Hello:
This is sorta a strange question but ill explain the situation and lets see if I can just give a simple so so answer to the customer as an idea only and not a qaurantee.
First customer has no idea on db gain type answers.
Customer is I know i know so don't bring it up operating at 25khz and finaly has accepted the fact that hes gotta go narrow band.
He wasn't my customer originaly and is dead set on maintaining his present tx range of a 30 mile radius and yes I can confirm from some out in the field testing that he is getting right at 30 miles radius.
Ok hes on UHF freqs transmitting simplex and tower is 100 foot with 120 ft of 1/2 inch Andrew heliax coax using a 10 db Omni at 25 watts.
Ok I have told him and this is where it gets sticky = He probably will drop from 30 to 20 or 25 miles range.
Hes not willing to take the loss.
Ok so if I take him from 25 watt mobiles to 50 waters and at the base do the same and add a 5db uhf johnny cake rf pre amp.
What added range do you all think id be able to say for range performance ect.
I realize the complications involved with rf squelch noise with too high gain ect but believe I can deal with that and get by that issue.
So above situation wattage double pre amp added what do you think he could possibly get for tx range compared to his present 30 miles but going to 12.5 nb and double the wattage from 25 to 50 watts.'
I have done some rf preamp testing and I can get .20mv at 12 db from .35mv at 12db which was original so some rf gain was gained.
Whats everyones thought ?
Satelite
Wattage output versus tx range ?
Moderator: Queue Moderator
Re: Wattage output versus tx range ?
I have an old Motorola Radio Calculator slide rule. It shows a 10% range increase when going from 25-watt radios to 50-watt radios.
It shows a 3 dB system gain increase to have the same 10% range increase.
It shows a 3 dB system gain increase to have the same 10% range increase.
Re: Wattage output versus tx range ?
Simple answer - range is range is range is range. This discussion was beat to death on the lead up to the NB deadline. His range won't change just because he narrowbands. Otherwise, we would all experience instantaneous range changes as deviation fluctuates as a function of speech. I know the pocket protector league can *prove* it changes with some really kewl math, but I throw the BS flag on that play. The key to narrowbanding is to not be a lazy tech. Test the radio before you hand it back. Too many people just checked the 12.5khz box, and blew it into the radio without testing it afterwards. If he gets 30 miles now, he'll get 30 miles again.
A word of caution - the NB deadline expired some time ago, but your customer kept operating proving that the FCC was not going to enforce it. However, his license has probably been retired if he didn't bother to submit for a modification. So, before you do anything for this guy, make sure he is licensed and current. Sounds like he's buying new equipment from you. Now would be a good time to get that done. Otherwise, he can keep being a pirate, and he won't be your problem.
As for how much does 3db buy you in terms of range - not much. Range is determined more by terrain, height over terrain, and ground cover. Power and gain at the antenna are just two of the factors that ultimately determine the coverage footprint. Generally, 3db gets you better quieting in the same area, but not much additional area. If his coverage is a 30 mile radius around his main transmitter, and it were drawn on a map as a circle, 3db will add a pencil width to the circle. It's going to be measured in feet, not miles. If you really want to increase range, you have to do it in factors of 10 by both increasing antenna height, and increasing transmitter power, though improving receiver performance is just as good, but harder to do. Then we're talking miles added to the footprint.
If you want, send me a PM with your email addy, plus the lat/long of his base station antenna. I'll need rcvr sense, xmit pwr, and ant gain of the mobiles he's using too. I'll plot it out, and send it back to you as a kmz that you can view in Google Earth. That should help you see what 3db does and does not do.
A word of caution - the NB deadline expired some time ago, but your customer kept operating proving that the FCC was not going to enforce it. However, his license has probably been retired if he didn't bother to submit for a modification. So, before you do anything for this guy, make sure he is licensed and current. Sounds like he's buying new equipment from you. Now would be a good time to get that done. Otherwise, he can keep being a pirate, and he won't be your problem.
As for how much does 3db buy you in terms of range - not much. Range is determined more by terrain, height over terrain, and ground cover. Power and gain at the antenna are just two of the factors that ultimately determine the coverage footprint. Generally, 3db gets you better quieting in the same area, but not much additional area. If his coverage is a 30 mile radius around his main transmitter, and it were drawn on a map as a circle, 3db will add a pencil width to the circle. It's going to be measured in feet, not miles. If you really want to increase range, you have to do it in factors of 10 by both increasing antenna height, and increasing transmitter power, though improving receiver performance is just as good, but harder to do. Then we're talking miles added to the footprint.
If you want, send me a PM with your email addy, plus the lat/long of his base station antenna. I'll need rcvr sense, xmit pwr, and ant gain of the mobiles he's using too. I'll plot it out, and send it back to you as a kmz that you can view in Google Earth. That should help you see what 3db does and does not do.
Re: Wattage output versus tx range ?
Bill_G: “…range is range is range is range…”
Well, it is and it isn’t. In terms of path loss and RF signal level – yes.
In terms of useable communications range – not necessarily.
Bill_G: “…Otherwise, we would all experience instantaneous range changes as deviation fluctuates as a function of speech…”
In fact, that IS exactly what happens. It is a well-known fact that the signal-to-noise improvement intrinsic to the FM mode increases with increasing deviation. Correspondingly, reduced deviation decreases the effect. Consequently, in terms of operational range – range based on Delivered Audio Quality, the industry has determined that narrowband (+/-2.5 vs. +/-5) costs you 3dB of operational range.
Hence, the statement “…His range won't change just because he narrowbands.” is not accurate.
If you perform coverage analysis for the same system – first with a wideband configuration and second with narrowband – you will see the effect. That is, you will see that effect if you are using a state-of-the-art coverage prediction tool designed in accordance with accepted industry practice as defined in the TSB-88 series of documents.
Well, it is and it isn’t. In terms of path loss and RF signal level – yes.
In terms of useable communications range – not necessarily.
Bill_G: “…Otherwise, we would all experience instantaneous range changes as deviation fluctuates as a function of speech…”
In fact, that IS exactly what happens. It is a well-known fact that the signal-to-noise improvement intrinsic to the FM mode increases with increasing deviation. Correspondingly, reduced deviation decreases the effect. Consequently, in terms of operational range – range based on Delivered Audio Quality, the industry has determined that narrowband (+/-2.5 vs. +/-5) costs you 3dB of operational range.
