Satellite pass prediction and contact window computation
Add --here, --location CITY, and Arg.enum to contact CLI
Location can be specified three ways:
--lat 34.05 --lon=-118.25 (coordinates)
--location la (city preset via Arg.enum)
--here (auto-detect via IP geolocation)
Known cities: la, sf, nyc, london, paris, tokyo, ksc, kourou,
baikonur, bangalore, sydney. Cmdliner provides tab completion
and error messages for invalid city names.
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bin/main.ml
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bin/main.ml
···
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open Cmdliner
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(* ── Location ─────────────────────────────────────────────────────── *)
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type city =
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| LA
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| SF
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| NYC
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| London
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| Paris
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| Tokyo
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| KSC
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| Kourou
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| Baikonur
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| Bangalore
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| Sydney
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type location =
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| Here
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| City of city
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| Coordinates of { lat : float; lon : float }
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let city_coords = function
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| LA -> (34.05, -118.25, "Los Angeles")
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| SF -> (37.77, -122.42, "San Francisco")
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| NYC -> (40.71, -74.01, "New York")
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| London -> (51.51, -0.13, "London")
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| Paris -> (48.86, 2.35, "Paris")
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| Tokyo -> (35.68, 139.69, "Tokyo")
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| KSC -> (28.57, -80.65, "Kennedy Space Center")
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| Kourou -> (5.24, -52.77, "Guiana Space Centre")
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| Baikonur -> (45.96, 63.31, "Baikonur")
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| Bangalore -> (12.97, 77.59, "Bangalore")
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| Sydney -> (-33.87, 151.21, "Sydney")
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(* ── Location resolution ───────────────────────────────────────────── *)
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let geolocate_ip () =
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let ic =
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Unix.open_process_in
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"curl -sf 'http://ip-api.com/json/?fields=lat,lon,city' 2>/dev/null"
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in
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let s = try input_line ic with End_of_file -> "" in
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let _ = Unix.close_process_in ic in
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(* Minimal JSON parsing: {"city":"X","lat":N,"lon":N} *)
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let find_float key =
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match String.split_on_char '"' s |> List.find_index (fun x -> x = key) with
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| Some i -> (
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let after = String.split_on_char '"' s in
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let rec nth n = function
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| [] -> None
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| x :: rest -> if n = 0 then Some x else nth (n - 1) rest
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in
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match nth (i + 1) after with
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| Some chunk ->
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(* chunk is like ":34.029," — extract the number *)
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let num =
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String.to_seq chunk
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|> Seq.filter (fun c ->
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(c >= '0' && c <= '9') || c = '.' || c = '-')
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|> String.of_seq
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in
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float_of_string_opt num
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| None -> None)
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| None -> None
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in
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let find_string key =
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match String.split_on_char '"' s |> List.find_index (fun x -> x = key) with
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| Some i ->
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let parts = String.split_on_char '"' s in
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let rec nth n = function
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| [] -> None
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| x :: rest -> if n = 0 then Some x else nth (n - 1) rest
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in
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nth (i + 2) parts
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| None -> None
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in
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match (find_float "lat", find_float "lon") with
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| Some lat, Some lon ->
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let city = Option.value ~default:"Unknown" (find_string "city") in
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Some (lat, lon, city)
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| _ -> None
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let resolve_location = function
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| Coordinates { lat; lon } -> (lat, lon)
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| City c ->
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let la, lo, name = city_coords c in
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Fmt.pr "Using %s (%.2fN, %.2fE)@." name la lo;
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(la, lo)
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| Here -> (
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match geolocate_ip () with
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| Some (la, lo, name) ->
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Fmt.pr "Detected: %s (%.4fN, %.4fE)@." name la lo;
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(la, lo)
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| None -> Fmt.failwith "Could not detect location (needs curl + network)")
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(* ── Helpers ────────────────────────────────────────────────────────── *)
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let read_file path =
···
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(* ── Predict command ────────────────────────────────────────────────── *)
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let predict_cmd tle_path lat lon alt days min_el () =
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let predict_cmd tle_path loc alt days min_el () =
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let lat, lon = resolve_location loc in
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let tle = parse_tle tle_path in
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let gs = Contact.ground_station ~lat ~lon ~alt in
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let passes =
···
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(List.length passes) lat lon days min_el
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end
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let predict_term =
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let tle_path =
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Arg.(
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required
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& opt (some string) None
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& info [ "tle" ] ~docv:"FILE" ~doc:"Path to TLE file.")
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in
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let city_enum =
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Arg.enum
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[
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("la", LA);
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("sf", SF);
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("nyc", NYC);
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("london", London);
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("paris", Paris);
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("tokyo", Tokyo);
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("ksc", KSC);
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("kourou", Kourou);
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("baikonur", Baikonur);
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("bangalore", Bangalore);
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("sydney", Sydney);
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]
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let location_term : location Term.t =
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let lat =
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Arg.(
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required
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value
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& opt (some float) None
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& info [ "lat" ] ~docv:"DEG"
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~doc:"Ground station latitude (degrees, positive north).")
