MEDWAY RAYNET GROUP Affiliated to the Radio Society of Great Britain

Raynet Wireless WAN on 2.4 GHz

The Raynet WAN is used to transmit JPEG still images of high quality, MPEG Movie clips and MPEG 4 Video over long distances using 802.11b (Wi-Fi) 802.11g is also being investigated..

Introduction - IEEE 802.11b

IEEE 802.11b (Wi-Fi) uses Direct Sequence Spread Spectrum (DSSS), using a bandwidth of 22 MHz to transmit data with speeds of up to 11 Mb/sec, However over greater distances this can reduce to 1Mb/sec

A Wi-Fi system can use any of thirteen 22-MHz-wide sub-channels across the allocated 83.5 MHz of the 2.4 GHz frequency band.

The system uses 22 MHz wide Direct Sequence Spread Spectrum, with 5 MHz channel spacing.

A maximum of three Wi-Fi networks can co-exist without interfering with one another. (Typically using channels 1,5 &9) For Amateur use 6 channels (1 - 6) lie in the UK amateur band and so for higher power usage only 2 channels can be used at one site without frequency crossover. (either 1 and 5, or 2 and 6, or 1 and 6) This is not a problem as will be covered later.

IEEE802.11 Wi-Fi defines operation within the 2400 to 2483.5MHz frequency range (2473 - 2495.0 in Japan) There are 13 DSSS carrier frequencies for use throughout the world are shown below:

note * denotes within the UK 2.4GHz Amateur Band.

11 channels (US, Canada), 13 channels (Europe), 14 channels (Japan)

Channels 12 and 13 were added for IEEE 802.11b Wi-Fi giving 13 FCC Channels and 11 ETSI Channels The Japenese channels are at a higher frequency band.

For standard amateur operation 2400 MHz - 2450 MHz (UK) channels 1 to 6 can be used. Although on this Amateur band it is permitted to transmit up to 400W PEP (26dBW) this does not include DSSS and so a special licence may be required for this project. A power not exceeding 10 Watts EIRP would be sufficient to cover up to 25Km.

For channels above 2450 (channels 7 to 13) the power output at the Aerial socket should revert to the standard output 24dbm (251mW) FCC in the USA and 20dbm (100mW) ETSI for use in Europe. (The European standard ETS 300 328 now states a total EIRP of -10dbW (More recently -3dbW) Not exceeding 500mW EIRP )

Channel 7 is 2442 +/- 11 MHz = 2453 MHz is outside the UK amateur band. Therefore Channels 7 - 13 can only be used at 200 - 500 mW EIRP.

Equipment To Use.

There are a number of options:-

PCI Card * The PCI Card is for use with a desktop computer. It potentially can produce the highest data rate of 10Mb/s as it is connected via a parallel bus. Not as useful for Raynet use but would be useful for a fixed station and for one transfering the images to the internet via an ASDL link as at G3VPA location. The great advantage of the card illustrated is that it has an external aerial socket. See Aerial section. Typical price £50 - £60
PC Card For use with laptop computers, can be fast with the parallel connection. But the aerial output is a compromise as it is screened by the PC in one direction, also it does not project to far out from the laptop to prevent potential damage. However it is possible to obtain PC Cards with External Aerial sockets as illustrated. Typical Price £40 - £60	Standard PC Card above. PC Card with Aerial sockets below.
USB Connection * Very convenient as the USB unit can be placed up to 5 metres from the PC or Laptop using an amplified USB lead. Therefore it could be used on a 4-5 metre mast to gain distance by height. Speed could be limited by the USB port connection to under 1 Mb/s but this is not a problem as the throughput speed of IEEE802.11b falls off with transmitter distance. 802.11 USB adapters can be obtained that have external aerials see Aerial and Amplifier Section. Typical Price £40 - £50
Access Point * The Access point typically will interface to a main computer system via an Ethernet connection. The illustrated unit has 2 aerials to provide gain by space diversity. Typical Price £80 - £150.

Useful Links for Equipment, http://www.expansys.com/d_wireless.asp

Amplifiers

For use in the amatuer band an amplifier would be useful, these typically boost the power to 500mW or 1W. This is useful to overcome the cable loss to an external aerial. The best option for Raynet would be the masthead or outdoor aerial.

