The two types of spectrum analyzers are
, 1. Fliter Bank Spectrum analyzer.
2. Super hetero dyne Spectrum analyzer.
1. Filter Bank Spectrum analyzer
2. Super hetero dyne Spectrum analyzer
The modern spectrum analyzers use a narrow band super heterodyne receiver. Super heterodyne is nothing but mixing of frequencies in the super above audio range. The functional block diagram of super heterodyne spectrum analyzer or RF spectrum analyzer as shown in the Figure 7.2
The RF input to be analyzed is applied to the input attenuator. After attenuating, the signal is fed to low pass filter.
The low pass filter suppresses high frequency components and allows low frequency components to pass through it. The output of the low pass filter is given to the mixer, where this signal is fixed with the signal coming from voltage controlled or voltage tuned oscillator. This oscillator is tuned over 2 to 3 GHz range. The output of the mixer includes two signals whose amplitudes. are proportional to the input signal but their frequencies are the sum and difference of the input signal and the frequency of the local oscillator. Since the frequency range of the oscillator is tuned over 2 to 3 GHz, the IF amplifier is tuned to a narrow band of frequencies of about 2 GHz. Therefore only those signals which are separated from the oscillator frequency by 2 GHz are converted to Intermediate Frequency (IF) band. This IF signal is amplified by IF amplifier and then rectified by the detector. After completing amplification and rectification the signal is applied to vertical plates of CRO to produce a vertical deflection on the CRT screen. Thus, when the saw tooth signal sweeps, the oscillator also sweeps linearly from minimum to maximum frequency range i.e., from 2 to 3 GHz. Here the saw tooth signal is applied not only to the oscillator (to tune the oscillator) but also to the horizontal plates of the CRO to get the frequency axis or horizontal deflection on the CRT screen. On the CRT screen the vertical axis is calibrated in amplitude and the horizontal axis is calibrated in frequency.
Application:
These analyzers are widely used in the field of,
1. Bio medicals
2. RADARS
3.Oceangraphy
, 1. Fliter Bank Spectrum analyzer.
2. Super hetero dyne Spectrum analyzer.
1. Filter Bank Spectrum analyzer
2. Super hetero dyne Spectrum analyzer
The modern spectrum analyzers use a narrow band super heterodyne receiver. Super heterodyne is nothing but mixing of frequencies in the super above audio range. The functional block diagram of super heterodyne spectrum analyzer or RF spectrum analyzer as shown in the Figure 7.2
The RF input to be analyzed is applied to the input attenuator. After attenuating, the signal is fed to low pass filter.
The low pass filter suppresses high frequency components and allows low frequency components to pass through it. The output of the low pass filter is given to the mixer, where this signal is fixed with the signal coming from voltage controlled or voltage tuned oscillator. This oscillator is tuned over 2 to 3 GHz range. The output of the mixer includes two signals whose amplitudes. are proportional to the input signal but their frequencies are the sum and difference of the input signal and the frequency of the local oscillator. Since the frequency range of the oscillator is tuned over 2 to 3 GHz, the IF amplifier is tuned to a narrow band of frequencies of about 2 GHz. Therefore only those signals which are separated from the oscillator frequency by 2 GHz are converted to Intermediate Frequency (IF) band. This IF signal is amplified by IF amplifier and then rectified by the detector. After completing amplification and rectification the signal is applied to vertical plates of CRO to produce a vertical deflection on the CRT screen. Thus, when the saw tooth signal sweeps, the oscillator also sweeps linearly from minimum to maximum frequency range i.e., from 2 to 3 GHz. Here the saw tooth signal is applied not only to the oscillator (to tune the oscillator) but also to the horizontal plates of the CRO to get the frequency axis or horizontal deflection on the CRT screen. On the CRT screen the vertical axis is calibrated in amplitude and the horizontal axis is calibrated in frequency.
Application:
These analyzers are widely used in the field of,
1. Bio medicals
2. RADARS
3.Oceangraphy
