detectionband option possibly not working

[engineeratomic]

Hi Richard
I am running meteor_radar.py with the following options:

~/vMeteorRadio/bin/python ~/MeteorRadio/src/meteor_radar.py -v -s 20 --detectionband -125 125

In the daily log files, I am getting a lot of entries that are a long way out from the specified detectionband bandwidth which are being triggered either by internal (i.e. the Nooelec dongle) or external interference.

Ver,Y,M,D,h,m,s,Bri,Dur,freq,ID,Long,Lat,Alt,Tz
RMOB,2026,06,26,00,21,20.118,14.90,0.05,-837.28,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,00,25,01.411,14.22,0.05,50.78,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,00,25,15.720,13.87,0.05,-846.44,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,00,26,13.009,22.04,0.16,-59.08,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,00,30,00.201,14.79,0.05,-846.44,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,00,33,15.498,15.12,0.05,-727.42,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,00,34,14.480,13.59,0.05,-846.44,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,00,40,48.242,15.77,0.05,-68.24,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,00,46,27.227,13.20,6.94,-837.28,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,01,06,28.720,12.86,0.05,-828.12,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,01,13,26.348,15.39,0.05,23.32,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,01,23,40.966,16.45,2.57,-59.08,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,01,28,20.750,14.39,0.05,-828.12,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,01,33,24.946,13.08,0.05,-837.28,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,01,34,49.270,13.69,4.53,-150.63,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,01,50,33.097,13.68,6.12,-150.63,Willaston_UK,-2.47810,53.06383,60.0,0
RMOB,2026,06,26,01,58,39.380,14.76,1.91,-809.81,Willaston_UK,-2.47810,53.06383,60.0,0

Am I doing something wrong?

Thanks

Martyn

[rabssm]

You are probably picking up noise (maybe from lightning strikes?) as your SNR threshold setting is only 20 (~13 dB). Try increasing the SNR threshold to the default of 45 (~16dB).

[engineeratomic]

I'll try that but I am puzzled why the entries are being logged. If the detection band is +/- 125 hz, why am I seeing entries with frequencies at -809Hz or -150Hz?

[rabssm]

The detection is made if the SNR threshold is exceeded within the detection band. In your case this is +/-125 Hz either side of the GRAVES frequency. The frequency logged in the RMOB file (the freq item in each row of the RMOB file) is the offset in Hz at which the event began. This is done to try to log the maximum Doppler shift detected and is done on a larger frequency range, but it will be incorrect if there is another signal above the SNR threshold in the larger frequency band.

RMOB file format is:
Ver,Y,M,D,h,m,s,Bri,Dur,freq,ID,Long,Lat,Alt,Tz

[engineeratomic]

Thanks Richard. That makes sense.

Sorry I troubled you.