Metrics Provided by the W-CDMA or W-CDMA (with HSDPA) Over Air Measurement
This section contains descriptions of the individual W-CDMA or W-CDMA (with HSDPA) transmitter metrics in the Metrics view of the screen. For expected result values and possible causes of error if the expected results are not met, see "Interpretation of Over the Air Measurement Results"
Freq (Frequency)
Frequency is the selected transmitter operating frequency you have entered (or calculated from the channel number you have entered).
Freq Error (Frequency Error)
Frequency error is the frequency difference between your transmitter's actual center frequency and the frequency (or channel) you entered.
Scramble Code
The Scrambling Code being measured (manual or auto). In W-CDMA or W-CDMA (with HSDPA), each Access Network (or BTS) output signal is scrambled by multiplying each of its data channels by a unique pseudo-noise (PN) code. In the W-CDMA specifications, this is referred to as a Scrambling Code.
Noise Floor
Noise Floor is the average power level of all the inactive channels.
Carr Feedthru or Carr FT (Carrier Feedthrough)
Carrier Feedthrough is a result of the RF carrier signal feeding through the I/Q modulator and riding on the output circuitry without being modulated.
EVM Pilot and EVM Comp (Pilot (CPICH) and Composite Error Vector Magnitude
EVM is the measure of signal quality specified as a percent of noise to pure signal. It is the difference between the measured waveform and the theoretical modulated waveform (the error vector). EVM metrics are used to measure the modulation quality of a transmitter. The 3GPP standard requires the Composite EVM not to exceed 17.5% for normal W-CDMA (defined as Test Models 1 and 4), and not to exceed 12.5% in the case of 16QAM HSDPA (defined as Test Model 5).
PCDE (Peak Code Domain Error)
PCDE takes the noise and projects the maximum impact it will have on all OVSF codes. PCDE is the maximum value for the code domain error for all codes (both active and inactive).
In W-CDMA or W-CDMA (with HSDPA), specifically to address the possibility of uneven error power distribution, the EVM measurement has been supplemented with PCDE. The 3GPP standard requires the PCDE not to exceed -33 dB at a spreading factor of 256, but the Conformance Test adds in a Test Tolerance of 1dB. This gives a Conformance Limit for Peak Code Domain Error of -32dB at a spreading factor of 256.
Utilization
Utilization is a ratio of the active OVSF codes to the total SF512 codes, expressed as a percentage. Even though active control channels such as the pilot are included in the utilization measurement, utilization is an indication of the traffic that is being carried by the base station.
For example, W-CDMA or W-CDMA (with HSDPA) signal with CPICH, PCCPCH, SCCPCH using SF256, and PICH, would use 8 of 512 SF512 codes, giving a utilization of 1.6%.
Pk Util (Peak Utilization)
Peak Utilization is the peak level of all the valid Utilization measurements while on the same Scrambling code. In Scrambling code Auto mode this measurement is reset if the Scrambling code changes or the Reset Metrics button is used. In Scrambling code Manual mode this measurement is reset only if the Reset Metrics button is used.
NOTE: Pressing [Reset Metrics] also causes a restart of your analyzer.
Avg Util (Average Utilization)
Average Utilization is the average level of all the valid Utilization measurements while on the same Scrambling code. In Scrambling code Auto mode this measurement is reset if the Scrambling code changes or the Reset Metrics button is used. In Scrambling code Manual mode this measurement is reset only if the Reset Metrics button is used.
NOTE: Pressing [Reset Metrics] also causes a restart of your analyzer.
Chan Pwr (Channel Power)
Channel Power is the integrated power within a defined bandwidth. For W-CDMA or W-CDMA (with HSDPA) the channel bandwidth is 3.84 MHz. Channel Power measures the power the base station is transmitting across the entire 3.84 MHz W-CDMA or W-CDMA (with HSDPA) channel.
CPICH (Common Pilot Channel)
Common Pilot Channel (CPICH) is the channel that carries the scrambling code. The CPICH metric reports the power in this channel in dBc. By default, the CPICH Limits are set to Off. If you set CPICH Limits On, the default upper limit value is 0 dBc, and the lower limit value is -20 dBc.
NOTE: The CPICH default limits are set at a level suitable for catching only gross errors when field testing live signals. To perform conformance testing, you will need to set the limits to your own specifications. Conformance testing for Test Model 2 (TM2), for example, requires that the CPICH limits are set to ±2.9 dB, that is, to -7.1 dB and -12.9 dB with a -10 dBc signal.
Amp Cap (Amplifier Capacity)
Assuming the Amplifier Capacity parameters are set properly, the Amplifier Capacity measurement is an estimate of the amount of power amplifier capacity that is being used, expressed in percent of maximum. When an amplifier is transmitting at maximum output power, it is said to be at 100% of its capacity. For example, an amplifier with a maximum output power of 12 watts would be at 50% of capacity when transmitting 6 watts and at 100% of capacity when transmitting at 12 watts.
The percentage of amplifier capacity generally increases as the number or level of the traffic channels increase.
Pk Amp Cap (Peak Amplifier Capacity)
Peak Amplifier Capacity is the peak level of all the valid Amplifier Capacity measurements while on the same Scrambling code. In Scrambling code Auto mode this measurement is reset if the Scrambling code changes or the Reset Metrics button is used. In Scrambling code Manual mode this measurement is reset only if the Reset Metrics button is used.
NOTE: Pressing [Reset Metrics] also causes a restart of your analyzer.
Avg Amp Cap (Average Amplifier Capacity)
Average Amplifier Capacity is the average level of all the valid Amplifier Capacity measurements while on the same Scrambling code. In Scrambling code Auto mode this measurement is reset if the Scrambling code changes or the Reset Metrics button is used. In Scrambling code Manual mode this measurement is reset only if the Reset Metrics button is used.
NOTE: Pressing [Reset Metrics] also causes a restart of your analyzer.