TSAT 3000 - 3.7 GAIN PARAMETERS; 3.7.1 GAIN_TX_REF

TSAT 3000 - Telemetry and data transfer via SATellite
TSAT 3000 Configuration Parameter Description, January 2013 Page 51 of 124
3.7 GAIN PARAMETERS
Rx/Tx Gain is controlled by reading onboard A/D-Converters, and writing to the onboard D/A-
Converters. See description of MIB parameters below, and
ADC + DAC PARAMETERS.
3.7.1 GAIN_TX_REF
Ver <= 30.4.1: Default 0.0, Range –50.0… 0.0
Ver >= 30.5.0: Default 0.0, Range –50.0…4095.0
Control the “Automatic Tx-Gain Control (AGC)” facility.
Ver <= 30.5.0:
Not Used.
Ver >= 30.6.0:
Enable or disable Tx AGC.
Tx-Detector value (
ADC_1_TX_RF_LEVEL) is fetched when packets are sent, and Tx-Gain
DAC (
DAC_21_TX_GAIN) regulated up/down until desired output level is reached. The Tx-Gain
DAC setting is limited to a value in the range defined by
GAIN_TX_DAC_{MIN | MAX}.
Value Description
–50.0 … –0.0
Enable AGC. Output level given in dBm.
Convert dBm => Target Tx-Detector value, and adjust Tx-Gain DAC until desired
Tx-Detector is reached.
0.0
Disable AGC. Tx-Detector is nevertheless fetched each second
to give
measurements to the NMS ‘TSAT 3000 Hardware Diagnostics’ window.
1.0
TEST. Disable AGC.
Tx-Detector will never
be fetched.
2.0
TEST. Disable AGC.
Tx-Detector is fetched each time a packet is sent on both Primary and Secondary
Inbound carrier – See Note 3 next page
3.0
TEST. Disable AGC.
Tx-Detector is fetched each time a packet
is sent, and average value calculated.
4.0 … 4095.0
ELSE
i.e. 0.0 … 4.0
TEST. Enable AGC. Output level given in Detector units.
Adjust Tx-Gain DAC until desired Tx-Detector value (4…4095) is reached.
You may enable or disable:
• “Automatic Tx-Gain Control” - GAIN_TX_REF.
• “Static Tx-Gain” -
GAIN_TX_OVERRIDE.
• “End-to-End Tx-Gain Control” -
GAIN_TX_END2END_TARGET.
The priority of these 3 Tx-Gain control mechanisms is:
1) Set “Static Tx-Gain” when this function is enabled.
2) With Tx-Signal (
SWITCH_TX_SIGNAL) disabled: Adjust to desired output level when
“Automatic Tx-Gain Control” is enabled. Then enable the Tx-Signal.
3) After initial adjustment, the “End-to-End Tx-Gain” will regulate output level – if it is enabled.
Otherwise, “Automatic Tx-Gain” will take control (when it’s enabled).
Note 1: For your information:
1 dBm = approx. 66 Tx-Detector units
1 dBm = approx. 53 Tx-Gain DAC units.
1 dBm = approx. 1 dB E
b
/N
0
received at remote side.