Posts Tagged ‘DATV’

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

Moving Pictures! First dabbles in Amateur TV

I am always keen to try something new and I've spent the last couple of weeks experimenting with some Amateur Television ATV and Digital ATV (warning this post is bit of ramble and information overload)

They say "a picture paints a thousand words"and I've always liked the idea of sending pictures via radio having dabbled with sending and receiving SSTV and SSDV, including pictures from High Altitude Balloons (HABs) like the Hamfest HAB flight I did back in 2015


But I've also been intrigued by "Fast scan TV" to transmit moving images. I've seen demonstrations at conferences and in online videos and joined the British Amateur Television Club BATC a few years ago but apart from reading the CQ-TV magazine I had not done anything mainly due to expense and investment I mistakenly thought I would need to make.

Recently I have seen mention of using easy and low cost equipment to get on the air on 5.6GHz (the 6 cm amateur band) using cheap modules intended to transmit “First Person Video” (FPV) back from drones.
 
These simple units can be used without any modifications to get on air. A number of operators have used them with high gain WiFi panel and/or dish antennas with a clear line of sight path to send pictures to stations using the same equipment over paths in excess of 50km, the current record is over 160km. Chris Leviston M0KPW has an excellent website describing his 5.6GHz system http://www.5-6ghz-atv.co.uk/ and there is more information at the BATC Wiki https://wiki.batc.org.uk/5.6_GHz

Inspired I ordered some kit from eBay a few weeks back, a receiver module and transmitter arrived quite quickly (no slow boat from China this time)


The equipment is powered by a 12V supply and input and output is a composite video signal and audio. It can be fed by a standard camera or video source but I dug out an old Raspberry Pi and soon had it generating and transmitting a test card with the required call sign overlay. The modules are channelised, the displayed 33 number is bank 3, channel 3 which is 5.665GHz selected by the BATC since it sits inside the amateur allocation,


Over the week I refined the Pi software, adding the Pi camera and various libraries in python to generate video with informational overlay, adding a GPS allowed calculation of the locator square when out portable. I have put it in a box (sorry no picture of that) and a switch to flip between live video and test card. I also had a bash at making some double biquad antennas. Regularly updating my twitter feed with various milestones (I recommend you follow me)

While browsing the BATC website for information I spotted that there was an ATV Academy workshop being organised by the Telford and District ARS, giving people the opportunity of finding out a bit more about ATV and people could bring along their equipment and projects for advice. So at the last minute I decided to go but because of the distance could only really go on the Saturday. But it was well worth it and a great day. I was made to feel welcome by everyone there and was able to show off my modest achievements on 5.6GHz and learned about the BATC Portsdown Transceiver and MiniTioune receiver projects, even buying the parts to build the receiver.

The academy coincided with a BATC Activity weekend and they were going up to the summit of the nearby Long Mynd to operate on the Sunday. Since I wasn't there I had planned to go to a local high point to see if I could make contact with some of the other operators and stations and got the kit ready on a cheap lighting tripod. I was going to use an old portable satellite dish with one of my double biquads at the feed point.

The satellite dish is inverted because they are offset so when the dish is vertical they are actually pointing around 20 degrees upward towards the TV satellite (in the UK). So for terrestrial use with low elevation they work better inverted. (see here for better description of offset dishes)

I did venture out but I chickened out setting up due to a combination of a surprisingly busy road, fly tipping and very hot conditions. Due to the the fly tipping in the lay-by I didn't want to be seen getting stuff out of car boot! especially as a few cars had slowed down as they passed.

Nevermind I have ordered couple of cheap high-gain mesh dish antennas so when they arrive I will get out again and arrange some skeds, hopefully roping in some of the radio club.

In addition to the 5.6GHz stuff I have also taken possession of an ADALM-PLUTO SDR from Analog Devices. It is inexpensive (£90/$100) and designed to allow educational experimenting in software defined radio. It is a SDR receiver and low-power transmitter. They had been in short supply but availability has improved.

Charles Brain G4GUO has added support for the device into the DATV Express software. I am hoping to use it for some experiments in RB-TV (Reduced bandwidth TV) so I can actually use my NoVs

I took the PLUTO along to the ATV workshop and was able to see it transmitting and being received by other peoples receivers. So last night I got out the two satellite receivers I have and with a little bit of persuasion with settings got some DVB-S DATV transmitted and received.
Anyway, that is enough for now.. but will try to keep the blog updated as I experiment some more, but follow my twitter account @nerdsville for realtime updates 73 Andrew

CQ-DATV mags free

See http://cq-datv.mobi/ebooks.php .

CQ-DATV is available for free download. I have not tried amateur TV but some remarkable results are being achieved by DATV in the 146-147MHz band. Like all things in our hobby, you can only do so much. I think the use of digital techniques has given amateur TV a new lease of life.

Four Metre Band and OFCOM rubbish decisions?

There was an announcement on the RSGB and OFCOM sites advising some UK full licence holders that 70.5 to 71.5MHz is being made available for one year by special permission for further digital experiments, a bit like 146-147MHz here in the UK.

Sorry, but has OFCOM gone stark raving mad???

I can see no good justification for this 1MHz of spectrum. 2m was already under-used and the 146-147MHz allocation is probably being used by a tiny handful of people from time to time only.  DATV tests could quite as easily happen at 70cms.

I can think of far better parts of the spectrum OFCOM could have allocated e.g 100kHz around 40MHz (for Es propagation experiments), 73kHz, below 8.3kHz and a contiguous 5MHz allocation. Oh no, these require a brain to be engaged by OFCOM people.

Maybe this is an April fool’s wind-up, although  I suspect it is true.

Surely if OFCOM wants to further real experimentation in radio science there are better ways of going about it?  Yet again, I am totally unimpressed. Between OFCOM and the RSGB, I think this is, yet again, a stupid stupid decision. So we now have 2MHz of extra spectrum for 12 months that a very few might use. Big deal. OFCOM, engage brains, think radio science. If you want to help grow future engineers that we so badly need, these allocations will not help at all. Think again!

See http://www.rsgb.org/ .
See http://www.70mhz.org/ .

AmateurLogic.TV 33: One Jam Packed Show

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George visits the Twit.tv studios and interviews Randy Hall, K7AGE. Tommy visits the Huntsville Hamfest. Jim builds an Audio Isolation Interface. Peter shows us the DATV QSO Party.


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