8
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 approxi12.5dBm. 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.
Test Points F and G
RF local oscillator (LO):
The behavior of the RF VCO can be monitored at Test
Point F.
The VCO output should be locked at the channel frequency
minus the IF (374MHz.) This means that the VCO will have
to lock between 2038MHz and 2110MHz. The output power
at test point F is approximately -6dBm. Ideally, the tuning
voltage of the VCO, when locked, falls between 0.5V and
2.2V. The tuning voltage of the RF VCO can be observed at
Test Point G.
Test Points H and I
IF local oscillator (LO):
The IF VCO is a discrete design and operates at 748MHz
(i.e., twice the IF frequency). The output frequency of this
VCO does not need to be varied; thus, minimal tuning range
is required.
The output frequency of this VCO can be observed at Test
Point H.
Ideally, the tuning voltage of the IF VCO, when locked, falls
between 0.5V and 2.2V. The tuning voltage of the IF VCO
can be observed at Test Point I.
TABLE 1. IEEE 802.11 CHANNELS
CHANNEL
NUMBER
CHANNEL
FREQUENCY
GEOGRAPHIC
USAGE
1
2412MHz
US, CA, ETSI
2
2417MHz
US, CA, ETSI
3
2422MHz
US, CA, ETSI
4
2427MHz
US, CA, ETSI
5
2432MHz
US, CA, ETSI
6
2437MHz
US, CA, ETSI
7
2442MHz
US, CA, ETSI
8
2447MHz
US, CA, ETSI
9
2452MHz
US, CA, ETSI
10
2457MHz
US, CA, ETSI, FR, SP
11
2462MHz
US, CA, ETSI, FR, SP
12
2467MHz
ETSI, FR
13
2472MHz
ETSI, FR
14
2484MHz
Japan
†
KEY: US = United States, CA = Canada, ETSI = ETSI countries
(except France and Spain), FR = France, SP = Spain.
†
In Japan, authorization for Channels 1 through 11 is pending.
FIGURE 7. TRANSMITTED 2.4GHz SIGNAL SPECTRUM
(TEST POINT E)
FIGURE 8. RF LOCAL OSCILLATOR OUTPUT AT CHANNEL 8
(TEST POINT F)
FIGURE 9. IF LOCAL OSCILLATOR OUTPUT (TEST POINT H)
Application Note 9864
