{"id":1284,"date":"2021-01-09T10:34:07","date_gmt":"2021-01-09T10:34:07","guid":{"rendered":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/?post_type=chapter&#038;p=1284"},"modified":"2024-07-19T17:28:15","modified_gmt":"2024-07-19T17:28:15","slug":"6-2-general-design-process","status":"publish","type":"chapter","link":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/chapter\/6-2-general-design-process\/","title":{"raw":"6.3 General Design Process","rendered":"6.3 General Design Process"},"content":{"raw":"https:\/\/www.youtube.com\/watch?v=cGvyzRVPS1w\r\n\r\nGiven the payload and housekeeping data necessary to downlink from the satellite, the COMMS specialist must define a communication architecture with many free parameters. This process follows:\r\n<p style=\"padding-left: 40px\">1. Choose a radio frequency. This frequency dictates the maximum <a href=\"https:\/\/en.wikipedia.org\/wiki\/Bandwidth_(signal_processing)\">bandwidth <\/a>available and depends on the class of the mission. Many CubeSat missions apply for <a href=\"http:\/\/www.arrl.org\/frequency-allocations\">amateur <\/a>or <a href=\"https:\/\/en.wikipedia.org\/wiki\/LowFER\">experimental <\/a>class frequencies.<\/p>\r\n\r\n\r\n[caption id=\"attachment_4532\" align=\"aligncenter\" width=\"1104\"]<img src=\"http:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-content\/uploads\/sites\/147\/2021\/02\/6-5.jpg\" alt=\"\" width=\"1104\" height=\"814\" class=\"wp-image-4532 size-full\" \/> <a href=\"https:\/\/en.wikipedia.org\/wiki\/High_frequency#\/media\/File:HighFrequency.png\">High Frequency: A Big Picture of High-Frequency position in the entire electromagnetic spectrum.\u00a0 Image by Arkrishna.<\/a>[\/caption]\r\n<p style=\"padding-left: 40px\">2. Choose a modulation scheme. The modulation scheme determines the required signal-to-noise ratio.<\/p>\r\n<p style=\"padding-left: 40px\">3. Choose coding algorithms, which affect not only the signal-to-noise ratio but also the data rate.<\/p>\r\n<p style=\"padding-left: 40px\">4. Analyze the available contact time the satellite will get using the available ground stations, orbit, and constellation design if relevant. Contact time is directly proportional to how quickly spacecraft can downlink data and frequently mission operators can issue commands.<\/p>\r\nAfter defining multiple options for each aspect of the communication architecture, for each alternative:\r\n<ol>\r\n \t<li style=\"font-weight: 400\">Compute the required data rate from all sources (depending on orbit)<\/li>\r\n \t<li style=\"font-weight: 400\">Use the link budget equation to size the antenna\/transmitter so we have enough margin over the signal-to-noise ratio. This ensures all alternatives meet the requirements<\/li>\r\n<\/ol>\r\nOnce alternative architectures are defined, use other metrics such as total subsystem cost or risk to select one alternative. Note: Often, this is an iterative process, and we may change our requirements depending on feasibility.\r\n\r\n<iframe src=\"https:\/\/docs.google.com\/forms\/d\/e\/1FAIpQLSfVGTs74AxDZt7xEqk-dQEdDvIU5BmxDJpvYxMrRqGeGayV7Q\/viewform?embedded=true\" width=\"640\" height=\"1365\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\">Loading\u2026<\/iframe>","rendered":"<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"6.3 Communications: General Design Process\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/cGvyzRVPS1w?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p>Given the payload and housekeeping data necessary to downlink from the satellite, the COMMS specialist must define a communication architecture with many free parameters. This process follows:<\/p>\n<p style=\"padding-left: 40px\">1. Choose a radio frequency. This frequency dictates the maximum <a href=\"https:\/\/en.wikipedia.org\/wiki\/Bandwidth_(signal_processing)\">bandwidth <\/a>available and depends on the class of the mission. Many CubeSat missions apply for <a href=\"http:\/\/www.arrl.org\/frequency-allocations\">amateur <\/a>or <a href=\"https:\/\/en.wikipedia.org\/wiki\/LowFER\">experimental <\/a>class frequencies.