Thursday, June 3, 2010

Digitally Linking Analog Repeaters

Those from Wisconsin might be familiar with the Wisconsin Interstate Network. It's a wide area coverage UHF linked repeater system, composed of nearly 20 systems throughout the state. It is all RF linked, so from an emergency commutations standpoint it's very handy resource.

Now imagine if you can if it was all linked digitally, but still using RF, not the internet.

It would not be very expensive to convert the analog audio to digital at each site and run inexpensive outdoor ethernet cable up the tower instead of a hardline line for linking. Since each analog repeater site is at significant heights, achieving line-of-site linking on 3 GHz or 900 MHz should be possible.

If you did this, you would have a high-speed statewide digital RF backbone independent from the internet, that not only connects all the analog sites, but has plenty of bandwidth left over.

ARES / user LAN access could be on 440 or 900 MHz. I'm talking about sending 20 MB of pictures from your ARES incident across the state in seconds. Or hooking an IP phone up and having a fairly secure conversation if the situation warrants it.

All this is possible, all fairly inexpensively. You just have to think different.

Wecomm is a smaller linked repeater network project going on in the state, that I have blogged about before.

They are building data networks into their site deployments.

What I am showing above is a very inexpensive way to stream audio digitally. Wecomm (so far) has been using expensive JPS Ratheon ARA-1 radio interface devices to accomplish this.

USB server adapters are fairly new. They allow you to use USB devices as network devices... cheaply.

When you are dealing with many sites, far away, the idea of having a computer at each site is less than ideal. Fairly inexpensively you could build a computer with no moving parts using flash drives to increase reliability..... But can you do this for under $50?

If a plug and play solution is what you seek, check out the CAT CL-100 Internet/802.11/HSMM Linking Controller.

1 comment:

M C said...

It's funny, I own exactly one "normal" radio, a handheld 2m, that only gets used when I'm aligning a microwave dish between towers. My partner will be at one end with a Ubiquiti radio and I'll be at the other reading signal strengths back and forth over the walkie talkie.

The real useful activity happens entirely in the digital domain and activity such as voice is just another service on our system of multi-megabit links.

I've been backordered on my Xagyl gear since early April (They now tell me late June will be my ship date), but I'm hoping this will open up a whole new chapter of Part 97 experience.