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In simulator, broadcast FM radio station goes through IF of FM receiver where our oscilloscope is connected to view tuned in signal. Bottom is audio output stage of FM receiver.
If we connect our oscilloscope to display IF frequency that our oscilloscope can show on screen we can convert higher frequency signals downward (heterodyning). If we have old receiver and do not overload the input signal we can tune to high frequency signals with the important advantage is that it gives the receiver a constant bandwidth over its tuning range that we can view.
American Radio Relay League (ARRL) shows one Scope Bandwidth Extender in Chapter 25 of 2010 ARRL Handbook.
With satellite dishes, the microwave downlink signal received by the dish is converted to a much lower IF at the dish, to allow a relatively inexpensive coaxial cable to carry the signal to the house.
At the cable company's set top box, the signal is converted to a lower IF of 480 MHz for filtering, by a variable frequency oscillator. This is sent through a 30 MHz bandpass filter, which selects the signal from one of the transponders on the satellite, which carries several channels. Further processing selects the channel desired, demodulates it and sends the signal to the television.
Some IF frequencies that have been used
110 kHz was used in Long wave broadcast receivers.
Analogue television receivers using system M: 41.25 MHz (audio) and 45.75 MHz (video). Note, the channel is flipped over in the conversion process in an intercarrier system, so the audio IF frequency is lower than the video IF frequency. Also, there is no audio local oscillator, the injected video carrier serves that purpose.
Analogue television receivers using system B and similar systems: 33.4 MHz. for aural and 38.9 MHz. for visual signal.
FM radio receivers: 262 kHz, 455 kHz, 1.6 MHz, 5.5 MHz, 10.7 MHz, 10.8 MHz, 11.2 MHz, 11.7 MHz, 11.8 MHz, 21.4 MHz, 75 MHz and 98 MHz. In double-conversion superheterodyne receivers, a first intermediate frequency of 10.7 MHz is often used, followed by a second intermediate frequency of 470 kHz. There are triple conversion designs used in police scanner receivers, high-end communications receivers, and many point-to-point microwave systems. Modern DSP chip consumer radios often use a 'low-IF' of 128kHz for FM.
AM radio receivers: 450 kHz, 455 kHz, 460 kHz, 465 kHz, 467 kHz, 470 kHz, 475 kHz, 480 kHz.
Satellite uplink-downlink equipment: 70 MHz, 950–1450 MHz (L-band) downlink first IF.
Terrestrial microwave equipment: 250 MHz, 70 MHz or 75 MHz.
Radar: 30 MHz.
RF Test Equipment: 310.7 MHz, 160 MHz, 21.4 MHz.
Noticing the IF range when we are looking at gear might be consideration to consider.
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