Время начала работы в эфире: Came to life on 18th July 2004
QRA-локатор: Located in Solihull IO92CK
Время работы: Week Days 1600 to 1000. On all over the week end
Location Solihull West Midlands. 12k SE of Birmingham City
G4LCH
UK’s First Wide Split UHF Half Duplex Digital Repeater
The GB3DX team are happy to announce the creation of the UK’s first wide split Internet linked half duplex repeater based in the Solihull area (IO92CK).
The team currently holds several NOV’s all of which are currently active providing links to GB3DX in the 6m and 70 cms spectrum.
Following a recommendation from RA / OfCom which due to the confusion that simplex links create we in the first instance decided to create EchoTone which provides courtesy tones to the Echolink system.
EchoTone provides the user of an Echolink enabled link, audio feedback whilst using a simplex link.
The next natural progression was for the GB3DX team to embrace in full the OfCom recommendation and create the first ever UHF wide split half duplex Internet linked repeater.
Here is the extract of the document in question.
Use of the VHF and UHF bands is strongly supported. The 432 MHz UHF band is a popular choice, with respondents highlighting that it has the most capacity available. Some respondents desired more frequencies in the 145 MHz VHF band; others stated that greater use of the 70 MHz band could be encouraged, and there were also those who sought use of 50 MHz and 28 MHz.
Some respondents argued that, as simplex gateway operation can cause confusion (because inbound transmissions are not heard by all), half-duplex operation should be encouraged with ‘personal wide-split repeaters’ in the UHF bands. Half-duplex operation is currently possible by applying for two NoVs.
You may wish to download the full document from the following location, this makes interesting reading.
We have created is two independent simplex links, one operating on 434.525 MHz and the other operating on 430.075 MHz, both links operate using a single high specification antenna system.
The linking or repeating capability is provided by the Echolink system.
The half duplex system is strange to understand at first, there are many operating modes, either of these will operate but in the case of simplex operation where both stations use the same operating frequencies you will not be able to hear any UHF stations that are operating via the system.
To use the half duplex repeater please program you transceiver for the following operating frequencies:
Receive 434.525 MHz
Transmit 430.075 MHz
Repeater shift – 4.45 MHz
Or
Receive 430.075 MHz
Transmit 434.525 MHz
Repeater Shift +4.45 MHz
Or you can operate in simplex mode on either frequency.
You can also operate on the opposite frequency, this is where the two simplex links com into their own, one station can transmit and receive on 434.525 MHz and another on 430.075 MHz they will be able to communicate with each other due to the internet link between both simplex links.
The tones received back from the links / half duplex repeater can be confusing also
When operating using a split then you will always receive the Morse “I” when you transmit or another station using the half duplex features transmits.
When operating simplex you will receive a Morse “K” when you stop transmitting and the Morse “I” when the internet station completes their transmission.
I am planning to add an addition to the EchoTone system to fully support
UK based half duplex repeater operation.
The repeater it self is a single antenna installation using high specification cavities supplied and built by Ian G8PWE, Ian has done an excellent Job of creating these specialist devices that are built to the same specifications as the main repeater’s antenna installation.
The 430.075 MHz transceiver is an Alinco DR-430 which has been heavily modified for repeater use by Mark G4LCH with the addition of a carrier operated relay (COR) and audio sampling to provide flat audio for better quality.
The 434.525 Transceiver is a Kenwood TM702E that has been modified to provide the COR, +/- 2.5 KHz deviation plus similar audio tailoring to its counterpart. The Information to make these modifications was kindly provided by Kenwood UK’s technical support.
The antenna in use is a commercial 4 stack provided my Steve M0KQU this antenna performs very well.
The output specifications of all transmitting components is as follows.
Power Output = 10 Watts erp
Antenna = UHF 4 stack at 10 Mtrs
Max Dev. +/- 2.5 kHz
ASL = 160 Mtrs
The Internet using Echolink and a high-speed 3Mbs cable link protected by dedicated hardware firewalls provides the half duplex repeater support.
The same facilities that GB3DX provides are also available, X-MIT ID (RF finger printing software) is being used on both UHF transceivers.
We are actively encouraging the use of XMITID to assist in the identification of radio equipment used through the repeater.
We have also enabled the use of DTMF tones on the system to allow you to steer the repeater to the link / repeater you require.
The DTMF short cuts have also been programmed to mirror the shortcuts available on GB3DX the list of DTMF shortcuts is available from the GB3DX web site at http://www.gb3dx.com/ .
We hope that you enjoy using the new half duplex repeater which will be used not only to provide a much needed internet linked UHF repeater in the Solihull area but also to design and test even more exciting features for the main GB3DX repeater.
I would like to make a special mention and thanks to all of the members of the Wythall Amateur Radio Society that provided the inspiration and encouragement through the projects design and built. And the help of Peter G4KQU, Ian G8PWE and Steve M0KQU and Iain G0RDI, without their help, guidance and expertise this project would never have been completed.
The repeater will be available for most of the day and all weekends, Mark G4LCH works from his home location and is able to monitor the repeaters usage. In line with current UK regulations we are unable at this time to operate the wide split repeater in unattended mode.
As you will agree this system provides many important technical answers. We are always happy to discuss any aspect of the system. It may be used in very diverse applications, emergency communications is one example when a receive frequency becomes noisy then one can disable the receive part of the one half of the half duplex system and it will sill operate this is important for organizations such a Raynet etc that may be able to use this technology to overcome local interference. This is only one of the many uses for a half duplex repeater system.
We hope you enjoy this exciting development and look forward to hearing / working you through the repeater.
Applications for NoVs must be made through the RSGB's Datacommunications Committee. You can apply on-line for an NoV by clickinghere.
XMIT_ID allows you to record and catalogue the unique "fingerprint" that is part of every FM radio's transmission. This can be used for transmitter identification.
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