OpenBTS: Kalibrasi

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Sumber: http://gnuradio.org/redmine/wiki/1/OpenBTSClockCalibration


Jika kita tidak mempunyai peralatan lab yang baik dan kita ingin mengetahui akurasi clock USRP, kita dapat menggunakan aplikasi Kalibrator (Copyright (c) 2009 Joshua Lackey, Alexander Chemeris). Tentunya kita tidak mungkin memperoleh hasil yang baik seperti hi-tech lab, tapi cukup lah untuk mengetahui error kalibrasi clock yang ada.

Contents

[edit] Download

Download dari

http://thre.at/kalibrate/kal-v0.4.1.tar.bz2
git clone https://github.com/ttsou/kalibrate-uhd kalibrate-uhd

[edit] Compile

cp kal-v0.4.1.tar.bz2 /usr/local/src/
cd /usr/local/src
tar jxvf kal-v0.4.1.tar.bz2 
cd /usr/local/src/kal-v0.4.1
./bootstrap && CXXFLAGS='-W -Wall -O3' ./configure && make

[edit] Menjalankan

cd /usr/local/src/kal-v0.4.1/src/
./kal -h

Hasil

kalibrate v0.4.1, Copyright (c) 2010, Joshua Lackey

Usage:
	GSM Base Station Scan:
		kal <-s band indicator> [options]

	Clock Offset Calculation:
		kal <-f frequency | -c channel> [options]

Where options are:
	-s	band to scan (GSM850, GSM900, EGSM, DCS, PCS) 
	-f	frequency of nearby GSM base station
	-c	channel of nearby GSM base station
	-b	band indicator (GSM850, GSM900, EGSM, DCS, PCS)
	-R	side A (0) or B (1), defaults to B
	-A	antenna TX/RX (0) or RX2 (1), defaults to RX2
	-g	gain as % of range, defaults to 45%
	-F	FPGA master clock frequency, defaults to 52MHz
	-v	verbose
	-D	enable debug messages
	-h	help

[edit] Scanning 1800

Menjalankan

cd /usr/local/src/kal-v0.4.1/src/
./kal -s 1800 -F 64000000 -b DCS

Hasil

kal: Scanning for DCS-1800 base stations.
DCS-1800:
 	chan: 513 (1805.4MHz + 14.952kHz)	power: 5336.89 
	chan: 514 (1805.6MHz + 14.954kHz)	power: 1927.35
	chan: 517 (1806.2MHz + 14.952kHz)	power: 3715.71
	chan: 518 (1806.4MHz + 14.983kHz)	power: 1717.65
	chan: 519 (1806.6MHz + 14.969kHz)	power: 5159.38
	chan: 520 (1806.8MHz + 14.951kHz)	power: 2017.03
	chan: 542 (1811.2MHz + 15.092kHz)	power: 4554.77
	chan: 544 (1811.6MHz + 15.084kHz)	power: 3730.97
	chan: 569 (1816.6MHz + 15.181kHz)	power: 6196.37
	chan: 570 (1816.8MHz + 15.172kHz)	power: 1924.81
	chan: 613 (1825.4MHz + 15.237kHz)	power: 15746.19
	chan: 614 (1825.6MHz + 15.242kHz)	power: 6683.53
	chan: 616 (1826.0MHz + 15.260kHz)	power: 12953.63
	chan: 617 (1826.2MHz + 15.248kHz)	power: 4816.39
	chan: 620 (1826.8MHz + 15.224kHz)	power: 4274.58
	chan: 625 (1827.8MHz + 15.268kHz)	power: 3613.13
	chan: 626 (1828.0MHz + 15.313kHz)	power: 1926.56
	chan: 627 (1828.2MHz + 15.274kHz)	power: 3536.15
	chan: 628 (1828.4MHz + 15.267kHz)	power: 2346.39
	chan: 629 (1828.6MHz + 15.288kHz)	power: 7923.44
 	chan: 632 (1829.2MHz + 15.316kHz)	power: 5417.85
 	chan: 633 (1829.4MHz + 15.312kHz)	power: 2652.96
   	chan: 689 (1840.6MHz + 15.602kHz)	power: 3734.25
 	chan: 692 (1841.2MHz + 15.587kHz)	power: 11674.51
	chan: 693 (1841.4MHz + 15.586kHz)	power: 5294.69

