Digital receiver performance in the presence of image frequencies

摘要

A digital Radio Frequency (RF) receiver may exhibit image frequencies and these image frequencies may be mathematically related to the intermediate frequency (IF) that is utilized for transmission and reception. In accordance with an embodiment, channel switching may be performed to identify an appropriate receive frequency in the presence of image frequencies on other channels. In accordance with another embodiment, data on a receive channel is evaluated to determine whether the data is inverted, and then appropriate correction may be performed on subsequently received data.

主权项

1. A method for receiving a message transmitted on one of a plurality of channels of a hop sequence of a multi-hop communication system, each channel having an associated frequency, the method comprising the steps of:
scanning the plurality of channels in the hop sequence; determining for each of the scanned channels a value indicative of signal strength on the channel; tuning a receiver to a first channel of the scanned channels, the first channel having a signal strength value that satisfies a threshold; while tuned to the first channel, evaluating the first channel in an attempt to detect a preamble of the message on that first channel; if the preamble is detected on the first channel, tuning the receiver to a second channel in the hop sequence and evaluating the second channel in an attempt to detect the preamble on that second channel; if no preamble is detected on the second channel, tuning the receiver back to the first channel and receiving a remainder, which includes a start frame delimiter (SFD), of the message on that first channel; and if the preamble is detected on the second channel, then maintaining the receiver tuned to the second channel and receiving the remainder of the message on that second channel.