new radios for fire house around w'gabba area

[chanjyj]

I disagree that a good signal strength is critical for a digital system. Well, to qualify that statement I bit further I suppose it would depend on the digital system itself.

I guess in the end it will boil down to either P25 or TETRA. TETRA is a different cake from analogue. While its FEC is robust the number of sites required should be rather more than what they are using now, so it's an apples to oranges comparison.

I have no had experience with P25 implementation so I cannot comment. However, for DMR (which I think in terms of characteristics is quite comparable to Phase 2 P25) I have seen with my own eyes where the analogue signal barely broke the noise floor, but DMR was a clear copy.

Whatever the case is, a new digital system will require an overhaul of ALL infrastructure, including repeaters. With the exception of a DMR system, I dread to think the cost of a P25 or TETRA infrastructure statewide.

[bustercc]

Just to clarify regarding the radios.
They are Motorola APX6000. They are replacing all portable radios not just swift water rescue. This is in
response to the Qld Flood Inquiry which found that communications were hampered during the flood
crisis because the portable radios were not waterproof. They are analogue and digital.

[brisescannerdude]

Just to clarify regarding the radios.
They are Motorola APX6000. They are replacing all portable radios not just swift water rescue. This is in
response to the Qld Flood Inquiry which found that communications were hampered during the flood
crisis because the portable radios were not waterproof. They are analogue and digital.

It makes sence for fire dept to use waterproof radios and to be honest I don't think you would loose one easly onsite as they stick out like dog .....

[brisescannerdude]

I disagree that a good signal strength is critical for a digital system. Well, to qualify that statement I bit further I suppose it would depend on the digital system itself.

I guess in the end it will boil down to either P25 or TETRA. TETRA is a different cake from analogue. While its FEC is robust the number of sites required should be rather more than what they are using now, so it's an apples to oranges comparison.

I have no had experience with P25 implementation so I cannot comment. However, for DMR (which I think in terms of characteristics is quite comparable to Phase 2 P25) I have seen with my own eyes where the analogue signal barely broke the noise floor, but DMR was a clear copy.

Whatever the case is, a new digital system will require an overhaul of ALL infrastructure, including repeaters. With the exception of a DMR system, I dread to think the cost of a P25 or TETRA infrastructure statewide.

Signal strength is part of it, there are also other issues with digital, distance and local climate - just look how successful the digital tv rollout has been and requirement for some people who have analog services to move to satellite based VAST service because digital fails to work. I know some will say there are a huge difference between digital tv and digital two way radio but in the real world it comes down the receiver recovering the 1 and 0's in the right order and reassembling them into something a radio can use. Lets not start of the logistics of getting a signal form the radio back to the base site.

[chanjyj]

I disagree that a good signal strength is critical for a digital system. Well, to qualify that statement I bit further I suppose it would depend on the digital system itself.

I guess in the end it will boil down to either P25 or TETRA. TETRA is a different cake from analogue. While its FEC is robust the number of sites required should be rather more than what they are using now, so it's an apples to oranges comparison.

I have no had experience with P25 implementation so I cannot comment. However, for DMR (which I think in terms of characteristics is quite comparable to Phase 2 P25) I have seen with my own eyes where the analogue signal barely broke the noise floor, but DMR was a clear copy.

Whatever the case is, a new digital system will require an overhaul of ALL infrastructure, including repeaters. With the exception of a DMR system, I dread to think the cost of a P25 or TETRA infrastructure statewide.

Signal strength is part of it, there are also other issues with digital, distance and local climate - just look how successful the digital tv rollout has been and requirement for some people who have analog services to move to satellite based VAST service because digital fails to work. I know some will say there are a huge difference between digital tv and digital two way radio but in the real world it comes down the receiver recovering the 1 and 0's in the right order and reassembling them into something a radio can use. Lets not start of the logistics of getting a signal form the radio back to the base site.

I don't think it would be prudent for me to go into technical systems here. Distance so far has not proved to be a limiting factor for P25 or DMR, anymore so than current analogue systems; in some cases they have actually been better. TETRA is a different piece of cake and I won't be lumping it together.

Digital comes in many flavours and I think to lump them together as one system is a fallacy.

If you would like, I could explain more, but it is hard to do on an internet forum. I'm relatively ok with teaching, but one thing I found is it starts getting much easier to comprehend with a blackboard rather than powerpoints or typed material.

[brisescannerdude]

I don't think it would be prudent for me to go into technical systems here. Distance so far has not proved to be a limiting factor for P25 or DMR, anymore so than current analogue systems; in some cases they have actually been better. TETRA is a different piece of cake and I won't be lumping it together.

Digital comes in many flavours and I think to lump them together as one system is a fallacy.

If you would like, I could explain more, but it is hard to do on an internet forum. I'm relatively ok with teaching, but one thing I found is it starts getting much easier to comprehend with a blackboard rather than powerpoints or typed material.

You can not lump all of the technology together as they were built and designed to meet different needs and then vendors took it to market.

I do agree digital has got a lot better as the hardware and software has matured but based on what I have seen it still has issued in some areas of qld which has made the sell to the locals harder as they do not see it as an upgrade but downgrade. That said it could come down to system design, poor setup, wrong technology etc but when you work with people on the ground perception is a big factor to overocme and some vendors are driven by $$$ than wanting to provide a viable long term solution.

as for learning I would like to know more as this new technology is interesting and working knowing - please pm me and we can talk offline

[chanjyj]

I don't think it would be prudent for me to go into technical systems here. Distance so far has not proved to be a limiting factor for P25 or DMR, anymore so than current analogue systems; in some cases they have actually been better. TETRA is a different piece of cake and I won't be lumping it together.

Digital comes in many flavours and I think to lump them together as one system is a fallacy.

If you would like, I could explain more, but it is hard to do on an internet forum. I'm relatively ok with teaching, but one thing I found is it starts getting much easier to comprehend with a blackboard rather than powerpoints or typed material.

You can not lump all of the technology together as they were built and designed to meet different needs and then vendors took it to market.

I do agree digital has got a lot better as the hardware and software has matured but based on what I have seen it still has issued in some areas of qld which has made the sell to the locals harder as they do not see it as an upgrade but downgrade. That said it could come down to system design, poor setup, wrong technology etc but when you work with people on the ground perception is a big factor to overocme and some vendors are driven by $$$ than wanting to provide a viable long term solution.

as for learning I would like to know more as this new technology is interesting and working knowing - please pm me and we can talk offline

Feel free to PM me.

I'm posting this here though, for the benefit of anyone who might read it. Theoretical applications are just that - theoretical. Sometimes you wonder why something in theory that "should work" doesn't, then you realise there are a 101 possible problems outlined in theoretical papers that you cannot possibly anticipate, or even figure out.

Sometime back (in Singapore) I was having an issue with poor signals in an area which should not have had poor signals. It was baffling, considering I was on a bridge with no obstruction for 250m and fresnel zones were supposedly clear. In the end the problem was traced back to multi-pathing. While there is a ton of research on multi paths, there is nothing till date that can simulate multipathing in a city. There is too many variables.

Let me liken it to predicting the weather - you can get a rough idea of what might happen, but sometimes the unexpected shower comes, or the rainstorm that was supposed to come never appears. Maybe a bird flapped it's wings 1000 miles away?

The best way to learn is to actually trial out something, which I think is not possible for the QLD state network. The costs are prohibitive. The only way they can try work things out is on paper, and as I have seen with my own eyes, paper allows for tremendous hiccups.

Ok, I've gone off on a tangent. I'll stop my OT.