work on building my own HF upconverter that will use an OCXO that is stable to 200ppb (that's 200 parts per BILLION!), not something typical like the 25ppm, 5ppm's that are commonly available for a very reasonable cost.

(click to see larger)

The idea here is that I am primarily a CW operator.  My current Pan Adapter setup runs off the 9 Mhz IF output from my Yaesu FTDX-5000.  This then routes through a LNA, Bandpass Filter, and into an HF Upconverter where it comes out at 134 Mhz...this is where the RTL SDR Dongle operates via HDSDR.

I had a RTL SDR Dongle which was stable to about 60ppm, and the HF Upconverter was stable to about 25ppm for many years.  This meant that there was almost always some dicking around involved with keeping the Pan Adapter Software "HDSDR" lined up with the FTDX-5000's stable IF output.  Thing could drift at least for several hours slowly up the band until it warmed up and as long as the Temperatures in the room didn't vary too much things were 'close enough' to be useful.

NOW I have a 0.5ppm RTL SDR Dongle.  This thing is quite accurate, however my old HF Upconverter was still only accurate to 25ppm.  So I swapped out it's 125 Mhz LO with a TCXO that was stable to 5ppm (more or less, mostly LESS) the net result was that after about 2.5 hours the total drift was around 1.1Khz.  This is still REALLY CRAPPY for CW (Morse Code) which is very narrow bandwidth.

While Talking to Nooelec.com recently we swapped emails back and forth for quite some time.  I found better TCXO's, and then came across the idea of using an OCXO.

The benefit of an OCXO is that they warm up VERY quickly compared to other LO's and once warmed up remain VERY stable.  Trouble is I could only find an OCXO that is in the 100 Mhz LO range which could get me to the 200ppB level at a reasonable price and delivery time.  So that's what I'm going with for this little mini project.  The downside to using a 100 Mhz LO is that the output of the 9 Mhz IF from the FTDX-5000 will be one 109 Mhz.  Pretty close to the FM Broadcast band.  In the past I've not had a lot of trouble with this sort of thing, mostly because I used a FM Broadcast Band STOP Filter in line with everything.  

So I can't really use the Band STOP Filter anymore.  However, this may not really be a problem.  The LNA4HF has a LO Pass filter, which should keep anything > 30 Mhz out of the primary input.  So that will help.  I'll keep all the coax lines very short (just a few inches) and use female-female type connectors to link all the components together.  I'll also keep everything shielded, and grounded as best I can.  I think this will work out ok.  

I'm planning to use an LNA4HF which includes a LOW-PASS filter in it already.  This then will route to a Mini-Circuits SBL-1+ Mixer.  Also I'll be using a 100 Mhz LO (200ppb) going into the SBL-1+ Mixer.  Output of that will route into the RTL SDR Dongle from Nooelec.

This "SHOULD" result in a MUCH more stable upconverted signal being fed into the RTL SDR Dongle.  That's the plan at this point anyway...this is sort of a side-project, but I wanted to share my thoughts on attempting to do this.

This is a review of a similar device and should help if you don't quite understand the problem I've been describing. 

I'll post more details on the various bit's and pieces I use and pix of the finished project when I'm done.

Also a Note: Nooelec.com says they're working on something new that may resolve all of this within 10-12 weeks, and something else in the range of 3-6 months.  They wouldn't indicate what exactly they were talking about.  So that's why I'm moving forward with this little end-of-winter mini-project.

More details and where to get the various components I use as I get them.  Most of this I already know, but some may change.  So...stay tuned. (no pun intended! HAR!)

Here is a list of what I'm planning to use and where I got them:

• Nooelec 0.5ppm RTL SDR Dongle
• 100 Mhz OCXO (200ppb) (3.3vdc) [datasheet] - [MORE DETAIL ON THE BUILD]
• LNA4HF (12vdc)
• 13.8 to 12vdc Buck Converter (test may not use this)
• 3.3vdc Buck Converter (to power the OCXO from a 12vdc supply)
• Mini-Circuits "SBL-1+" Mixer

Here is an example of how simple this really is:

VIDEO (Adam Alicajic)

VIDEO (W2AEW)

While this is super simple to setup as seen in his video, I expect that I'll have some technical issues getting this to work as well as my "Ham It Up v1.2", at first.  But that's OK, because it should be way more stable than the Ham It Up since it's using an OCXO.  (I sure hope).

Anyway, this is going to be a learning experience for me.  I've never done this before, at least not like this.  I'll post mod's to this plan right here on this page as updates.  

One thing I'd like to do is in front of the LNA4HF would be to place a 9 Mhz Band Pass Filter that is 2.5 Mhz wide.  I don't really know how wide the 9Mhz IF is coming out of the FTDX-5000 but it seems to be at least THAT wide.  THE LNA4HF's LO Pass Filter should keep a lot of crap out of things to start with.  This idea is just to have more control of what gets in is all.

I MAY have to attenuate the OCXO output a bit, I've heard these things can be really strong, and if so I may have to use some in line attenators at least I may have to experiment around with that some.

