RF Output Power for Axient Digital PSM Systems at Scale
Introduction
For technicians designing Axient Digital PSM systems at scale, this page provides technical documentation on RF output power when Axient Digital PSM transmitters are connected to compatible combiner and splitter devices like the AD8C 8-port combiner and the AD221 2-way combiner/splitter.
Calculating Net RF Output Power
The net RF output power delivered to the final transmit antenna destination is dependent on the transmitter device, frequency band, operational preset, combiner level, and the selected RF level.
The net RF output power is determined according to the following equation:
[RF OUTPUT POWER OF THE SELECTED RF LEVEL] - [COMBINER LEVEL LOSS] + [SIGNAL GAIN COMPENSATION] = [NET RF OUTPUT POWER]
Each of the terms in the above equation are explained in more detail below.
RF Level
RF output power values per RF level are discrete values that are specific to each transmitter device, frequency band, and operational preset.
See RF output power values by RF level (dBm)
See RF output power values by RF level (mW)
Combiner Level Loss
Values for combiner level loss are discrete, preset values for each combiner level.
If an additional combiner is connected downstream of an AD8C, the transmitter antenna output will sum together the total combiner level loss of all connected combiners up to a 32:1 combiner level.
| Combiner Level | Combiner Level Loss |
| 2:1 or 1:2 | 4 dB |
| 4:1 | 8 dB |
| 8:1 | 11 dB |
| 16:1 | 15 dB |
| 32:1 | 19 dB |
Signal Gain Compensation
If there enough available RF output power to compensate for the combiner level loss, the transmitter will compensate by increasing RF output power equal to the combiner level loss. If not, then the transmitter will only compensate with available power, which is the difference between the total available RF output power and the RF output power of the selected RF level.
If [RF OUTPUT POWER OF THE SELECTED RF LEVEL] + [COMBINER LEVEL LOSS] > [AVAILABLE RF OUTPUT POWER],
Then [SIGNAL GAIN COMPENSATION] = [AVAILABLE RF OUTPUT POWER] - [RF OUTPUT POWER OF THE SELECTED RF LEVEL],
Else [SIGNAL GAIN COMPENSATION] = [COMBINER LEVEL LOSS]
Values for available RF output power are discrete values that are specific to each transmitter device and operational preset.
See available RF output power values by operational preset (dBm)
See available RF output power values by operational preset (mW)
RF System Gain
Inside the channel or RF carrier menu of the transmitter device is the RF System Gain menu. RF System Gain menu displays net RF output power information as the RF level and connections to external combiners (e.g., combiner levels) are adjusted in real time.
RF Power Mapping
When designing Axient Digital PSM systems at scale, having data on net RF output power across all combiner levels is critical. RF power mapping provides a full overview of the limitations of larger combiner configurations. This may also help determine scenarios when decreasing the combiner level and/or increasing the number of transmit antennas would benefit overall performance.