Ground Station starting from version v2.50 is able to control several AV receivers at a time, allowing to simulaneous change of its working frequency or predefined channels.
Present firmware allows to control Comtech modules and compatible (Fox, Rangevideo) working on frequecies in range from 900 to 1400 MHz in 10 MHz step.
Ground station allows to store up to 21 predefined channels (in 3 separaqte banks 7 channels each). It allows to cover different channel frequencies used by different transmitters.
Communication protocol is typical I2C. On picture below is shown ground station board with marked connector and its pin assignment of SDA, SCL and GND pins. These pins are available on typical 4 pins connector.
Note unused pin between GND and SCL has internally +5V and avoid any shortcut of this pin to others.
All existing wires connected to SCL and SDA lines of RF modules have to be disconnected (and loose wires insulated to avoid shortcuts).
Ground station (and I2C protocol itself) allows to control multiple RF modules at a time (typically 2 modules for GroundStation’s diversity inputs). In this case this same pins SDA, SLC and GND respecively from each module should be connected together ( e.g. SDA form first module should be connected to SDA form second module and then connected to SDA in Ground Station).
Different modules may have different pinout for SCL and SDA pins. GND is usually connected to RF metal case.
It is recommended to solder additional capacitor 100pF (100 pico farads) between SCL line and GND close to the RF module, especially when wires between GS and receiver are long.
Maximum signal wires length should not exceed 1 meter. It may be shielded wire or just plain twisted wires.
Below are pictures of popular receivers tested with GroundStation
4-channel Fox-like module with dip-switch channel selection:
Lawmate receiver (in small black case):
Fox 800 with LED display
All control of RF modules is made on video preview page.
At the bottom of the screen there are four buttons:
[Dn] – Step down current frequency (10MHz step)
[Up] – Step up curren frequency (10MHz step)
[>>] – Scan for next video channel
[current frequency] – when pressed new page will be opened with predefined channels frequency. On this page user may select existing channel, set (add) new channel or remove exiting.