HDMI repeaters - some thoughts...
Posted: Wed Dec 16, 2020 11:28 am
Looking at the excellent video quality on GB3FT where Tim is driving the Ryde HDMI output directly into a Chinese encoder box which then produces both the BATC stream and an IPTS output for transmission, I think it is probably time for repeaters to say goodbye to the yellow phono plug!
* HDMI switches with RS232 control are readily available and could form the heart of the system. https://www.ebay.co.uk/itm/HDMI-Switch- ... SwcItavLsM or a 3 port is much cheaper https://www.ebay.co.uk/itm/Ex-Pro-3-Por ... 1438.l2649
* A Raspberry Pi could act as both a test pattern HDMI generator and control the switch by sending RS232 commands when a trigger on the GPIO port is received from the Ryde receivers or other inputs.
* A Ryde receiver on each band providing Multi Symbol rate reception.
* A BATC stream receiver to provide internet access.
* Composite to HDMI conversion can be done on a Rpi and provides input from FM receivers and mast cams etc. We have the basis of this in the Portsdown video monitor.
* H264 / H265 encoder box with HDMI input producing BATC stream and IPTS for transmission. Currently, this would drive a PLuto running F5OEO firmware to generate SI etc but could potentially drive a Portsdown IPTS input if a solution for SI on the IPTS input is provided.
Insertion of .750 talkback audio could be an issue but could potentially be done by an HDMI embedder on the output of the switch or inserted by FFMPEG at the SI generation stage.
PTT control could be done by the control PI to save electricity bills and whilst legally we do not need callsign ident by morse as long as it is in the DVB SI, the control Pi could send it every 15 mins if desired.
One concern would be glitches caused by the switch or intermittent Ryde reception and the effect on the encoder.
Thoughts, comments, issues, things I've missed and offers to write the Control Pi s/w all welcome!
Noel - G8GTZ
* HDMI switches with RS232 control are readily available and could form the heart of the system. https://www.ebay.co.uk/itm/HDMI-Switch- ... SwcItavLsM or a 3 port is much cheaper https://www.ebay.co.uk/itm/Ex-Pro-3-Por ... 1438.l2649
* A Raspberry Pi could act as both a test pattern HDMI generator and control the switch by sending RS232 commands when a trigger on the GPIO port is received from the Ryde receivers or other inputs.
* A Ryde receiver on each band providing Multi Symbol rate reception.
* A BATC stream receiver to provide internet access.
* Composite to HDMI conversion can be done on a Rpi and provides input from FM receivers and mast cams etc. We have the basis of this in the Portsdown video monitor.
* H264 / H265 encoder box with HDMI input producing BATC stream and IPTS for transmission. Currently, this would drive a PLuto running F5OEO firmware to generate SI etc but could potentially drive a Portsdown IPTS input if a solution for SI on the IPTS input is provided.
Insertion of .750 talkback audio could be an issue but could potentially be done by an HDMI embedder on the output of the switch or inserted by FFMPEG at the SI generation stage.
PTT control could be done by the control PI to save electricity bills and whilst legally we do not need callsign ident by morse as long as it is in the DVB SI, the control Pi could send it every 15 mins if desired.
One concern would be glitches caused by the switch or intermittent Ryde reception and the effect on the encoder.
Thoughts, comments, issues, things I've missed and offers to write the Control Pi s/w all welcome!
Noel - G8GTZ