1. JJY Simulator Ai-Ling, Chen 2016/4/15
[2016-Fall] WNFA lab3 - JJY
JJY Simulator
Ai-Ling, Chen
2016/4/15

2. Introduction

3. What is the purpose of using JJY?
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
Reference :

4. Service area of JJY
Because Taiwan is out of range, the JJY signal from Japan is weak.
Is timing synchronization function of radio-controlled clocks unuseful in Taiwan?
Source：

5. Getting Started

6. 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 Time Coordinated) …

7. Alligator clip wire
Radio-controlled clock
Zigduino
LED(Debug)
Gnd
Micro USB

8. 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)

9. 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)  (BCD)
Reference :

10. … 𝒎(𝒕) 𝒄𝒐𝒔(𝟐𝝅 𝒇 𝒄 𝒕) 𝒇 𝒄 =𝟒𝟎𝒌𝑯𝒛, 𝟔𝟎𝒌𝑯𝒛 t(s) power 1 2 3 4 0.2 s 0.5 s
full power
reduced power
marker …
𝒎(𝒕)
𝒔 𝒕 =𝒎 𝒕 ∗ 𝐜𝐨𝐬 𝟐𝝅 𝒇 𝒄 𝒕
𝒔(𝒕)為送出的訊號
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)
𝒄𝒐𝒔(𝟐𝝅 𝒇 𝒄 𝒕)
𝒇 𝒄 =𝟒𝟎𝒌𝑯𝒛, 𝟔𝟎𝒌𝑯𝒛
Source ：

11. JJY time code
Source：

12. 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
Reference :

13. Note: make sure that the selected transmitting station is correct
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 :

14. Grade

15. Grade Deadline:5/24(Tue.) 23:59 email to wn@csie.ntu.edu.tw
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 time.
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%

16. Contact to TAs : facebook https://www.facebook.com/groups/wn15spring/
Office hour : Tue. CSIE R424