Orbit Data Messages (CCSDS 502.0-B-3)
Split ocaml-transport into ocaml-cltu and ocaml-cop1
- ocaml-cltu: CLTU encoding/decoding (CCSDS 231.0-B) with BCH(63,56),
ASM sync markers (131.0-B), and stream sync parsers
- ocaml-cop1: COP-1 state machines (CCSDS 232.1-B) for FOP-1 (ground)
and FARM-1 (flight) with Eio service layer
- cltu-eio: CLTU/ASM send/recv over Eio flows
- cop1-eio: COP-1 service layer with Eio timer management
+95
-11
+95
-11
test/interop/gmat/test.ml
+95
-11
test/interop/gmat/test.ml
···
148
148
(rel *. 100.0) sv.epoch)
149
149
svs
150
150
151
-
(* Interpolation: value at a known epoch should match the data point. *)
152
-
let test_leo_interpolation_at_epoch () =
151
+
(* MISSION-READY TEST: Interpolation accuracy.
152
+
GMAT uses Lagrange order 7; we use linear interpolation.
153
+
At the midpoint between two 60s-spaced LEO data points, linear interpolation
154
+
should match within ~0.1 km (LEO curvature over 30s).
155
+
If this fails, our interpolation is not mission-grade. *)
156
+
let test_leo_interpolation_midpoint () =
153
157
let oem = parse_oem "leo_7day.oem" in
154
158
let seg = List.hd (Odm.segments oem) in
155
159
let svs = Odm.state_vectors seg in
156
-
(* Pick a data point in the middle and interpolate at its exact epoch *)
157
-
let mid = svs.(5000) in
158
-
match Odm.interpolate seg with
159
-
| exception _ -> Alcotest.fail "interpolate raised exception"
160
-
| _interp ->
161
-
(* Just verify interpolation function exists and doesn't crash on this OEM *)
162
-
()
160
+
(* Use vectors 5000 and 5002 (120s apart). The "truth" at the midpoint
161
+
is vector 5001 (GMAT propagated, not interpolated). Our interpolation
162
+
between 5000 and 5002 should approximate 5001. *)
163
+
let epoch_to_unix e =
164
+
match Ptime.of_rfc3339 (e ^ "Z") with
165
+
| Ok (t, _, _) -> Ptime.to_float_s t
166
+
| Error _ -> Alcotest.failf "bad epoch: %s" e
167
+
in
168
+
let t0 = epoch_to_unix svs.(5000).epoch in
169
+
let t2 = epoch_to_unix svs.(5002).epoch in
170
+
let t_mid = (t0 +. t2) /. 2.0 in
171
+
match Odm.interpolate seg t_mid with
172
+
| None -> Alcotest.fail "interpolation returned None"
173
+
| Some interp ->
174
+
let truth = svs.(5001).Odm.pos in
175
+
let dx = interp.x -. truth.x in
176
+
let dy = interp.y -. truth.y in
177
+
let dz = interp.z -. truth.z in
178
+
let err = Float.sqrt ((dx *. dx) +. (dy *. dy) +. (dz *. dz)) in
179
+
(* Linear interpolation over 120s LEO arc: expect ~0.01-0.1 km error.
180
+
Mission-grade (Lagrange 7) would be < 1e-6 km.
181
+
This test documents the actual error — if it exceeds 1 km, something
182
+
is very wrong. If it's > 0.01 km, we know linear is insufficient. *)
183
+
Printf.printf
184
+
" LEO interpolation error (linear, 120s arc): %.6f km (%.1f m)\n" err
185
+
(err *. 1000.0);
186
+
if err > 1.0 then Alcotest.failf "interpolation error > 1 km: %.6f km" err;
187
+
(* Flag if error is > 10 m — this means linear interpolation is not
188
+
mission-grade for LEO at 60s step *)
189
+
if err > 0.01 then
190
+
Printf.printf
191
+
" WARNING: linear interpolation error > 10 m — not mission-grade\n"
192
+
193
+
(* MISSION-READY TEST: Interpolation on Molniya near perigee.
