Final Ui Test: Sinad; Probing/Troubleshooting Tables And Diagrams - Nokia NPD-4 Series Technical Documentation Manual

NPD-4
Troubleshooting — RF
caused by excess loss/insufficient gain in the receiver chain, (and sometimes by excess
noise in the receiver). Check for correct signal levels and AGC values/voltages as
described in the Probing/Troubleshooting Tables and Diagrams section.

Final UI test: SINAD

Signal-to-Noise-and-Distortion (SINAD) is similar to a sensitivity/FER measurement for
CDMA, but is used in AMPS.
A low-level signal (typically at a sensitivity level of -116.0 dBm) is injected into the
receiver, and SINAD is read off the call box, with 12 dB as the passing limit.

Probing/Troubleshooting Tables and Diagrams

When measuring CDMA transmit signals, if the spectrum analyzer does not have a CDMA
personality card, then the CDMA signal power can be approximated by setting the Resolu-
tion Bandwidth to 1 MHz and using the marker. This is because CDMA signal power is
measured by integrating power over a 1.23 MHz bandwidth, and the marker measures
power at only one frequency.
In most cases, probing is done in local mode (i.e., not in a call). Situations may arise
whereby the troubleshooter may need to probe while in a call; however, in some cases
probing may disturb the circuit so that the call drops.
Although the tables list power levels for many combinations of AGC values, it is generally
only necessary to check one combination. The extra information is provided in case it
may be useful in an unexpected situation. Likewise, although probing points and signal
level information are given for each point in the receiver and transmitter chains, the
troubleshooter is not expected to probe each point on every phone, only the suspected
trouble spots.
Absolute power measurements were made with an Agilent (HP) 85024A active high
impedance probe. Other probes can be used (but should be high impedance so that the
measurement does not load the circuit) but may very well have a different gain, there-
fore adjust the absolute measurements accordingly. Also, adjust measurements if using a
probe attenuator.
Where a range is given for loss, typically the higher loss occurs at the band edges.
Power depends on the impedance of the circuit. For example, if a filter has a nominal loss
of 5 dB, then straightforward probing on the input and output, then subtracting, might
not result in 5 dB since the input impedance might be different from the output imped-
ance. However, after mathematically adjusting the power on either the input or output
to compensate for the difference in impedance, 5 dB is then calculated. Most compo-
nents in the RF section have the same input and output impedance (50 ohms), but where
this is not the case, absolute power is noted in the tables in dBm, rather than loss or gain
in dB.
When testing the CDMA receiver, it is easier to inject a CW tone into the receiver. The
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CCS Technical Documentation
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