Page 99 - Complete Wireless Design

Modulation

98 Chapter Two

12. Carrier-to-noise ratio (CNR) at P1dB , measured 250 kHz from the
INPUT
carrier with a spectrum analyzer (RBW, VBW, VID AVG, SPAN settings
must be specified) at the receiver’s output, measured in dBc.
13. CNR at n miles (using an adjustable attenuator between the CW signal
generator and the receiver’s front end for simulated free-space path loss)
at the receiver’s output, measured in dBc.
14. Signal level at n miles (using an adjustable attenuator between the CW
signal generator and the receiver’s front end for simulated free space path
loss) at the receiver’s output, measured in dBm.
15. VSWR at band center, a dimensionless ratio.
16. Group delay variations (GDV) across entire channel, measured in ns.
17. DC drawn from power supply, measured in mA.
18. Attenuation of potential interferers injected in certain out-of-band chan-
nels, and measured at the output in dB of attenuation.
19. BER testing with a BERT.
The following are the minimum tests that should be performed on a digitally
modulated transmitter. Most of these tests require that a CW test signal be inject-
ed into the transmitter’s input IF, at the center of one of its channels, and at below
P1dB power levels, with the output taken from the transmitter’s RF output.
Transmitter tests:

1. Gain from input IF to output RF, measured in dB.
2. Gain flatness across channel, measured in dB (sweep entire channel with
frequency generator).
3. Frequency accuracy after warm-up, measured in Hz.
4. Frequency stability over a certain temperature range after a specified
period of warm-up, measured in Hz.
5. Frequency drift over a set time at 25°C, measured in Hz, from turn-on to
full warm-up.
6. P1dB output power, measured in dBm.
7. Phase noise of local oscillator at 10 kHz offset from carrier in dBc, mea-
sured in dBc/Hz/10 kHz.
8. Two-tone IMD at RF output, measured in dBc.
9. In-band internally generated spurs with no input signal, measured in
dBm and Hz.
10. 3-dB bandwidth of channel, measured in Hz.
11. VSWR at band center, a dimensionless ratio.
12. Group delay variations (GDV) across entire channel, measured in ns.
13. LO feedthrough at transmitter output, measured in dBm.
14. DC drawn from power supply, measured in mA.
15. BER testing with a BERT.
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