Contact is being made here, with questions and very interesting discussion topics, which need to be addressed and answered. Please do not hesitate to contact me with any relevant support material, knowledge and experience. We are all learning about Wires X and System Fusion, the hobby marches onwards and upwards.
Q1 What is the difference between a NODE and ROOM and why is it preferable to connect to a ROOM rather than a NODE as mentioned on this website and in relation to GB3SP.
Q2 Another enquiry is "how is it possible to have a repeater transmitter on and be able to receive an incoming signal at the same time and on the frequency same band"
Some information on Q2 to follow soon, a very good question.
NODES AND ROOMS - discussion as follows:-
I will explain what I understand about a Node and a Room, based on my personal and practical experience of having both for a few years.
My NODE consists of an FTM-100D transceiver, an HRI-200 interface box, USB interface cable, 50 Ohm dummy load a laptop computer, a Wi Fi internet connection to router and BT twisted pair telephone line. A picture of this is seen in the History page in this website.
In short, its a low power radio repeater providing connection to the internet and the Yaesu Wires X network and allows me to talk to stations in all parts of the World and GB3SP using just a handheld radio such as FT1 XD and FT2D. The wireless range of my node is limited to less than 100 metres and this works very well as direct communication with GB3SP is unreliable. My system works in the digital mode only, but nodes can be set for analogue working if required.
When I set this up, I had to send an email to Yaesu and they then set my Node up on their system and also gave me a unique number, they also allocated a Room and which also has a different unique number. The whole process was straightforward and swift to complete.
I should mention, that times have moved on and new technology has given us the Yaesu PDN system of setting up a Node. PDN stands for Personal Digital Node and does not involve any extra cost such as the purchase of the HRI-200 box. I understand that all Yaesu System Fusion equipment can now use the PDN system and comes pre installed with the necessary firmware. Updates can be downloaded and installed for older equipment from the Yaesu website free of charge and with comprehensive installation instructions to be followed to the letter. I advise NOT to take any shortcuts!
GB3SP also has its own Node similar to the above and is installed with Peter GW4VRO but with a special NoV issued by Ofcom to allow a radio link to the repeater itself and thus in the same way connecting GB3SP to the Yaesu Wires X worldwide network and which other System Fusion equipped stations can use. My personal Node cannot be used by anyone else and so I do not require a special Nov
ROOM
Well, the definition of a WIRES X Room with due acknowledgement and to paraphrase Dewey L. Hee, WB7OEV is as follows:
It’s a WIRES X Network community space to which multiple Nodes can connect simultaneously. A place where all amateur station can link to each other via local Node and communicate with each other.
Also, the dictionary definition of a Room is a ‘space that can be occupied or in where something can be done’
This is it in a nutshell and may I at this point might I suggest downloading the PDF called ‘WIRES X - The Bible’ its 169 pages of everything you want to know about WIRES X and is easy to find on a Google search. It has become a little dated but apart from the PDN
system introduced this year (2019) it is a brilliant reference source to have to hand at all times.
WIRES X The Bible
So let me explain my understanding about a WIRES X Room and again from my personal use of same, it’s just a location in cyberspace on the internet somewhere and where we as amateur radio enthusiasts can meet up in ‘virtual space’ just like sitting in a room or conference hall for a meeting or seminar and where there is a wealth of knowledge to be gleaned and where questions can be answered by so many experts on anything related to this subject and the hobby in general.
These Rooms have names such as ‘CQ UK’ , ‘America Link’, ‘Texus Nexus’ and yes even ‘GW3XJQ-ROOM’ and they all have a unique DTMF number ID mine being 41478. There are hundreds of Rooms and they cover the whole world. It’s a wealth of information available from just pressing the correct buttons. It reminds me of my book by John Clarricoats ‘World at Their Fingertips’ a great read.
We do now literally have the World at our fingertips and by pressing a few buttons on a handheld transceiver we can dial up the World of Amateur Radio. It’s marvellous isn’t it? My personal node ID number 31478 can be moved to sit in any of these Rooms and thus I can then hear all the activity in whatever Room I decide to connect to via my Node comprising the FTM100 D and the HRI 200 box. I can for example put a call out on the America Link and where there are at least 100 other nodes and repeaters connected.
So potentially, there could be many hundreds of amateurs available to talk to at any one time; it really is good and especially when other traditional means of wireless communication are not available. But an important note as always is that it’s far better to connect to a Room and actually put out a call and not just sit there and listen for someone else to make the first move. Nothing changes, ‘its use it or lose it’ if we don’t use the EM spectrum and support the alternative technology provided for us, then we may live to regret it. We should not allow ourselves to become complacent, what do you think?
Room connect rather than Node?
Generally speaking and particularly in relation to GB3SP it is always better to connect to the Room rather than the node when its available.
The GB3SP Node is set to 'sit in the GB3SP Room' it will default set to this state.