Hence, the statement “…His range won't change just because he narrowbands.” is not accurate.
If you perform coverage analysis for the same system – first with a wideband configuration and second with narrowband – you will see the effect. That is, you will see that effect if you are using a state-of-the-art coverage prediction tool designed in accordance with accepted industry practice as defined in the TSB-88 series of documents.
Re: Wattage output versus tx range ?
... and then there is the rest of us.
Re: Wattage output versus tx range ?
Hello:
Yes i figured his license was most likely canceled since he didn't mod it for nb.
He is aware that the license will need to be updated if not reaply for.
But that's another day.
Right now im only concerned with what i can do to maintain the 30 miles he has versus the loss he most likely will see at 12.5 nb.
Id like to believe that going from 25wb to 12.5nb wouldn't change tx range but it has in many cases here and i do a complete alignment but still see an average loss of 5 miles or more from wb to nb operation.
Well i have seen and read two opposing views and i respect both but im not going to be able to say one way or the other with much info at this point to try to give him a better view of what we would maintain for tx range.
He didn't come to me first but several down the line and its my opinion that with his stead foot attitude on the tx range that if i come up short he will be my worst customer with an attitude.
More i think on it i believe the other shops most likely and willing pushed him out there doors due to the same attitude im seeing .
Ill just let him live in the nest hes made and let him walk too.
Satelite
Yes i figured his license was most likely canceled since he didn't mod it for nb.
He is aware that the license will need to be updated if not reaply for.
But that's another day.
Right now im only concerned with what i can do to maintain the 30 miles he has versus the loss he most likely will see at 12.5 nb.
Id like to believe that going from 25wb to 12.5nb wouldn't change tx range but it has in many cases here and i do a complete alignment but still see an average loss of 5 miles or more from wb to nb operation.
Well i have seen and read two opposing views and i respect both but im not going to be able to say one way or the other with much info at this point to try to give him a better view of what we would maintain for tx range.
He didn't come to me first but several down the line and its my opinion that with his stead foot attitude on the tx range that if i come up short he will be my worst customer with an attitude.
More i think on it i believe the other shops most likely and willing pushed him out there doors due to the same attitude im seeing .
Ill just let him live in the nest hes made and let him walk too.
Satelite
Re: Wattage output versus tx range ?
We don't knowingly work on unlicensed systems. We would work with him towards getting a license, but stop all maintenance on his current system until he was. He can rent radios from us using our license until his comes through. Tough situation. Been there.
I still call BS on range loss on narrowbanding. None of our customers lost any range. OTOH, we have crazy mountainous terrain around here that isolates systems and reduces range naturally. It's hard to find 60 miles without a lump of rock in our way. Maybe the guys in the plains states with lots of flat have experienced otherwise. We haven't seen it around here except when someone's radios were misaligned ala no one ever checked the 12.5kc settings in the years leading up to the mandate.
I still call BS on range loss on narrowbanding. None of our customers lost any range. OTOH, we have crazy mountainous terrain around here that isolates systems and reduces range naturally. It's hard to find 60 miles without a lump of rock in our way. Maybe the guys in the plains states with lots of flat have experienced otherwise. We haven't seen it around here except when someone's radios were misaligned ala no one ever checked the 12.5kc settings in the years leading up to the mandate.
-
sabersco
- Posts: 32
- Joined: Sat Feb 18, 2012 10:17 am
- What radios do you own?: Saber III, HT1250, XTS5K, APX
Re: Wattage output versus tx range ?
Ive tried to find such info a long time ago for month ! for a repeater ...
You might want look at what we call an EGLI calculator for LOS propagation (vhf and uhf) :
there is plenny of online not 100% accurate but ....
one one good site is:
http://www.netcontrol.com/eng/services/ ... alculator/
do not forget cable and and connector attenuation !!!
hope it helps
scott
You might want look at what we call an EGLI calculator for LOS propagation (vhf and uhf) :
there is plenny of online not 100% accurate but ....
one one good site is:
http://www.netcontrol.com/eng/services/ ... alculator/
do not forget cable and and connector attenuation !!!
hope it helps
scott
Re: Wattage output versus tx range ?
I'd run away from this one. Far, far, away. If he even thinks he's going to lose range by narrowbanding, then no matter what you do he's going to lose range in his mind, and you'll never hear the end of it. Been dere, done dat...
Re: Wattage output versus tx range ?
There is also Radio Mobile available for free. It has a learning curve, but many people offer online and email help to get you going. It will demonstrate how insignificant 3db is in overall coverage. It will also remove some of the mysteries of system performance.sabersco wrote:Ive tried to find such info a long time ago for month ! for a repeater ...
You might want look at what we call an EGLI calculator for LOS propagation (vhf and uhf) :
there is plenny of online not 100% accurate but ....
one one good site is:
http://www.netcontrol.com/eng/services/ ... alculator/
do not forget cable and and connector attenuation !!!
hope it helps
scott
Re: Wattage output versus tx range ?
+1gtriever wrote:I'd run away from this one. Far, far, away. If he even thinks he's going to lose range by narrowbanding, then no matter what you do he's going to lose range in his mind, and you'll never hear the end of it. Been dere, done dat...
UHF 25W into 10db at 100ft working 30 mile radius to unspecified mobiles is already working far beyond the horizon. That's absolute gravy. Almost unbelievable. They have to be using the radios to the limits of receiver performance.
Re: Wattage output versus tx range ?
Hello:Bill G
Just some clarification and not upset so please don't take it that way.
WE haven't worked on his radios.
We don't knowingly work on unlicensed radios either.
He walks in asking and telling us what he wants.
I try to my best to obtain answers but cant.
You earlier stated that this topic had been beaten to death and it sure was whipped ill give ya that
Well I too read on this very topic and it has not been settled then nor has it now.
Reading the replies its still up for debate with no obvious winner yet to date.
I do see your point in some most likely just clicking the nb box and not doing a full tune alignment but many of the shops here do full tuning as I have personaly done it and watched other tech friends do it .
