Integrated burst FSK receiver
First Claim
1. A frequency shift keying (FSK) receiver, comprising:
- an RF converter configured to convert an RF signal to a digital sampled signal;
a frequency determiner configured to generate a frequency indicator signal that is proportional to a change in frequency of the digital sampled signal; and
a detector configured to determine a data value based on the frequency indicator signal;
wherein the frequency determiner comprises;
a first mixer configured to mix a local oscillator signal with a carrier offset signal to provide an adjusted local oscillator signal that has been compensated for a carrier offset in the digital sampled signal, wherein the carrier offset signal is calculated by averaging a plurality of samples of the frequency indicator signal;
a second mixer configured to mix the digital sampled signal with the adjusted local oscillator signal to provide I and Q signal components from the digital sampled signal;
a rectangular to polar conversion module configured to convert the I and Q signal components into an amplitude and phase of the digital sampled signal; and
a derivative module configured to receive the phase of the digital sampled signal and produce the frequency indicator signal based on a derivative of the phase of the digital sampled signal.
4 Assignments
0 Petitions
Accused Products
Abstract
An integrated burst FSK receiver is provided to receive and interpret an RF signal using FSK modulation. The integrated burst FSK receiver uses a programmable RF local oscillator to mix a received signal down to an IF range or baseband, where it is filtered and sampled for subsequent digital processing. Digital filtering and detection are employed to improve overall bit error rate performance and receiver sensitivity. A programmable digital low-pass or band-pass filter can also be used to suppress interference. A matched filter correlator can be used for detection and symbol timing adjustment in one mode, while an adaptive frequency comparator can be used in another mode. Circuits are provided that estimate carrier offset, frequency deviation and signal strength. These measurements can then be used to optimize the receiver performance. A method for receiving and interpreting an RF signal using FSK modulation is also provided.
25 Citations
13 Claims
-
1. A frequency shift keying (FSK) receiver, comprising:
-
an RF converter configured to convert an RF signal to a digital sampled signal; a frequency determiner configured to generate a frequency indicator signal that is proportional to a change in frequency of the digital sampled signal; and a detector configured to determine a data value based on the frequency indicator signal; wherein the frequency determiner comprises; a first mixer configured to mix a local oscillator signal with a carrier offset signal to provide an adjusted local oscillator signal that has been compensated for a carrier offset in the digital sampled signal, wherein the carrier offset signal is calculated by averaging a plurality of samples of the frequency indicator signal; a second mixer configured to mix the digital sampled signal with the adjusted local oscillator signal to provide I and Q signal components from the digital sampled signal; a rectangular to polar conversion module configured to convert the I and Q signal components into an amplitude and phase of the digital sampled signal; and a derivative module configured to receive the phase of the digital sampled signal and produce the frequency indicator signal based on a derivative of the phase of the digital sampled signal. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A frequency shift keying (FSK) receiver, comprising:
-
an RF converter configured to convert an FSK modulated RF signal to a digital sampled signal; a frequency determiner configured to generate a frequency indicator signal that is proportional to a change in frequency of the digital sampled signal; and a correlation detector comprising; a header detector configured to detect a header pattern, associated with the frequency indicator signal, that indicates a type of message to be decoded, wherein the header detector includes a header correlator and peak detector for each type of message to be detected; a data detector configured to detect a data value associated with the frequency indicator signal; and a sample centering module configured to provide a sample time to the data detector to improve the precision of a sample rate used to sample the data value associated with the frequency indicator signal. - View Dependent Claims (8, 9, 10, 11, 12, 13)
-
Specification