Sonar noise interference rejection
A marine sonar device comprises a display, a sonar element, and a processing element. The display displays sonar images. The sonar element generates a sonar beam during a ping and presents transducer signals. The processing element is configured to instruct the sonar element to generate the sonar beam at a first frequency during a first ping, receive a first transducer signal resulting from received reflections of the sonar beam at the first frequency, filter the first transducer signal to exclude frequencies other than the first frequency, instruct the sonar element to generate the sonar beam at a second frequency during a second ping, the second frequency being different from the first frequency, receive a second transducer signal resulting from received reflections of the sonar beam at the second frequency, and filter the second transducer signal to exclude frequencies other than the second frequency.
1. A marine sonar device comprising:
a display configured to display sonar images;
a sonar element configured to
generate a sonar beam during a ping into one of a plurality of sectors of a body of water, each sector corresponding to a range of projection angles with respect to the sonar element, and
present transducer signals;
a non-transitory memory element; and
a processing element in communication with the display, the sonar element, and the memory element, the processing element configured to—
instruct the sonar element to generate the sonar beam into each sector, one frequency per sector, the sonar beam being generated at a different one of a plurality of frequencies into at least adjacent sectors, wherein the frequencies of the sonar beam include a first frequency and the values of other frequencies are within a range of a value of the first frequency plus or minus 20%,
receive one of a plurality of transducer signals per ping, each transducer signal resulting from received reflections of the sonar beam in the corresponding sector at the corresponding generated frequency for each sector,
filter each transducer signal to exclude frequencies other than the corresponding generated frequency,
calculate sonar data from each transducer signal, and
generate a single sonar image from all of the sonar data.
2. The marine sonar device of claim 1 , wherein the sonar data from each sector corresponds to an area of the sonar image and the sonar data from all of the sectors forms the entire sonar image.
3. The marine sonar device of claim 1 , wherein the frequencies of the sonar beam include an array of frequencies, with a number of frequencies equivalent to a number of sectors, and the processing element is further configured to generate the sonar beam into the sectors in numerical order, each sector receiving the sonar beam at a frequency with a value different from the previous sector.
4. The marine sonar device of claim 1 , wherein the frequencies of the sonar beam include an array of frequencies, with a number of frequencies equivalent to a number of sectors, and the processing element is further configured to generate the sonar beam into each sector at a frequency randomly chosen from the array.
5. A marine sonar device comprising:
a display configured to display sonar images;
a sonar element configured to
generate a sonar beam during a ping into one of a plurality of sectors of a body of water, each sector corresponding to a range of projection angles with respect to the sonar element, and
present transducer signals;
a non-transitory memory element; and
a processing element in communication with the display, the sonar element, and the memory element, the processing element configured to repeatedly—
instruct the sonar element to successively generate the sonar beam into the sectors wherein the sonar beam is generated into one frequency per sector, each sector receiving the sonar beam at a different one of a plurality of frequencies and a different frequency for at least two consecutive pings, wherein the frequencies of the sonar beam include a first frequency and the values of other frequencies are within a range of a value of the first frequency plus or minus 20%,
receive one of a plurality of transducer signals per ping, each transducer signal resulting from received reflections of the sonar beam in the corresponding sector at the corresponding generated frequency for each sector,
filter each transducer signal to exclude frequencies other than the corresponding generated frequency,
calculate sonar data from one transducer signal per ping, and
generate a single sonar image from the sonar data from all of the sectors.
6. The marine sonar device of claim 5 , wherein the sonar data from each sector corresponds to an area of the sonar image and the sonar data from all of the sectors forms the entire sonar image.
7. The marine sonar device of claim 5 , wherein the frequencies of the sonar beam include an array of frequencies, with a number of frequencies equivalent to a number of sectors, and the processing element is further configured to generate the sonar beam into the sectors in numerical order, the sectors receiving the frequencies in the order that they occur in the array.
8. The marine sonar device of claim 7 , wherein the processing element is further configured to generate the sonar beam at the first frequency in the array on the ping after it has generated the last frequency in the array.
9. The marine sonar device of claim 5 , wherein the frequencies of the sonar beam include an array of frequencies, with a number of frequencies equivalent to a number of sectors, and the processing element is further configured to generate the sonar beam into each sector at a frequency randomly chosen from the array.