So yes - so so tx range versus great range depends on a well tuned rig.
And here ive heard loss and some also said no change but most said loss.
Im thinking once you had him walk into your shop and dealt with him youd want to eradicate him like the pest hes been here with the NOPE WONT DO YOU GOTTA GIVE ME THE 30 MILES OR NO DEAL !
And I just heard that one after I posted here the next day so you most likely know what the ending agreement was - Yep you got it NOPE NO DEAL
I believe I stated right off the bat yeah I know I know per the wb per nb issue and felt everyone had figured out that it would be handled when and if the customers concerns were settled and an agreement struck.
Im not one to waste my time and money on anyones radio needs till I know we have a working agreement.
I don't have anyway of knowing whether he will abandon his system or continue to operate it so it will be just a matter of time till he gets caught if he does by causing issues = He hasn't exactly been laying low with the other radio shops so he will hang himself eventualy .
So I made the decision above to let him walk .
I appreciate everyones views but the topic is just as tough to answer as it was a year ago even though we now have some experience with nb under our belts.
I just don't feel I can give him what hes asking for and the smart move is to back away and let him pursue his radio issues elsewhere.
Hes already driven over 50 miles to see me and im only one of at least ten shops of different brands so hes obviously had issues with the others or he wouldn't have contacted me.
Hes not even Motorola as we are hes Kenwood so I advised he to go to them which he said he had and they sold him the system .
I know the owner and his employees very well and well enough that they call the Motorola word the m word as cussin and it costs 25cents everytime I say so I just drop 5 dollars in the m can when I go back to the guys doin repairs
They have nothing good to say and they too walked because hes too demanding and unrealistic per there view.
Well I can tell you his attitude raises my blood pressure when dealing with him in my shop.
Nope im walking away and already have.
But like to continue on the discussion as id still be interested in anybodys views and thoughts.
Because we actualy did see roughly a 10 to 15 percent reduction in range by going from 25wb to 12.5nb on many systems.
And so did several of the other shops that I converse with.
And yes we here do enjoy flat terrain for miles and 30 miles at 25 wb when it was legal was quite commonly experienced on a day to day operation.
Its now dropped to 25 miles or so to be expected.
Most were happy a few wernt so you win some and lose some.
Satelite
Just some clarification and not upset so please don't take it that way.
WE haven't worked on his radios.
We don't knowingly work on unlicensed radios either.
He walks in asking and telling us what he wants.
I try to my best to obtain answers but cant.
You earlier stated that this topic had been beaten to death and it sure was whipped ill give ya that
Well I too read on this very topic and it has not been settled then nor has it now.
Reading the replies its still up for debate with no obvious winner yet to date.
I do see your point in some most likely just clicking the nb box and not doing a full tune alignment but many of the shops here do full tuning as I have personaly done it and watched other tech friends do it .
So yes - so so tx range versus great range depends on a well tuned rig.
And here ive heard loss and some also said no change but most said loss.
Im thinking once you had him walk into your shop and dealt with him youd want to eradicate him like the pest hes been here with the NOPE WONT DO YOU GOTTA GIVE ME THE 30 MILES OR NO DEAL !
And I just heard that one after I posted here the next day so you most likely know what the ending agreement was - Yep you got it NOPE NO DEAL
I believe I stated right off the bat yeah I know I know per the wb per nb issue and felt everyone had figured out that it would be handled when and if the customers concerns were settled and an agreement struck.
Im not one to waste my time and money on anyones radio needs till I know we have a working agreement.
I don't have anyway of knowing whether he will abandon his system or continue to operate it so it will be just a matter of time till he gets caught if he does by causing issues = He hasn't exactly been laying low with the other radio shops so he will hang himself eventualy .
So I made the decision above to let him walk .
I appreciate everyones views but the topic is just as tough to answer as it was a year ago even though we now have some experience with nb under our belts.
I just don't feel I can give him what hes asking for and the smart move is to back away and let him pursue his radio issues elsewhere.
Hes already driven over 50 miles to see me and im only one of at least ten shops of different brands so hes obviously had issues with the others or he wouldn't have contacted me.
Hes not even Motorola as we are hes Kenwood so I advised he to go to them which he said he had and they sold him the system .
I know the owner and his employees very well and well enough that they call the Motorola word the m word as cussin and it costs 25cents everytime I say so I just drop 5 dollars in the m can when I go back to the guys doin repairs
They have nothing good to say and they too walked because hes too demanding and unrealistic per there view.
Well I can tell you his attitude raises my blood pressure when dealing with him in my shop.
Nope im walking away and already have.
But like to continue on the discussion as id still be interested in anybodys views and thoughts.
Because we actualy did see roughly a 10 to 15 percent reduction in range by going from 25wb to 12.5nb on many systems.
And so did several of the other shops that I converse with.
And yes we here do enjoy flat terrain for miles and 30 miles at 25 wb when it was legal was quite commonly experienced on a day to day operation.
Its now dropped to 25 miles or so to be expected.
Most were happy a few wernt so you win some and lose some.
Satelite
Re: Wattage output versus tx range ?
I created a plot in a relatively flat part of the country - Wichita KS.
base = 25W with 10db gain dipole antenna pattern, -117db rcvr sense, at 100ft elevation with 2db total losses
mobile = 25W with 3db gain dipole, -117db rcvr sense, at 6ft elevation, and .5db loss.
Red shows the 25W coverage with green overlayed showing the 12.5W coverage (3db down). The customer has a 82% chance of success 30 miles out at 25W, and a 75% chance of success at 12.5W.
base = 25W with 10db gain dipole antenna pattern, -117db rcvr sense, at 100ft elevation with 2db total losses
mobile = 25W with 3db gain dipole, -117db rcvr sense, at 6ft elevation, and .5db loss.
Red shows the 25W coverage with green overlayed showing the 12.5W coverage (3db down). The customer has a 82% chance of success 30 miles out at 25W, and a 75% chance of success at 12.5W.
Re: Wattage output versus tx range ?
Hello Bill
I didn't spec the mobiles antennae in the beginning but I do know the one was an antenna specialist at 5db gain on the mobile he showed up in.
