Introduction

In 2007 the Port Elizabeth Amateur Radio Society embarked on a 5.8GHz WiFi network for use of all club members that reside within the urban areas of Port Elizabeth , Uitenhage, Despatch and Jeffreys Bay.  The scope is to provide the infrastructure for members to connect to a club computer network to provide file transfer and sharing facilities between members.  Experimentation using Voice over IP protocols to link to the club repeater network will also be possible, as will a Telnet connection to the club Packet Bulletin Board System, ZS0NTP on Lady’s Slipper.  File uploading and downloading from this BBS will then be possible at far higher speeds than is presently available via the conventional 1200bd VHF packet radio network.  (Conventional packet services will still be available for members not within the coverage areas proposed above). 

Technology used

The De Facto industry standard being employed by public domain providers is being utilized here.  This is in the form of Microtik embedded single board computers functioning as routers, with plug-in Mini PCI wireless cards for the air interface.  (see www.routerboard.com) Due to the popularity of this equipment, prices are very reasonable.  These radio cards are dual band items that can operate in the 2.4GHz and 5.8GHz bands.  However, the 5.8GHz band has been chosen due to the loading already present on the 2.4GHz band.  

High site equipment comprises an RB532 routerboard with daughterboard to accommodate up to four radio cards.  On the main hub site ( Mount Road ) we employ the larger more powerful RB600 Routerboard with four on-board radio slots.  We have added its daughterboard to provide a total of 8 radio slots at this site. This will allow sectorised coverage at a later date, should usage dictate.  On the smaller rural sites, a single omni-directional antenna are used.  Site interconnection is provided by means of dedicated high gain parabolic dish antenna links.  The Internet connection ties into the main hub site by means of a dedicated point to point link to our sponsor ADSL line termination site.  At present, there are two "filler" sites located at members' QTH's, which act as local Access Points, but tie into the main network in the same way as a standard user does.. 

Connection speed from user to high site depends on the signal strength received at each end, the amount of on-channel interfering activity and the wireless standard used.  The backbone links are being designed to provide an expected 54Mbps thanks to high signal levels achieved through the use of 31dBi antennas.  The same speeds are possible to the end user. No bandwidth limitations will be applied on the network, providing no abuse takes place. 

Added facilities

The BBS PC at Lady’s Slipper is interconnected to the Ethernet port of the router board via a local LAN switch, thereby allowing access to this machine via the wireless network as well as the usual packet network.  All the presently fitted packet network ports are configured under AGWPE on this machine, and will thus be available to users over the wifi network.  So any wifi user can connect to the packet facilities without having any radio equipment available at home.  A packet gateway (iGate) for APRS has been installed on the BBS machine to gate all the South African APRS traffic to and from the other APRS servers, onto the local Packet APRS network.

Further facilities at the Mount Road site is the implementation of Voice over IP for Repeater access – in the form of an IRLP connection to the town repeater.  This allows international repeater access by licenced amateurs. 

A remote controlled HF rig interface program is installed at Lady’s Slipper, and interfaced to a Icom IC-718 HF rig using the CIV and audio interface.  This allows PEARS wifi members access to the HF bands from home, without actually owning an HF set.  This is ideal for townhouse complex dwellers, who are prohibited from erecting large HF antenna systems.  Audio interfacing to this HF Rig is via Skype - search for "zs0ntp_hf" as a Skype user, request to become a contact, and if accepted, you can make a call to ZS0NTP and couple to the HF rig audio.  Voice calls are automatically answered once users are verified.  A video feed is also available of the inside of the container, using a standard webcam.  This currently shows internal and external temperatures as displayed on an airconditioner control panel.

Some experimentation has been done with IP video cameras over the network.  Most notably would be one at Lady’s Slipper to allow a view from the mountaintop in various directions, under remote Pan-Tilt-Zoom control.  (Any donations?)

Internal email server

An internal email server program has been loaded at the QTH of ZS2AAW, which allows all WiFi users email address on the peham.co.za domain.  Internal emails between members do not go out via the internet, but rather get delivered internally via the WiFi network.  But these PEARS email addresses are accessible from the internet, and any number of such email addresses can  be created, so all PEARS WiFi members will have an email address such as <firstname>@peham.co.za

 Always-on Internet connection

An always-on 7Mbps ADSL internet connection is included as an added incentive for new members to join the society, and subscribe to the wireless network facilities.  This internet connection is essential for the operation of the club's IRLP node located at the Mount Road repeater site and WiFi hub, as well as the APRS gateway which feeds the Lady's Slipper APRS Node.  In addition, there will not be any profits drawn from the operation of this network – all subscriptions would be calculated to merely cover running costs such as ADSL line rental, depreciation, maintenance etc.  Excess funds will be channeled back into the network in the form of expansion and upgrades.

The limiting factor is the bandwidth of the internet connection point, and to limit monthly rental costs, this will be chosen to suit the number of subscribers.  This internet bandwidth is shared amongst all the users at any instant.  But because internet browsing traffic is not continuous, a very pleasant browsing experience will be had.  It can be seen that this network will be many times faster than dial-up speeds, without the call duration costs inherent with a dial-up connection, and available 24 hours a day (always online), to all PEARS members within reach and who have subscribed.

Click on this thumbnail below for the "bigger picture":

.pdf version

Services available

As presented at the South African Radio League "Radio Technology in Action" Seminar in Port Elizabeth in May 2008, the following systems are available for internal WiFi members to connect to