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What is tracking in superheterodyne receiver?
the maintenance of the coordinated variation of the resonant frequencies of oscillatory circuits of, for example, a superheterodyne receiver, that are tuned by means of a single control knob.
What is the role of the local oscillator in the Superhet receiver?
Local oscillators are used in the superheterodyne receiver, the most common type of radio receiver circuit. In satellite television reception, the microwave frequencies used from the satellite down to the receiving antenna are converted to lower frequencies by a local oscillator and mixer mounted at the antenna.
Why is tracking important in a superhet receiver?
To suppress the unwanted image, the tuning of the RF stage and the LO may need to “track” each other. In some cases, a narrow-band receiver can have a fixed tuned RF amplifier. In that case, only the local oscillator frequency is changed. In most cases, a receiver’s input band is wider than its IF center frequency.
What is 3pt tracking?
Simultaneously, three point tracking combines the paddler and trimmer tracking. The three frequencies of correct tracking i.e. at which zero tracking error exists are normally 600 KHz, 1500 KHz and geometric mean of the two i.e. 950 KHz. It is possible to keep the tracking error below 3 KHz.
Why if is used in receiver?
Superheterodyne receivers tune in different frequencies by adjusting the frequency of the local oscillator on the input stage, and all processing after that is done at the same fixed frequency: the IF. A more important advantage is that it gives the receiver a constant bandwidth over its tuning range.
Is there a way to track the oscillator?
The problem with using identical capacitor sections is that the LO has a proportionally narrower tuning range than the front end, so tracking will be poor. It can be improved by adding a padding capacitor in series with the LO tuning capacitor.
Where is the oscillator above or below the RF?
First of all, there are two basic heterodyning schemes, one where the local oscillator frequency is above the RF, and one where the LO is below the RF. In either case, the goal is to produce an intermediate frequency – IF – which peaks in amplitude as radio stations are “tuned in” across the frequency band of interest.
Can a superhet radio remove the image signal?
Removing the image signal is a key requirement in the performance of the superhet radio. With the local oscillator set to 0.75 MHz and with an IF of 0.25 MHz, it has already been seen that a signal at 1.0 MHz mixes with the local oscillator to produce a signal at 0.25 MHz that will pass through the IF filter.
What are the facts about the superheterodyne receiver?
There are several facts about the superheterodyne receiver image response that can be summarised quite easily. Image is twice the IF away from the wanted signal: Frequencies that enter the IF are spaced from the local oscillator by an amount equal to the intermediate frequency. Therefore if one frequency is LO + IF, the other one will be LO – IF.