Date of application: 01/27/2021
Project description: We are replacing our old 4MS/s DVB-S transmitter, which is a DTX-1 based unit with a DVB-S2 unit and making the move to 1MS/s along the BATC guidelines.
We are also replacing the old RX units with Ryde type units for the 23cm & 70cm digital inputs. The aim is to go digital end-to-end by using 4 way HDMI switcher, so in essence we are totally rebuilding the digital side of the repeater.
As the Lime SDR did not appear to be available at the time of starting the transmitter project, I have used the following items for the transmitter:
1: Raspberry Pi 4 2GB model
2: HDMI capture dongle
3: Adalm Pluto with F5OEO firmware installed
4: 32GB Sandisk SD card
I am using ffmpeg on Debian to do the business on the Pi, with hardware detection based on how it is achieved in the Portsdown source code.
Basic testing of the TX unit is now complete and we are happy with the results. Ongoing work is the Ryde RX units (Bob, G7AVU is doing these), and the HDMI switcher, which I will be tackling next.
Benefits to ATV community: The benefit is mainly that we can consume less bandwidth, as per BATC advice, but a side benefit from our replacement of the digital inputs is that we can take advantage of DVB-S2 inputs at lower symbol rates, meaning Pluto/Lime low cost TX becomes possible with good performance from H264.
Total amount of funding requested: £210.15