User Manual

9
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).
Test Points C and D
IF Transmit Signal:
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.
Test Point E
RF Transmit Signal:
The optional SMA connector can be used to hook up a
Spectrum Analyzer for RF evaluation. Note that L4 (1.5nH)
must be removed and C141 (15pF) and C37 (150pF) must
be installed to activate the connector See (Figure 3).
This is the up-converted spread spectrum output of the card.
The center frequency of this signal is 2412-2484MHz
depending on the channel of operation. The output power of
the signal is approximately +12.5dBm. The peaks of the
sidelobes of the output spectrum (i.e., the regrowth) are
normally adjusted by the ALC/AGC to be 30dB below the
peak of the spectrum per requirements of IEEE 802.11.
The following table delineates the IEEE 802.11 channels and
their corresponding center frequencies. Although information
contained in Table 1 is deemed to be accurate, local regulatory
authorities should be consulted before using such equipment.
FIGURE 8. IF TRANSMIT SIGNAL BEFORE SAW FILTER
(TEST POINT C)
FIGURE 9. IF TRANSMIT SIGNAL AFTER THE SAW FILTER
(TEST POINT D)
TABLE 3. IEEE 802.11 CHANNELS
CHANNEL
NUMBER
CHANNEL
FREQUENCY
GEOGRAPHIC
USAGE
1 2412MHz US, CA, ETSI, MKK
2 2417MHz US, CA, ETSI, MKK
3 2422MHz US, CA, ETSI, MKK
4 2427MHz US, CA, ETSI, MKK
5 2432MHz US, CA, ETSI, MKK
6 2437MHz US, CA, ETSI, MKK
7 2442MHz US, CA, ETSI, MKK
8 2447MHz US, CA, ETSI, MKK
9 2452MHz US, CA, ETSI, MKK
10 2457MHz US, CA, ETSI, FR, SP, MKK
11 2462MHz US, CA, ETSI, FR, SP, MKK
12 2467MHz ETSI, FR, MKK
13 2472MHz ETSI, FR, MKK
14 2484MHz Japan
†
KEY: US = United States, CA = Canada, ETSI = ETSI countries
(except France and Spain), FR = France, SP = Spain.
†In Japan, Channel 14 requires Japanese Transmit Filter.
FIGURE 10. TRANSMITTED 2.4GHz SIGNAL SPECTRUM
(TEST POINT E)
Application Note 9949