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Add graphical signal meter for APRS decoding

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Backend changes (routes/aprs.py):
- Remove -q h flag from direwolf to enable audio level output
- Add parse_audio_level() to extract levels from direwolf output
- Add rate-limiting (max 10 updates/sec, min 2-level change)
- Push meter events to SSE queue as type='meter'

Frontend changes:
- Add signal meter widget to APRS sidebar
- Horizontal bar gauge with gradient (green->cyan->yellow->red)
- Numeric level display (0-100)
- "BURST" indicator for levels >70
- Status text (weak/moderate/strong signal)
- "No RF activity" state after 5 seconds of silence
- CSS styles in static/css/modes/aprs.css

Also added UK region to dropdown (same freq as Europe: 144.800)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Smittix
2026-01-15 22:03:08 +00:00
parent f4282cb608
commit cd168da760
4 changed files with 273 additions and 5 deletions
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75
routes/aprs.py
View File

@@ -50,6 +50,12 @@ aprs_station_count = 0
aprs_last_packet_time = None
aprs_stations = {} # callsign -> station data
# Meter rate limiting
_last_meter_time = 0.0
_last_meter_level = -1
METER_MIN_INTERVAL = 0.1 # Max 10 updates/sec
METER_MIN_CHANGE = 2 # Only send if level changes by at least this much
def find_direwolf() -> Optional[str]:
"""Find direwolf binary."""
@@ -275,14 +281,64 @@ def parse_weather(data: str) -> dict:
return weather
def parse_audio_level(line: str) -> Optional[int]:
"""Parse direwolf audio level line and return normalized level (0-100).
Direwolf outputs lines like:
Audio level = 34(18/16) [NONE] __||||||______
[0.4] Audio level = 57(34/32) [NONE] __||||||||||||______
The first number after "Audio level = " is the main level indicator.
We normalize it to 0-100 scale (direwolf typically outputs 0-100+).
"""
# Match "Audio level = NN" pattern
match = re.search(r'Audio level\s*=\s*(\d+)', line, re.IGNORECASE)
if match:
raw_level = int(match.group(1))
# Normalize: direwolf levels are typically 0-100, but can go higher
# Clamp to 0-100 range
normalized = min(max(raw_level, 0), 100)
return normalized
return None
def should_send_meter_update(level: int) -> bool:
"""Rate-limit meter updates to avoid spamming SSE.
Only send if:
- At least METER_MIN_INTERVAL seconds have passed, OR
- Level changed by at least METER_MIN_CHANGE
"""
global _last_meter_time, _last_meter_level
now = time.time()
time_ok = (now - _last_meter_time) >= METER_MIN_INTERVAL
change_ok = abs(level - _last_meter_level) >= METER_MIN_CHANGE
if time_ok or change_ok:
_last_meter_time = now
_last_meter_level = level
return True
return False
def stream_aprs_output(rtl_process: subprocess.Popen, decoder_process: subprocess.Popen) -> None:
"""Stream decoded APRS packets to queue.
"""Stream decoded APRS packets and audio level meter to queue.
This function reads from the decoder's stdout (text mode, line-buffered).
The decoder's stderr is merged into stdout (STDOUT) to avoid deadlocks.
rtl_fm's stderr is sent to DEVNULL for the same reason.
Outputs two types of messages to the queue:
- type='aprs': Decoded APRS packets
- type='meter': Audio level meter readings (rate-limited)
"""
global aprs_packet_count, aprs_station_count, aprs_last_packet_time, aprs_stations
global _last_meter_time, _last_meter_level
# Reset meter state
_last_meter_time = 0.0
_last_meter_level = -1
try:
app_module.aprs_queue.put({'type': 'status', 'status': 'started'})
@@ -293,6 +349,18 @@ def stream_aprs_output(rtl_process: subprocess.Popen, decoder_process: subproces
if not line:
continue
# Check for audio level line first (for signal meter)
audio_level = parse_audio_level(line)
if audio_level is not None:
if should_send_meter_update(audio_level):
meter_msg = {
'type': 'meter',
'level': audio_level,
'ts': datetime.utcnow().isoformat() + 'Z'
}
app_module.aprs_queue.put(meter_msg)
continue # Audio level lines are not packets
# multimon-ng prefixes decoded packets with "AFSK1200: "
if line.startswith('AFSK1200:'):
line = line[9:].strip()
@@ -489,7 +557,7 @@ def start_aprs() -> Response:
# -r 22050 = sample rate (must match rtl_fm -s)
# -b 16 = 16-bit signed samples
# -t 0 = disable text colors (for cleaner parsing)
# -q h = quiet: suppress audio level heard line (keeps packet output)
# NOTE: We do NOT use -q h here so we get audio level lines for the signal meter
# - = read audio from stdin (must be last argument)
decoder_cmd = [
direwolf_path,
@@ -498,7 +566,6 @@ def start_aprs() -> Response:
'-r', '22050',
'-b', '16',
'-t', '0',
'-q', 'h',
'-'
]
decoder_name = 'direwolf'
@@ -843,4 +910,4 @@ def scan_aprs_spectrum() -> Response:
os.remove(tmp_file)
except Exception:
pass

