Additional hardware support for GB7BS
The major part of the supporting hardware for GB7BS is the Internet connection.
After a failed use of the 2.4GHz Band (Due to over population of the band around G7FBD's QTHr) we moved to the 5GHz band.
After a period of research we opted for the Ubiquiti Power Beam M5-400 network solution. This package can be used in both commercial and non-commercial parts of the band and indeed is used by commercial companies.
The AirOS installed on the equipment provides a secure and easy control of the system parameters, using this, we had a low power -4dBm link set up on the bench within an hour (it may have been quicker if we had read the manual. But AirOS is just that easy to use).
The makeup of the dish assembly
The Packing List.
The hardware is a very well designed assembly, with all parts being integral. The 400 relates to the 400mm prime focus reflector that forms part of the final assembly. The feed horn itself has a signal strength led display on the side of it, and has an RJ45 connector where you connect the data.
The device also comes with a Power over Ethernet (PoE) power injector which provides the 24v to power the transceiver built into the feed horn.
THE Power over Ethernet unit (PoE)
Side view of mounting
Following documented safety, the reflectors were not fitted to the units during this initial testing phase.
Once happy we were linking devices across the 5GHz link, it was then time to fit the equipment. By January 26th we had a link to Lansdown, which was not only stable and interference free, but proved faster and more secure solution, than the 2.4GHz equipment we had tested earlier.
The PowerBeam M5-400 utilises TDMA on 4 timeslots to manage traffic across the link, and is providing a measured throughput >> of 38Mbps. It's kind of fitting using a TDMA solution for a TDMA repeater :-)
Polar Diagram of the PowerBeam M5-400
The allocation of TDMA Timeslots
The "B" end at G7FBD QTH. (TV antenna sticking out the side!)
The NanoBeam (PowerBeam) M5-400
The "A" end on the tower at Lansdown.
SPECIFICATIONS OF THE MICROWAVE LINK
• Type: PowerBeam PBE-M5-400
• Frequency: 5GHz (non commercial section)
• Dish Reflector: 400mm
• Dish Gain: 25dBi
• Power rating: 8W
• Link speed: Better than 38Mbps under 80% load
• Processor: Atheros MIPS74K @560MHz
• Memory: 64MB DDR2 + 8MB Flash
• Dimensions: 420 x 420 x 275mm
• Weight: 1.75Kg
• Gain: 25dBi
• Frequency: 5.170 – 5.875GHz
• Max VSWR: 1.5:1
• Down tilt: +2' (IO81SK) -2' (IO81TK)
• Wind Loading: 342.5N@200Km/h
• Rain: Wind Driven MIL-STD810 G Method 506.5
• Polarisation: Dual Linear
GB7BS Link Budget Parameters
• TX Power: +4dBm (0.0025W)
• ERP: +29dBm (0.8W)
• Free space loss: 123.3dB
• Predicted signal level: -94.3dBm
• Overall system receive level: -69.3dBm
• Fade margin: 24.71dBm
• Indicated levels in AirOS: -72dBm
5GHz Link Path Profile
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