So if I read your graph and post right your showing a 7 percent loss which well ill admit is not 15 percent as worst loss we see.
Just for curiousity can you do a graph on a 25 watt mobile with the 5 db and then another with 50 watt db ?
He had kenwoods suposably at 25 watts but I wonder now if in fact they weren't 50 watters and that might explain why hes getting 50 miles tx.
We did not touch his equipment since no middle ground was being made so don't know what hes actualy got other than what he told us.
Ill ask the kenwood shop that sold them to him out of couriousity next week.
The systems I have seen getting the 30 miles were high powered and not 25 watts so HMMM ?????
I think your onto what id like to see for an answer as in comparison of narrow versus wide per a graph .
Itll be interesting to have to at least show customers what the out come should look like.
Also would you again include the percent of chances of 30 miles per nb and wb .
That was an excellent way of stating its chances of 30 miles.
The info you used is pretty much dead on for specs in your inputs as I see most.
If you would id like to see the town of Spencer Iowa as the center.
Hes actualy outside Algona Iowa 50 miles east of Spencer but im not interested in this for him any longer but here in my area.
I should mention the site im wondering about is 55 ft higher than spencer and its a harvester silo that id like to put up another system on and that it would be from that 55ft higher ground that the ant would be aprox 100 ft high with 120 ft 1/2 inch Andrew heliax at 50 watts and 10 db base Omni fiber glass.
Id like to see what difference it might show with that for specs.
Then I can show 25 kHz for the hams and 12.5 kHz for the uhf biz people.
Still not going to have anything to do with him but at least now its making some sense per the view anyway.
Thanx Satelite
I didn't spec the mobiles antennae in the beginning but I do know the one was an antenna specialist at 5db gain on the mobile he showed up in.
So if I read your graph and post right your showing a 7 percent loss which well ill admit is not 15 percent as worst loss we see.
Just for curiousity can you do a graph on a 25 watt mobile with the 5 db and then another with 50 watt db ?
He had kenwoods suposably at 25 watts but I wonder now if in fact they weren't 50 watters and that might explain why hes getting 50 miles tx.
We did not touch his equipment since no middle ground was being made so don't know what hes actualy got other than what he told us.
Ill ask the kenwood shop that sold them to him out of couriousity next week.
The systems I have seen getting the 30 miles were high powered and not 25 watts so HMMM ?????
I think your onto what id like to see for an answer as in comparison of narrow versus wide per a graph .
Itll be interesting to have to at least show customers what the out come should look like.
Also would you again include the percent of chances of 30 miles per nb and wb .
That was an excellent way of stating its chances of 30 miles.
The info you used is pretty much dead on for specs in your inputs as I see most.
If you would id like to see the town of Spencer Iowa as the center.
Hes actualy outside Algona Iowa 50 miles east of Spencer but im not interested in this for him any longer but here in my area.
I should mention the site im wondering about is 55 ft higher than spencer and its a harvester silo that id like to put up another system on and that it would be from that 55ft higher ground that the ant would be aprox 100 ft high with 120 ft 1/2 inch Andrew heliax at 50 watts and 10 db base Omni fiber glass.
Id like to see what difference it might show with that for specs.
Then I can show 25 kHz for the hams and 12.5 kHz for the uhf biz people.
Still not going to have anything to do with him but at least now its making some sense per the view anyway.
Thanx Satelite
Re: Wattage output versus tx range ?
As requested - Spenser IA.
base = 50W with 10db dipole at 100 feet, -117db rcvr sense, and 2db loss
mobile = 50W with 5db dipole at 6ft, -117db rcvr sense, and .5db loss
Red is 50W and green is 25W (3db down).
25W has 96% chance of success at 30 miles out, and 50W has 98% chance.
I should mention, as plotted, Algona has a 70% chance of using this site successfully.
base = 50W with 10db dipole at 100 feet, -117db rcvr sense, and 2db loss
mobile = 50W with 5db dipole at 6ft, -117db rcvr sense, and .5db loss
Red is 50W and green is 25W (3db down).
25W has 96% chance of success at 30 miles out, and 50W has 98% chance.
I should mention, as plotted, Algona has a 70% chance of using this site successfully.
Re: Wattage output versus tx range ?
Hello Bill_G
Ok your chart does show hes most likely getting the 30 miles and yes I agree your chart would show Algona iowa at a 70 percent chance per the 30 miles because Algona iowa is in a hole but hes outside Algona where the terrain levels out away from the hole so id probably say he is getting the 30 miles again and still gets into algonas hole since hes on the holes egde allowing him in for use.
Well at least your chart agrees with what I see around here for coverage.
I did look up the chart site you are using or at least I think its where you were but I didn't get to find it at the site.
Where is the webb site and how do I use it ?
Pretty cool site now that ive seen the results of the charts .
Thank You
Satelite
Ok your chart does show hes most likely getting the 30 miles and yes I agree your chart would show Algona iowa at a 70 percent chance per the 30 miles because Algona iowa is in a hole but hes outside Algona where the terrain levels out away from the hole so id probably say he is getting the 30 miles again and still gets into algonas hole since hes on the holes egde allowing him in for use.
Well at least your chart agrees with what I see around here for coverage.
I did look up the chart site you are using or at least I think its where you were but I didn't get to find it at the site.
Where is the webb site and how do I use it ?
Pretty cool site now that ive seen the results of the charts .
Thank You
Satelite
Re: Wattage output versus tx range ?
It's called Radio Mobile. Click on the Download link on the left side of the screen.
Re: Wattage output versus tx range ?
Here is how I prefer to plot a system. Same assumptions as above at 50W, but this time a bit more conservative prediction plotted in an easy to understand form. Red bad (<-117db, rx failure), green good (>-107db, DAQ3 or better), yellow somewhere in between (-117db to -107db, DAC2 to DAQ3). This is something I could build to, and guarantee. It's also easy to see areas of concern quickly. If, for example, the project was expected to cover Estherville, we would know right away that a single tower in Spencer wouldn't satisfy the requirement. There would also be coverage issues in Spirit Lake if the PD or FD were supposed to serve that area. Likewise, there are coverage issues towards the south and west within the primary footprint down in some water shed areas. You would know this going into a meeting with the customer, and you could demonstrate that raising the tower a few feet, or bumping the power to 100W wouldn't fix it - that something else needed to be done.
