The Knucker project is to develop a reduced-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. The Knucker is not intended to be capable of receiving commercial broadcast TV transmissions.
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!
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....
The PCBs and Tuners went on general relase in March 2021. The receive software is included in the Portsdon 4 build from that date.
Interim receive software has also been included in the Ryde build (accessed through the SSH Console Menu).
The Knucker may be used as a DVB-T receiver in conjunction with the Portsdown 4 or Ryde receiver. In Ryde, the DVB-T option is selected by either selecting a DVB-T Band or Preset using the remote control. It cal also be accessed from the ssh console menu.
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 150 kHz to 2 MHz wide OFDM, frequency range 44 to 1002MHz. The receiver software is included in the Portsdown 4 (touchscreen) and the Ryde (SSH Console Menu control with HDMI display).
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.
Feasibility design which was never built.
This was the first prototype build and not on general release. The old BOM and schematics are available here, but do not use them unless you are sure that you have an old board, and not the one that has been on sale since January 2021: File:Knucker.xlsx
First general release PCB - released 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
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, apply power to the Knucker board, and connect the USB port to the PC - you should here the Windows bing bong sound. Note that to program the module in a Knucker PCB, power must be applied to the PCB (unlike the MiniTiouner).
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'
Charles G4GUO has developed a core Linux DVB-T receiver application using information provided under a non-disclosure-agreement from the manufacturerm, so only the compiled binary (for a Raspberry Pi) is available for download.
The receive software 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.
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
Both the Portsdown 2020 and the Portsdown 4 have an H264 DVB-T transmit capability when used with the LimeSDR Mini.
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.