2.4 GHz 1 Watt Indoor SmartAmp This amplifier is for installation indoors near the radio itself. Designed for extending the range of 2.4 GHz wireless radio devices, the Smart-Amp is particularly effective when used with Direct Sequence or Frequency Hopping Spread Spectrum radio modems. The unit provides the transmit power amplification as well as receive signal gain. The built-in dynamic power sensor in SmartAmps adjusts the Radio Frequency (RF) power output level by reading the input signal power. This auto gain adjustment delivers the maximum output power at various input levels while keeping the distortion at a minimum. * Integral Lightning Protection * Receive Bandpass Filter * Cast Aluminum Construction * Power and Transmit LED * Heavy Duty "N" connectors * 110 volt plug in DC Power Supply * Frequency Range 2400 - 2500 MHz * Receive Gain 17 dB typical * Output Power 1000 mW (30 dBm) * Input Power 0 dBm (1 mW) Minimum - 23 dBm Max * Dimensions (LxDxH) 4.5" x 3" x 1.2" * Made in U.S.A. Click here for more information about this amplifier. [pdf] Normal Price: $ 385.00 Typical Price: $ 280.00
2.4 GHz 1 Watt Outdoor SmartAmp * This amplifier is for use outdoor located near the aerial. Designed for extending the range of 2.4 GHz wireless radio devices, the Smart-Amp is particularly effective when used with Direct Sequence or Frequency Hopping Spread Spectrum radio modems. The unit provides the transmit power amplification as well as receive signal gain. The built-in dynamic power sensor in SmartAmps adjusts the Radio Frequency (RF) power output level by reading the input signal power. This auto gain adjustment delivers the maximum output power at various input levels while keeping the distortion at a minimum. * Mast Mountable * Integral Lightning Protection * Receive Bandpass Filter * Low 3.5dB Recieve Noise Figure * Cast Aluminum Construction * Power/Transmit LED * Durable UV-Stable Finish * Heavy Duty "N" connectors * 110volt plug in DC Power Supply * Made in U.S.A. * Frequency Range 2400 - 2500 MHz * Receive Gain 15 - 18 dB (17 dB typical) * Output Power 1000 mW (30 dBm) * Min Input Power 5 mW * Dimensions (LxDxH) 4.25" x 3.25" x 1.75" Click here for more details with this amplifier! [pdf] Normal Price: $ 579.00 Typical Price: $ 399.95
Router w/ Rainproof Box It is ideal to build Repeaters in combination of two CPE Routers, or one CPE Router and one Access Point. * Processor AMD 100 MHz * Memory 16 MB SDRAM * CF Memory 16 MB CF Card * Operating System Linux 2.4.13 Kernel Click here for more information! Normal Price: $ 399.99 Typical Price: $ 299.99
2.4 GHz Band Pass Filter This is a 2.4Ghz 3 Pole Band Pass Filter. If you have an installation where other Aerials are in close proximity to Typical ISM band Aerial, this filter should help to resolve any interferance problems you will encounter. These filters are also used to make Typical installation more "friendly" by filtering out any spurious emissions that Typical gear may be producing outside the ISM band. The unit has a N Male on one side and a N Female on the other. * Center Frequency 2442 MHz * Pass Pand 2400 - 2483.5 MHz * 3 dB Insertion Loss * Pass Band Variation 1.0 dBc max * Return Loss 10 dB * Rejection 2700 MHz and 1900 MHz, 45 dB * 3 Cermaic Poles Normal Price: $ 89.00 Typical Price: $ 49.99

