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Monday, 13 May 2019

Off-Topic: I am selling my house! Anyone interested?


I am selling my house and thought that some of the readers of my blog might actually consider moving to Portugal...

Here is the a link to all the information:

This house is around 15-20 minutes from downtown Porto and about 10 minutes from the airport.

It is discrete from the outside, but offers much space and even has a small gym with finish sauna.

The house is in a very quiet neighbourhood and can be left closed for long periods of time - ideal if you want to live half a year in Porto and half a year somewhere else.

Oh... Internet and cable TV is available with the latest technology (up to 1GBit/s).

Let me know if you are interested!.


Monday, 22 April 2019

Quick preview: Gone are the notches of the SMA/NWT devices!


Everyone using the SMA/NWT/D6 devices know that there is this issue with the "notch" that appears on transponders/signals with less than 500kHz bandwidth.

See full description of the issue here:

It looks like this:

Well, I am proud to announce that today I finished the top item on my TODO list, regarding the VMA Simple Spectrum Analyser software: an automatic removal of these notches!

When this function is activated, the software will look for the notches and filter them out. This is not 100% correct, I know, but the spectrum does look much better and many measurements that were not possible before, can now be done.

This is how the same signal looks with the "Notch" checkbox checked:

The "notch filtering" will apply to all traces/measurements!

Here two more samples of my local FM radio band.

Without "notch filtering":

With "notch filtering":

Notice how the radio station frequencies can now be recognized correctly, because the notches are not messing up the center frequency of the carrieres/transponders.

The new software version will be published soon - there still are some fixes required.

New version available for download!


Monday, 15 April 2019

New "Simple Spectrum Analyzer" device: meet the D6 JTGP-1033


Some of the users of my VMA Simple Spectrum Analyser software have pointed out that there is this rather new device being sold on AliExpress:

The first thing that strikes the eye is the price of just US$55.68/€49.98 and that includes shipping!

And yes, it comes with two ADF4351, which means that this device is a direct competitor to the NWT4000 - at less than the third of the price! How is that even possible?

Well, I ordered one to check it out...

I had to wait a long time for the package to arrive, due to the fact that I placed the order on the first day of Chinese New Year holidays (they deserve holidays, too), which meant that the order took two weeks to get processed. Another month later, it arrived without having gone through customs, which was nice.

The package included:

  • one D6 device - just the PCB without any case, as shown in the folloowing two pictures
  • one rather high quality USB cable
  • two SMA cables
  • a small bag with three M810 IC's - note that these are the components that break if you attach a DC current to the IF or if you exceed the maximum input power (I think it is +10dBm, but I normally don't dare to go above 0dBm)
Here are two pictures of my D6 PCB:

It seems I got the v2.03 revision. I know there is a V2.032 revision, too, but I have no clue what changed.

Also, when the order was processed, I received a download link that included the usual WinNWT/LinNWT software that Chinese sellers bundle with this range of devices.

Note that this is not legal, as the author of WinNWT/LinNWT has not given any permission for them to do so. On a side note, the author (DL4JAL) of this software removed it completely from his website! I assume he got fed up with all inquieries of unhappy users, when he did not have anything to do with it! WinNWT/LinNWT was programmed in the context of German "Funkamateur" magazine ( for the NWT-9 and NWT-500 range of original devices.

Interestingly and to my great surprise, the provided arquive did include much more! It has the full SDK of the D6, including schematics and even the source code of the firmware!

It actually gets even stranger, as the arquive included the SDK for a whole range of other RF products, commonly sold by Chinese online sellers.

And, yes, the archive included Keil (, along with a keygen to activate it...

Anyway, I hooked up the D6 and started my software and the first thing I noticed is that my software freezes in the middle of the first sweep. After restarting my software, the sweep works fine and noticably faster than with SMA/NWT devices. The refresh rate is about 3 times faster, so you get an almost real-time spectrum (about 1-2 FPS). And it does not matter if you select 500 or 1000 samples.


But unfortunately, the second thing I noticed is that the noise floor is at around -70dBm, that is 10dB more than the SMA/NWT devices). Thus, the sensitivy is much lower.

The following two pictures compare the same signal measured with the SMA and the D6:

Picture 1: DVB-T transponder at 754MHz as seen by the D6

Picture 2: DVB-T transponder at 754MHz as seen by the SMA

Another particularity of the D6 is that the TG (Tracking Generator) functionality is activated by a small button on the PCB, rather than being always on like on the NWT.

It does work and my initial tests were to my satisfaction. Finally a cheap device that allows antenna tuning and filter measurement!

Task #1: Fix my software to support the D6 without the freezes. I am happy to say that this has been done and you can download a new version of my software with support for the D6! You need to select this device in the SETUP tab (it is the last on the list).

Task #2: Try to compile the firmware source code. After some struggling I was able to set everything up and I am now able to compile the source code. This will allow me to try to implement a few changes to hopefully speed up the spectrum refresh rate.

Task #3: Flash the compiled firmware. This requires a programmer like this one:

Warning: Don't buy the cheapest offer of this kind and make 100% sure that you are buying the ST-Link V2 device. My first purchase arrived, but I got a simple USB-RS232 PLL interface, which looks exactly the same. Got a refund from eBay, but still annoying! Look at all the pictures of the offer, as often the first picture shows the ST-Link V2 but the other pictures show what you will be really getting...