This plot also supports your grouchy customer's guesstimate that he got 30 mile radius coverage in that area. I'm envious.
This plot also supports your grouchy customer's guesstimate that he got 30 mile radius coverage in that area. I'm envious.
Re: Wattage output versus tx range ?
Herllo Bill_G
Im impressed because what you state about Estherville and spirit lake coverage from the chart you put up is EXACTLY what our customers see for coverage.
If they are entering or leaving esthervile ( Estherville is in a hole also) they have no coverage but but outside of town on egde good coverage.
Some other towns that are low in holes that exhibit this same issue is Lin Grove and Peterson Ia.
Now Spirit Lake Iowa does provide radio comms but you do hear the scratchy in the signal but usable just not fm clear bragging rights.
But on the other hand for whatever reason the coverage going north just blows 40 to 45 miles away = Its been talked and thought to death as to why but I think its terrain-the antenna propagation favors that direction as its mounted on the tower- and that that tower txs at 75 watts and also has a rf preamp installed with 7/8 inch hard line = But still just 120 ft high.
Ill run that one just for kicks and giggles and see what it shows for north per its specs.
Not sure he gets that 40 to 45 miles daily but he tells it like it does or at least a lot of the time it does.
When ever we repair his system he drives north to see if its back to normal as his test.
I just clench my teeth when he does that drive test as well hey 40 - 45 mile tx test is unheard of but he does it and presents the thumbs up after doing so as an approval.
Thank you for the site Bill_G
Satelite
Im impressed because what you state about Estherville and spirit lake coverage from the chart you put up is EXACTLY what our customers see for coverage.
If they are entering or leaving esthervile ( Estherville is in a hole also) they have no coverage but but outside of town on egde good coverage.
Some other towns that are low in holes that exhibit this same issue is Lin Grove and Peterson Ia.
Now Spirit Lake Iowa does provide radio comms but you do hear the scratchy in the signal but usable just not fm clear bragging rights.
But on the other hand for whatever reason the coverage going north just blows 40 to 45 miles away = Its been talked and thought to death as to why but I think its terrain-the antenna propagation favors that direction as its mounted on the tower- and that that tower txs at 75 watts and also has a rf preamp installed with 7/8 inch hard line = But still just 120 ft high.
Ill run that one just for kicks and giggles and see what it shows for north per its specs.
Not sure he gets that 40 to 45 miles daily but he tells it like it does or at least a lot of the time it does.
When ever we repair his system he drives north to see if its back to normal as his test.
I just clench my teeth when he does that drive test as well hey 40 - 45 mile tx test is unheard of but he does it and presents the thumbs up after doing so as an approval.
Thank you for the site Bill_G
Satelite
Re: Wattage output versus tx range ?
We lost range on all of our Fire Channels after narrowbanding. I would say we lost 3 - 9 miles in spots.Bill_G wrote:I still call BS on range loss on narrowbanding. None of our customers lost any range. OTOH, we have crazy mountainous terrain around here that isolates systems and reduces range naturally. It's hard to find 60 miles without a lump of rock in our way. Maybe the guys in the plains states with lots of flat have experienced otherwise. We haven't seen it around here except when someone's radios were misaligned ala no one ever checked the 12.5kc settings in the years leading up to the mandate.
Schrodinger's Radio: It is simultaneously too loud and too quiet, but you will never know which until someone transmits.
Re: Wattage output versus tx range ?
Backing up Bill_G here; where I have USED infrastructure that he has worked on in the crazy mountains we have here in Oregon, I agree with him that a properly set up radio system should have no difference in range after going narrowband, but I think what happens is some of the radios that do both 25 and 12.5 have a middle of the road receiver that for the lack of a better description, aren't as hot when it comes to a 12.5 signal.
Mountain Wave Search & Rescue http://www.mwave.org
Support Search & Rescue: Get Lost!
Support Search & Rescue: Get Lost!
-
AL7OC
- Posts: 179
- Joined: Fri May 21, 2010 1:13 am
- What radios do you own?: Motorola, Icom, Thales, Tekk
Re: Wattage output versus tx range ?
Old school thoughts - you need 6db power increase to achieve a 3db signal increase at the receiver. Usually you need at least 6db (4x) power increase to get a noticeable change in received signal quality. Square law... A 3db increase in TX output power, plus a 3 DB gain antenna, plus cleaning up transmission line loss will start to make a difference.
Decreasing modulation index (deviation/max mod frequency) below 1 degrades an FM signal's noise immunity. 12.5 kHz NBFM with 2.5k max mod frequency gives an index of about 1. Not great FM performance. The whole point of using FM is to take advantage of a degree of noise immunity. If you keep decreasing deviation with the same audio bandwidth, FM system performance will degrade.
Decreasing modulation index (deviation/max mod frequency) below 1 degrades an FM signal's noise immunity. 12.5 kHz NBFM with 2.5k max mod frequency gives an index of about 1. Not great FM performance. The whole point of using FM is to take advantage of a degree of noise immunity. If you keep decreasing deviation with the same audio bandwidth, FM system performance will degrade.
Pierre
AL7OC
AL7OC
Re: Wattage output versus tx range ?
Shoot me lat/long, band, base/repeater (simplex/duplex), tx pwr, rcvr sense (or model of base/rptr), ant height, ant gain (or ant model), line type if known, mobile or portable specs, mobile ant gain, and anything else that might be useful to know, and I'll put up a plot of your system.tuckerm wrote:We lost range on all of our Fire Channels after narrowbanding. I would say we lost 3 - 9 miles in spots.Bill_G wrote:I still call BS on range loss on narrowbanding. None of our customers lost any range. OTOH, we have crazy mountainous terrain around here that isolates systems and reduces range naturally. It's hard to find 60 miles without a lump of rock in our way. Maybe the guys in the plains states with lots of flat have experienced otherwise. We haven't seen it around here except when someone's radios were misaligned ala no one ever checked the 12.5kc settings in the years leading up to the mandate.
Re: Wattage output versus tx range ?
