Mobile and Vehicular Network Lab [2015-Fall] WNFA lab2 - JJY JJY Simulator Chang-Jung, Huang / Guan-Ting, Chen 2015/3/27

Mobile and Vehicular Network Lab

[2015-Fall] WNFA lab2 - JJY

JJY SimulatorChang-Jung, Huang / Guan-Ting,

Chen2015/3/27


3

INTRODUCTION


4

• 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

http://jjy.nict.go.jp/index-e

http://jjy.nict.go.jp/index-e


5

• 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?


6

GETTING STARTED


7

• 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)–…


8

Alligator clip wire

Radio-controlled clock

Zigduino

LED(Debug)

Gnd

Micro USB


9

• 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)


10

• 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


11

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


12

• JJY time code

Source： http://en.wikipedia.org/wiki/JJY


13

• 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

http://www.nist.gov/pml/div688/grp40/wwvb.cfm




14

• 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


15

GRADE


16

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%

http://goo.gl/ZfKIXe

http://goo.gl/ZfKIXe


17

• Contact to TAs :– facebook

https://www.facebook.com/groups/wn15spring/

– Email : [email protected]– Office hour : Thur. 16:00~17:00@ CSIE

R424

Documents

Mobile and Vehicular Network Lab [2015-Fall] WNFA lab2 - JJY JJY Simulator Chang-Jung, Huang / Guan-Ting, Chen 2015/3/27