NDC comm HWB3163 manual Application Note Explanation of Test Points, Test Points A- A1, and B-B1

Application Note 9864

Explanation of Test Points

All measurements were taken using the “Continuous Transmit” or “Continuous Receive” features of the PTU diagnostic software. Unless otherwise noted, spectrum measurements included in this section were obtained using a Hewlett-Packard 54006A 500Ω probe and 11742A coaxial blocking capacitor and do not indicate the actual amplitude of the signal owing to losses associated with the probe. Unless noted, 11Mbps CCK modulation was employed.

Many of the signals are differential (i.e., balanced with respect to ground). These are denoted by + (plus) and

-(minus) symbols following the signal name (e.g., RX I+ and RX I-).

Test Points A- A1, and B-B1

Transmit I and Q:

Test Points C and D

IF Transmit Signal:

FIGURE 5. IF TRANSMIT SIGNAL BEFORE SAW FILTER

(TEST POINT C)

	FIGURE 6. IF TRANSMIT SIGNAL AFTER THE SAW FILTER
FIGURE 4. TRANSMIT I AND Q SIGNALS AT THE OUTPUT	(TEST POINT D)
OF THE HFA3861 (TEST POINTS A-A1 AND B-B1)

NOTE: BPSK mode is used for the plots in this figure. Therefore, I and Q are identical.

The I and Q are both differential signals and, as such, consist of I+, I-, Q+, and Q- respectively. As these are balanced signals, data is measured using a Tektronix P6247 Differential Probe. For example in the measurement of the I signal, the probe is bridged between Test Points A (I+) and A1 (I-).

Transmit In-phase and Quadrature (I+ and Q+) signals are the spread baseband single-bit I and Q digital data that are outputted at the programmed chip rate (N).

The intermediate frequency (IF) transmit signal is a spread spectrum signal centered at 374MHz with a 17MHz bandwidth.

The SAW filter is used to shape the sidelobes.

Test point C is at the input of the SAW Filter whereas D is at the output.

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