Repeater Controller

The BATC ATV Repeater Controller uses a Raspberry Pi 4 as a fully-featured, but simple-to-implement, ATV repeater controller. Every repeater is different and the controller is designed as a core logic that can be used as the basis for an ATV repeater. The design is flexible with a large number of parameters in a text editable config file so that users can configure it to meet their own needs.

The controller is intended to be used with an HDMI Video switch, but can also be used with other switchers including older composite video designs.

The outline requirement specification is here media:BATC ATV repeater controller.pdf

Typical operation

The BATC repeater controller controls single or multiple video switchers either by InfraRed, I2C or GPIO pins. It also generates a carousel of scenes and has an on-board DTMF decoder.

Carousel

The carousel can be configured to show up to 99 scenes. The content and duration displayed of each scene is set in the configuration file and the scene can be one of the following:

• Status screen generated by the controller
• jpg or png images played out by the controller
• Video files (in future release).
• Any input on the video switcher, so can display inputs such mast cams, weather stations or Quad video displays.

The still images are read each time before display so can be regularly updated by an external source.

Valid signal input

On receipt of a valid signal from, for example, a Ryde receiver, the controller will, key the transmitter, play an image for .5 seconds indicating which input has been activated and then switch to that input. When the receiver closes, the logic will play a "K" image and optional "K" in Morse and go back to the carousel.

The receiver input switching line can be directly from a Ryde receiver or an external source such as a sync detector on an analogue source. Note do NOT exceed 3.3 volts on the GPIO input.

Ident signal

In order to comply with licensing regulations, a video and/or audio ident can be generated at an interval set in the config file.

DTMF control

An on-board DTMF decoder will allow input selection by remote control and also enable GPIO pins to be toggled to enable the control of external equipment.

Power saving

To enable power saving by turning the repeater transmitter off during quiet periods, a number of options are available such as only key the transmitter when in repeat mode, do not key the transmit during the night time and only key the transmitter to display the carousel for the first 30 minutes of every hour.

Repeater system sample builds

A number of example configurations are shown on this page Repeater system configurations

Hardware control

The controller will interface to the following:

• Video switches via IR transmitters - up to 2 IR transmitters can be configured separately allowing multiple video switches to be cascaded.

• Video switchers via hardware lines driven from the RPi GPIO lines (note 3.3v logic output)

• i2c

The IR and i2c commands for each input are set in the config file.

i2c interface

Future releases may support i2c video switches and relay boards. I2c Interface details are here: DATV Repeater i2c Interface.

Audio switching

The controller supports the i2c controlled Audio switch designed for GB3SQ. Details of the 8 channel input audio switch PCB can be found here: DATV repeater audio switch

Configuring IR Switching

The IR codes for the video switches used on a repeater will need to be entered in the configuration file - see Repeater Controller configuration.

Full details on how to read your IR commands and then configure the system are here: Configuring IR for HDMI Switching

IR Transmitter Control Circuits

Here are example IR transmitter control circuits for the single and dual switch cases:

Customisation and configuration

While this software is designed to work "out of the box" it will need to be configured for each individual repeater.

Some configurations can be done using the SSH menu and some real-time control is possible using the ssh Console Menu.

For a detailed description of the configuration details see the Repeater Controller configuration page.

DTMF control

The BATC repeater controller uses an onboard DTMF detector which detects DTMF from the mic input on a USB audio dongle (using a standard Portsdown white USB dongle).

Full details of the functions that can be set by DTMF and their configuration are on this page DATV repeater DTMF commands

GPIO Connections

The repeater controller uses the RPi GPIO port for the following:

• Accepts up to 8 signal detect inputs

• IR / I2C drive output

• GPIO outputs to control video switchers.

• Auxilliary equipment status monitoring inputs

• Auxilliary equipment control outputs

The exact pins used for each function are set in the configuration file.

Care MUST be taken to buffer the 3.3 volt logic levels used on the Raspberry Pi GPIO pins.

A list of GPIO connections is here: Repeater GPIO Connections.

Composite video input

In order to enable analogue receivers and equipment, such as mast cameras, to be connected to an HDMI switcher, BATC has developed a composite to HDMI converter.

Based on the Ryde software running on a Pi3 or Pi4, it uses a Fushicai EasyCap and provides a high-quality converter even with noisy FM video signals.

Build an SD card with the Ryde software and after updating to release 03/03/22 select Option 8 on the Settings Menu in the SSH Console Menu.

Then manually edit the file /home/pi/ryde-build/cv_config.txt where you can set audio out, 16:9/4:3 and the ident caption.

After rebooting with a Fushicai EasyCap connected, the HDMI output will show the Composite video input and carry the audio from the dongle.

Note This is not a Ryde facility, the Ryde build was just a convenient starting point for the software build.

Switching Logic

A detailed description of the operation of the switching logic can be found here: Repeater Switching Logic.

Project status

The target release date is the end of March 2022.

Jan 22 - Alpha release for testing

Feb 10th 2022 - A Beta release version of the software is available for download: https://github.com/BritishAmateurTelevisionClub/atv-rptr

Note this is NOT the final release and there will be bugs! Please provide feedback on the forum.

Feb 15th - Feature freeze until first release in March

Software download

The BATC controller is available for download at https://github.com/BritishAmateurTelevisionClub/atv-rptr

Please follow the instructions carefully and note the controller runs on the Buster Lite OS and not Bullseye.

Depending upon demand we may sell preprogrammed SD cards in the BATC shop.

Future requirements

Currently, we are not adding additional features until the design is proven to be stable.

The following features have been identified for inclusion in future releases:

• Implement battery-backed clock (for no internet/power cuts). Will serve NTP to Rydes on same network

• VLC Carousel Play of videos

• i2c accessory switch operation (Entries exist in config file, but not yet coded)

Further information

See https://forum.batc.org.uk/viewtopic.php?f=82&t=7750