Repeater Controller

The BATC ATV Repeater Controller uses a Raspberry Pi 4 as a fully-featured, but simple-to-implement, ATV repeater controller. The design is intended to be used with an HDMI Video switch, but can also be used with older composite video designs.

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.

Initial design and construction information will be published here to enable collaborative development, but will be subject to change as the project develops.

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

Typical operation

The BATC repeater controller will control either a single or multiple video switchers either by InfraRed, I2C or GPIO pins and will generate a carousel of scenes.

Carousel

The carousel can be configured to show up to 99 scenes which are played out from the controller RPi and can be .jpg or .png images, an input on the video switcher for example mast cam, or a video file (in future release). 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

The controller RPi also generates images for the K sequence and input identification. 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 enable the beacon for the first 30 minutes of every hour.

Hardware control

The controller will interface to the following:

• Video switches via IR transmitters (note 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. Initial support for the Audio switch designed for GB3SQ. Future releases may support I2C video switches and relay boards.

The IR and I2C commands for each input are set in the config file.

Configuring IR Switching

The IR codes for the HDMI switches used on each repeater will need to entered in the configuration file.

Full details are here: Configuring IR for HDMI Switching

Customisation

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

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

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

DTMF control

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

The following functions can be changed using DTMF commands - actual command sequence is entirely flexible and set in the config file. It is recommended that some command sequences such as shut down are publicly available and have been grouped in the example config file (see Repeater Controller configurationas keeper commands.

Suggested keeper functions

dtmfkeepertxoff

dtmfkeepertxon

dtmfkeeperreboot

dtmftalkbackaudioenable

dtmftalkbackaudiodisable

User codes for direct input select (use dtmfreset to deselect)

dtmfstatusview

dtmfquadview

dtmfselectinput0

dtmfselectinput1

dtmfselectinput2

dtmfselectinput3

dtmfselectinput4

dtmfselectinput5

dtmfselectinput6

dtmfselectinput7

RPi GPIO Accessory DTMF Control examples

dtmfoutputs=1 dtmfgpioout1pin=15 dtmfgpioout1label=shack_light dtmfgpioout1on=31 dtmfgpioout1off=41

dtmfinputs=1 dtmfgpioin1pin=8 dtmfgpioin1label=cabinet_door

i2c Accessory DTMF Control examples

MCP23017. Max 16 lines either in or out i2cioaddress=0

i2cdtmfoutputs=1 i2cdtmfgpioout1pin=a0 i2cdtmfgpioout1label=shack_heater i2cdtmfgpioout1on=51 i2cdtmfgpioout1off=61

i2cdtmfinputs=1 i2cdtmfgpioin1pin=b0 i2cdtmfgpioin1label=cabinet_lid

GPIO Connections

The repeater controller accepts up to 8 signal detect inputs on the GPIO input pins and uses IR / I2C or GPIO outputs to switch external switchers.

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

An initial list of GPIO connections is here: Repeater GPIO Connections.

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 - Aplha release for testing

Feb 10th 2022 An early Beta version of the software (not yet ready for use, but good enough for shack-based testing) can be found here: https://github.com/BritishAmateurTelevisionClub/atv-rptr

Further information

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