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& info [ "lat" ] ~docv:"DEG" ~doc:"Latitude (degrees north).")
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in
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let lon =
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Arg.(
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value
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& opt (some float) None
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& info [ "lon" ] ~docv:"DEG" ~doc:"Longitude (degrees east).")
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in
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let here =
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Arg.(value & flag & info [ "here" ] ~doc:"Auto-detect via IP geolocation.")
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in
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let city =
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Arg.(
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value
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& opt (some city_enum) None
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& info [ "location"; "l" ] ~docv:"CITY" ~doc:"Known city.")
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in
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let combine lat lon here city =
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match (lat, lon, here, city) with
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| Some la, Some lo, _, _ -> Coordinates { lat = la; lon = lo }
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| _, _, _, Some c -> City c
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| _, _, true, _ -> Here
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| _ -> Fmt.failwith "Specify --lat/--lon, --location CITY, or --here"
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in
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Term.(const combine $ lat $ lon $ here $ city)
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let predict_term =
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let tle_path =
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Arg.(
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required
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& opt (some float) None
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& info [ "lon" ] ~docv:"DEG"
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~doc:"Ground station longitude (degrees, positive east).")
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& opt (some string) None
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& info [ "tle" ] ~docv:"FILE" ~doc:"TLE file.")
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in
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let alt =
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Arg.(
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value & opt float 0.0
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& info [ "alt" ] ~docv:"KM"
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~doc:"Ground station altitude in km (default: 0).")
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& info [ "alt" ] ~docv:"KM" ~doc:"Altitude in km (default: 0).")
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in
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let days =
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Arg.(
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value & opt float 3.0
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& info [ "days"; "d" ] ~docv:"DAYS"
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~doc:"Prediction window in days (default: 3).")
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& info [ "days"; "d" ] ~docv:"N" ~doc:"Days to predict (default: 3).")
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in
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let min_el =
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Arg.(
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value & opt float 5.0
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& info [ "min-el" ] ~docv:"DEG"
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~doc:"Minimum peak elevation in degrees (default: 5).")
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& info [ "min-el" ] ~docv:"DEG" ~doc:"Min peak elevation (default: 5).")
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in
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let doc =
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"Predict satellite passes. Location via --lat/--lon, --location NAME, or \
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--here."
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in
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let doc = "Predict satellite passes over a ground station." in
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let info = Cmd.info "predict" ~doc in
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Cmd.v info
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Cmd.v (Cmd.info "predict" ~doc)
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Term.(
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const predict_cmd $ tle_path $ lat $ lon $ alt $ days $ min_el
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const predict_cmd $ tle_path $ location_term $ alt $ days $ min_el
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$ Vlog.setup "contact")
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(* ── Next command ───────────────────────────────────────────────────── *)
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let next_cmd tle_path lat lon alt min_el () =
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let next_cmd tle_path loc alt min_el () =
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let lat, lon = resolve_location loc in
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let tle = parse_tle tle_path in
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let gs = Contact.ground_station ~lat ~lon ~alt in
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let passes =
···
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Arg.(
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required
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& opt (some string) None
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& info [ "tle" ] ~docv:"FILE" ~doc:"Path to TLE file.")
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in
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let lat =
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Arg.(
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required
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& opt (some float) None
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& info [ "lat" ] ~docv:"DEG" ~doc:"Ground station latitude.")
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in
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let lon =
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Arg.(
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required
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& opt (some float) None
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& info [ "lon" ] ~docv:"DEG" ~doc:"Ground station longitude.")
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& info [ "tle" ] ~docv:"FILE" ~doc:"TLE file.")
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in
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let alt =
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Arg.(
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value & opt float 0.0
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& info [ "alt" ] ~docv:"KM" ~doc:"Ground station altitude in km.")
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value & opt float 0.0 & info [ "alt" ] ~docv:"KM" ~doc:"Altitude in km.")
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in
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let min_el =
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Arg.(
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value & opt float 5.0
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& info [ "min-el" ] ~docv:"DEG" ~doc:"Minimum peak elevation.")
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& info [ "min-el" ] ~docv:"DEG" ~doc:"Min peak elevation.")
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in
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let doc = "Show the next satellite pass." in
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let info = Cmd.info "next" ~doc in
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Cmd.v info
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Cmd.v (Cmd.info "next" ~doc)
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Term.(
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const next_cmd $ tle_path $ lat $ lon $ alt $ min_el
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const next_cmd $ tle_path $ location_term $ alt $ min_el
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$ Vlog.setup "contact")
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(* ── Main ───────────────────────────────────────────────────────────── *)