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Tuesday, 17 January 2017

Good old times... Just "found" my old site at Geocities!

Hi,

Do you guys remember Geocities? That was a free website hoster and a pretty popluar one, too.

Well, I was searching Google for JTAG interfaces and saw a familiar picture, showing my JTAG interface collection. A couple of clicks later and guess what: my Geocities page still exists!


Want to check it out? Click here: http://www.geocities.ws/dazed1970/

Cheers,
Vitor

Saturday, 14 January 2017

KWS VAROS 109: New firmware 0.9a available!

Hi,

KWS Electronic just published a new firmware version for their satellite meter KWS VAROS 109.


What is new?

Disable AFC-Function to show df
AFC (Automatic Frequency Control) 
The device operates with the AFC switched on in the standard settings. This means that if the DVB-S/S2 receiver detects a frequency offset between the transmitter and the receiver, the tuner on the receiver is adjusted accordingly so that the frequency offset disappears. 
However, if, for example, the frequency drift of an LNB is to be observed, it is useful to switch off the AFC. In this case, the device shows the frequency offset in the display (df = …).
The resolution is 0.1 MHz. The sign in front of the value is determined by the following relationship:
 
fLNB = finstrument + Δf 
with fLNB = LNB frequency, finstrument = adjusted frequency in the intrument, Δf = frequency drift
Programming via DiSEqC-Sequence
DiSEqC Script
Newer multiswitches for single-cable systems are programmable by DiSEqC-signals (like JULTEC a2CSS series). Usually manufacturers provide special program adaptors and PC-software tools. But this programming is also possible by this measuring receiver with the DiSEqC-Script function. A set of DiSEqC commands according EN 50494/50607 can be easily edited in a common texteditor end saved with the ending .dsq. Appropriate files can you get from the manufacturer (e.g. JULTEC). These files must be stored on an USB-stick which can be connected to the measuring receiver. The script function sends the of DiSEqC commands line by line over RF-connector to the DiSEqC-Uint.
Do the DiSEqC Script
First, the device has to be in initial state (running measurements stop by pressing ESC).Plug the USB-Stick containing the Script-Files to the receiver and connect the the DiSEqC-Uint via RF-Connector. Selecting LNB -> DiSEqC Script, choose one of the “.dsq-files” shown in a directory and by pressing ENTER the function starts. A window shows the first comment of the script file and the currently processed line. In the last line of the window a possible DiSEqC-Responce is shown.
Script structure
Sample of a DiSEqC-Script:WideBand mode UAS 474 2 x 950..3000 MHzE2 7F FB 40 00 00 03 52 00 00 03 52; LOF 9,75 GHz, IF 950..3000 MHzE2 7F FB FE; store data// comment

  • First line: Comment, which is show during the whole processing.
  • Further lines: DiSEqC-Commands composed of hexadecimal figures and a blank between each 2 Bytes. A command must start in the first column of a line and is terminated by a semicolon. The rest of the line is treated as a comment.
  • A double backslash // marks a comment.
  • An exception is the „18V“, which must be in an own line. Thereby the LNB-Voltage is set to 18V to create an UNICABLE standard transmission. The LNB-Voltage gets back to 14V after the next DiSEqC-Command was transferred.
This is very interesting for two reasons:

  1. Professional installers can now program many SCR devices directly with the KWS VAROS 109 instead of having to use (purchase) special programmers. This will work with all SCR devices that use DiSEqC command scripts for programming.
  2. It is now possible measure and monitor the frequency drift of the LNB, due to the fact that the AFC function can now be turned off and the KWS VAROS 109 then displays the measured frequency drift.
  3. Satellite DX'er who are lucky enough to own this field meter can use a great hack: the "Programming via DiSEqC-Sequence" can be used for something pretty cool!

    Do you remember the DirecTV B-Band Converter (BBC), used in combination with the DirecTV Ka-Band triple LNB?

    If not, take a look here: http://www.tele-audiovision.com/TELE-audiovision-1305/eng/vitorsworkshop.pdf

    Right! In order to use this LNB for Ka-Band reception in Europe, you need to use the BBC to upconvert the Ka-Band from the LNB, which downconverts the L-Band to 250MHz750MHz, to the regular 1650MHz-2150MHz. This is commonly done by modding the BBC.

