Knucker

The Knucker project is to develop a variable bandwidth DVB-T USB receiver and transmitter for use on the lower VHF bands and HF. It will also have applications for mobile stations on 437MHz and above.

Why DVB-T

DX!!

DVB-T can be used in environments where phase distortion and multi-pathing means DVB-S does not work. Typical applications include mobile video transmissions and bands below 70MHz :-)

We don't need DVB-T except for 29 / 50 MHz and mobile - it won't replace DVB-S for other bands and QO100!

Why Knucker

Why not?

Knucker is a dialect word for a kind of water dragon, living in knuckerholes in Sussex and Charles, the lead developer, also lives in Sussex....

https://en.wikipedia.org/wiki/Knucker

Timescales

December 2020 - Currently the project is at the design phase with a proof of concept receiver working on breadboard hardware.

January 2021 - beta testing in progress

The planned project release is currently March 2021 (but subject to change). 400 Serit NIMs on order due early March in plenty of time for the sporadic E season :-)

Receiver

The Knucker may be used as a DVB-T receiver in conjunction with the Ryde receiver. The interim software solution in the Ryde is only available via the SSH menu (option 11 "DVB-T RX") (DVB-T reception is NOT possible via the Ryde's onscreen menus). Choosing option 11 leads to the "Ryde DVB-T receiver" menu which allows receive parameters for DVB-T ONLY to be set.

Hardware

Charles G4GUO and the Knucker team have developed a variable bandwidth DVB-T receiver with USB interface around the Serit 4762 NIM / tuner.

Draft specifications are 100KHz to 2MHz wide OFDM, frequency range 44 to 1002MHz

Note: the 4762 NIM is capable of DVB-T and DVB-S but the DVB-S is NOT (repeat NOT) supported in any BATC applications due to restricted frequency range and lack of low SR capability.

The PCB design by Mike G0MJW is based on the MiniTiouner Version 2 board.

Note that the DVB-T input to the NIM is the bottom F type nearest the PCB.

Version 1

Feasibility design which was never built.

Version 2

This was the first prototype build and not on general release - BOM and schematics are available here: File:Knucker.xlsx

Version 3

First general release PCB - limited availability in January 2021. General release March 2021

Note 1 - the use of a 3 pin 1.2v regulator which is different from the 5 pin variable 1.2v regulator on the MiniTuioner V2 PCB

Note 2 - Use the F type nearest the PCB for DVB-T reception

Schematic is here: media:Knucker schematic V3.pdf

BOM is here media:knucker BOM V3.xlsx

USB Module

The USB module will require reprogramming with the xml file in this zip using the FTDI program called FT Prog - the standard MiniTiouner USB module from the BATC will not work but can be re-programmed as follows:

Download and install the FTDI FTprog software from here:

Download, unzip and save this file File:combituner.zip It will save as Knucker DVBT.xml

Put the USB module in to the PCB and connect the USB port to the PC - you should here the Windows bing bong sound.

Run FTprog:

Go - File>open template and open the .xml file

Go - Devices>Scan and parse

Your screen should now look like this:

Right click on the "Device:0" line

Apply template - select the template you have opened.

Right click again - Program Device

Go - Devices>Scan and parse and it should show your device as programmed.

Full instructions on how to program the unit are here: http://www.vivadatv.org/viewtopic.php?f=80&t=379. After reprogramming confirm you have been succesful by doing a "scan and parse" action and ensuring that ProductDesc is shown as 'CombiTuner-Express'

Software

Charles G4GUO has developed a core Linux DVB-T receiver application.

Portsdown

This has been integrated into the Portsdown 4 system to give a narrow band DVB-T receive capability. https://forum.batc.org.uk/viewtopic.php?f=103&t=7158

Ryde set top box

An interim SSH Menu-driven version has also been integrated into the Ryde Build. No remote control functions are available in this build, although full integration with Ryde is on the to-do list.

Transmit

Portsdown system

Due to excellent cooperation between Charles and Dave, a Portsdown DVB-T transmitter using the Pluto SDR has been integrated into the Portsdown 4.

The first official release was made on 1st February 2021

https://forum.batc.org.uk/viewtopic.php?t=7158&p=26210#p26210

DATV Express

Charles G4GUO has developed a variable bandwidth OFDM version of the DATVexpress software. Version 1.25lp17 works for DVB-T with the DATV Express card.

It does work in some configurations with the Pluto (and possibly the LimeSDR) but these SDRs are not yet properly supported.

For initial testing, set the DATV Express to use Mono MPA audio and DVB-T using the settings shown below.