Wednesday, 11 December 2013

DVB-T ATV UT100C Getting there: Transmitting video files , getting constellation diagrams



I have had success with transmitting video files, both test and HDMI ones I have captured off my camcorder via a Avermedia DarkCrystal HD Capture Pro PCI-E card. It all works as intended at full frame rate.

The UT100C works well with files, even Full HD. Dongle at 1mW to rabbit's ears antenna, received off main house TV antenna.

There is new software for the UT100C at  https://www.dropbox.com/sh/dvshv74hvjkau3a/uifV9Ve95l

I was using Windows 8 but swapped back to Windows 7. Not sure it makes much difference as there is now a signed Windows 8 driver.

Some receiver screenshots:

The image and channel properties at 16QAM. TV receiver software is ProgDVB. It works, its free, its been around a long time.


The 16QAM constellation diagram from Crazyscan2 with TBS 6220.  (I think this is very neat! All praise crazycat69!)


Re-transmitted at 64QAM as per Australian DVB-T standard.



The band scan showing my strong signal and the FTA stations further up the band. I should do the same with my BladeRF, although it only does about 20 MHz bandwidth..


I am only using a Haswell Pentium, working hard. It locks at full screen. (yes, they do make them and only cost $80!)  Although I will have to use something better.


On the transmitter side, modulation parameters, while TSPlayer is running. It plays files in a loop which is handy for testing.

 

 
 
The dongle is on a i5 Haswell, which does things with ease. The video file transmitting puts very little  load on the CPU as there is no encoding.
 
 
 



Still working on live transmission. I haven't tried audio, even with files, but the latest software is meant to support it.

Any comments welcome on how to get live TX going at full frame rate. Email vk4zxi(at)outlook.com.

Saturday, 7 December 2013

Improvised DVB-T test instrumentation

Improvised DVB-T test instrumentation

My last post was on snooping on DVB-S signals from satellites. I found some useful software to do that, Crazyscan and Blindscan. However, the author of Crazyscan also wrote Crazyscan 2 for DVB-T but needs specific TV hardware:  http://sourceforge.net/p/crazyscan/wiki/Info/

I ordered a TBS 6220 (DVB-T) (~$100) as well a TBS 6925 (DVB-S) (~$300), both pci-e cards, direct from the manufacturerhttp://www.tbsdtv.com/ . With courier delivery, they arrived within a week.

Setting up the TBS 6220 is straight forward and works well as a TV card with DreamTV; mainly to confirm that the device works. I put both cards in and software for both, but things got messy. Removing the TBS-6925 and its software, including auto start programs, fixed everything. I need to walk before I run.

My interest is with Crazyscan2. Setting it up is easy, just putting all the needed files in the same directory.

The result is amazing: a scan over 1 GHz at 1 MHz increments, albeit for DVB-T stations and slow; well seconds! I am used to the BladeRF. But they are two different animals.


The screen shot the VHF/UHF spectrum from my TV antenna aimed at Mt Tamborine. The DVB-T stations can be seen the left side of the shot.

However, clicking in the middle of the peak of a DVB-T signal gives me what I have been chasing, the constellation diagram! It also gives other data for the signal down the bottom of the slot.


The constellation diagram gives an idea of the quality of the signal and any issues with modulation, amplifiers and antenna.

So for about $100 for the card and a modern computer, I finally have a means of checking my DVB-T TX, hopefully the subject of the next post.