Satellite pass prediction and contact window computation
contact: split test.ml into test_contact.ml + runner (E600/E605)
Move the test functions into a Test_contact module exposing a [suite]
value, and reduce test.ml to the single Alcotest.run call. This fixes
both "missing test_contact.ml" (E605) and the "Alcotest.run only in
test.ml" (E600) requirements.
+97
-97
+1
-97
test/test.ml
+1
-97
test/test.ml
···
1
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(** Tests for ocaml-contact.
2
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3
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GMAT reference: station_contacts_report.txt from GMAT R2026a shows 14
4
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contact windows from LA (34.05 N, 241.75 E) over 3 days for an ISS-like
5
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orbit. Our predictions should find a similar number of passes with
6
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comparable timing.
7
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8
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Source: GMAT R2026a, station_contacts.script. *)
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(* Same TLE used in the GMAT script *)
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let tle_string =
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"ISS (ZARYA)\n\
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1 25544U 98067A 26001.00000000 .00001764 00000+0 39538-4 0 9991\n\
14
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2 25544 51.6416 45.0000 0008003 90.0000 0.0000 15.49560000 15"
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-
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let parse_tle () =
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match Sgp4.parse_tle_string tle_string with
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| Ok tle -> tle
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| Error e -> Alcotest.failf "TLE parse error: %a" Sgp4.pp_error e
20
-
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(* LA ground station (same as GMAT script) *)
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let la = Contact.ground_station ~lat:34.05 ~lon:(-118.25) ~alt:0.071
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-
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let predict_passes () =
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let tle = parse_tle () in
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let passes = Contact.predict tle la ~duration_days:3.0 in
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Fmt.pr " Found %d passes over LA in 3 days\n" (List.length passes);
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List.iteri
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(fun i p ->
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Fmt.pr " %2d: %s max_el=%.1f deg dur=%.0fs\n" (i + 1)
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p.Contact.aos_epoch p.max_elevation p.duration)
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passes;
33
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(* GMAT found 14 passes. Our SGP4-based prediction may differ slightly
34
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(different force model, different elevation threshold) but should be
35
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in the same ballpark: 10-18 passes. *)
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Alcotest.(check bool)
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"reasonable pass count" true
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(List.length passes >= 8 && List.length passes <= 20)
39
-
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let pass_properties () =
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let tle = parse_tle () in
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let passes = Contact.predict tle la ~duration_days:3.0 in
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List.iter
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(fun p ->
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(* All passes should have positive duration *)
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Alcotest.(check bool) "positive duration" true (p.Contact.duration > 0.0);
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(* Max elevation should be above min_elevation (default 5 deg) *)
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Alcotest.(check bool) "max el >= 5 deg" true (p.max_elevation >= 5.0);
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(* Max elevation should be physical (< 90 deg) *)
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Alcotest.(check bool) "max el <= 90 deg" true (p.max_elevation <= 90.0);
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(* Duration should be physical (< 15 min for LEO) *)
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Alcotest.(check bool) "duration < 15 min" true (p.duration < 900.0);
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(* AOS before LOS *)
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Alcotest.(check bool) "AOS < LOS" true (p.aos_time < p.los_time))
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passes
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let elevation () =
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let tle = parse_tle () in
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(* At epoch, satellite may or may not be visible *)
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let epoch_unix = Sgp4.epoch_unix tle in
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match Contact.elevation tle la epoch_unix with
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| None -> Alcotest.fail "elevation returned None"
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| Some el ->
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Fmt.pr " Elevation at epoch: %.1f deg\n" el;
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(* Should be a valid angle *)
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Alcotest.(check bool) "valid elevation" true (el >= -90.0 && el <= 90.0)
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let no_passes_wrong_incl () =
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(* An equatorial satellite (0 deg inclination) should never pass over
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LA at 34 deg latitude — or at most barely graze the horizon *)
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let eq_tle_str =
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"EQUATORIAL\n\
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1 99999U 26001A 26001.00000000 .00001764 00000+0 39538-4 0 9991\n\
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2 99999 0.0000 45.0000 0008003 90.0000 0.0000 15.49560000 15"
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in
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match Sgp4.parse_tle_string eq_tle_str with
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| Error _ -> () (* TLE may not parse — that's OK *)
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| Ok tle ->
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let passes =
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Contact.predict tle la ~duration_days:1.0 ~min_elevation:10.0
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in
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Fmt.pr " Equatorial sat passes over LA (>10 deg): %d\n"
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(List.length passes);
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(* Should find 0 or very few passes *)
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Alcotest.(check bool) "few/no passes" true (List.length passes <= 2)
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let () =
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Alcotest.run "contact"
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[
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( "pass-prediction",
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[
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Alcotest.test_case "predict passes" `Quick predict_passes;
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Alcotest.test_case "pass properties" `Quick pass_properties;
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Alcotest.test_case "elevation" `Quick elevation;
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Alcotest.test_case "equatorial no passes" `Quick no_passes_wrong_incl;
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] );
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]
1
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let () = Alcotest.run "contact" [ Test_contact.suite ]
+94
test/test_contact.ml
+94
test/test_contact.ml
···
1
+
(** Tests for ocaml-contact.
