Sunday, May 24, 2009

APRS in a Linksys Router

From the Ham Radio at Maker Faire 2009 - APRS demo PART 3. Chris Kantarjiev, K6DBG demonstrates APRS (Automatic Position Reporting System) gear that he has collected, built and modified. This segement features a modified Linksys router (WRT54 series) and a small APRS tracking kit, "OpenTracker," produced by Argent Data Systems. (Video by NQ1R/ARRL.

Chris is running an APRS gateway on the Linksys router, taking the need for a computer out of the picture. It talks to the Linksys router over it's internal serial port. A TNC connection cable hangs out the back.

For more info see:

Monday, May 4, 2009

WeComm Digital Audio Repeater Linking

Wisconsin Emergency Communications (WeComm) is developing a statewide repeater system / voice network to provide base coverage throughout Wisconsin. Another imitative is to implement a modern high speed digital network. Both are for state, district and local ARES/RACES, skywarn, public service, and normal amateur radio communications.

The wide area analog repeaters are interlinked using SIP analog radio adapters. The Asterisk based conferencing software is virtually limitless. It provides the flexibility to connect individual repeaters into a statewide configuration, or to disconnect them to serve smaller areas or districts meeting specific needs.

This is a private VOIP network / reflector, unlike; IRLP and EchoLink. (Although the capability to link to such networks is still possible). Using IRLP, EchoLink or some other Wide Area Network linking services doesn't allow the control and flexibility that creating ones own off-network conferencing bridge. The aforementioned systems have a limited number of reflectors available and you are bound to their rules. Once the modern high speed digital network gets in gear the VOIP audio can actually be carried over these links instead of the internet.

SIP / digital audio repeater linking allows you to route / (think digipeat) . This is a great way to connect repeaters together that have quite a distance between them (or poor radio path).

SIP radio linking is also compatible with telephone circuits, and 21st century digital radio systems such as APCO-25, and D-Star. Such high speed multi-media interconnecting backbones can support radio linking of today as well as of the future.

Friday, May 1, 2009

1.25 m/ 220 MHz HSMM XR-1

This is an interesting product with lots of possibilities. It's a powerful 802.11 non line of sight radio module. Designed for Metering Applications as an built to order- 180-280 MHz Frequency Band. (There is a minimum quantity of 1000 piece per order due to the custom frequency, but it does work out to about $150 per unit.)

The XR1 would fit into the 1.25m amateur (220MHz) band frequency wise. However there is a gap in the band. As most hams are aware, we have 219-220 MHz secondary, and 222-225 MHz primary. It would be nice if the full 219 to 225 MHz was available.

Like all Atheros based radios, the XR1 specs references that channel size can be set. Even with the minimum channel size 5 MHz it wouldn't fit into 222MHz band, but there may be ways to reduce the overall spectrum requirements. Could the transmission envelope be modified to be narrower channel? That would be a good question for the guys at Ubiquiti Networks, or the Atheros MadWifi project.

Lets not forget the channel may be 5-MHz but...keep in mind Carson's Rule, the channel may be 5-MHz but...the signal bandwidth could be much higher.

If a 2.5 MHz channel option was coded the throughput would still be very usable.

This card does not have these capabilities and is not legal for sale in the US. But I don't think that would be a major obstacle for hams if it could be modified to fit into the 220 MHz ham band.

The reason I point it out is because it is the first VHF 802.11 radio I have ran across.