1996  mkdir kalibrate
 1997  cd kalibrate/
 1998  git clone https://github.com/steve-m/kalibrate-rtl
 2000  cd kalibrate-rtl/
 2002  less README 
 2003  ./bootstrap 
 2004  ./configure 
 2005  make
 2007  cd src/
 2009  ./kal 
 2010  ./kal -s GSM900
Found 1 device(s):
  0:  Generic RTL2832U (e.g. hama nano)

Using device 0: Generic RTL2832U (e.g. hama nano)
Found Rafael Micro R820T tuner
Exact sample rate is: 270833.002142 Hz
kal: Scanning for GSM-900 base stations.
GSM-900:
	chan: 72 (949.4MHz + 18.936kHz)	power: 172769.47
	chan: 83 (951.6MHz - 15.994kHz)	power: 180280.54

 2011  ./kal -c 72   #### Note that not using -e here leads to inaccurate results.
Found 1 device(s):   #### See the next example for proper usage.
  0:  Generic RTL2832U (e.g. hama nano)

Using device 0: Generic RTL2832U (e.g. hama nano)
Found Rafael Micro R820T tuner
Exact sample rate is: 270833.002142 Hz
kal: Calculating clock frequency offset.
Using GSM-900 channel 72 (949.4MHz)
average		[min, max]	(range, stddev)
+ 17.588kHz		[16590, 18719]	(2129, 424.765808)
overruns: 0
not found: 113
average absolute error: -18.526 ppm

 2018  ./kal -e -52 -c 83 -v       ### Here the initial error is set to -52 ppm a value suggested based off
Found 1 device(s):                 ### LTE Cell Scanner and keenerd rtl_test results. But apparently just  
  0:  Generic RTL2832U (e.g. hama nano)   ### guessing works too. You have to get the FCCH-peak in the 270k
                                          ### bandwidth for GSM reception. If the initial error is too large
Using device 0: Generic RTL2832U (e.g. hama nano)  ### and uncorrected the peak might be outside the range.
Found Rafael Micro R820T tuner
Exact sample rate is: 270833.002142 Hz
kal: Calculating clock frequency offset.
Using GSM-900 channel 83 (951.6MHz)
	offset   1: -16280.91
	offset   2: -14628.91
	offset   3: -16121.81
	offset   4: -16232.36
	offset   5: -15499.85
	offset   6: -16057.75
	offset   7: -16061.89
	offset   8: -15724.05
	offset   9: -16140.40
	offset  10: -15567.01
	offset  11: -16990.69
	offset  12: -16427.62
	offset  13: -17941.18
	offset  14: -16587.76
	offset  15: -16605.32
	offset  16: -16128.01
	offset  17: -18540.40
	offset  18: -17188.02
	offset  19: -15987.50
	offset  20: -12743.42
	offset  21: -16160.04
	offset  22: -16162.10
	offset  23: -14313.80
	offset  24: -15438.90
	offset  25: -15846.99
	offset  26: -16747.90
	offset  27: -19116.90
	offset  28: -15687.89
	offset  29: -15466.79
	offset  30: -14348.93
	offset  31: -15944.11
	offset  32: -16106.31
	offset  33: -14329.30
	offset  34: -17024.78
	offset  35: -16357.36
	offset  36: -16275.75
	offset  37: -22596.53
	offset  38: -16132.14
	offset  39: -16088.75
	offset  40: -16256.12
	offset  41: -16133.17
	offset  42: -13698.05
	offset  43: -11377.60
	offset  44: -16126.97
	offset  45: -16429.69
	offset  46: -15881.09
	offset  47: -17529.99
	offset  48: -15668.26
	offset  49: -16101.15
	offset  50: -16133.17
	offset  51: -15836.66
	offset  52: -16864.64
	offset  53: -16022.63
	offset  54: -16133.17
	offset  55: -15995.76
	offset  56: -16186.90
	offset  57: -16287.11
	offset  58: -17677.73
	offset  59: -16191.03
	offset  60: -12085.31
	offset  61: -16153.84
	offset  62: -15828.40
	offset  63: -16177.60
	offset  64: -15584.57
	offset  65: -14298.31
	offset  66: -17359.52
	offset  67: -16865.67
	offset  68: -14212.56
	offset  69: -17597.14
	offset  70: -14665.07
	offset  71: -15873.85
	offset  72: -16114.58
	offset  73: -16281.95
	offset  74: -13565.81
	offset  75: -14272.48
	offset  76: -14738.43
	offset  77: -16058.79
	offset  78: -16776.82
	offset  79: -15500.89
	offset  80: -16062.92
	offset  81: -16422.46
	offset  82: -16136.27
	offset  83: -16644.58
	offset  84: -16059.82
	offset  85: -16287.11
	offset  86: -16036.06
	offset  87: -16154.87
	offset  88: -14685.74
	offset  89: -16711.74
	offset  90: -17473.17
	offset  91: -16364.60
	offset  92: -15458.53
	offset  93: -15965.80
	offset  94: -16846.04
	offset  95: -19664.47
	offset  96: -15726.11
	offset  97: -16290.21
	offset  98: -16140.40
	offset  99: -16511.31
	offset 100: -15690.99
average		[min, max]	(range, stddev)
- 16.064kHz		[-17188, -14349]	(2839, 527.594788)
overruns: 0
not found: 622
average absolute error: -35.119 ppm