X20/X20S and Ethos v1.2.10 User Manual
The telemetry source will automatically switch depending on the active RX. The RX
internal sensor displays the ID of the active RX that is sending telemetry, i.e. RX1, RX2
or RX3.
When the receiver telemetry source changes, linking of the receiver S.Ports will
automatically continue telemetry from S.Port connected external sensors. However
please note that it does not link internal receiver sensors. RSSI, VFR, RxBatt, ADC2 and
RX(n) sensor data is sent for the source receiver, so that does change depending on the
source.
Simultaneous telemetry from three receivers will come later. Further developments are
expected in this area.
Sensor Types:
1. Internal Sensors
FrSky radios and receivers have built-in telemetry functions to monitor the strength of
the signal being received by the model.
RSSI
Receiver Signal Strength Indicator (RSSI): A value transmitted by the receiver in
your model to your transmitter that indicates how strong the signal is that is being
received by the model. Warnings can be set up to warn you when it drops below a
minimum value, indicating that you’re in danger of flying out of range. Factors
affecting the signal quality include external interference, excessive distance, badly
oriented or damaged antennas etc.
ACCESS
The default alarms for ACCESS are 35 for 'RSSI Low' and 32 for 'RSSI Critical'.
Loss of control will happen when the RSSI drops to around 28.
ACCST
The default alarms for ACCESS are 35 for 'RSSI Low' and 32 for 'RSSI Critical',
while for ACCST they are 45 and 42 respectively. Loss of control will happen
when the RSSI drops to around 28 for ACCESS and 38 for ACCST.
The warning for when telemetry is lost completely is announced as 'Telemetry Lost'.
Be aware that further alarms will NOT sound, because the telemetry link has failed,
and the radio can no longer warn you of an RSSI or any other alarm condition. In
this situation it is wise to turn back to investigate the problem.
Note that when the radio and receiver are too close (less than 1m) the receiver
may be swamped causing spurious alarms, resulting in an annoying "Telemetry
Lost" - "Telemetry Recovered" alarm loop.
VFR
Prior to ACCESS V2.1, RSSI was based on a combination of received signal strength
and lost frame rate. Lost frames have now been removed from the RSSI
calculation, and added as a new sensor VFR (Valid Frame Rate) to provide a
measure of Link Quality.
A warning can be set up to warn you when VFR drops below a minimum value,
indicating that the link quality is becoming dangerously low. The default 'Low value
warning' is 50.
RxBatt
Another standard internal sensor is the receiver battery voltage.
114
rev 3
Summary of Contents for TANDEM X20
Page 1: ...X20 and Ethos User Manual...