Yeah. There is definitely a difference in model performance. Hood River Co loves their VHF CDM mobiles over their XTL's.KE7JFF wrote:Backing up Bill_G here; where I have USED infrastructure that he has worked on in the crazy mountains we have here in Oregon, I agree with him that a properly set up radio system should have no difference in range after going narrowband, but I think what happens is some of the radios that do both 25 and 12.5 have a middle of the road receiver that for the lack of a better description, aren't as hot when it comes to a 12.5 signal.
Re: Wattage output versus tx range ?
Do the Hood River XTL's have their pre-amps enabled?
XTL's all have a built in 4dB ( Ithink) pre-amp but not all flashcodes have the pre-amp option available.
Once I changed my XTL flashcode and enabled the pre-amp, its RX performance was more or less equal to my CDM and MCS2000 - maybe the MCS2000 just has the edge but there was very little difference.
Without the XTL pre-amp enabled, I was very disappointed with my XTL RX sensitivity!!!
Its like the CDM and MCS both have their "pre-amps" automatically enabled whereas on the XTL the pre-amp is switchable as long as you have the correct flashcode otherwise you have a slightly deaf RX.
I think all XTL versions should have the option to enable the pre-amp - it should NOT be dependant on the flashcode!!
XTL's all have a built in 4dB ( Ithink) pre-amp but not all flashcodes have the pre-amp option available.
Once I changed my XTL flashcode and enabled the pre-amp, its RX performance was more or less equal to my CDM and MCS2000 - maybe the MCS2000 just has the edge but there was very little difference.
Without the XTL pre-amp enabled, I was very disappointed with my XTL RX sensitivity!!!
Its like the CDM and MCS both have their "pre-amps" automatically enabled whereas on the XTL the pre-amp is switchable as long as you have the correct flashcode otherwise you have a slightly deaf RX.
I think all XTL versions should have the option to enable the pre-amp - it should NOT be dependant on the flashcode!!
Re: Wattage output versus tx range ?
Good to know. Thanks! I'll pass it on to the guys that maintain their mobiles.g8tzl2004 wrote:Do the Hood River XTL's have their pre-amps enabled?
XTL's all have a built in 4dB ( Ithink) pre-amp but not all flashcodes have the pre-amp option available.
Once I changed my XTL flashcode and enabled the pre-amp, its RX performance was more or less equal to my CDM and MCS2000 - maybe the MCS2000 just has the edge but there was very little difference.
Without the XTL pre-amp enabled, I was very disappointed with my XTL RX sensitivity!!!
Its like the CDM and MCS both have their "pre-amps" automatically enabled whereas on the XTL the pre-amp is switchable as long as you have the correct flashcode otherwise you have a slightly deaf RX.
I think all XTL versions should have the option to enable the pre-amp - it should NOT be dependant on the flashcode!!
Re: Wattage output versus tx range ?
I keep reading about 12.5KHz narrowband having "less range".
Sometimes I think this is just because the squelch setting has NOT been adjusted when the radios are reprogrammed to 12.5KHz spacing?
In service mode there are separate squelch settings for 25 and 12.5KHz spacing - so maybe the spacing gets changed to 12.5KHz but the 12.5KHz squelch setting just gets left at the "high" factory default level?
A 12.5KHz signal will surely travel as far as a 25KHz signal and will open a correctly adjusted squelch if it is set low enough?
I always set my squelch level manually - I lower it ( just using the laptop up/down keys to adjust actual SQ number settings - its very easy) until the squelch fully opens on no signal and then slowly increase the SQ until it just closes. I then TX a low level signal on the SQ test freq and see if the SQ will close again when I drop carrier (this is due to hysteresis whereby the SQ opens at a lower level than it closes). When the SQ always closes when the signal disappears, I know I am at the absolute SQ threshold. I usually then increase the SQ by 2 or 3 units so that the SQ is only opening on a very low but actually just readable signal. If you leave the SQ setting at the threshold, it will open on unreadable signals - good for working DX!!!!
My real world experience is that a receiver set to 12.5KHz spacing usually hears better than a 25KHz receiver (2-3dB better) due to the better signal to noise. So in theory you should get better range with narrowband. I think the issue is whether the lower deviation makes it harder to copy really weak in the noise signals. When I am working FM DX, you automatically talk it up so that the other station can hear better - so maybe this is the downside of narrow band...BUT when normal users are complaining about less range with narrowband, do they say "my squelch is opening but I can't make out what is being said" or do they say that they "receive absolutely nothing"?
Any hams with an FT817 or similar radio should try toggling between narrow spacing (6KHz filter for 12.5KHz spacing) and wide spacing (15KHz filter for 25Khz spacing) when listening to a very weak in the noise FM signal. You will hear a very noticeable improvement in the signal when you switch to narrow spacing!!!
Sometimes I think this is just because the squelch setting has NOT been adjusted when the radios are reprogrammed to 12.5KHz spacing?
In service mode there are separate squelch settings for 25 and 12.5KHz spacing - so maybe the spacing gets changed to 12.5KHz but the 12.5KHz squelch setting just gets left at the "high" factory default level?
A 12.5KHz signal will surely travel as far as a 25KHz signal and will open a correctly adjusted squelch if it is set low enough?
I always set my squelch level manually - I lower it ( just using the laptop up/down keys to adjust actual SQ number settings - its very easy) until the squelch fully opens on no signal and then slowly increase the SQ until it just closes. I then TX a low level signal on the SQ test freq and see if the SQ will close again when I drop carrier (this is due to hysteresis whereby the SQ opens at a lower level than it closes). When the SQ always closes when the signal disappears, I know I am at the absolute SQ threshold. I usually then increase the SQ by 2 or 3 units so that the SQ is only opening on a very low but actually just readable signal. If you leave the SQ setting at the threshold, it will open on unreadable signals - good for working DX!!!!
My real world experience is that a receiver set to 12.5KHz spacing usually hears better than a 25KHz receiver (2-3dB better) due to the better signal to noise. So in theory you should get better range with narrowband. I think the issue is whether the lower deviation makes it harder to copy really weak in the noise signals. When I am working FM DX, you automatically talk it up so that the other station can hear better - so maybe this is the downside of narrow band...BUT when normal users are complaining about less range with narrowband, do they say "my squelch is opening but I can't make out what is being said" or do they say that they "receive absolutely nothing"?
