LeanDVB Receiver within the Portsdown Transmitter

[G8GKQ]

F5OEO had included F4DAV's innovative LeanDVB receiver software within the Transmitter software build, and from software release 201612310 this is included in the core functionality of the Portsdown transmitter. The software is described on page 18 of CQ-TV 252 and at http://www.pabr.org/radio/leandvb/leandvb.en.html.

On a Raspberry Pi 3 using an RTL-SDR, it will receive anywhere between 24 – 1766 MHz and decode at up to 500KS/s and display on the touchscreen LCD. I used an RTL-SDR from http://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ but there are cheaper ones available.

LeanDVB2.jpg (157.07 KiB) Viewed 7688 times

The software is not as good as MiniTioune at digging signals out of the noise, and sometimes takes a while to lock, but is well worth playing with as a stand-alone test receiver. It uses the same parameters (frequency, SR, FEC) as are set for the Portsdown transmitter, either through the console interface or on the touchscreen.

For those of you who want to try to improve it's capability by tweaking the sample rate, the settings can be adjusted in the file /home/pi/rpidatv/scripts/leandvbgui.sh on the Portsdown software build. It is a shell script, so you will just need to restart the receiver to apply the new settings. If you find improvements, please publish them here and I will put them in the core build.

I need to make clear that this is NOT the "Portsdown DATV Receiver", just an added capability within the transmitter. The Portsdown receiver will be based on the MiniTioune software with a new Serit tuner.

Dave, G8GKQ

[M0YDH]

Dave
I'm pleased to read about the dongle capability. I have one to hand. I'm a brand new member and have everything to get save for the Pi peripherals that I already have. The prospect of buying a Windows 10 laptop to run all of Minitiouner USB receiver [also still to be bought] is a deep intake of breath moment.
Brilliant project and will get my PI 3, peripherals and tuner in your shopping list in CQTV254. Well done!
73
David M0YDH

[g8gtz]

Hi David,

Just replied to your email but no need for a shiny laptop - Chris MW0LLK has Tutioune running on a £40 windows tablet. https://twitter.com/tannets/status/806504102037508096

73
Noel - G8GTZ

[G1NSV]

Hi Everyone
I have been reading all the posts and articles related to the Portsdown project, and have become really confused by all of the various permutations that seem in essence to be the same thing. As I have a Pi3 with screen and camera and as I will be working alone I need a receiver to run with the Minitioune software. Could someone make a list of the basic building blocks to achieve a cross shack system. Then all of the nice to have could come later, I have become very confused with all of the various permutations possible. Moving from analogue to digital ATV is a big step for me and working on my own its even harder. I do at the moment use a RTL dongle to recieve Weather sat pictures and have previously built various analogue ATV receivers. The local to me ATV repeater has stopped (no site) so I am looking forward to trying this mode on 146 mhz etc.
Dave
G1NSV

[g8gtz]

Hi Dave,

The one thing we tried to do with Portsdown was put together a clear and defined package and I do agree the LeanDVB rxr does start to add to the confusion again. To be clear LeanDVB is not a core part of the Portsdown project and is NOT the Proposed Portsdown receiver - it is simply a monitoring receiver facility that was already in the F5OEO s/w which Portsdown uses and can be ignored unless you want to use it.

We've done a lot of work on documenting the project in the last couple of days on the BATC wiki https://wiki.batc.tv/The_Portsdown_Transmitter. I suggest you take a look at all the info there and come back here and post if you have any questions and comments.

I think I've answered your specific question about recievers under the FAQ https://wiki.batc.tv/Portsdown_transmitter_FAQ and the bottom line is until the Filter modulator card is available you can only run QPSKRF or Ugly mode which is reduced bandwidth at 333Ks and so you will need Minituner and a 70cms up converter (Just realised we need to write that bit up on the wiki!)

Note to all members - you too can contribute to the Wiki and help build the knowledge base!!!

73
Noel - G8GTZ

[G8GKQ]

Dave

Yes - there is a lot of information for the beginner to take on. We are trying to put it together in a readable form, but perhaps we do need a higher-level overview. The current information is summarised on the Wiki here: https://wiki.batc.tv/The_Portsdown_Transmitter

In summary, in addition to your RPi3, Camera and touchscreen, you will need a filter/modulator board (under development) and some RF filters and power amplifiers.

You could use LeanDVB with the RTL-SDR for receive, but it is not very good at picking signals out of the noise. We are developing the Portsdown receiver, which will use a tuner and PCB, which will then connect to a computer by USB for receive. Again, under development.

Hope that helps

Dave, G8GKQ

[G1NSV]

Many Thanks for all of the information, I will now print up the Wiki information and read it all, I will then be in a better position to make some progress with getting together a system, I have another amateur who lives about 25k from me and we have a reasonable path for 2M and 77 but we have tried and tried with ATV at 1255 but no success since the repeater went off air. This new DATV method offers a new approach, so I am keen to give it a go, also being a pensioner I have to keep the cost down otherwise I get ear ache from the sewing and knitting department!!