This means that the GB3SP Room can accommodate multi way communication between other Nodes and Repeaters connected to the Wires X network. All communication within the Room can therefore be heard by everyone participating and also everyone within radio range of GB3SP.
When a user makes a Wires X link on GB3SP and wants to say connect to one of the popular busy Rooms such as CQ UK and America Link for example and then proceeds to listen before making a call then this is perfectly normal and valid use of the system. Using the repeater as a purely listening 'DX' receiver is frowned upon and discouraged as bad practise. Wires X is there to be used and enjoyed of course, but for amateur radio discussion and exchange of thoughts and ideas.
The problem arises when a user possibly from a distance does not realise that GB3SP repeater Node has an associated Room. The user station connects to the Node and in effect excludes any other station from joining in the QSO apart from those within the coverage area of the repeater itself. Any other user will simply be shown a 'BUSY' message from the node, in other words its one to one communication and is annoying especially for personal node users who want to hear and join in to GB3SP activity and where they cannot receive a direct RF signal from it.
And so, the message, is to please Connect to the GB3SP Room where you want to hear and work all the local stations and anyone else who may be 'sitting in the Room'. Its much easier to understand for those users who have their own personal HRI -200 Node as they can see all the Nodes and Repeaters sitting in the GB3SP Room. We do see quite regularly 'DX' Nodes sitting in GB3SP Room and who may well reply to your call through GB3SP, in Digital Voice only of course. In these cases, you do not have to make a Wires X link to GB3SP using the DX button.
One point that has come to mind, is, that since Yaesu introduced the PDN (Personal Digital Node) system early 2019 those operators do not get allocated their own Room when they apply for a WiresX ID. But they can connect to the GB3SP Room.
This all sounds a bit confusing and maybe I will re draft it; but if there are any questions please let me know.
Oh, and a final final, PLEASE remember to disconnect the GB3SP Node from Wires X on completion of your QSO. Long press on star button or the Band button, check the manual for your particular radio model.
Q2 CAVITY FILTER
Pye AE 450F cavity notch filter as used on GB3SP Mark 1 1978
The above spectrum analyser (SA) display illustrates how a repeater such as GB3SP can relay radio signals with a transmitter and receiver operating at the same time and with the two frequencies less than 0.4% shifted from one another. Without high performance cavity filters the receiver would be de-sensed by the transmitter and would effectively mean that the receiver could not hear any incoming signals. Marker one (M1) shows the Tx frequency, 433.100 MHz and M2 the Rx frequency of 434.700 Mhz. The difference frequency (split) is 1.600 MHz and the cavity filter provides a 'notch' of -27.3 dB.
Cavity filters are used; a classic Pye AE450 F is shown above and the SA display shows the pass reject characteristic of a modified filter AE450 F and which is tuned to give a deep attenuation notch on the transmitter frequency of 433.100 MHz and with a pass frequency of 434.700 MHz being the receiver input frequency for GB3SP. This filter would thus be connected between the receive aerial and the input to the repeater receiver. This allows the wanted signals to pass through with minimal loss, but the notch tuning reduces the adverse affect on receive due to the high RF field strength resulting from the transmitted signal. Each cavity filter will give around 30 dB of rejection and in this case the figure is 27.3dB, this is a power ratio factor of around 500:1.
It is generally accepted that for an amateur repeater to work efficiently and to not suffer from receiver de-sense, a rejection of unwanted signal would be at least -100dB. Therefore, more than one cavity filter would be required of this type and this attenuation can usually be obtained, or better with three high quality cavity filters having around 35 dB per element. The only downside with using more filter elements, is that the losses are additive and so, the received signal and the RF power output from the transmitter can be attenuated by up to 50 % or 3 dBs. On receive this is not such a problem, since modern receivers are very sensitive and the actual signal to noise ratio remains fairly constant through the filtering, whereas a loss of 50% transmitter power needs to be addressed, by ensuring minimal cable losses and a good aerial with some gain.
A similar set of cavity filters is connected between he transmitter output and the feeder cable to the aerial The response curve will be similar to the above but a mirror image with the notch frequency being 434.700 MHz and the pass frequency being 433.100 MHz. This will reduce significantly the transmitter noise affecting the performance of the receiver, whilst passing the transmitter RF with minimal loss. It is also possible to connect a number of similar cavity filters together and form a duplex filtering system, called a duplexer. This arrangement enables the use of a single aerial for both transmit and receive and has been used on many amateur and commercial repeaters, including GB3SP in the past. This arrangement has benefits in terms of cost savings and especially where commercial mast rental depends on charges per aerial attachment. Very sophisticated aerial combiners can also be used to run a number of repeaters on the same aerial.
This is a very brief non technical description of how by using cavity filters GB3SP is able to transmit and receive very weak incoming signals at the same time. There is much more information to be had online and practical designs for making your own cavity filters. However, a well appointed mechanical engineering workshop is almost essential to produce quality low loss filters. Much can be learnt from using commercial filters, as they have to be tuned correctly and again much information is freely available to guide you through the procedure.
to be continued …………..