[2016-Fall] WNFA lab3 - JJY

[2016-Fall] WNFA lab3 - JJY

JJY Simulator Ai-Ling, Chen

2016/4/15

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.html

Reference : http://en.wikipedia.org/wiki/JJY 4

• 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 lab3?

– 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 Tim e Coordinated)

– …

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Alligator clip wire

Radio-controlled clock

Zigdui no

LED(Debu g)

Gnd

Micro USB

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• Hardware list

– Radio-controlled clock ( 電波鐘 ) x 1 – Alligator clip wire x 1

– LED x 1

– 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 co de 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 r educed power

– Encode Japan Standard Time(JST) using binary-coded decimal(BCD)  JJY time code

• Ex. 39 (in decimal) 

Reference : http://en.wikipedia.org/wiki/JJY 10

t(

s) er

1 2 3 4

0.2 s

0.5

s 0.8

s

0.5 full s

power

reduced power

marke r

1 0 1

…

…

Source ： http://www.hill2dot0.com/wiki/index.php?title=Image:MLG0010-carrier.jpg 11 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)

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送出的訊號  

• JJY time code

Source： http://en.wikipedia.org/wiki/JJY 12

• WWVB

– For United States

– Signal transmitted from WWVB is 60 kHz ca rrier wave

– The transmission rules and the signal for mat are a little different

– Official website

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

Reference : http://en.wikipedia.org/wiki/WWVB 13

• 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 i s correct

– “JPN” displayed on the top right corner of the clock  rece iving JJY signal

– “USA” displayed on the top right corner of the clock  recei ving WWVB signal

– Full instructions are given in the manual

Reference : http://en.wikipedia.org/wiki/Radio_clock 14

GRADE

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Mobile and Vehicular Network Lab

• Deadline:5/24(Tue.) 23:59 email to wn@csie.ntu.edu.tw

– Email subject:[WN]lab3_teamXX – [WN]lab3_teamXX.zip

• source code(JJY + WWVB)

• report(.pdf)

• Demo-5/24(Tue.)

– Please register the demo slot. And come to CSIE R424 at that tim e. 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 pr oblems encountered : 20%

– Peer Assessment : 10%

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• Contact to TAs :

– facebook

https://www.facebook.com/groups/wn15spri ng/

– Email : wn@csie.ntu.edu.tw

– Office hour : Tue. 1320-1410@ CSIE R424

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