Any hams with an FT817 or similar radio should try toggling between narrow spacing (6KHz filter for 12.5KHz spacing) and wide spacing (15KHz filter for 25Khz spacing) when listening to a very weak in the noise FM signal. You will hear a very noticeable improvement in the signal when you switch to narrow spacing!!!
Re: Wattage output versus tx range ?
Hello Bill_G
I looked at the site you provided for doing the propagations and im more than confused on how to use it ect.
Anyway I was wondering if youd do another chart on the very same info I gave above post for spencer iowa and use all the same specs with the exception take the base from 50 watts to 100 watts and do it in the green with splattered red chart as you posted as the first option.
I have always heard youd gain aprox 15 percent more range by doubling the output of a system and curious what your chart has to say on that.
Obviously that's if terrain didn't stop you I know but I think the terrain at spencer might show the increase without land stopping it for this situation.
So Spencer Iowa with the hill its at being 50 ft higher than spencer itself on a metal silo 100 ft high using 120 ft 1/2 inch heliax hard line at 100 watts tx output into a 10db gain fiberglass Omni base antennae .
Still 50 watt mobiles with 5db gain antenaes.
But im wondering what would the base cover at 100 watts not so much if a 50 w mobile can get to it just whats the increase of range from the above 50 watt base to a 100 watt base.
Granted I understand the 50w mobile may not get back to a 100 watt base ect.
I always called that an alligator station - BIG MOUTH NO EARS .
And that's not what im suggesting only want to see chart as a comparison of doubled wattage output versus range increase.
Thank You
Satelite
I looked at the site you provided for doing the propagations and im more than confused on how to use it ect.
Anyway I was wondering if youd do another chart on the very same info I gave above post for spencer iowa and use all the same specs with the exception take the base from 50 watts to 100 watts and do it in the green with splattered red chart as you posted as the first option.
I have always heard youd gain aprox 15 percent more range by doubling the output of a system and curious what your chart has to say on that.
Obviously that's if terrain didn't stop you I know but I think the terrain at spencer might show the increase without land stopping it for this situation.
So Spencer Iowa with the hill its at being 50 ft higher than spencer itself on a metal silo 100 ft high using 120 ft 1/2 inch heliax hard line at 100 watts tx output into a 10db gain fiberglass Omni base antennae .
Still 50 watt mobiles with 5db gain antenaes.
But im wondering what would the base cover at 100 watts not so much if a 50 w mobile can get to it just whats the increase of range from the above 50 watt base to a 100 watt base.
Granted I understand the 50w mobile may not get back to a 100 watt base ect.
I always called that an alligator station - BIG MOUTH NO EARS .
And that's not what im suggesting only want to see chart as a comparison of doubled wattage output versus range increase.
Thank You
Satelite
Re: Wattage output versus tx range ?
Here you go. Plotted the same as above so you can see the difference - not much. Green is the absolute limit of the 50W which follows all the way out to where the yellow ends above, and the yellow in this picture is what an additional 50W gets you.
Re: Wattage output versus tx range ?
Interesting plot - does this confirm my posting from 6 months ago - "Whats the point of buying a 110W radio"!! hi hi
Re: Wattage output versus tx range ?
Maybe.g8tzl2004 wrote:Interesting plot - does this confirm my posting from 6 months ago - "Whats the point of buying a 110W radio"!! hi hi
But, it's also an argument for/against going to 10W from 5, or changing antenna gain, or anyplace you need to see the 3db difference. This is generally how it shows up - a whisper thin speckle around the edges. They might be important speckles. That's why you have to look at it. 3db is not Christmas. It's more like a pack of mints - nice to have, but if you lost it, you might not notice.
Re: Wattage output versus tx range ?
Bill - any views on my above post about SQ levels and that a 12.5 KHz narrowband signal will always travel as far as a 25KHz signal and the "less range" issue is maybe due to the 12.5KHz spaced channel having a higher SQ level. Are users who report less range saying "the narrowband signal is opening the SQ but I can't make out what is being said"...or do they report that they "hear nothing"?
Re: Wattage output versus tx range ?
Hello:
Well the second chart at 100 watts as you said - Doesn't show much gain .
I was hoping the extra 50 watts at the 100 watt output would have filled in the voids in the pattern in around Estherville up through Jackson as an example which would have been a plus but its harder for me to see on your red chart but still looks like no gain at all in helping tx into the area.
I was hoping on the uhf signal doing the bounce around and into the void areas I hear some speak of.
But doesn't look like it from chart.
Still looking like no gain in fill in on the 50 watt void areas though.
Looks like 50 watts would be the best option to me.
Satelite
Well the second chart at 100 watts as you said - Doesn't show much gain .
I was hoping the extra 50 watts at the 100 watt output would have filled in the voids in the pattern in around Estherville up through Jackson as an example which would have been a plus but its harder for me to see on your red chart but still looks like no gain at all in helping tx into the area.
I was hoping on the uhf signal doing the bounce around and into the void areas I hear some speak of.
But doesn't look like it from chart.
Still looking like no gain in fill in on the 50 watt void areas though.
Looks like 50 watts would be the best option to me.
Satelite
Re: Wattage output versus tx range ?
Yep. That's what I said earlier - if your coverage were a perfect circle, adding 3db would be a pencil width. But! adding 3db does increase the quieting in your primary service area. It does help penetrate buildings. It does make what you already have *better* because fade / multipath / picket fencing / et al are constantly changing as you move around. You get and give 3db all the time. Given a choice of 50W or 100W, I'd go with 100W every time mostly because the equipment is hardier, and partly because I would get some long term benefit.
Re: Wattage output versus tx range ?
Hello Bill_G
So if the above coverage at 100 watts was done.
How much improvement would be seen by changing the 1/2 inch hardline out to say 1 inch hard line ?
Lentgh aprox 120 ft.
Itll help on tx wattage loss some im sure but id suspect not much in way of transmit range of the base but what would it do for a 50 watt mobile with a 5db gain antennae ?
