Tuesday, 14 August 2018

MiniTiouner DATV Receiver built

At the weekend I built my MiniTiouner DATV receiver. I'd purchased the PCB, tuner module, 1V regulator and programmed USB interface module from the BATC stand at the Telford ATV Academy the previous weekend. The remaining components that I didn't already have were ordered from Digikey using the handy spreadsheet on the BATC Wiki and I sourced a suitable DC-DC Converter from eBay.

The build was straightforward and there are some instructions by Mike G0MJW but only really referenced them for the commissioning stage, checking voltages etc. I was pleasantly surprised to see a large degree of protection on the board, fuses both filament and poly-fuse, reverse protection and zener diodes in the circuit.

The MiniTiouner uses free to download DVB-S receive and analysis software called "Minitioune" written by F6DZP. The Software is hosted on the VivaDATV forum. So I registered and downloaded the software.

V8.0 of the software requires a pull-down resistor adding to the USB module to identify the type of board, so that was added (not pictured).

Power was connected and then plugged the USB lead into the PC (Windows 7 32bit) and it went off and installed drivers. The documentation said I should see two USB controllers, but I was seeing four?

There are several test programs included in the software package to test drivers and board and they were showing errors.

The PC I was using has had no end of serial USB devices plugged in and out over time so suspecting another Microsoft Windows "disappearing up its own backside" driver issue I tried it on another more vanilla machine but had the same problem.

This seemed to point to the USB interface (an FTDI FT2232H Mini Module) perhaps it wasn't programmed? So I downloaded the FTProg utility from FTDI but instead of seeing a FT2232H was showing it as a FT4232H device.

Doing a Google found a reference to the same problem. I downloaded the data-sheet and checking with a meter I could see pins CN2-5 and CN2-11(VIO) on the module didn't have 3.3V for some reason and as the post said if the VIO pin is missing 3.3V it defaults to a FT4232H. In the end I checked my soldering (no fault found) I removed the module from the socket to examine it and after re-seating it the board sprang to life so seems it was just a bad connection.

Eager to test I set up the ADALM-PLUTO SDR running DATVExpress as I'd done previously with the commercial set-top satellite receiver and we had a picture! It was time for a cup of tea!

Now it was working all that was left was to put it in a box.

I have only had a brief play with the software since the weekend but was interested to see if I could receive some RB-TV (Reduced bandwidth) So I set the Pluto and DATVExpress to transmit on 146.500MHz using a low symbol rate (250 Ksymbols/s) and it worked!  Bertie was wriggling a bit too much for a clear picture but I had now actually used my 146-147MHz NoV. Now just got to learn and understand the various modulations and settings.

I was able to try out another piece of software, the Spectrum Analyser from Steve Andrew for the SDRPlay. It turns the SDR receiver into a handy spectrum analyser with 10MHz bandwidth from 1kHz upto 2GHz and was able to check the output of the Pluto.

This wasn't a proper test setup by any means, the SDRPlay was still connected to the dual-band collinear outside the shack so the noise is the usual hash I see, but the Pluto was putting out a decent waveform, it did help putting on a proper resonant antenna (a spare mobile magmount) rather than the tiny one supplied.

I plan to do a bit more with the 5.6GHz FPV stuff before the weekend having took delivery of some nice grid antennas and hope to get out to try a contact or some tests with members of SKARS 73

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