The bandwidth of a filter is proportional to its center frequency. In receivers like the TRF in which the filtering is done at the incoming RF frequency, as the receiver is tuned to higher frequencies its bandwidth increases. The main reason for using an intermediate frequency is to improve frequency selectivity.
One extremely important yet not widely known characteristic of today’s high-performance RF signal analyzers is their use of a range of intermediate frequency (IF) filter bandwidth settings.
Put another way, RF stands for “radio frequency” which is a general term and could mean any high frequency signal; say greater than a few MHz. IF stands for “intermediate frequency” and is the frequency of a specific signal in a receiver.. The IF signal is obtained by multiplying the RF signal with an internal signal, one generated by the receiver.
Many RF systems incorporate an intermediate frequency (IF) that is lower than the carrier frequency and higher than the baseband frequency. An IF-based receiver is known as a heterodyne receiver. The use of an IF simplifies the design of tunable receivers and reduces the number of components that must be compatible with high frequencies.
The intermediate frequency is created by mixing the carrier signal with a local oscillator signal in a process called heterodyning, resulting in a signal at the difference or beat frequency.
IF Bandwidth. The received signal is converted from its source frequency to a lower intermediate frequency (IF). The bandwidth of the IF bandpass filter is adjustable from 40 kHz (for most PNA models) down to a minimum of 1 Hz. Reducing the IF receiver bandwidth reduces the effect of random noise on a measurement.
Learn RF Spectrum Analysis Basics. Page 2 Agenda • Overview: Spectrum analysis and its ... IF = intermediate frequency f LO 0 f in 0 0 f LO-f in f LO +f in f LO. Page 12 IF FILTER Input Intermediate Frequency (IF) Filter •IF Bandwidth: also known as resolution bandwidth and RBW •Provides shape of frequency
his article will discuss Intermediate Frequency (IF) sampling concepts of sub-sampling (or under sampling), noise processing gain, and the effects of interfering signals. Examples will be based on the GSM/EDGE communications standard where the channel bandwidth is 200 kHz and the sample rate is typically a multiple of 13 MHz. Sub-Sampling
bandwidth “W” – Speech- 4kHz ... Intermediate Frequency (IF) • Radio receiver design can be optimized for that frequency • IF filter and a demodulator for IF frequency. AM/FM Radio Spectrum • Recall that AM and FM have different radio frequency (RF) spectrum ranges: – AM: 540 kHz – 1600 kHz
If the demodulation circuit had to be wideband (say, able to work for any frequency from 88-108 MHz for FM), keeping a flat response across the entire frequency range would be difficult. Instead, the tuner is wideband and then beat (heterodyned) to a single intermediate frequency and sent to a very optimized demodulation circuit.