Voting networks

[vkcpolice]

Was wondering if anyone could explain to me how voting networks work used by the vic police and cfa. I know how trunking networks work. I just dont understand how the radios keep up to date with the closet towers. Cause on a scanner you always have to change frequencys every new area you go to.

[ymmlman]

Voting is like a mini scan group within the radio, with a couple of extra features and done on both sides of the conversation.

Voting systems almost without exception use two frequency systems (different receive and transmit frequency).

When a mobile radio or portable transmits, it is usually picked up by two or three (or more) base stations in the surrounding area. All of the base stations that pick up the signal, pass their received audio back to a central 'voting' controller. This voting controller analyses the signals from all bases and selects the base station with the 'best' received signal (the 'best' can be selected in several ways, at the moment we will leave it as selecting the 'best'). This best received audio is then passed to the transmitters on all sites that are connected to the voting controller, so that all radios in the coverage area hear the signal transmitted by the original radio. In addition, if there is a dispatcher connected to the system, they also get a copy of this best received signal.

So now we have every base station in the coverage area transmitting a copy of the best received audio. In the mobile and portable radios, the programming for a voting channel will have a range of received frequencies assigned to that one channel, which correspond to the base station transmitter frequencies (anything from 3 to 6 on the CFA metro channels). When a voting channel is selected on the radios, they automatically start rapidly scanning through the frequencies assigned to that channel. When they pickup a signal on any one of these frequencies, the scan is stopped but after a very short amount of time (less than 100ms), the radio does one more sample of each of the frequencies in the channel and does a measurement of the received signal strength of every frequency. The radio then selects the signal with the strongest signal, and outputs that to the speaker. At the end of the transmission, the radio waits a short amount of time (usually less than 1 second) to see if there is a subsequent transmission, before recommencing it's scan of all frequencies.

This is the biggest difference between a scan (multiple frequencies programmed but stopping on the first that has a signal), versus voting where every frequency programmed in the channel is scanned, but one more scan and measurement is done before the radio stops on a frequency.

So there are actually two parts of a voting channel. One is where the system selects the best signal from a radio to re-broadcast to everyone else, the other is where the radio selects the best signal from all of the active transmitters.

The biggest problems are normally the voting controller or radio 'mis-voting' where due to local interference or equipment problems the best signal is not selected. This is quite often seen when there are several radios in together and most will have good signal, but one will have a rubbish signal (because of a mis-vote). Quite often heard over the air where you may have heard a radio very well on a scanner, but a user may ask the dispatcher to repeat as the signal was broken. Most likely this is due to a mis-vote on the radio.

The second problem is the time it takes a radio to do the vote on large systems. To cover large areas you usually need lots of transmitters and lots of frequencies. But if you put too many frequencies into a vote channel, it takes too long to make the selection of the best as the radio has to stop and sample each frequency, even if there is no signal in that area. This usually limits the maximum number of frequencies in a voting channel to around 6. It's usually the best mix between good coverage, and fast voting. More frequencies gives you better coverage but slow voting, less frequencies gives you quick voting but problems with coverage in large areas without overlap from base transmitters on the same frequency.

[vkcpolice]

I kinda of still dont understand cause every single tower has a diferent input freqeuncy and cts code does this mean when a officer goes to transmit the radio transmits on 5-6 different freqeuncy s at the same time?

[Comint]

I kinda of still dont understand cause every single tower has a diferent input freqeuncy and cts code does this mean when a officer goes to transmit the radio transmits on 5-6 different freqeuncy s at the same time?

While each tower has its own input frequency, it also has a second input frequency that is common to all towers in that Vote Group, and that is the frequency that the Mobiles transmit on.

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Comint

[vkcpolice]

Sorry I just still don get it lol wouldnt a officer or cfa member know what there closest tower it and know the frequency and cts code I just dont understand if all towers listen for the strongest singnal then wouldnt this mean they would all have the same input Frqeuncys cause how would the radio know what oneto transmit on so its just mind boggaling me lol

[Comint]

Sorry I just still don get it lol wouldnt a officer or cfa member know what there closest tower it and know the frequency and cts code I just dont understand if all towers listen for the strongest singnal then wouldnt this mean they would all have the same input Frqeuncys cause how would the radio know what oneto transmit on so its just mind boggaling me lol

I am afraid to say that most Users have enough trouble knowing what Channel Number they are supposed to be operating on, in any particular area, and wouldn't even know the Frequency Band, let alone the actual Frequency.

And CTCSS - "what's CTCSS". They don't need to know, so they don't know.

And as for knowing the closest Tower. Ha Ha!
They get told that if they are in Area A, they use Channel X, and if they are in Area B, they use Channel Y, etc. End of Story.

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Comint

[Phil]

Sorry I just still don get it lol wouldnt a officer or cfa member know what there closest tower it and know the frequency and cts code I just dont understand if all towers listen for the strongest singnal then wouldnt this mean they would all have the same input Frqeuncys cause how would the radio know what oneto transmit on so its just mind boggaling me lol

I am afraid to say that most Users have enough trouble knowing what Channel Number they are supposed to be operating on, in any particular area, and wouldn't even know the Frequency Band, let alone the actual Frequency.

And CTCSS - "what's CTCSS". They don't need to know, so they don't know.

And as for knowing the closest Tower. Ha Ha!
They get told that if they are in Area A, they use Channel X, and if they are in Area B, they use Channel Y, etc. End of Story.

--
Comint

i tend to agree with Comint on this 99% of officers have no clue what is in there radio let alone care, they do get told to go to Channel X when they move to another area, the police will have a cheat sheet but that will only help them for there area.

[brisescannerdude]

Sorry I just still don get it lol wouldnt a officer or cfa member know what there closest tower it and know the frequency and cts code I just dont understand if all towers listen for the strongest singnal then wouldnt this mean they would all have the same input Frqeuncys cause how would the radio know what oneto transmit on so its just mind boggaling me lol

At the end of the day they are users and the system is there to provide a service - it is not there job to understand how radio system interconnect and communicate behind the sceens, that is for the radio branch people.

As a user of a mobile phone do you know where the nearest base station is and how the next hand off to the strongest cell will work? Personally I don't, I'm just wanting it to work when I need it and I see the end officers (users) very much see it the same way I do.

[vkcpolice]

Lol yes I do know what cell towers my network is bouncing off there's a app on android called antennas my phone does not even have a GPS and this app shows you where you are by triangalating your position and pointing you to the towers your connected to using Google maps only works for 2g networks for some reason but itsna fun little app

[melbourneradio]

I am afraid to say that most Users have enough trouble knowing what Channel Number they are supposed to be operating on, in any particular area, and wouldn't even know the Frequency Band, let alone the actual Frequency.

And CTCSS - "what's CTCSS". They don't need to know, so they don't know.

And as for knowing the closest Tower. Ha Ha!
They get told that if they are in Area A, they use Channel X, and if they are in Area B, they use Channel Y, etc. End of Story.

not quiet !!! although true to a larger degree ,,, some if not a larger pecent of cfa vols here in vic , are what we refer to as cranks !!! they have more radios and antennas than most ham operators ,, a few have given it a pretty good crack at putting me to shame !!! also in this area thre has been a number of radio exercises with hams and cfa/emergency services working together , so I would not be to sure of your last comment , it seems like a bit of a generalisation !!!

Lol yes I do know what cell towers my network is bouncing off there's a app on android called antennas my phone does not even have a GPS and this app shows you where you are by triangalating your position and pointing you to the towers your connected to using Google maps only works for 2g networks for some reason but itsna fun little app

il have to have a peek at this ,, it sounds geegy enough for me I have wifi analyser and that's a good time waster in public place looking at all the wifi networks

[knightcon]

Quick tutorial on voting systems the CFA way...

In VFA radio's there are around 200 hidden channels which do not show up on the radio. These are the base stations which are a part of the various voting groups and each one has its own frequency, they can also have their own CTCSS tone but many agencies including CFA, SES, and VICPOL reuse the same group of 2-5 CTCSS tones. What happens with voting is the radio is programmed with a Voting channel which appears to the end user like any other radio channel but in the background the radio is scanning through the various hidden radio channels on that vote group and locking in on the strongest system. Some of these voting systems use special voting hardware and a special voting frequency, others simply use voting enabled base stations which use the voice frequency as the voting frequency as well and they transmit a CTCSS tone in the background when a signal from the mobile or portable radio is received. The radio then knows the signal strength of the different base stations it can hit and selects the strongest signal and uses that base station for voice communications. Depending on the radios and the programing with some of these voting systems each transmission can be made to a different tower each time if you are passing through coverage of a number of towers.

Example of a voting system...

Please note these frequencies are examples only ant nor actual voting frequencies...

Visible Radio Channel - Vote 1
Hidden Tower 1 - 163.0000MHz TX / 164.0000MHz RX
Hidden Tower 2 - 167.0000MHz TX / 168.0000MHz RX
Hidden Tower 3 - 162.0000MHz TX / 161.0000MHz RX

Now the radio user will select on their Radio the "Vote 1" channel and the radio will always show that channel but if the radio is close to Tower 1 then it will be as if the program was...
Vote 1 - 163.0000MHz TX / 164.0000MHz RX

Then when the radio transmits later if they have moved and now have tower 3 as the strongest signal it will be as if it was programmed...
Vote 1 - 162.0000MHz TX / 161.0000MHz RX


Hope that explains it a bit for you. It is important to note however that this is the way that an analogue voting system works and not how a trunked radio network works which operates on a completely different principle.

[melbourneradio]

I would have not used the term "hidden" dont think that is to accurate but fairly good explanation ... the simple way is saying that voting is a type of scan !!!!

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