Useful Link http://www.fab-corp.com/

Aerials

24 dBi Die Cast Directional Aerial DieCast Parabolic Grid Aerials are made of diecast aluminum with grey color epoxy powder coat paint. They are shipped in two sections to reduce costs. Aerials are complete with Reflector, Patented Dipole and Heavy Duty brackets for 1" to 2.5" diameter poles. * Frequency Range 1700-2700 MHz * Gain 24 dBi * VSRW 1:1.5 average * Maximum Input Power 50 W * Wind Load @ 100mph 96lbs @ 140mph 188lbs * Polarization Vertical or Horizontal * 24 inch Pigtail w/ N Type Female * Adjustable Elevation * 8 degree beam width * Powder Coat Painted Die Cast Aluminum * Click here for more detail on this Aerial! [pdf] Typical Price: $ 58.99
14.5 dBi Enclosed Yagi 2.4 GHz Enclosed Yagi Aerial is completely sealed and cannot be disassembled by hand. Enclosed Yagi Aerial has 12.5 dB gain, constructed of 15 brass elements and has a folded dipole feed. The tubular radome is 18 inches long and 3 inches in diameter enclosed with two 2 inch stainless steel U-bolts for ease in mast mounting. * Frequency Range 2400-2500 MHz * Gain 12.5 dBd / 14.5 dBi * VSWR 2.1:1 * Polarization Vertical * N Female 32 Inch LMR-195 Pigtail Nornal Price: $ 199.00 Typical Price: $ 78.95
19 dBi Parabolic Grid Aerial These Grid Aerials are welded galvanized steel with grey color epoxy powder coat paint. Because of their design and color, they blend well with any background. This series of Aerial have a history of 100’s of thousands of successful field installations over the past 6 years. Aerials are complete with Reflector, Patented Dipole and Heavy Duty brackets for 1" to 2.5" diameter poles. These Aerial systems are designed for extreme wind environments. * Frequency Range 2400-2500 MHz * Gain 19 dBi * VSRW 1:1.5 average * Polarization Vertical or Horizontal * N Type Female Connector on pigtail * Adjustable Elevation * 17 degree beam width Click here for more information on this Aerial! [pdf] Typical Price: $ 41.99
24 dBi Mag Grid Aerial This Broadband Wireless die-cast grid Aerial is manufactured with magnesium alloy, stainless steel and aluminum. Weighs 33% less than aluminum Aerials with no rust! Comes with RG8 pigtail, 24 inches long. Can be mounted with up to a 60 degree tilt adjustment. 8 degree beam width for long-range highly directional applicaitions. Can be installed for either vertical or horizontal polarization. This Aerial is DC grounded for lightning protection. * Frequency Range 2400-2500 MHz * Gain 24 dBi * VSRW 1:1.5 average * Maximum Input Power 50 W * Wind Load @ 100mph 97lbs @ 140mph 199lbs * Polarization Vertical or Horizontal * 24 inch RG8 Pigtail w/ N Type Female * Adjustable Elevation * Tight 8 degree beam width * Click here for more detail on this Aerial! [pdf] Normal Price: $ 128.50 Typical Price: $ 79.95

Coax Cable Losses at 2.4GHz

Loss at 2.4 GHz

Times Microwave

LMR 1700 -- 1.7db loss / 33.3m     €70.00 approx per meter
LMR 1200 -- 1.99 db loss / 33.3m
LMR 900 -- 2.63 db loss / 33.3m  €40 approx per meter
LMR 600 -- 4.4 db loss / 33.3m
LMR 500 -- 5.48 db loss / 33.3m
LMR 400 -- 6.8 db loss / 33.3m  €4.00 approx per meter
LMR 300 -- 10.4 db loss / 33.3m
LMR 240 -- 12.9 db loss / 33.3m
LMR 100A -- 70.1 db loss / 33.3m

Andrew

1 5/8"  LDF-- 1.4 db loss / 33.3m
1 1/4" LDF -- 1.7 db loss / 33.3m
7/8" LDF -- 2.3 db loss / 33.3m
1/2" LDF -- 3.9 db loss / 33.3m Approx LMR 600 size 
1/2" Superflex -- 6.17 db loss / 33.3m Approx LMR 600 -- Flexible
3/8" LDF4-50A -- 3.3 db loss / 33.3m 
3/8" Superflex -- 6.84db loss / 33.3m

Other Companies 

CNT-400  -- 6.7 db loss / 33.3m €3.70m approx per meter

Belden 9913 -- 7.7db loss / 33.3m 

RG213 -- 15.2db loss / 33.3m

RG214 -- 15.2db loss / 33.3m double shielded

RG58 -- 32.2 db loss / 33.3m 

You also need to include connector loss.

END Under Construction below

Information for Aerial building: 1/2 wavelength is 61mm, and 1/4 wavelength is 30.5mm.

