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Mobile and Vehicular Network Lab
[2015-Fall] WNFA lab2 - JJY
JJY SimulatorChang-Jung, Huang / Guan-Ting,
Chen2015/3/27
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INTRODUCTION
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• What is JJY?– the call sign of a longwave time signal radio station
• What is the purpose of using JJY?– Used to synchronize consumer radio-controlled clocks
throughout Japan with Japan Standard Time(JST)
• In Japan, the station broadcasts the JJY signal from two sites– The Mount Otakadoya : 40 kHz signal– The Mount Hagane : 60 kHz signal
• Official website– http://jjy.nict.go.jp/index-e
Reference : http://en.wikipedia.org/wiki/JJY
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• Service area of JJY
Source: http://my.so-net.net.tw/fashions/QA-2.htm
Because Taiwan is
out of range, the JJY
signal from Japan is
weak.
Is timing
synchronization
function of radio-
controlled clocks
unuseful in Taiwan?
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GETTING STARTED
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• What is the purpose of lab2?– Simulating time signal by Zigduino– Synchronizing radio-controlled clocks with
radio signal (time signal)
• Time signal standard– JJY time code encoded JST(Japan
Standard Time)–WWVB time code encoded
UTC(Universal Time Coordinated)–…
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Alligator clip wire
Radio-controlled clock
Zigduino
LED(Debug)
Gnd
Micro USB
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• Hardware list– Radio-controlled clock (電波鐘 ) x 1
(shared)– Alligator clip wire x 1 (shared)– LED x 1 (shared)– Zigduino x 1 (used in lab1)–Micro USB line x 1 (used in lab1)
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• How to generate the JJY signal?– Duty cycle modulation, 40 kHz or 60 kHz signal– Rules : send one bit per second, a complete time
code every minute• 0 bits 0.8 s of full power followed by 0.2 s of reduced
power• 1 bits 0.5 s of full power followed by 0.5 s of reduced
power• Marker bits 0.2s s of full power followed by 0.8 s of
reduced power
– Encode Japan Standard Time(JST) using binary-coded decimal(BCD) JJY time code• Ex. 39 (in decimal) 0011 1001 (BCD)
Reference : http://en.wikipedia.org/wiki/JJY
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t(s)
power
1 2 3 4
0.2 s
0.5 s
0.8 s
0.5 sfull
power
reduced power
marker
1 0 1
…
…
Source : http://www.hill2dot0.com/wiki/index.php?title=Image:MLG0010-carrier.jpg
此次 lab的 carrier wave可用方波取代 sin波,因此可選擇使用 CTC Mode或是 PWM Mode來產生 (參考 lab1)
𝒎(𝒕 )送出的訊號
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• JJY time code
Source: http://en.wikipedia.org/wiki/JJY
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• WWVB– For United States – Signal transmitted from WWVB is 60 kHz
carrier wave– The transmission rules and the signal
format are a little different– Official website• http://
www.nist.gov/pml/div688/grp40/wwvb.cfm
Reference : http://en.wikipedia.org/wiki/WWVB
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• All you have to do are:– 1-1. JJY simulator (40 kHz and 60 kHz signal)– 1-2. The clock can be synchronized to the time sent by the
JJY simulator– 2-1. WWVB simulator– 2-2. The clock can be synchronized to the time sent by the
WWVB simulator
• Note: make sure that the selected transmitting station is correct– “JPN” displayed on the top right corner of the clock
receiving JJY signal– “USA” displayed on the top right corner of the clock
receiving WWVB signal– Full instructions are given in the manual
Reference : http://en.wikipedia.org/wiki/Radio_clock
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GRADE
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Grade
• Deadline:4/16(Thur.) 23:59 email to [email protected]– Email subject:[WN]lab2_teamXX– [WN]lab2_teamXX.zip
• source code(JJY + WWVB)• report(.pdf)
• Demo-4/16(Thur.)– Please register the demo slot. And come to CSIE R424 at that
time. http://goo.gl/ZfKIXe– All you should do are :
• 1. Perform synchronization with specific time given by TA in JJY format• 2. Perform synchronization with specific time given by TA in WWVB
format
• Grade– JJY : 40% – WWVB : 30%– Report : describe what team members have done(in detail), and
problems encountered : 20%– Peer Assessment : 10%
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• Contact to TAs :– facebook
https://www.facebook.com/groups/wn15spring/
– Email : [email protected]– Office hour : Thur. 16:00~17:00@ CSIE
R424