image frequency

The image frequency results in two stations being received at the same time, thus producing interference.

A high-speed video camera is also attached with an imaging frequency of 0-50 frames per second.

This image frequency is within the AM broadcast band.

One major disadvantage to the superheterodyne receiver is the problem of image frequency.

Any noise or random radio station at the image frequency can interfere with reception of the desired signal.

Subjects were instructed to breathe in synchrony to the imaging frequency of 20 frames per min.

Therefore we can express all the image frequencies as for any integer N (with being the actual signal frequency).

This made them extremely susceptible to image frequency interference, but at the time, the main objective was sensitivity rather than selectivity.

He knows that the Doppler effect has increased the image frequency by the factor 1 / (1 v/c).

The signal from the antenna is filtered sufficiently at least to reject the image frequency (see below) and possibly amplified.

The ability of a receiver to reject interfering signals at the image frequency is measured by the image rejection ratio.

Image frequency (f)

These allowed the use of much higher Intermediate Frequencies (typically around 440-470kHz) which eliminated the problem of image frequency interference.

These anisotropically downsampled images can be probed when the texture-mapped image frequency is different for each texture axis.

A receiver with inadequate filtering at its input will pick up signals at two different frequencies simultaneously: the desired frequency and the image frequency.

When the image rejection ratio is measured, the input signal levels of the desired and image frequencies must be equal for the measurement to be meaningful.

Since the frequency separation between the bandpass and the image frequency is , a higher intermediate frequency improves image rejection.

In heterodyne receivers, an image frequency is an undesired input frequency equal to the station frequency plus twice the intermediate frequency.

Image frequencies can be eliminated by sufficient attenuation on the incoming signal by the RF amplifier filter of the superheterodyne receiver.

The farther apart the bandpass frequency and the image frequency are, the more the bandpass filter will attenuate any interfering image signal.

This is the ratio (in decibels) of the output of the receiver from a signal at the received frequency, to its output for an equal-strength signal at the image frequency.

Practical receivers have a tuning stage before the converter, to greatly reduce the amplitude of image frequency signals; additionally, broadcasting stations in the same area have their frequencies assigned to avoid such images.

Sensitivity to the image frequency can be minimised only by (1) a filter that precedes the mixer or (2) a more complex mixer circuit [1] that suppresses the image.

When the signal is multiplied by (aka 'heterodyned with') the BFO waveform, it shifts the signal to to , which is known as the beat frequency or image frequency.

The image frequency is 2 f higher (or lower) than f, so employing a higher IF frequency f increases the receiver's image rejection without requiring additional selectivity in the RF stage.