Metrics Provided by the 1xEV-DO Tx and Over Air Analyzer Measurement
This section contains descriptions of the individual 1xEV-DO parameters in the metric display of the screen. For information on expected result values and possible causes of error if the expected results are not met, see "Interpreting the Display"
You can switch the display of the metric results Off by pressing [Display], and then setting [CDP and Metrics] to Off. Only the Freq, the PN Offset, and the Time Offset metrics will be displayed. All other metrics will appear as dashes.
If the OTA PN Scanner is turned On, and either the measured Pilot Dominance is not within its limits, or the measured Multipath Power is not within its limits, all metrics will be displayed in gray text. This indicates that because either one, or both, of Pilot Dominance and Multipath Power have not met their specified limits, all the results being displayed are inaccurate to an unknown degree, and may therefore be unreliable. Ensure that your signal meets the Pilot Dominance Limit and the Multipath Power Limit to ensure you collect accurate results.
Frequency
Frequency is the center frequency you entered.
Frequency Error
Frequency error is the frequency difference between your access network's actual center frequency and the frequency (or channel) you entered. With a valid time reference (GPS or ESC) this will have a range of ± 25KHz about the selected center frequency. For a pure frequency reference it is limited to ± 500Hz.
PN Offset
The PN Offset is a "short code" sequence that provides a unique identifier for each sector of each cell site. The PN Offsets are applied to the I and Q signals before modulation. PN Offsets are offset in time by 52.08 µs and they repeat every 26.666 ms. This yields 512 unique short code sequences (0-511). The access terminal needs the PN Offset to decode information in the Pilot channel and the MAC channel, both of which are transmitted by the access network.
Time Offset
The Time Offset compares the PN Offset timing with the overall system time. This measurement checks the start of the PN offset in comparison to the GPS signal, or to the Even Second Clock signal. For example, PN Offset 0 should repeat exactly on the rising edge of the Timing Reference. PN Offset 1 should repeat 52.08 µs after the rising edge of the Timing Reference, and so forth. Any deviation in time from that event is reported as a Time Offset.
Non Idle Power
The Non Idle Power is a measurement of the average power during an entire slot when the acquired slot is non-idle. When all of the acquired slots are idle (that is, when Idle Slots shows 100%), the measurement result is blanked out. The number of slots over which the acquisition is made is determined by the Update Interval, which itself is determined by the Meas Time setting.
Pilot + MAC Power
The Pilot + MAC Power is a measurement of the average power during the Pilot and MAC periods. When all of the acquired slots are idle (that is, when Idle Slots shows 100%), the measurement result is blanked out. The number of slots over which the acquisition is made is determined by the Update Interval, which itself is determined by the Meas Time setting.
On/Off Ratio
This refers to the Idle On/Off Power Ratio, which is ratio of the Pilot + MAC Power to the Idle Data Power. The result is blanked out when none of the acquisition slots are idle, that is, when Idle Slots shows 0%. The number of slots over which the acquisition is made is determined by the Update Interval, which itself is determined by the Meas Time setting.
Idle Data Power
The Idle Data Power is a measurement of the average power during the data period of an idle slot. When none of the acquired slots are idle (that is, when Idle Slots shows 0%), the measurement result is blanked out. The number of slots over which the acquisition is made is determined by the Update Interval, which itself is determined by the Meas Time setting.
Idle Slots
The Idle Slots measurement shows as a percentage, the number of idle slots out of the total number of slots. Exactly how this percentage figure is worked out depends on the Averaging State you have selected.
If averaging is Off, the precentage of idle slots since the last restart is reported.
If averaging is Off and your analyzer is in Single mode, the precentage of slots within the update interval is reported.
If averaging is On, the result displayed is the percentage of idle slots within 'n' capture intervals, where 'n' is the current average number. Once your desired number of averages has been reached, the result reported is the percentage of idle slots within the last 'n' measurement capture intervals.
Est Pilot Rho
Pilot Rho is the measure of the modulation quality for a 1xEV-DO transmitter. This measurement is analogous to measuring FM accuracy and distortion in an AMPS network or EVM in a TDMA system. A Rho value of 1.0 represents a perfect signal, indicating that all of the power is being transmitted correctly. Pilot Rho is only measured over the 96 pilot chips contained within every half-slot. The measurement result is blanked out when the code domain measurement does not synchronize to the received input signal. The number of slots over which the acquisition is made is determined by the Capture Interval, which itself is determined by the Meas Time setting.
Est MAC Rho
MAC Rho is the measure of the modulation quality for a 1xEV-DO transmitter. This measurement is analogous to measuring FM accuracy and distortion in an AMPS network or EVM in a TDMA system. A Rho value of 1.0 represents a perfect signal, indicating that all of the power is being transmitted correctly. MAC Rho is only measured over the 128 MAC chips contained within every half-slot. The measurement result is blanked out when the code domain measurement does not synchronize to the received input signal. The number of slots over which the acquisition is made is determined by the Capture Interval, which itself is determined by the Meas Time setting.
Max Inactive Ch
This is a measure of the Maximum Inactive Channel Power. The reported result is the maximum power in the separate I and Q channels when the MAC Channel Walsh Codes are inactive, relative to the total power in both the active and the inactive channels. The number of slots over which the acquisition is made is determined by the Update Interval, which itself is determined by the Meas Time setting.
The result reported is for the currently selected CDP type, for example, if the selected CDP type is Pilot, this will report the highest power level detected across the inactive channels within the 32 pilot codes.
Noise Floor
The Noise Floor is the average inactive Walsh code power level detected in the combined I and Q channels, relative to the total power in both the active and the inactive channels. The number of slots over which the acquisition is made is determined by the Update Interval, which itself is determined by the Meas Time setting.
The result reported is for the currently selected CDP type, for example, if the selected CDP type is Pilot, this will report the average power level detected across the inactive channels within the 32 pilot codes.
NOTE: Take care that you do not confuse Noise Floor with Idle Data Power. Idle Data Power is the power present in the data region of the Idle slots. Noise Floor is the average power present in the inactive Walsh Code channels.
Data Modulation Type
The Data Channel Modulation measurement returns the highest modulation detected within the measurement interval. There are three types of modulation, and hence four possible measurement results: QPSK, 8PSK, and 16QAM, and blank when no modulation is detected. QPSK is the lowest type of modulation, 8PSK is the next higher, and the highest modulation type is 16QAM. Only if all the slots within the measurement interval are idle will the result be blanked out. The number of slots over which the acquisition is made is determined by the capture interval, which itself is determined by the Meas Time setting.