Agilent Technologies Switch/Measure Manual de usuario descargar pdf (Pagina 14)

Graphical view of limits and specifications

As shown in Figure 10, the limit lines for BTS are dependent on a number of

factors, the most fundamental being the output power level of the transmitter.

The absolute limit values are also dependent on system—Figure 13 show limits

for E-GSM900. DCS1800 and PCS1900 use slightly different pass/fail criteria.

Practical measurements

In practice, most power-versus-time failures occur either towards the top of

the rising edge or falling edge. However, it is also important at most points in

the BTS lifecycle to ensure that the turn on/turn off ratio is sufficient. For this

measurement the analyzer used must have adequate dynamic range.

For the purposes of adjustment, it is extremely useful to view power versus

time in real time against the prescribed mask because many GSM transmitters

have multistage turn on/turn off circuits which require calibration.

When to use the measurement

From R&D through to installation, maintenance, and service, power-versus-

time measurements are used universally in GSM applications to check the

functioning of transmitters.

Phase 1 uses this limit

Phase 2 uses this limit

–30 dBc

–70 dBc or

–36 dBm

(highest)

10 8 147 bits

Time (µs)

not to scale

10 10 8 10

+1 dBc

–1 dBc

+4 dBc

Power

(dBc)

–6 dBc

–70 dBc or

–36 dBm

(highest)

Example: E-GSM900, BTS

–6 dBc

–30 dBc

Channels:

B, M, T. Single carrier

At least one slot on

Hopping:

RBW:

=> 300 kHz

Detection:

Zero span

Figure 10. Transmitted RF carrier power versus time, BTS, limits

Figure 11. Agilent E4406A VSA-series transmitter tester screen shot, PVT, high dynamic range-rising and falling edge

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 ... 35 36

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