oscillator is tuned to 1035 kHz. But a signal at 1490 kHz is also 455 kHz away from the local oscillator; so both the desired signal and the image, when mixed with the local oscillator, will appear at the intermediate frequency. This image frequency is within the AM broadcast band. 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. The unwanted frequency is called the image of the wanted frequency, because it is the "mirror image" of the desired frequency reflected about . A receiver with inadequate filtering at its input will pick up signals at two different frequencies simultaneously: the desired frequency and the image frequency. A radio reception which happens to be at the image frequency can interfere with reception of the desired signal, and noise (static) around the image frequency can decrease the receiver's signal-to-noise ratio (SNR) by up to 3dB. Early Autodyne receivers typically used IFs of only 150 kHz or so. As a consequence, most Autodyne receivers required greater front-end selectivity, often involving double-tuned coils, to avoid image interference. With the later development of tubes able to amplify well at higher frequencies, higher IF frequencies came into use, reducing the problem of image interference. Typical consumer radio receivers have only a single tuned circuit in the RF stage. Sensitivity to the image frequency can be minimized only by (1) a filter that precedes the mixer or (2) a more complex mixer circuit to suppress the image; this is rarely used. In most tunable receivers using a single IF frequency, the RF stage includes at least one tuned circuit in the RF front end whose tuning is performed in tandem with the local oscillator. In double (or triple) conversion receivers in which the first conversion uses a fixed local oscillator, this may rather be a fixed bandpass filter which accommodates the frequency range being mapped to the first IF frequency range. Image rejection is an important factor in choosing the intermediate frequency of a receiver. The farther apart the bandpass frequency and the image frequency are, the more the bandpass filter will attenuate any interfering image signal. Since the frequency separation between the bandpass and the image frequency is , a higher intermediate frequency improves image rejection. It may be possible to