194
+
High eccentricity + fast perigee passage = worst case for linear interpolation.
195
+
At 30s step near perigee (~10 km/s), curvature is extreme.
196
+
This SHOULD show large interpolation errors. *)
197
+
let test_molniya_interpolation_perigee () =
198
+
let oem = parse_oem "molniya_2day.oem" in
199
+
let seg = List.hd (Odm.segments oem) in
200
+
let svs = Odm.state_vectors seg in
201
+
(* Find a perigee passage (minimum radius) *)
202
+
let min_i = ref 0 in
203
+
let min_r = ref Float.infinity in
204
+
Array.iteri
205
+
(fun i sv ->
206
+
let r = vec3_norm sv.Odm.pos in
207
+
if r < !min_r then (
208
+
min_r := r;
209
+
min_i := i))
210
+
svs;
211
+
(* Interpolate between the points bracketing perigee *)
212
+
let i = !min_i in
213
+
if i < 2 || i >= Array.length svs - 2 then
214
+
Alcotest.fail "perigee too close to edge"
215
+
else
216
+
let epoch_to_unix e =
217
+
match Ptime.of_rfc3339 (e ^ "Z") with
218
+
| Ok (t, _, _) -> Ptime.to_float_s t
219
+
| Error _ -> Alcotest.failf "bad epoch: %s" e
220
+
in
221
+
let t0 = epoch_to_unix svs.(i - 1).epoch in
222
+
let t2 = epoch_to_unix svs.(i + 1).epoch in
223
+
let t_mid = (t0 +. t2) /. 2.0 in
224
+
match Odm.interpolate seg t_mid with
225
+
| None -> Alcotest.fail "interpolation returned None at perigee"
226
+
| Some interp ->
227
+
let truth = svs.(i).Odm.pos in
228
+
let dx = interp.x -. truth.x in
229
+
let dy = interp.y -. truth.y in
230
+
let dz = interp.z -. truth.z in
231
+
let err = Float.sqrt ((dx *. dx) +. (dy *. dy) +. (dz *. dz)) in
232
+
Printf.printf
233
+
" Molniya perigee interpolation error (linear, 60s arc): %.6f km \
234
+
(%.1f m)\n"
235
+
err (err *. 1000.0);
236
+
Printf.printf " Perigee radius: %.1f km, velocity: ~%.1f km/s\n" !min_r
237
+
(vec3_norm svs.(i).vel);
238
+
if err > 10.0 then
239
+
Alcotest.failf
240
+
"interpolation error > 10 km at Molniya perigee: %.3f km" err;
241
+
if err > 0.1 then
242
+
Printf.printf
243
+
" WARNING: linear interpolation error > 100 m at perigee — not \
244
+
mission-grade\n"
163
245
164
246
(* --- GEO 3-day ---
165
247
Source: GMAT R2026a, geo_3day.script.
···
359
441
Alcotest.test_case "epoch monotonic" `Quick test_leo_epoch_monotonic;
360
442
Alcotest.test_case "energy conservation" `Quick
361
443
test_leo_energy_conservation;
362
-
Alcotest.test_case "interpolation" `Quick
363
-
test_leo_interpolation_at_epoch;
444
+
Alcotest.test_case "interpolation midpoint" `Quick
445
+
test_leo_interpolation_midpoint;
364
446
] );
365
447
( "geo",
366
448
[
···
381
463
Alcotest.test_case "vis-viva consistency" `Quick test_molniya_vis_viva;
382
464
Alcotest.test_case "epoch monotonic" `Quick
383
465
test_molniya_epoch_monotonic;
466
+
Alcotest.test_case "interpolation at perigee" `Quick
467
+
test_molniya_interpolation_perigee;
384
468
] );
385
469
]