After getting hold of the ST-Link V2 (clone) and downloading the ST-LINK Utility (Freeware), I tried to program the device - but it took me a while and with the help of my friend CT2IOK, who told me the correct pin-out, I was finally able to flash the firmware I compiled. That was of course after reading out the original firmware (no protection, thank God!).

Here is the connection diagram:

Looking at the JTAG connector on the PCB, you will see pin 1 identified with the "+" symbol (3.3V).

Connect the ST-LINK V2 as follows:

   SWDIO > 4
   GND   > 3
   SWCLK > 2
   3.3V  > 1 (+)

So we now have a working original firmware backup and the possibility to change/improve the firmware. Great!

In fact others have already started to do so:

This left me with the bad performance of the D6. But I was pointed to this great development:

David F4HTQ describes how he modified the D6 and got an astonishing improvement, that makes the D6 rival the NWT!

David is the author of "SNA Sharp", another software that interfaces the SMA/NWT/D6 class of devices. Make sure to try it out;

Another modification was done by CT2IOK: he replaced the 25MHz TCXO with a better one (FOX924), which improved frequency stability and resulted in a correct frequency reading.

I have to implement these modifications when time allows, but meanwhile I made a case for the D6:

I printed it using the Markforged printers in our office:

If you want to try and print the case yourself, here are the required STL-files. Note that you need a rather good quality printer precision-wise, as the STL files are a close fit for the PCB and leave only 0.5 mm margin around it.

Let me know about your own modifications, enhancements, etc., on this very promising device!


Sunday, 24 March 2019

VMA Simple Spectrum Analyser - HP/Agilent 8590 Series Version: New functionality!


I have continued development of the "VMA Simple Spectrum Analyser - HP/Agilent 8590 Series Version" software and here are some nice screen shots:

Bug fix: Now the automatic transponder recognition works correctly!

The same for bandwidth measurement!

This picture shows LIVE, MIN, MAX and AVG traces. Note that Marker 1 is on top of the DVB-T transponder, while Marke 2 is on the noise floor, allowing measurement of delta-frequency and delta-power.

This is a brand new tab, only available in this particular software version: the GPIB File Manager allows copying and editing of DLP and KEYMAPS!

DLP are user programmable programs made in the 8590 series script language. This offers many possibilities to enhance the functionality of these devices.

In fact, HP sells "Personality Cards" containing DLP programs for a variety of measurement applications.

Use this tab to download/upload DLP files and edit them!

The  "VMA Simple Spectrum Analyser - HP/Agilent 8590 Series Version" software is not yet available on the download page, but feel free to contact me if you want to try it.


Friday, 1 March 2019

VMA Spectrum Analyser for HP 8590 Series: First version released!


I just released the first version of my "VMA Spectrum Analyser for HP 8590 Series" software.

Because both my units are still waiting for their respective PSU's to be repaired, I cannot really test the software, but it should work just fine.

You need to use Keysight Connection Expert 2018 and copy&paste the GPIB address into my software. It should not matter if you use a GPIB interface or the serial port, as long as you have the HP/Agilent 8590 Series connected through Keysight Connection Expert 2018.

The software should work with any of the 8590 series (HP or Agilent).

As usual, you need to download the software, extract the zipped folder and run the executable.

You will be guided through the SYSTEM CODE generation, which relies on the selected MAC Address. Send me the system code (v m a AT n o r c a m DOT p t) and I will send you back the required ACTIVATION CODE.

Download the software here: VMA Spectrum Analyser for HP 8590 Series


Saturday, 23 February 2019

VMA Simple Spectrum Analyser version for HP/Agilent 8590 series coming up!


I bought two broken 8594E (HP and Agilent) and while both were sold as broken, the HP unit does work, but with an unstable PSU.

While I am in the process of repairing both units, I already started development!

Here are some first in hand pictures:


Tuesday, 15 January 2019

New version of the SMA Simple Spectrum Software available and some bad news related with Google Maps!


After quite some time, I once again updated the SMA Simple Spectrum Analyser software.

No big changes, only minor bug fixes and some GUI enhancements.

But unfortunately I did notice that Google changed their Google Maps API to v3 and is discontinuing V2. This has some consequences for my software, see yourself:

The problem is that you need to have an "API key" with Google, to enable embedded Google Maps:

Basically, it is no longer free to use Google Maps in your own applications. This means that the "Log on Maps" funtionality of my software (affects all three versions: SMA/NWT, SSA3000X and CMU200/CRTU) will eventually be disabled or I may find a way that allows the user to put in his own Google Maps key.

Update (20/01/2019):

There are two work-arounds I can think of:

  1. The VMA Simple Spectrum Analyser gets a new configuration group in the setup tab for the user to insert his API key, which should be free for up to 300.000 hits/month (if I correctly understood the terms & conditions). I am not 100% sure how to implement this right now, as currently the required HTML template is static and embedded in the main executable.
  2. I could try to switch to Open Street Maps, which is a concurrent open source project ( This requires me to learn how to interface their API. Also, OSM does not include satellite images - only plain maps.
Let's see what I manage to do.

Is anyone actually using this feature of my software? Let me know!

If you don't even know what I am talking about: you can record a live spectrum with GPS and TIME staps on it.

Then you can replay this recorded spectrum in the office and select a given frequency to be stored in a separate log file, together with the respective GPS and TIME staps.

Finally, you can render this log file on a live map (currently Google Maps) and have the transmission power rendered as colored squares.

This is useful to determine reception maps, i.e. of your local DVB-T or WIFI provider.