    Well, with this field meter you can just program two scripts, to turn the BBC ON/OFF!
Script 1: "BBC-ON.dsq"

Turn BBC ON
E2 03 00; BBC ON
// E20300 - activate upconvertion from 250-750MHz to 1650-2150MHz

Script 2: "BBC-OFF.dsq"

Turn BBC OFF
E2 03 00; BBC OF
// E20200 - deactivate upconvertion from 250-750MHz to 1650-2150MHz

Example:

Using the script above, I hooked up my CATV signal cable to the BBC and from there to the KWS Varos 109 (which is a Satellite Field Meter, not designed for CATV measurements).


Of course, nothing will show up in the spectrum, which is rendered from 950MHz to 2150MHz, since my CATV cable only provides a signal up to about 820MHz.


Pop in a USB memory with the two scripts, they become available in the LNB -> DiSEqC menu.


I run the BBC-ON.DSQ script, which sends the E2 03 00 command to the BBC, activating it.


The KWS Varos 109 shows the progress of the script, displaying the last commented line of the script, which is pretty useful.


And "voilá" we are looking at the more than half of the CATV frequency range!


Zooming into the spectrum, we can clearly see and measure the analogue and digital CATV transponders - using a satellite field meter! Nice hack, considering the BBC can be purchased for little money at eBay. NOTE: you only get a 500MHz frequency band (250MHz-750MHz).


So, thumbs up to KWS Electronics! Always great to see commitment to products by providing new firmware with increased functionality.

Regards,
Vitor

Wednesday, 4 January 2017

Monitoring avionics communication with the VMA Simple Spectrum Analyser

Hi,

I received the ADF4351 version and here is a quick test monitoring the avionics radio frequency band.

At 121.1 MHz, pilots are communicating with the tower of the nearby airport.

On 119.0 MHz, you can see a faint signal: at this frequency the airport is broadcasting the local weather report.


Because it can take some time to register any communication, it is nice to have the waterfall diagram, which logs all communication inside the selected span.

Unfortunately, the ADF4350/ADF4351 has a rather low resolution when it comes to signals with small bandwidth. A closer look reveals, for example, that the signal at 121.1 MHz does not look right: it is an amplitude modulated signal (AM) and should not have an inverted spike in the centre:


You can read more about the ADF4350/ADF4351 capabilities in the datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/ADF4350.pdf.

Therefore I would rather recommend a RTL2832U based dongle for usage with SDR#, if you are into amateur radio applications. If you have been living on the dark side of the moon and never heard about these, then take a look here:
Notes:
  1. Airspy is the former "sdrsharp" website. They now sell the Airspy device, which is better than a regular RTL2832U based dongle, especially because it has higher resolution and greater frequency range. However, the base software, "sdrsharp" (or SDR#) is still free and compativle with RTL2832U based USB dongles).
  2. If you are looking to purchase such an RTL2832U USB dongle, AVOID the ones with an R820T tuner! They will constantly crash or freeze your computer. Currently, the best are the R820T2 tuners.
  3. Because these dongles are so cheap, there is no excuse to not purchase one! If you are reading this blog, then you either already use SDR# or you should download it now and get such a dongle!
  4. Of course, as everything in life, there is a big problem with SDR#: the spectrum is rendered through FFT (Fast Fourrier Transformation) and not SSA (Sweeped Spectrum Analysis). Because of that, you only get the frequency span of the device you are using (remember that the ADF4350/ADF4351 allow a span over 4GHz!):
    1. RTL2832U based dongles: up to 2.4MHz span
    2. Airspy: 10MHz span

Regards,
Vitor

Tuesday, 3 January 2017

VMA Simple Spectrum Analyser: New version with some graphics enhancements and bug fixes

Hi,

Today I published a new version of my software. It contains three small bug fixes:

  1. You couldn't enter a start frequency equal to the smallest possible frequency (35MHz or 138MHz).
  2. If you zoomed out of the span and reached the maximum, it would always default to 4263 MHz (= 4400MHz - 138MHz), even if you are using a device with the ADF4351 (35MHz - 4400MHz).
  3. I swapped the position of + and - buttons for the satellite identification sensitivity - now the position is consistent, for instance with the span + and - buttons.
I noticed these two bugs, because my 35MHz - 4400MHz device arrived today!

Because I was fooling around with the code, I implemented two new things, too:
  1. On the upper picturebox, I am drawing a waterfall colour scale, too. This should make it easier to interpret the waterfall diagram, regarding the selected amplitude settings.
  2. The thickness of the spectrum line now depends on the selected sample rate: the fewer samples, the bigger the line. This actually increases readability and masks the lower resolution. Hoefull you like it, too.
Here are 5 pictures showing my local DVB-T transponder rendered with all possible sample rates:






Regards,
Vitor