Table of Contents
Advertisement
Frequency Mod ulation
Conditions required to meet specification
*
: 200 Hz
• Peak deviation
• Modulation index (ModIndex) =PeakDeviation/Rate = Beta: 0.2 to 2000
1 MHz
• Channel BW:
• Rate: 20 Hz to 50 kHz
• SINAD bandwidth: (Channel BW) / 2
• Single tone - sinusoid modulation
Description
FM Deviation Accuracy
d
FM Rate Accuracy
Carrier Frequency Error
(ModIndex 100)
Carrier Power
a. This specification applies to the result labeled "(Pk-Pk)/2".
b. For optimum measurement of rate and deviation, ensure that the channel bandwidth is set wide
enough to capture the significant RF energy (as visible in the RF Spectrum window). Setting the chan-
nel bandwidth too wide will result in measurement errors.
c. Reading is a measured frequency peak deviation in Hz, and Rate is a modulation rate in Hz.
d. Reading is a measured modulation rate in Hz.
*.Peak deviation, modulation index ("beta"), and modulation rate are related by PeakDeviation = ModIndex
Each of these has an allowable range, but all conditions must be satisfied at the same time. For example, PeakDevia-
tion = 80 kHz at Rate = 20 Hz is not allowed, since ModIndex = PeakDeviation/Rate would be 4000, but ModIndex is
limited to 2000. In addition, all significant sidebands must be contained in Channel BW. For FM, an approximate
rule-of-thumb is 2
Rate is small, but both cannot be large at the same time.
84
Specifications
abc
[PeakDeviation + Rate] < Channel BW; this implies that PeakDeviation might be large if the
Supplemental Information
0.4 (rate + deviation) (nominal)
(0.01 Reading) (nominal)
0.5 Hz (nominal)
Same as
"Absolute Amplitude Accuracy"
on page 24
at all frequencies (nominal)
Rate.
Advertisement
Table of Contents