<\/p>\n<figure id=\"attachment_4532\" aria-describedby=\"caption-attachment-4532\" style=\"width: 1104px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-content\/uploads\/sites\/147\/2021\/02\/6-5.jpg\" alt=\"\" width=\"1104\" height=\"814\" class=\"wp-image-4532 size-full\" srcset=\"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-content\/uploads\/sites\/147\/2021\/02\/6-5.jpg 1104w, https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-content\/uploads\/sites\/147\/2021\/02\/6-5-300x221.jpg 300w, https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-content\/uploads\/sites\/147\/2021\/02\/6-5-1024x755.jpg 1024w, https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-content\/uploads\/sites\/147\/2021\/02\/6-5-768x566.jpg 768w, https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-content\/uploads\/sites\/147\/2021\/02\/6-5-65x48.jpg 65w, https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-content\/uploads\/sites\/147\/2021\/02\/6-5-225x166.jpg 225w, https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-content\/uploads\/sites\/147\/2021\/02\/6-5-350x258.jpg 350w\" sizes=\"auto, (max-width: 1104px) 100vw, 1104px\" \/><figcaption id=\"caption-attachment-4532\" class=\"wp-caption-text\"><a href=\"https:\/\/en.wikipedia.org\/wiki\/High_frequency#\/media\/File:HighFrequency.png\">High Frequency: A Big Picture of High-Frequency position in the entire electromagnetic spectrum.\u00a0 Image by Arkrishna.<\/a><\/figcaption><\/figure>\n<p style=\"padding-left: 40px\">2. Choose a modulation scheme. The modulation scheme determines the required signal-to-noise ratio.<\/p>\n<p style=\"padding-left: 40px\">3. Choose coding algorithms, which affect not only the signal-to-noise ratio but also the data rate.<\/p>\n<p style=\"padding-left: 40px\">4. Analyze the available contact time the satellite will get using the available ground stations, orbit, and constellation design if relevant. Contact time is directly proportional to how quickly spacecraft can downlink data and frequently mission operators can issue commands.<\/p>\n<p>After defining multiple options for each aspect of the communication architecture, for each alternative:<\/p>\n<ol>\n<li style=\"font-weight: 400\">Compute the required data rate from all sources (depending on orbit)<\/li>\n<li style=\"font-weight: 400\">Use the link budget equation to size the antenna\/transmitter so we have enough margin over the signal-to-noise ratio. This ensures all alternatives meet the requirements<\/li>\n<\/ol>\n<p>Once alternative architectures are defined, use other metrics such as total subsystem cost or risk to select one alternative. Note: Often, this is an iterative process, and we may change our requirements depending on feasibility.<\/p>\n<p><iframe loading=\"lazy\" src=\"https:\/\/docs.google.com\/forms\/d\/e\/1FAIpQLSfVGTs74AxDZt7xEqk-dQEdDvIU5BmxDJpvYxMrRqGeGayV7Q\/viewform?embedded=true\" width=\"640\" height=\"1365\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\">Loading\u2026<\/iframe><\/p>\n","protected":false},"author":914,"menu_order":3,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1284","chapter","type-chapter","status-publish","hentry"],"part":265,"_links":{"self":[{"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/pressbooks\/v2\/chapters\/1284","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/wp\/v2\/users\/914"}],"version-history":[{"count":13,"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/pressbooks\/v2\/chapters\/1284\/revisions"}],"predecessor-version":[{"id":4624,"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/pressbooks\/v2\/chapters\/1284\/revisions\/4624"}],"part":[{"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/pressbooks\/v2\/parts\/265"}],"metadata":[{"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/pressbooks\/v2\/chapters\/1284\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/wp\/v2\/media?parent=1284"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/pressbooks\/v2\/chapter-type?post=1284"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/wp\/v2\/contributor?post=1284"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks-dev.oer.hawaii.edu\/epet302\/wp-json\/wp\/v2\/license?post=1284"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}