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Sunday, 25 March 2018

VMA Simple Spectrum Analyzer for CRTU: Tracking Generator function is now supported!


One of the drawbacks of the CMU200/CRTU is the lack of a Tracking Generator. This is a useful functionality to measure filters, for example.

Well, I implemented a "software" driven Tracking Gerator:

You can download the new version here:


Saturday, 24 March 2018

VMA Simple Spectrum Analyser for CRTU: new version!


Here is a quick note to let you know that I just uploaded a new version of the VMA Simple Spectrum Analyser for CRTU (works with CMU200, also).

Besides some bug fixes and many optimizations, I added these new functions:

  1. When the Spectrum is started, it will read the current settings of the CRTU/CMU200. This way my software doesn't change any settings.
  2. You can now select the desired RF input port from my software.
  3. The GPIB address is now stored in the Registry.


  • My software uses a DLL of the Keysight Connction Expert 2018! This is the reason my software won't connect to any other VISA version.
  • You can download Keysight Connection Expert 2018 for free
  • It should run in parallel with other VISA installations (no guarantee, though... if you break your existing installation, you are on your own).


Friday, 9 March 2018

VMA Simple Spectrum Analyser for CRTU: Video posted on Youtube showing GPIB/USB interface performance! Amazing speed!


Just a quick update on my new VMA Simple Spectrum Analyser for CRTU software.

I just received the Agilent GPIB/USB Interface (waited almost 3 weeks for it to arrive from China).

Well, thanks to VISA, my software was all setup to use either RS232 or GPIB, so I just tried it out.

The results are great, as you can see on this Youtube video:

This is a great result speedwise and it motivates me to include all the new measurements and functionality that exist in the original VMA Simple Spectrum Analyser software for SMA/NWT devices.

Stay tuned!


Friday, 2 March 2018

ADALM-PLUTO ("Pluto SDR"): First hands-on impressions...


Here is my first experience with the ADALM-PLUTO:
  • Ordered in October 2017 at Mouser.
  • Received the item February, 28th 2018 - almost 5 months later... Patience is a virtue.
  • I paid a total cost of 90 Euro with shipping included and no customs issue.
  • Once the product was in stock at Mouser, shipping took 2-3 days.
What is in the box?
  • 2x Small SMA antennas
  • 1x SMA cable (female to female)
  • 1x USB Micro cable (like the ones used for modern smartphones)
Note: You need a USB charger to power the ADALM-PLUTO. It has two Micro-USB connectors, one is for connection to the PC, the other is for the power supply!

First steps (I only used Windows 10 @ 64bits so far):
  • Downloaded and  installed the drivers -> no issues
  • After reboot, I opened the browser with and got the ADALM-PLUTO welcome screen. Note that it does not matter that your PC is on a different subnet! This got me slightly confused in the beginning. Just type this address and off you go.
  • Did a putty connection over COM port at 9600 baud. Did the "hack" with no issues. This will increase the bandwidth from 70MHz up to 6GHz.
You just need to type these two commands on the PUTTY remote connection (note that on the telnet screen, the user is "root" and the password "analog":

# fw_setenv attr_name compatible
# fw_setenv attr_val ad9364
# reboot
  • Tried SDRsharp with the plugin -> no issues, but performance is much worse than with HackRF One (max. bandwidth is 5MHz, while HackRF One manages 10MHz without any problem - no sound clicking or other issues).
  • Tried sdrangel -> works great (albeit with smaller bandwidth than the HackRF One). Had issues with the TX plugin, turned out that Windows Protection thinks that one of the output sinks is a malware and deletes it. Made a rule to not scan sdrangel folder and now it works fine.
  • Tried Matlab -> works fine, but costs money (I have access to Uni license) and seems very similar to GNU Radio. Not sure what the benefit of having Matlab is, as I am not literate in Matlab.
  • Tried GNU Radio -> No sink to support Pluto SDR under Windows available: bummer
So far I was not too impressed by the ADALM-PLUTO, compared with the HackRF One. The "hackrf tools" included for the HackRF One, that allow to record and replay frequency ranges are pretty awesome (using hackrf_transfer). Also, there is more software available for the HackRF One, with much better support for Windows. Finally, you get a bigger effective bandwidth with the HackRF One.

Tried DATV-Express: AWESOME!!! This tool alone makes the purchase worth it. Being able to generate a DVB-S/DVB-S2 transponder that you can use to test SAT-Receivers without having access to a dish is amazing, especially considering that the hardware costs just 90 Euro! I have several Dektec Modulators, which cost a few thousand Euro (well, they support much higher bandwidth and functionality, but that is not the point).

I did have some issues with DVB-T, as the two field meter I tried only support 6, 7 or 8 MHz bandwidth. The ADALM-PLUTO does not support a continuous stream at this rate, so I couldn't test it further.

But DVB-S/S2 is great!


Much potential for the ADALM-PLUTO ("Pluto SDR"), at a great price but with an unacceptably high waiting time. This seems understandable, because the demand must be overwhealming. I cannot imagine this tool being actually used at schools, as you simply cannot get hold of it.

But I predict that many cool software applications will emerge for this product, once it is more easily obtainable.


Sunday, 25 February 2018

VMA Simple Spectrum Analyser for Rohde & Schwarz CRTU (works with CMU200, as well)


This picture says it all:

I just ported my "VMA Simple Spectrum Analyser" software for the Rohde & Schwarz CRTU!

It should work fine on the Rohde & Schwarz CMU200, as well, since it is the same base device.

Everything is working fine at this point, however, you need the following pre-requisites to get the software working:

  • You need a CRTU or CMU200 (of course)...
  • You need to have OPSW v5.x installed and activated
  • You need to install Keysight Instrument Control
  • You need to setup a GPIB to USB interface for fast spectrum refresh rate
  • Alternatively, you can use a RS232 connection setup at 115200 baud

  • This is still an early beta version. There are bugs and the software may not work for you.
  • A license is required. Run the program and follow the license assistant to generate a System Code. Send it to me (vma AT norcam DOT pt), you will receive a temporary Activation Code.

The following has NOT been tested:
  • Connection through GPIB-USB interface: I am waiting to receive mine...
  • CMU200: I only own two CRTU
  • Connection of a GPS receiver: should work, but obviously may not use the same COM port as the CRTU/CMU200
Please note the following:
  • If you set RBW too low, making a sweep take longer than the RS232 timeout, an error will happen. You may need to exit the software and open it again.
  • When the software crashes, it can happen, that the CRTU gets stuck on REMOTE mode. Restart the software, click on START and then on STOP to free the CRTU.

Sunday, 11 February 2018

And here is a GREAT video on the Fourier Transformation!


Ever wondered about the math behind spectrum analisys?

I have and though I have the basic understanding, I did enjoy this video so much, I decided to share it on my blog:


Sunday, 14 January 2018

VMA Simple Spectrum Analyzer: New version that allows measurements on the selected trace!


This was for a long time on my todo list: being able to carry out all measurements on the selected trace, instead of the LIVE trace.

Up to now all measurements like the bandwidth measurement would always consider the LIVE trace only. This was limiting, since other traces could be more useful. For instance, the MATH trace could have been configured to consider a compensation. This made it difficult to read the desired value of traces other than the LIVE trace.

I added a new ComboBox on the trace section (lower rigth side of the window): select the trace you want to base all measurements on and off you go! The software will show dB value of the mouse or any other measurement based on the selected trace.

This works with the MATH trace, as well, which was the hardest part to implement.

Hope you like it.