The Pilot & MAC power shows the average power of the Pilot and MAC Channels. It is an absolute number that is expressed in dBm or Watts.

Active Data Power is the average power of the Data Channel. When the slot is active, the data power should be very similar to the MAC & Pilot power (less than 2.5 dB difference). When the slot is idle, the Active Data Power should be at least 7 dB below the MAC & Pilot power if the instrument is connected directly to a base station.

During an active slot, Channel Power should be similar to Pilot & MAC power and should also be similar to Active Data Power. During an idle slot, channel power should be somewhere between the Pilot & MAC power and Data Power, because it is a weighted average of the two. When measuring an EVDO station with live traffic, channel power will vary according to how busy the downlink is, because channel power also depends upon the percentage of idle slots and active slots in the captured sample.

Noise floor is the average power of the inactive MAC channels, relative to the total MAC channel power. It is expressed in dB. When connected to a good EVDO source, the noise floor should be -31.5 dB or below. When noise or distortion is present (for example, in an over-the-air measurement), the noise floor can be considerably higher.

Frequency error is the difference between the received center frequency and the specified center frequency. This is only as accurate as the frequency reference that is being used and is typically more useful with a good external frequency reference or GPS.

The instrument can determine the data channel modulation type automatically. EVDO data channel has three modulation types: QPSK, 8PSK, and 16QAM. “Idle” is displayed when the slot is idle.

Each EVDO base station is identified by a unique PN Offset in its pilot signal. This is similar to CDMA.

Tau measures the time delay from the input trigger to the “start of a slot.” This means that Tau can be much larger than what is commonly seen in CDMA if the signal is not synchronized to the trigger.

Rho is a number between 0 and 1. A good signal should have a Rho that is close to 1. When connected to a good EVDO source, all Rhos should be 0.97 or above, and should decrease when the channel power is too weak. When noise or distortion is present, for example in an over-the-air measurement, Rhos can drop dramatically.

Rho Pilot is an indicator of the quality of the Pilot Channel.

Rho Data is an indicator of the quality of the Data Channel.

Rho MAC is an indicator of the quality of the MAC Channel.

Rho Overall 1 and 2 are both indicators of the overall quality of the EVDO signal during an active slot. They differ from each other in the sense that Rho Overall 1 measures from the beginning to the end of a half slot, while Rho Overall 2 measures from the middle of one half slot to the middle of another half slot. In general, they should have similar values.

Carrier Feedthrough measures the amount of unmodulated signal that is leaking through the transmitter.

The Data Channel in EVDO consists of 16 “I” sub channels and 16 “Q” sub channels. Each of these channels should have a power of approximately -15.05 dB relative to the total Data Channel power. When connected to a good signal source, the Data Code Min is usually larger than -15.5 dB, and the Data Code Max is usually less than -14.6 dB. The smaller the difference between these two values, the better the signal quality.

MAC channels are Walsh despread into 64 sub-channels (physical layer Subtype 0 or 1) or 128 sub-channels (physical layer Subtype 2). See the menu description for CDP MAC for color code details.

The strongest 9 PNs that are received are displayed. The length of the bar represents the absolute or relative power of the signal in dBm or dB. The strongest PN or the user-selected PN is color coded blue, those colored red are probably real pilots, and the remaining, which are color coded gray, are probably noise.

The length of the bar represents the relative power in the signal path in dB. Ec/Io and Tau are displayed below each bar. The strongest signal is color coded blue. The remaining signals are color coded red, or they are color coded gray if they are due to system noise.

 

Pilot Dominance is a measure of the strength of the strongest pilot compared to the next strongest pilot in the same channel. This should be > 10 dB in order to make good demodulator measurements.

Multipath Power is a measure of the total amount of power in the dominant signal (that is being spread in time due to multipath echoes) relative to its power in the main transmission path. This should be < 0.4 dB in order to make good measurements.

The pilot power compared to the total channel power during the pilot time slot.

The occupied bandwidth is calculated as the bandwidth containing 99% of the transmitted power in a 2.5 MHz span.

This view shows the time domain view of an EVDO half-slot. The Slot Type selection in the Setup menu determines the priorities regarding which slot is displayed.

This shows the estimated percentage of idle or active slots in the total number of slots captured. Expect the idle percent (%) to be low and the active percent to be high when many EVDO users are connected to a base station.