Power Output on 2.4 GHz

In UK Amatuer band 400 watts is the total power allowed from amateur operation on Channel 1 to 6 if you are using a 0dBi Aerial. However it is not necessary and could be dangerous to use this power.
An amplifier of between 1 - 4 Watts is adequate Note: 4Watts = 36dBm = 6dBW
Equivalent power output(dBm) = power in (dBm) + Aerial gain (dBi)
Equivalent power output(dBW) = power in (dBW) + Aerial gain (dBi)

Most "omni-directional" Aerial's are usually about 8dBi.
for a 4 watt Equivalent power output you only need to put in 28dBm (631mW) of power into an 8dBi Aerial.

  If using a 21dBi aerial or dish then you only need to put in 15dBm (31mW) into the aerial or dish to realise 4W EIRP.

Possible Interference signals (Wide Band)

Amateur TV

18 MHz FM signal on 
ATV CHANNEL 1 FM TV
2406.000 - 2424.000
and
ATV CHANNEL 2 FM TV 18 MHz wide
2430.000 - 2448.000

Other signals

These frequencies are also used by low power FM TV Transmitters (extenders), phones, video and audio links.

The Wireless LAN frequencies are shared with other users including Amateur.

Amateurs using this mode are not limited to 4 Watts EIRP power as long as they stay in the Amateur segment.
Other voice, TV and data users also share this frequency range.

Suggestions to help minimize future interference on the 2.4GHz band

One likely source of wide band interference to Wireless LAN on 2.4GHz is local 18 MHz wide FM Television; although there are many low power transmitters in use, high power equipment is also available. As 802.11 is using DSSS (Spread Spectrum it is not that susceptable to distant stations on the same frequency.

It is interesting to note that some ATV stations have started going to higher power due to the background noise increasing on 2.4GHz ( due to wireless LAN),
Amateur 70 CM band; ATV uses Horizontal Aerial, Digital uses vertical Aerial and all links use the minimum power needed and narrow beamwidth Aerial.

The majority of wireless LAN seems to be using vertical and ATV users need to use horizontal Aerial for distance work therefore use use vertical Aerial to help prevent interference.

EIRP = Effective Isotropic Radiated Power.

Notes:

If you wish to use up to 4 Watts the highest channel that can be used is (6), 2452 -11 = 2439 MHz.

Three Wi-Fi networks can coexist without interfering with one another if channels 1, 5 and 9 are used in for the full 4 Watts EIRP.

IEEE 802.11b Wi-Fi 

IEEE 802.11b Wi-Fi supports true multipoint networking with such data types as broadcast, multicast, and unicast packets.

 The MAC address built into every device allows a virtually unlimited number of devices to be active in a given network. 

These devices contend for access to the airwaves using carrier sense multiple access with collision avoidance (CSMA/CA).

The Wi-Fi physical layer uses direct-sequence spread spectrum (DSSS) at four different data rates using a combination of differential binary phase-shift keying (DBPSK) for 1 Mb/sec, differential quaternary phase-shift keying (DQPSK) for 2 Mb/sec, and QPSK/complementary code keying (CCK) for the higher speeds: 5.5 and 11 Mb/sec.

The RF power level is typically between 30 and 100 mW (up to 20 dBm) in most commercial WLAN systems but cards are available with 300 mW output.

Basic information for Raynet

The Amateur and ISM bands overlap, all the commercial equipment will operate in the Amateur band.

Why not have a central server?
The problem with having a central server is there are only three frequencies
you can use in one location before the channels overlap.
There are a large number of users  in this ISM band so a large powerful site
is not a good idea in a city area, you can get away with this in the country
for now.
A series of small cells with links is the only way things can work once a
more than a few people link together.

Why not use an amplifier?
While you can get amplifiers for this band it's easy to get very high
Aerial gain.
There are come commercial sites that are using amplifiers and low gain omni
Aerial but they still keep to 4Watts EIRP.

How do I start?
The simplest way to get going is to purchase an Access Point (AP) such as a D-Link
DWL-100AP and plug in an external Aerial.
Some people are using PCI cards such as  Compaq WL210  or PCMCIA cards such
as a Compaq WL110.
It is best to check prices first as equipment is coming down in price.

Aerials

Because of the high frequency an aerial with a high gain can be made in a compact size. 16 - 21 dbi gain aerials increase the range considerably.

Useful aerial links:

http://www.hyperlinktech.com/web/antennas_2400.php

   http://www.rojone.com.au/

In Progress.