I added some more filters after reading THIS and THIS to my design.

WARNING: my resulting design is meant to be modular enough to I can play around with OFF THE SHELF things as I wish.  This isn't a FROM SCRAP project and therefore it's a LOT more pricey than it would really need to be.  So be advised I'm already aware that I'm going at this from an expensive direction, and that there are cheaper ways to get/build filters etc.  This is intentional for what I'm attempting to do.  

NOTE ALSO: I'm aware that it's possible to get and use OTHER LO frequencies for this upconverter and that using a 100 Mhz LO can be problematic.  (so you don't have remind me :-)

Mixers I will test with:

The SBL-1+ from MiniCircuits looks like THIS.

The ZX05-1L+ from MiniCircuits looks like THIS.  (but costs 2/3 more @ around $37.00) It's advantages include already mounted SMA connectors all around.  Specs aren't the same as the SBL-1+ but they are similar enough that I may try one of these in the future. UPDATE I actually have ordered this, and one other similar.  I believe this mixer is +3db and the other one I ordered similarly configured is a +7db.

The ZP-10514-S+ from MiniCircuits looks like THIS. (and costs about 2x as much as the ZX05-1L-+)

100 Mhz LO 2x Frequency Multiplier Idea:

The ZX90-2-13+ from MiniCircuits looks like THIS. Depending on how strong the OCXO output really ends up being it may be possible to use this device (with it's 11db loss) to 2x the 100 Mhz output of the OCXO up to 200Mhz.  The Mixers above should handle that frequency range.   This would make the output in my setup from all of this to be at 209Mhz which would avoid the issue of the FM Broadcast band on the output to the RTL Dongle.  This item is simple SMA type connectors (plug and play) so would be easy to test and the price is reasonable around $35.00.  (I haven't ordered this, but keeping the idea in my mind).  The reason this might be useful is if the RTL Dongle needs to be placed far away from the upconverter, the output of the upconverter would be 100 Mhz higher than the FM Broadcast band....and EASILY filtered out with a band stop filter if needed.  I honestly don't think I'd need to go this route, but it's something to consider, for many reasons.  Lets say you wanted to use a different OCXO frequency because it was cheaper or something, this might help you get he output into a range that's more to your liking.  It has a fair amount of loss so the LO would really need to have some decent output (I think) but anyway...I just didn't wanna loose this detail in case I want to play with it later.

Everything for this has been ordered, and now I wait.  I'll post updates and pictures as things progress right on this post page.

[MORE DETAIL ON THE BUILD]

(OCXO with Controllable Voltage Divider to Pin 1)

(subject to change, just a starting point concept)

After some reading I settled on using this OCXO it's a +2dbm 100 MHz 200ppb

I have several Mixers at this point.  I have an SBL-1+ which is a +7dbm mixer, a ZP-10514-S+ which is also a +7dbm mixer, and THIS ZX05-1L+ which is a +3dbm mixer.

After further reviewing the spec sheet for the OCXO I have it appears to me that the +3dbm mixer is probably the best choice of the bunch.  While I don't see a lot of difference in the Spectrum being displayed I suspect this +3dbm is better matched to the OCXO output. (I'm kind of guessing based on a very basic understand).

Nice Power Line Noise Visualization - HackRF, SDR#, VAC, and Spectrum Lab

I wanted to get a real nice noise signature of the Power Line Noise issue here.  What I ended up doing was to use a Windows 7 machine (for a change).  I used the following:

• SDR# 'sdrsharp'
• HackRF One
• Spectrum Lab

The newer SDR# includes and Audio FFT however, I'm unable to resolve how to alter the bandwidth of it down to < 1 Khz in audio frequency.  It seems STUCK at 0-18Khz or so.  This is too wide to be able to really see the 60hz spike and it's harmonics of 120hz 180hz, and so no.  They just don't even register in it's FFT for some reason.  SOOO....

Since the built-in Audio FFT doesn't resolve down to < 1Khz I setup trusty Virtual Audio Cable (I use line 2 for this, because other software I use uses Line 1 already).  So this pipes the AM audio out of SDR# via Virtual Audio Cable (Line 2) and then I setup Spectrum Lab to listen on that same VAC line.

Turns out this is PERFECT.  It's as good, but even better in that there's a TON I can inside Spectrum Lab, like line graphs, alerts, etc...for monitoring over long periods of time.

So here's a screen shot of Spectrum Lab (v2.78b25) setup to use VAC Line 2 (noted above) as well as SDR# below it.  

Look how simple it is to ID the 60 hz audio and it's harmonics.  Um....schweet.

(click to see larger)

I tried using GNURADIO and it's Audio Source, but damned if I can't figure it out on Windows.  It's fairly simple on Linux, but Windows is a different animal with GNURADIO.  Kinda of a let down.  It'd be nice to create flow graphs from my fancier/faster Windows machine that I could port over to my Linux machine and vice-versa but that's not happening.

Here's a few more views of that Spectrum Lab can do: