Basically I don't have much to do with UHF CB repeaters unless I'm out in the country where they are meaningfully used.
Playing around with a new radio for the car I tuned through Sydney's UHF CB repeaters. I can't say I was supprised by the number of morons, or the quality of the idiots on offer, they really have been draging the good name of fuckwits down to a lower level.
Anyhow, I put a small amount of thought to it and wondered how one would go about building a fuckwith proof, or at least a f**kwit tollerant repeater.
The most obvious step is to put CTCSS on it. But it doesn't take long before your more persistant village idiot works out how to turn it on or at worst buys a subtone board.
Listening to the verbal excriment a little more closely I notice two types of junk transmissions.
Really long overs where a users ego is only limited by the repeater timeout.
and
Really short overs where a user gets in a quick insult.
Listening to legitimate overs on simplex channels, most overs tend to be either short replies or 10 to 20 second overs.
So we can base repeater use on these qualities.
Set the repeater timeout to 20 seconds.
It sounds unreasonablly short, but this timeout only boots a user... it isn't a repeater timeout.
So how do you determine between different users ?
Well that's actually very simple .... rotate the CTCSS.
Lets just say we figure on 4 users plus a no CTCSS user. 5 users total.
The repeater scans through the 4 subtones and the no tone squelch. Treating no tone like the 5th tone.
The moment somebody transmits using a sub tone (or no tone) the repeater operates ... the timeout begins.
20 seconds and the repeater times out, but only times out that CTCSS.
If the user transmits for less than 20 seconds ... the repeater will lock out his CTCSS for 20 seconds.
If another user transmits, using a different CTCSS, then the second CTCSS will now have the same timeout parameters,
but, a second user will reduce that last user's timeout to something like 3 seconds.
When a user's timeout expires, the repeater's output will beep (obviously at the 3 second and 20 second intervals.
If a CTCSS tone steps on the timeout tail, it is locked out for 20 "accumulative" seconds.
This way jammers or repeater hogs will effectively be locked out. They may be able to jam the input and prevent use of the repeater, but nobody will hear them do it. The repeater will just appear to be off air each time they attempt to jam a transmission.
You could then had extra lockout modes on top of that.
You could add more or less sub tones.
Since only one radio can run one subtone at a time, repeater kings are effectively knocked on the head unless they have more than one radio or can rotate CTCSS tones quickly and then, the repeater still can choose at random which tones to scan. The more tones, the less chance any one person has of holding the repeater.
Now comes the exciting part .....
Space diversity.
As we all know, one idiot can timeout and hold the timeout on a repeater. It is a simple Denial of Service type attack. Even weak users can effectively time out a repeater from underneath repeater hogs.
Space diversity comes in several forms. Two kinds that I can think of would work very well for UHF CB repeaters.
The first consists of an omni antenna with an array of directional antennas (like small yagis). A station keys up the repeater and the repeater then selects the best space diverse antenna or at its simplest, switches to that directional antenna for the duration of that over. Other users will find it hard to jam that user. The antenna can also be deselected if it times out the repeater in an attempt to ignore any signals coming from the jamer's general direction.
The other kind is to have a repeater as usal. But with several inputs located in several different locations.
The repeater then selects the best input and locks it for the duration of the over. That input can also be locked out fo the next over again resisting attempts from idiots.
Applying the same rule as before. If the repeater sees a stronger signal on any other input during the over, it can lock out that input for a short period ofter the over in attempt to lock out a jammer giving other stations more of a chance to use the repeater.
In each case the repeater rewards good behaviour and attempts to lock out bad behaviour.