2
+
3
+
GMAT reference: station_contacts_report.txt from GMAT R2026a shows 14
4
+
contact windows from LA (34.05 N, 241.75 E) over 3 days for an ISS-like
5
+
orbit. Our predictions should find a similar number of passes with
6
+
comparable timing.
7
+
8
+
Source: GMAT R2026a, station_contacts.script. *)
9
+
10
+
(* Same TLE used in the GMAT script *)
11
+
let tle_string =
12
+
"ISS (ZARYA)\n\
13
+
1 25544U 98067A 26001.00000000 .00001764 00000+0 39538-4 0 9991\n\
14
+
2 25544 51.6416 45.0000 0008003 90.0000 0.0000 15.49560000 15"
15
+
16
+
let parse_tle () =
17
+
match Sgp4.parse_tle_string tle_string with
18
+
| Ok tle -> tle
19
+
| Error e -> Alcotest.failf "TLE parse error: %a" Sgp4.pp_error e
20
+
21
+
(* LA ground station (same as GMAT script) *)
22
+
let la = Contact.ground_station ~lat:34.05 ~lon:(-118.25) ~alt:0.071
23
+
24
+
let predict_passes () =
25
+
let tle = parse_tle () in
26
+
let passes = Contact.predict tle la ~duration_days:3.0 in
27
+
Fmt.pr " Found %d passes over LA in 3 days\n" (List.length passes);
28
+
List.iteri
29
+
(fun i p ->
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Fmt.pr " %2d: %s max_el=%.1f deg dur=%.0fs\n" (i + 1)
31
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p.Contact.aos_epoch p.max_elevation p.duration)
32
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passes;
33
+
(* GMAT found 14 passes. Our SGP4-based prediction may differ slightly
34
+
(different force model, different elevation threshold) but should be
35
+
in the same ballpark: 10-18 passes. *)
36
+
Alcotest.(check bool)
37
+
"reasonable pass count" true
38
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(List.length passes >= 8 && List.length passes <= 20)
39
+
40
+
let pass_properties () =
41
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let tle = parse_tle () in
42
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let passes = Contact.predict tle la ~duration_days:3.0 in
43
+
List.iter
44
+
(fun p ->
45
+
(* All passes should have positive duration *)
46
+
Alcotest.(check bool) "positive duration" true (p.Contact.duration > 0.0);
47
+
(* Max elevation should be above min_elevation (default 5 deg) *)
48
+
Alcotest.(check bool) "max el >= 5 deg" true (p.max_elevation >= 5.0);
49
+
(* Max elevation should be physical (< 90 deg) *)
50
+
Alcotest.(check bool) "max el <= 90 deg" true (p.max_elevation <= 90.0);
51
+
(* Duration should be physical (< 15 min for LEO) *)
52
+
Alcotest.(check bool) "duration < 15 min" true (p.duration < 900.0);
53
+
(* AOS before LOS *)
54
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Alcotest.(check bool) "AOS < LOS" true (p.aos_time < p.los_time))
55
+
passes
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+
57
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let elevation () =
58
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let tle = parse_tle () in
59
+
(* At epoch, satellite may or may not be visible *)
60
+
let epoch_unix = Sgp4.epoch_unix tle in
61
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match Contact.elevation tle la epoch_unix with
62
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| None -> Alcotest.fail "elevation returned None"
63
+
| Some el ->
64
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Fmt.pr " Elevation at epoch: %.1f deg\n" el;
65
+
(* Should be a valid angle *)
66
+
Alcotest.(check bool) "valid elevation" true (el >= -90.0 && el <= 90.0)
67
+
68
+
let no_passes_wrong_incl () =
69
+
(* An equatorial satellite (0 deg inclination) should never pass over
70
+
LA at 34 deg latitude — or at most barely graze the horizon *)
71
+
let eq_tle_str =
72
+
"EQUATORIAL\n\
73
+
1 99999U 26001A 26001.00000000 .00001764 00000+0 39538-4 0 9991\n\
74
+
2 99999 0.0000 45.0000 0008003 90.0000 0.0000 15.49560000 15"
75
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in
76
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match Sgp4.parse_tle_string eq_tle_str with
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| Error _ -> () (* TLE may not parse — that's OK *)
78
+
| Ok tle ->
79
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let passes =
80
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Contact.predict tle la ~duration_days:1.0 ~min_elevation:10.0
81
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in
82
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Fmt.pr " Equatorial sat passes over LA (>10 deg): %d\n"
83
+
(List.length passes);
84
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(* Should find 0 or very few passes *)
85
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Alcotest.(check bool) "few/no passes" true (List.length passes <= 2)
86
+
87
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let suite =
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( "contact",
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[
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Alcotest.test_case "predict passes" `Quick predict_passes;
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Alcotest.test_case "pass properties" `Quick pass_properties;
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Alcotest.test_case "elevation" `Quick elevation;
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Alcotest.test_case "equatorial no passes" `Quick no_passes_wrong_incl;
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] )