83
static/css/modes/aprs.css
View File

@@ -46,3 +46,86 @@
.aprs-stat-label {
color: var(--text-muted);
}
/* Signal Meter Styles */
.aprs-signal-meter {
margin-top: 12px;
padding: 10px;
background: rgba(0,0,0,0.3);
border: 1px solid var(--border-color);
border-radius: 4px;
}
.aprs-meter-header {
display: flex;
align-items: center;
gap: 8px;
margin-bottom: 8px;
}
.aprs-meter-label {
font-size: 10px;
font-weight: bold;
letter-spacing: 1px;
color: var(--text-secondary);
}
.aprs-meter-value {
font-size: 12px;
font-weight: bold;
font-family: monospace;
color: var(--accent-cyan);
min-width: 24px;
}
.aprs-meter-burst {
font-size: 9px;
font-weight: bold;
color: var(--accent-yellow);
background: rgba(255, 193, 7, 0.2);
padding: 2px 6px;
border-radius: 3px;
animation: burst-flash 0.3s ease-out;
}
@keyframes burst-flash {
0% { opacity: 1; transform: scale(1.1); }
100% { opacity: 1; transform: scale(1); }
}
.aprs-meter-bar-container {
position: relative;
height: 16px;
background: rgba(0,0,0,0.4);
border-radius: 3px;
overflow: hidden;
margin-bottom: 4px;
}
.aprs-meter-bar {
height: 100%;
width: 0%;
background: linear-gradient(90deg,
var(--accent-green) 0%,
var(--accent-cyan) 50%,
var(--accent-yellow) 75%,
var(--accent-red) 100%
);
border-radius: 3px;
transition: width 0.1s ease-out;
}
.aprs-meter-bar.no-signal {
opacity: 0.3;
}
.aprs-meter-ticks {
display: flex;
justify-content: space-between;
font-size: 8px;
color: var(--text-muted);
padding: 0 2px;
}
.aprs-meter-status {
font-size: 9px;
color: var(--text-muted);
text-align: center;
margin-top: 6px;
}
.aprs-meter-status.active {
color: var(--accent-green);
}
.aprs-meter-status.no-signal {
color: var(--accent-yellow);
}