[edit] Scanning 900

Untuk Clock 64MHz Menjalankan

cd /usr/local/src/kal-v0.4.1/src/
./kal -s 900 -F 64000000 -b GSM900

Untuk Clock 52MHz Menjalankan

cd /usr/local/src/kal-v0.4.1/src/
./kal -s 900 -F 52000000 -b GSM900 -vv

Hasil

FPGA clock : 52000000
Decimation : 192
Sample rate: 270833.343750
kal: Scanning for GSM-900 base stations.
channel detect threshold: 9458.928125
GSM-900:
	chan: 36 (942.2MHz + 423Hz)	power: 194131.34 
	chan: 37 (942.4MHz + 428Hz)	power: 50474.90
	chan: 38 (942.6MHz + 412Hz)	power: 50189.51
	chan: 39 (942.8MHz + 397Hz)	power: 14175.00
	chan: 40 (943.0MHz + 483Hz)	power: 38742.63
	chan: 41 (943.2MHz + 510Hz)	power: 50648.68
	chan: 61 (947.2MHz + 503Hz)	power: 73085.29
	chan: 62 (947.4MHz + 490Hz)	power: 18121.82
	chan: 66 (948.2MHz + 512Hz)	power: 16138.32
	chan: 68 (948.6MHz + 491Hz)	power: 18167.35
	chan: 113 (957.6MHz + 548Hz)	power: 24349.49
	chan: 114 (957.8MHz + 493Hz)	power: 11841.20
	chan: 115 (958.0MHz + 520Hz)	power: 20344.80
	chan: 119 (958.8MHz + 505Hz)	power: 31772.62
	chan: 120 (959.0MHz + 535Hz)	power: 10510.76
	chan: 123 (959.6MHz + 565Hz)	power: 18004.66

[edit] Scanning 850

Menjalankan

cd /usr/local/src/kal-v0.4.1/src/
./kal -s 850 -F 64000000

Hasil

[edit] Scanning Channel

Menjalankan

cd /usr/local/src/kal-v0.4.1/src/
./kal -c 513 -F 64000000 -b DCS

Hasil

kal: Calculating clock frequency offset.
Using DCS-1800 channel 513 (1805.4MHz)
average		[min, max]	(range, stddev)
+ 17.109kHz		[17087, 17136]	(50, 14.080007)
overruns: 0
not found: 0


[edit] Kalkulasi Kalibrasi

Misalnya kita menggunakan BTS pada channel 47 untuk kalibrasi

./kal -F 52000000 -c 47

Hasil

kal: Calculating clock frequency offset.
Using GSM-900 channel 47 (944.4MHz)
average		[min, max]	(range, stddev)
+ 501Hz		[479, 524]	(45, 13.227342)
overruns: 0
not found: 0


Misalnya kita menggunakan BTS pada channel 61 untuk kalibrasi

./kal -F 52000000 -c 61

Hasil

kal: Calculating clock frequency offset.
Using GSM-900 channel 61 (947.2MHz)
average		[min, max]	(range, stddev)
+ 494Hz		[481, 504]	(23, 6.454695)
overruns: 0
not found: 0


[edit] Proses Kalibrasi

[edit] Ukur

Gunakan Kalibrate untuk mengukur offset frekuensi, misalnya pada channel 52

./kal -f 945400000

Misalnya hasilnya adalah

kal: Calculating clock frequency offset.
Using GSM-900 channel 52 (945.4MHz)
average		[min, max]	(range, stddev)
+ 498Hz		[429, 555]	(126, 32.384548)
overruns: 0
not found: 165

[edit] Hitung Offset

Hitung dengan asumsi

  • Frekuensi Clock 20MHz
  • Kanal 52 atau frekuensi 945.4MHz
  • Offset hasil pengukuran + 500Hz

Maka clock 20MHz harus di offset sebesar

-500Hz/945.4MHz*20MHz=-10.6 Hz

Tepatnya menjadi

19,999,990 Hz

[edit] Set Ulang ClockTamer

Set ulang OSC pada ClockTamer menggunakan

sudo screen /dev/ttyACM0 115200,cs8,-ixon,-ixoff

Beberapa pilihan setting

SET,,OSC,19999991
SET,,OSC,19999990
SET,,OSC,19999989
STE

[edit] Scan Ulang Frekuensi

Hasilnya harus lebih baik

cd /usr/local/src/kal-v0.4.1/src
./kal -s 900 -F 52000000 -b GSM900 -vv

Semoga hasilnya memperoleh offset yang lebih baik, seperti

FPGA clock : 52000000
Decimation : 192
Sample rate: 270833.343750
kal: Scanning for GSM-900 base stations.
channel detect threshold: 6922.106769
GSM-900:
	chan: 36 (942.2MHz -  34Hz)	power: 192896.03
	chan: 37 (942.4MHz -  30Hz)	power: 48710.69
	chan: 38 (942.6MHz -  13Hz)	power: 31109.57
	chan: 64 (947.8MHz +  68Hz)	power: 15319.56
	chan: 66 (948.2MHz +  65Hz)	power: 14363.92
	chan: 109 (956.8MHz +   2Hz)	power: 12547.61
	chan: 112 (957.4MHz -  88Hz)	power: 10748.52
	chan: 113 (957.6MHz +  42Hz)	power: 22609.95
	chan: 114 (957.8MHz +  36Hz)	power: 18037.21
	chan: 115 (958.0MHz +  61Hz)	power: 15508.45
	chan: 116 (958.2MHz +  80Hz)	power: 10971.88
	chan: 119 (958.8MHz +  65Hz)	power: 24555.23
	chan: 123 (959.6MHz +  25Hz)	power: 16705.38

[edit] Referensi

[edit] Pranala Menarik

[edit] Persiapan

[edit] OpenBTS 2.6

[edit] OpenBTS 2.8

[edit] Multi OpenBTS 2.8

[edit] Ettus E110

[edit] GPRS

[edit] Power Amplifier

[edit] Lain Lain

[edit] Catatan Legal dan Pendukung

[edit] Catatan Sejarah

[edit] Dokumentasi Video

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