1. Lesson #1 – What is D-Star?
D-Star University
Lesson #1 – What is D-Star?

2. In the days before D-Star…
When two or more people wanted to talk, they could turn on their radios, pick a frequency and chat via analog simplex.

3. Of course, that doesn’t always work…
Sometimes the distances are too great, or there are obstacles in the way.

4. So we use repeaters!
A repeater re-transmits the signal between users, allowing people to talk over greater distances and around obstacles.

5. Repeaters can be linked….
Two or more repeaters can be linked together, either over the air or through an internet connection. A group of repeaters linked together is known as a “reflector”.

6. Repeaters can be linked….
Reflectors can cover world-wide areas. You may have heard or spoken on local analog repeaters that are connected to reflectors via EchoLink or IRLP

7. questions? (up next – history of D-Star)

8. How did D-Star start?
In 1998 the Japanese government funded an effort by the Japan Amateur Radio League (JARL) to develop a new digital communications mode specifically for amateur radio use. In 2001 the D-Star specification was published by JARL. Icom begins selling D-Star capable radios in April 2004.

9. How did D-Star start?
In 2008, Robin Cutshaw (AA4RC) releases DPlus specification, creating the first D- Star reflectors. In 2006 there were 48 D-Star users, by 2009 there are over 10,000 users. Today there are over 50,000. In 2016 the first D-Star satellite was put into orbit (OUFTI-1) Dayton 2016 – Kenwood previews new D- Star capable HT

10. So how does D-Star work?
Every D-Star radio contains an AMBE voice encoder/decoder (vocoder) chip. This chip takes analog speech and converts it into digital information. This chip can also take encoded digital speech and de- code back to analog sound. All D-Star audio is encoded and decoded in the radio. Instead of radio waves carrying analog sound information, they carry ones and zeros. Everything else is the same.

11. You can use D-Star for simplex…

12. You can use D-Star on repeaters…

13. You can even talk across the world on D-Star reflectors!

14. questions? (up next – digital vs analog signals)

15. Digital vs Analog Signals – The Waveform
Analog signals are transmitted as continuous form waves, while digital signals are transmitted in discrete steps representing one or zero.

16. Digital vs Analog Signals – Sampling Rate
Digital signals are created by ‘sampling’ an analog data source. The sampling rate determines how closely the digital signal matches the analog original. Signals with a high sampling rate will sound closer to the original, but will also consume more data.

17. Digital vs Analog Signals – Error Correction
Analog signals degrade with no way to restore them to original quality. Digital signals can be verified for correctness via checksums and other tools. The signal can then be repaired before being passed on. As a result, digital signals do not ‘fade’, they simply drop out once they can no longer be repaired.

18. questions? (up next – D-Star vs other modes)

19. How does D-Star compare?
How is voice transmitted?
MODE
ANALOG or DIGITAL
Analog FM
Analog
IRLP
Analog protocol, digital transport
EchoLink
D-Star
Digital
DMR
Fusion

20. How does D-Star compare?
Can I have my own personal access point, or do I need a repeater?
MODE
PERSONAL ACCESS POINT?
Analog FM No
IRLP
Very limited
EchoLink
Yes
D-Star
DMR
Yes*
Fusion

21. How does D-Star compare?
Can I create and share my own reflectors?
MODE
CREATE OWN REFLECTORS?
Analog FM No
IRLP
EchoLink
D-Star
Yes
DMR
Yes*
Fusion

22. How does D-Star compare?
How wide is the signal?
MODE
BANDWIDTH
Analog FM
12.5 KHz to 25 KHz
IRLP
EchoLink
D-Star
6.25 KHz
DMR
12.5 KHz with two timeslots
Fusion
12.5 KHz

23. How does D-Star compare?
How does the signal sound?
MODE
AUDIO QUALITY
Analog FM
Best
IRLP
EchoLink
D-Star
Good
DMR
Better
Fusion

24. questions? (up next – personal access points)

25. Personal Access Points
What’s that?
A way to get onto a reflector without using a repeater.
Connects your D-Star radio to the reflector you select using an internet connection.
Cheap, easy to build and highly portable access points have driven the explosion of D-Star.
Most D-Star QSOs don’t happen on repeaters!

26. Personal Access Points
Do I need one?
No.
Why would I want one?
Because you’re a ham, which means you love hacking stuff!
Use D-Star reflectors in the car.
Keep in touch over D-Star when travelling.
You don’t have to share - connect to what you want, when you want.
Can be the cheapest entry point into D-Star

27. Personal Access Points
Two basic types:
The Transceiver Type – This type of access point connects your D-Star capable radio to a reflector over the internet. It consists of the transceiver device, a computer to run the transceiver device and an internet connection.
This type takes digital D-Star information coming out of your radio and sends it to the reflector.

28. Personal Access Points
Two basic types:
The Vocoder Type – This type of access point is used without a D-Star capable radio. The access point device contains the same AMBE vocoder chip as a D-Star radio. Analog audio is taken from a connected computer (via a headset) and digitized in the access point device. The encoded audio is sent to the reflector via an internet connection.

29. questions? (up next – lesson 2: getting on the air with D-Star)