100
templates/index.html
View File

@@ -5949,6 +5949,9 @@
let isAprsRunning = false;
let aprsPacketCount = 0;
let aprsStationCount = 0;
let aprsMeterLastUpdate = 0;
let aprsMeterCheckInterval = null;
const APRS_METER_TIMEOUT = 5000; // 5 seconds for "no signal" state
function checkAprsTools() {
fetch('/aprs/tools')
@@ -6052,6 +6055,10 @@
updateAprsStatus('listening', data.frequency);
document.getElementById('aprsStatusStations').textContent = '0';
document.getElementById('aprsStatusPackets').textContent = '0';
// Show signal meter
document.getElementById('aprsSignalMeter').style.display = 'block';
resetAprsMeter();
startAprsMeterCheck();
startAprsStream();
} else {
alert('APRS Error: ' + data.message);
@@ -6071,10 +6078,13 @@
isAprsRunning = false;
document.getElementById('startAprsBtn').style.display = 'block';
document.getElementById('stopAprsBtn').style.display = 'none';
// Hide sidebar status bar
// Hide sidebar status bar and signal meter
document.getElementById('aprsStatusBar').style.display = 'none';
document.getElementById('aprsSignalMeter').style.display = 'none';
document.getElementById('aprsMapStatus').textContent = 'STANDBY';
document.getElementById('aprsMapStatus').style.color = '';
// Stop meter check interval
stopAprsMeterCheck();
if (aprsEventSource) {
aprsEventSource.close();
aprsEventSource = null;
@@ -6099,6 +6109,9 @@
updateAprsStatus('tracking');
}
processAprsPacket(data);
} else if (data.type === 'meter') {
// Update signal meter
updateAprsMeter(data.level);
}
};
@@ -6108,6 +6121,91 @@
};
}
// Signal Meter Functions
function resetAprsMeter() {
aprsMeterLastUpdate = 0;
const bar = document.getElementById('aprsMeterBar');
const value = document.getElementById('aprsMeterValue');
const burst = document.getElementById('aprsMeterBurst');
const status = document.getElementById('aprsMeterStatus');
if (bar) {
bar.style.width = '0%';
bar.classList.remove('no-signal');
}
if (value) value.textContent = '--';
if (burst) burst.style.display = 'none';
if (status) {
status.textContent = 'Waiting for signal...';
status.className = 'aprs-meter-status';
}
}
function updateAprsMeter(level) {
aprsMeterLastUpdate = Date.now();
const bar = document.getElementById('aprsMeterBar');
const value = document.getElementById('aprsMeterValue');
const burst = document.getElementById('aprsMeterBurst');
const status = document.getElementById('aprsMeterStatus');
if (bar) {
bar.style.width = level + '%';
bar.classList.remove('no-signal');
}
if (value) value.textContent = level;
// Show burst indicator for high levels (>70)
if (burst) {
if (level > 70) {
burst.style.display = 'inline';
// Remove and re-add to trigger animation
burst.style.animation = 'none';
burst.offsetHeight; // Trigger reflow
burst.style.animation = null;
} else {
burst.style.display = 'none';
}
}
// Update status text
if (status) {
status.className = 'aprs-meter-status active';
if (level < 10) {
status.textContent = 'Low signal / noise floor';
} else if (level < 30) {
status.textContent = 'Weak signal detected';
} else if (level < 60) {
status.textContent = 'Moderate signal';
} else {
status.textContent = 'Strong signal / packet burst';
}
}
}
function startAprsMeterCheck() {
// Check for no-signal state every second
aprsMeterCheckInterval = setInterval(function() {
if (aprsMeterLastUpdate > 0 && (Date.now() - aprsMeterLastUpdate) > APRS_METER_TIMEOUT) {
// No meter updates for 5 seconds - show no-signal state
const bar = document.getElementById('aprsMeterBar');
const status = document.getElementById('aprsMeterStatus');
const burst = document.getElementById('aprsMeterBurst');
if (bar) bar.classList.add('no-signal');
if (burst) burst.style.display = 'none';
if (status) {
status.textContent = 'No RF activity / silence';
status.className = 'aprs-meter-status no-signal';
}
}
}, 1000);
}
function stopAprsMeterCheck() {
if (aprsMeterCheckInterval) {
clearInterval(aprsMeterCheckInterval);
aprsMeterCheckInterval = null;
}
}
function processAprsPacket(packet) {
// Update packet log
const logEl = document.getElementById('aprsPacketLog');

20
templates/partials/modes/aprs.html
View File

@@ -17,6 +17,7 @@
<select id="aprsRegion">
<option value="north_america">North America (144.390)</option>
<option value="europe">Europe (144.800)</option>
<option value="uk">UK (144.800)</option>
<option value="australia">Australia (145.175)</option>
<option value="japan">Japan (144.640)</option>
</select>
@@ -48,4 +49,23 @@
<span class="aprs-stat"><span class="aprs-stat-label">PACKETS:</span> <span id="aprsStatusPackets">0</span></span>
</div>
</div>
<!-- Signal Meter -->
<div id="aprsSignalMeter" class="aprs-signal-meter" style="display: none;">
<div class="aprs-meter-header">
<span class="aprs-meter-label">SIGNAL</span>
<span class="aprs-meter-value" id="aprsMeterValue">--</span>
<span class="aprs-meter-burst" id="aprsMeterBurst" style="display: none;">BURST</span>
</div>
<div class="aprs-meter-bar-container">
<div class="aprs-meter-bar" id="aprsMeterBar"></div>
<div class="aprs-meter-ticks">
<span>0</span>
<span>25</span>
<span>50</span>
<span>75</span>
<span>100</span>
</div>
</div>
<div class="aprs-meter-status" id="aprsMeterStatus">Waiting for signal...</div>
</div>
</div>