With the Portsdown and Longmynd software and Minitiouner hardware, the worldwide ATV community has access to some very valuable open source resources and based on these, BATC believe the community has the resources to develop a dedicated DATV receiver.
The primary use cases would be a dedicated DATV receiver for home station use and a low symbol rate DATV receiver with reliable lock detection for remote use at ATV repeater sites. We have developed the following specification and are now looking for a small team of people (or one person) to pick this up and develop a project which will sit alongside Portsdown and Longmynd projects
Outline specification would be:
RF and de-modulation capability
DVB-S and DVB-S2 demodulation is required - frequency range, symbol rate range and FEC choices will be the same as the MiniTiouner system https://wiki.batc.org.uk/MiniTioune
Reception of SCPC transport streams and decoding MPEG 2, H264 and H265 video and MP3 and AAC audio streams. Reception of MCPC streams is not a primary requirement but could be a future enhancement.
The decoded video and audio would be presented on the HDMI port with embedded audio or on a composite video port with separate analogue audio feeds. Simultaneous outputs are not required and the port in use would be selected via the system set up menu.
It is envisaged the project will use the MiniTiouner USB tuner card https://wiki.batc.org.uk/MiniTiouner_hardware_Version_2 [Edit - hardware or design] Ideally the host hardware will be the Raspberry Pi 4 although other readily available supported Linux hardware could be used.
No integrated screen is required and the output will be displayed on either an HDMI or Composite monitor.
An infrared remote control is required and it is envisaged the project will use existing standard control hardware and codes – eg https://thepihut.com/products/xmbc-ir-r ... 6YQAvD_BwE
A hardware tuner lock signal should be provided, probably from the RPi GPIO lines.
The user would be expected to provide case and PSU etc.
It is envisaged the project would use the Longmynd open source Linux ATV receiver developed by Heather Lomond and available here: https://github.com/BritishAmateurTelevi ... b/longmynd
A significant amount of the functionality required for this project is available within the Longmynd implementation in the BATC Portsdown project by Dave Crump and can be used as a basis for this project. https://github.com/BritishAmateurTelevi ... own-buster
On initial start up the software should default to composite video out and take the user in to a system set up menu where parameters such as video output, Terrestrial / Satellite operation, LNB volts, LNB offset and the default RF and decode parameters would be selected. Set up of any frequency pre-sets would also be done from this menu.
On normal start up, the decoded video output using the default setup parameters should be displayed.
From the default screen a channel set up menu should be accessible by pressing a single button. This will allow selection of RF frequency (if satellite operation is selected in system menu this will include the LNB offset) and Symbol rate – a number of pre-set frequency options is desirable. Exit will take you to video output display and a button to take you to the system menu would be displayed.
A selectable banner showing receive status, MER and SI information should be displayed across the bottom of the video window.
The initial requirement is for a standalone DVB-S / S2 receiver although future enhancements could include remote control over SSH, the ability to view BATC live streams and a TS UDP output. All these functions are already available in the BATC Portsdown / Longmynd system code.
The BATC will support development of this project and use of the BATC github, forum and wiki is encouraged. BATC would be willing to provide bursary funding to cover project costs etc.
If you are willing and able to have a crack at this project, we'd love to hear from you!
Noel - G8GTZ
No transmit required - thank you!
My first thoughts would be a modified Express board with larger FPGA, USB2 replaced with USB3, HDMI capture,
DVB ASI and NIM.
The FPGA would handle all the multiplexing of the TxDACs, NIM, HDMI capture onto and off of the USB3 interface.
It would be simply too expensive to add any form of CPU to the board and also with the rate of technological development
would be obsolete before it was available for sale.
The main issue for us is agreeing on the requirement, finding a suitable (inexpensive) manufacturer for the finnished product
and providing technical support, as team members don't want to be burdened with supporting something for many years to come.
There is also the issue of sales (BATC are reluctant to exceed the VAT threshold, DATV-Express LLC is located in the U.S and of course the UK is
no longer a member of the EU). I have suggested selling via Amazon or the Amateur Radio Dealer chain but those ideas didn't go down too well.
Some time ago I have similar idea. I see Hat for RPi who have Serit tuner and work directly via GPIO+I2C. I experimented with longmynd code and now I2C is working directly from RPi header to tuner (bypassing USB I2C). Not tested real receiving, but modified longmynd don't throw any errors when stated. Now there is biggest challenge: write working code for GPin+DMA as kernel driver. I see two character devices /dev/serit0 /dev/serit1 who can be read with "vlc -i /dev/serit0" player (or whatever). RPi is nice, but other alternative is something with Allwinner H5 SoC where TS hardware is already integrated into chip.
Now that sounds really interesting. My apologies, but I have many questions:
Do you think that it is necessary to use a Kernel Driver to get the parallel TS stream into the RPi for display? Or might there be a simpler solution?
Not too familiar with the Allwinner series. Did you have some particular OrangePi board in mind? What would be the advantage over the RPi 4 which has hardware H264 and H265 decoders?
We (the BATC) would be really interested in supporting the development of some sort of proof-of-concept for an RB-TV set-top box. Our hardware preference is for the RPi 4 (as it is readily available and has good long-term support and home constructors are not scared of it), but if there is a another better solution, that would be OK. There are others in the community who would be able to help with the project.
Grateful for your thoughts