With less rx signal loss should help but how much ?
Portables would even see some exta range id think since better rx hearing ?
Satelite
So if the above coverage at 100 watts was done.
How much improvement would be seen by changing the 1/2 inch hardline out to say 1 inch hard line ?
Lentgh aprox 120 ft.
Itll help on tx wattage loss some im sure but id suspect not much in way of transmit range of the base but what would it do for a 50 watt mobile with a 5db gain antennae ?
With less rx signal loss should help but how much ?
Portables would even see some exta range id think since better rx hearing ?
Satelite
Re: Wattage output versus tx range ?
Come on now. You're a tech. Go find the cable specs on the interwebs. Do the math. No lazy peoples allowed. Mkay?Satelite wrote:Hello Bill_G
So if the above coverage at 100 watts was done.
How much improvement would be seen by changing the 1/2 inch hardline out to say 1 inch hard line ?
Lentgh aprox 120 ft.
Itll help on tx wattage loss some im sure but id suspect not much in way of transmit range of the base but what would it do for a 50 watt mobile with a 5db gain antennae ?
With less rx signal loss should help but how much ?
Portables would even see some exta range id think since better rx hearing ?
Satelite
I used 2.5db total losses into a 10db gain ant yielding system gain +7.5db. I doubt you'll gain more than a couple db by using bigger cable, but you'll lose some dropping to 50W and dropping antenna gain. You already how insignificant 3db is as demonstrated above. You might march the line back a few speckles here and there, but the overall plot will remain about the same. When you want big changes to coverage, you have to put in big changes to the system, and you have to think in terms of 10. Height is your friend.
Re: Wattage output versus tx range ?
Hello Bill_G
True im a tech just not as good at the charting ect.
And yes I wasn't thinking youd gain a lot by the larger cable and ill admit it I did look at the loss per the 1/2 and 1 inch hard lines.
But I did think you would have gained a mile or so just due to the bigger cables less losses ect.
But your saying it wouldn't change much at all which did surprise me.
With the short distance I was referring to I didn't see a lot of gain but still thought might see some noticeable gain.
But you did confirm my suspicion that not much but wasn't thinking basicly none.
And ill add that I too looked into a rf pramp added in the rxcr and mobile wise not much gain - but with a 4 watt hand held it did help well enough that it cleared the portable up but the tx was maybe I said maybe an extra two miles in when talking to a base.
Satelite
True im a tech just not as good at the charting ect.
And yes I wasn't thinking youd gain a lot by the larger cable and ill admit it I did look at the loss per the 1/2 and 1 inch hard lines.
But I did think you would have gained a mile or so just due to the bigger cables less losses ect.
But your saying it wouldn't change much at all which did surprise me.
With the short distance I was referring to I didn't see a lot of gain but still thought might see some noticeable gain.
But you did confirm my suspicion that not much but wasn't thinking basicly none.
And ill add that I too looked into a rf pramp added in the rxcr and mobile wise not much gain - but with a 4 watt hand held it did help well enough that it cleared the portable up but the tx was maybe I said maybe an extra two miles in when talking to a base.
Satelite
Re: Wattage output versus tx range ?
See the second map of Spencer? That shows a 10db differential. The third map shows a 3db differential. Notice the difference in the yellow areas. 3db is almost nothing in radio world. It increases your quieting in a given area. It does not add miles. Even if it did add one mile this instant, that will change in a minute, an hour, or on any day when you have an inversion, or don't have one, or when a big truck parks next to a steel shed, or when the big truck moves. 3db comes and goes in the snap of your fingers. And if you are depending on that 3db to get you that last mile, heaven help you because it's not always there.
All you have to do to prove it to yourself is sit in some location with a spectrum analyser for a few hours monitoring a trunking control channel with the min and max traces turned on. Even with line of sight, you will see at least a 3db difference. Park someplace where you don't have line of sight, depending on the obstructions and the multipath possibilities, you will see huge changes over time. Depending on the terrain, you may experience dawn and dusk events that wipe out your link to a site for brief periods. The whole concept of diversity antennas, and MIMO was born out of this reality.
Watch a voting system sometime as a mobile calls in. You can have a half dozen receivers unsquelched, and the voted rcvr is switching from moment to moment. Fascinating to watch actually, especially if you have a rough idea where he's calling in from. You'll say to yourself "I didn't think you could hit that site from there", and you can't *reliably*, but it does occasionally, and clearly enough to be voted a few times during a call. After a while, you'll become familiar with a systems voter statistics, and get a feel what what is normal, and what isn't, and know when a receiver might be having a problem before the customer experiences any problems.
Range is something you can state probabilities about. You can even publish reasonably accurate percentages of time you'll have success communicating in specific areas. You can even use them to help you design a system that will deliver that one extra mile your customer covets, and put that mile into 99% if they so desire. But, a simple materials change from one coax to another, or changing the antenna, at a single site, is generally not how it's going to happen.
All you have to do to prove it to yourself is sit in some location with a spectrum analyser for a few hours monitoring a trunking control channel with the min and max traces turned on. Even with line of sight, you will see at least a 3db difference. Park someplace where you don't have line of sight, depending on the obstructions and the multipath possibilities, you will see huge changes over time. Depending on the terrain, you may experience dawn and dusk events that wipe out your link to a site for brief periods. The whole concept of diversity antennas, and MIMO was born out of this reality.
Watch a voting system sometime as a mobile calls in. You can have a half dozen receivers unsquelched, and the voted rcvr is switching from moment to moment. Fascinating to watch actually, especially if you have a rough idea where he's calling in from. You'll say to yourself "I didn't think you could hit that site from there", and you can't *reliably*, but it does occasionally, and clearly enough to be voted a few times during a call. After a while, you'll become familiar with a systems voter statistics, and get a feel what what is normal, and what isn't, and know when a receiver might be having a problem before the customer experiences any problems.
Range is something you can state probabilities about. You can even publish reasonably accurate percentages of time you'll have success communicating in specific areas. You can even use them to help you design a system that will deliver that one extra mile your customer covets, and put that mile into 99% if they so desire. But, a simple materials change from one coax to another, or changing the antenna, at a single site, is generally not how it's going to happen.