diff options
| -rw-r--r-- | src/kernel/ao_report.c | 62 |
1 files changed, 58 insertions, 4 deletions
diff --git a/src/kernel/ao_report.c b/src/kernel/ao_report.c index 1a0e9e16..f2263154 100644 --- a/src/kernel/ao_report.c +++ b/src/kernel/ao_report.c @@ -52,6 +52,60 @@ static const uint8_t flight_reports[] = { static __pdata enum ao_flight_state ao_report_state; +/* + * Farnsworth spacing + * + * From: http://www.arrl.org/files/file/Technology/x9004008.pdf + * + * c: character rate in wpm + * s: overall rate in wpm + * u: unit rate (dit speed) + * + * dit: u + * dah: 3u + * intra-character-time: u + * + * u = 1.2/c + * + * Because our clock runs at 10ms, we'll round up to 70ms for u, which + * is about 17wpm + * + * Farnsworth adds space between characters and + * words: + * 60 c - 37.2 s + * Ta = ------------- + * sc + * + * 3 Ta + * Tc = ---- + * 19 + * + * 7 Ta + * Tw = ---- + * 19 + * + * Ta = total delay to add to the characters (31 units) + * of a standard 50-unit "word", in seconds + * + * Tc = period between characters, in seconds + * + * Tw = period between words, in seconds + * + * We'll use Farnsworth spacing with c=18 and s=12: + * + * u = 1.2/18 = 0.0667 + * + * Ta = (60 * 17 - 37.2 * 12) / (17 * 12) = 2.812 + * + * Tc = 3 * Ta / 19 = .444 + * + * Tw = 1.036 + * + * Note that the values below are all reduced by 10ms; that's because + * the timer always adds a tick to make sure the task actually sleeps + * at least as long as the argument. + */ + static void ao_report_beep(void) __reentrant { @@ -62,13 +116,13 @@ ao_report_beep(void) __reentrant return; while (l--) { if (r & 8) - mid(AO_MS_TO_TICKS(600)); - else mid(AO_MS_TO_TICKS(200)); - pause(AO_MS_TO_TICKS(200)); + else + mid(AO_MS_TO_TICKS(60)); + pause(AO_MS_TO_TICKS(60)); r >>= 1; } - pause(AO_MS_TO_TICKS(400)); + pause(AO_MS_TO_TICKS(360)); } static void |