W9WDX B: DStar Repeater Coverage

Moleculo said:

Now that the W9WDX DStar repeater is fully functioning, I decided to model the coverage once the antenna is in it's final installation location. This map shows a fairly detailed coverage analysis provided by ve2dbe.com/towercoverage.com.

Obviously the green area is the predicted good coverage. The testing we've performed indicates that the yellow area typically results in R2D2.

The problem I set out to solve is that although there are quite a few DStar repeaters in the L.A. area, coverage in the San Gabriel Valley was basically non-existant. This area represents an area of about 285 square miles and a population of about 1.5 million people. The main green area on the map is virtually an exact overlay of the San Gabriel Valley, which is surrounded by hills and the Angeles National Forest mountain range to the north. The interesting addition is the wedge of coverage that cuts through the valley between the two hill ranges to the south, following the 605 Freeway toward Long Beach. Based on this map, the repeater might be able to be accessed as far away as the front side of Catalina Island.

Not bad for a cheap home-brew DStar setup!

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Moleculo said:

I should get a commission from Icom .

D-Star offers several interesting capabilities not available with traditional analog modes:

1. Reduced bandwidth - This is a technical advantage and not necessarily a functional benefit. The signal is only about 12.5Khz wide which means more stations & repeaters can operate within a given bandwidth
2. The ability to send data and voice at the same time. You can include status messages and GPS/APRS messages while using voice modes. This offers a convenient way to send updates to others about where you are or what you're doing while keying up a voice conversation with others.
3. Most D-Star repeaters are connected via the internet - once you learn how to connect to DStar reflectors and other repeaters, you can talk to other hams around the world using your HT or mobile. This is a little different than IRLP or Echolink because the system employs "reflectors" which are like hubs that many repeaters can connect to.
4. Direct callsign calls - you can punch in a specific station you would like to talk to on a repeater and only that station's radio will break open the squelch to hear you.
5. Callsign routing - once you key up on a repeater, the system knows where you are at and anyone else on DStar that wants to talk to you can just punch in your callsign, key up their radio and let the system find you.

There are other interesting things, but these are the highlights. Since I've picked up a DStar radio, I've found that it's a lot of fun and also a great new learning exercise!

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Moleculo said:

From best to least:
- Chanel = Elecraft
- Yves Saint Lauren = Icom
- Louis Vuitton = Kenwood
- Coach = you're not getting a radio.

Hope that adds perspective, LOL

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Moleculo said:

• Repeater: $250 (includes two Motorola GM300 radios, cabinet, power supply, RICK cables) You could probably do this part a little cheaper)
• Programming cable for Motorola Radios: $15
• Antenna: $60
• Star*Board (Enables D-Star on regular radios): $137
• New cabinet thermal fan: $20
• Duplexer: $100
• Coax cost not included

Keep in mind that you obviously need the antenna and duplexer regardless of the type of repeater you use. If you want to make this an apples to apples comparison to an Icom system, I paid about $400 for DStar radios and board which are the basic requirements. You need to spend about $3000 for an Icom repeater controller and RF module to start the same build.

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