High-Speed Wireless Networking in the UHF and Microwave Bands

[William "Bill" Kisse, W3MSH]

I have been active with the Ashton Radio Communications Society - main repeater 147.00 Mhz. in Ashton/Silver Spring, MD

To advance the Amateur Radio art, we recently installed the beginnings of our 3.4 Ghz. microwave network, main node at 180 feet on our transmitter site in Ashton.

We've chosen 3.4 Ghz. as this spectrum is not shared with any other entity and has a very low noise floor.  Please keep in mind that if we "don't use it we'll lose it" at 3.4 Ghz.and this is extremely valuable RF real estate!

The attached article published by David Bern, W2LHX in this month's QST provides more information on a high-speed microwave network that will blanket the Washington,DC / Baltimore, MD metro areas, accessible to any Hams that wish to access.  

Future connectivity to Philadelphia/ NYC / the entire East Coast is in the works.

There are many exciting advantages to a network of this type from inexpensive and virtually unlimited SDR-based satellite receivers on our current analog / digital repeaters, reliable fault-tolerant data connection among users (VOIP/Video/Photo/Email), and any number of applications supported by IP-addressable devices.

Not to mention support for public service events/disasters.

Plans are to incorporate 1.2 Ghz / 900 Mhz / 440 Mhz equipment and systems as best meet user needs and (especially at 440 Mhz.) to offer as wide coverage as possible.

Please contact me or Dave Bern directly if you need more information about the system or access.

All Microwave / RF/ IT Amateur Radio professionals are welcome to contribute to this new and exciting chapter in Amateur Radio and we welcome your support on any level.

This is as exciting and revolutionary as our repeater systems were in the early 70's.

Truly a new chapter in Amateur Radio technology and I am deeply proud to be a part!

73,

Bill

W3MSH

[Ken Jamrogowicz]

Hi Bill - nice to see some activity here on BOAR

 

Do you have anyone on 'the other end' of your 3.4 GHz system?

 

I wonder if you could provide more info on the SDR-based satellite receivers?  I think SDR for repeater receivers would be really great since you could have a noise blanker that works in the FM mode - something I have never seen in analog radios.

 

Are you considering using an IP based repeater controller like Asterisk app_rpt? (There is an Asterisk Hub on the MAIPN backbone).

Asterisk allows not just satellite receivers, but receiver voting over the IP connection.  That is analog of course. DSTAR and DMR are a natural fit, but have fewer users.

 

I have to mention that the Grid Pirates, Packrats and North East Weak Signal Society might take issue with the idea that the 3.4 GHz band is unused,  In fact, they would probably appreciate it if you would avoid using the seven (5-MHz) channels centered on 3456 - assuming you are using 20 Mhz BW. In other words, the frequencies from 3440-3470.  That still leaves lots of channels of course.

 

And - I have to mention (the elephant in the room) that most of what goes across the internet is not permitted in FCC part-97 operation on 3.4 GHz.  I know Dave's paper is very careful to tippy-toe around that issue, stating that it will be "Amateur Radio Internet Applications" that will be carried on the network and only radio amateur users will be allowed to access. This presents some issues for emergency services since non-hams will want/need to send messages on the system. There is also the thorny issue that part 97 does not allow encryption and some government agencies will not use communication links that are not encrypted.

 

MAIPN (for example) has several Internet Gateways that allow general-purpose internet traffic to pass.  I wonder how you plan to handle that type of thing?  This is not my area of expertise but I suppose it may be possible to block access to the internet gateways while installing some VLAN arrangement that still allows you to reach your destination across the backbone.    I am interested in solutions to this issue, since I would like to try some "channel -2" operation here.

 

73

Ken

[Corey Koval]

What equipment is out there that can utilize 3.4GHz? I would love to check some if it out.

Ken,
I am thinking about building a purely SDR repeater over at Unallocated Space. I have the hardware to do it. We even have a set of 440 duplexers. I have been working on the software. It seems I will need a little more CPU power than what I have though.

On Sunday, November 1, 2015 at 10:20:30 AM UTC-5, William "Bill" Kisse, W3MSH wrote:

[Ken Jamrogowicz]

A "pure" 440 MHz SDR would need an A/D conversion at about 1 GHz although you could under-sample with some consequent loss of sensitivity and/or dynamic range. In any case, your CPU would be "drinking from a fire hose"   Normally an FPGA is used for the first steps of processing at these speeds and that requires some very special programming talents ... perhaps you know all this :-)

73

Ken

 

Re 3 GHz: Ubiquiti makes several things. One is called the Rocket M3 (not 365) and a smaller one with integrated antenna is called the NanoStation M3 or NS M3. Flytec Computers is one dealer. Also sold on eBay.

[Corey Koval]

It would not be direct sampling. I would be using something like an RTL-SDR on the receive side, and a HackRF on the transmit side.

It appears you can get the Rocket M3 on amazon: http://smile.amazon.com/gp/product/B00KWKVUIE/ref=s9_dcbhz_bw_d0_g147_i1_sh

[Ken Jamrogowicz]

Well ... you could make it work, but the dynamic range and image rejection of the RTL-SDR dongle are simply awful and it would never function well in a typical repeater environment  ;-(

 

Ken

 

PS - sorry I forgot Amazon. These days you will find the same seller on Amazon, eBay and again with their own web site. Sometimes the prices (including shipping) are different, so it is useful to compare.

 

Remember that the M3 requires an external antenna.  A useful one will cost more than the radio itself.