scanners. thoughts, comments and ideas...
- Thread starter Bbasso
- Start date
1911
Expedition Leader
Depends on what you consider to be "shtf". In the event of a natural disaster like a hurricane (or anything else that disrupts the normal functioning of the electric grid), most of the regular emergency services radios will be down because the transmitters depend on grid electric power. When that happens, the usual recourse is battery-operated ham radios, so you would be better off with a multi-band ham radio.
I've got an old Bearcat BCT7 I bought for my SAR vehicle several years ago. It's one of the few that scan CB, and I thought that would be good for SAR. Anyway, during a recent storm I found that our cheap 'emergency radios' wouldn't pick up NOAA weather, but the scanner does. Then when we dumped AT&T Uverse, and they didn't want the little 12V UPS back, I decided to adapt the UPS to power the scanner. Turns out it uses the same plug connector, so all I had to do was plug the scanner into the UPS. Voila', a decent little scanner with enough battery backup to last for days.
4RunAmok
Explorer
Many cities run their systems with redundant power backups.. So they'll be working for a little while after a grid loss..
The problem with old scanners like that is they just don't work on todays systems. Many are 800mhz digital systems. Scanners that work on these are in the $400-$500 price range and will usually have digital in their name or description..
sixbennetts
Adventurer
Agreed, many municipalities these days, even some smaller ones, are trunked. A lot of the older scanners don't trunk-track, so you gotta buy new to keep up with them.
I know this won't help when the merd hits the ventilateur, but I use an Android smartphone. I also have a bluetooth stereo in my truck. By pairing my smartphone with my stereo, and using one of the scanner apps, I can stream my local fire/ems, etc., through my truck speakers.
I use this one:
https://play.google.com/store/apps/...?t=W251bGwsMSwxLDEsImNvbS5zY2FubmVycmFkaW8iXQ..
Again, a delicate system and not to be relied on in an emergency, but what it IS handy for, (besides the obvious), is getting good info from a certain area when trouble hits. Been listening to NYC and NJ freqs a lot over the last week or two.
I know this won't help when the merd hits the ventilateur, but I use an Android smartphone. I also have a bluetooth stereo in my truck. By pairing my smartphone with my stereo, and using one of the scanner apps, I can stream my local fire/ems, etc., through my truck speakers.
I use this one:
https://play.google.com/store/apps/...?t=W251bGwsMSwxLDEsImNvbS5zY2FubmVycmFkaW8iXQ..
Again, a delicate system and not to be relied on in an emergency, but what it IS handy for, (besides the obvious), is getting good info from a certain area when trouble hits. Been listening to NYC and NJ freqs a lot over the last week or two.
DaveInDenver
Middle Income Semi-Redneck
Assuming they are even still analog, a lot have already gone digital and encrypted to boot.
Since becoming a volunteer fire fighter last year I have had a pager that get all the dispatch traffic. I am signed off to have and use a radio, but need to buy my own. Most guys in my department buy radios like the Motorola 1250.
Channel banks can be cloned from other radios. So, when we work with USFS, we plug in and clone, and then use that bank. We only have Sheriff's department here, no local cops, but most guys have all their channels programed.
If our power goes down, we have about 5 days back up power but some of the repeaters will shut down after a few hours, so our range will be limited.
For home, I would like to be able to communicate 2 ways with HAM, Aircraft, CB, FRS, and EMS. I need to research what various radios will do. Can HAM radios tune in stuff like 122.95 on VHF? I keep an old hand help aircraft radio on at my hangar to hear who comming in. My wife would like to be able to hear the same traffic at home too, especially when we are out working the crop with our helicopter.
D.
Channel banks can be cloned from other radios. So, when we work with USFS, we plug in and clone, and then use that bank. We only have Sheriff's department here, no local cops, but most guys have all their channels programed.
If our power goes down, we have about 5 days back up power but some of the repeaters will shut down after a few hours, so our range will be limited.
For home, I would like to be able to communicate 2 ways with HAM, Aircraft, CB, FRS, and EMS. I need to research what various radios will do. Can HAM radios tune in stuff like 122.95 on VHF? I keep an old hand help aircraft radio on at my hangar to hear who comming in. My wife would like to be able to hear the same traffic at home too, especially when we are out working the crop with our helicopter.
D.
HenryJ
Expedition Leader
The difference will not be perceptible. Tests performed put the average loss at 6%. Most electronics today have some form of audio compensation to level the audio output making this tiny difference zero.
I have run into a few cases where audio levels were significantly lower, however this was not related to the change in bandwidth. It was either a audio output correction that was required on a new repeater or, improper programming of a radio.
All your old receivers will work just fine.
BTW, analog radios and digital radios can both operate narrowband. You do not have to have a digital radio.
The fire chiefs association in Oregon has recommended not using digital radios on a fire scene. We had two fire fighters killed when they were not heard sending a MayDay. They tried numerous times and were not heard due to the digital radio they were using.
Why? In a digital radio the processor receives the modulation (voice) it converts it and sends it in a very small packet to the receiving radio where the processor translates it and produces the audio that you hear. The processor decides what is sound and what is background.
In an analog radio the modulation is received and transmitted as waves. Everything is sent to the receiver and your brain decides what it hears.
Digital radios can be very crisp and clear, however they may filter out the sounds of sirens, RF from the fire, calls for help, etc. For that reason they will not be used in the fire service. I think the technology is still evolving. Some day it may get there. Not today. It still needs work before we put our lives at risk.
Sorry for the novel, back to your regularly scheduled thread....
Well, you may be able to recieve all the services you want, but not only do I know of any radio that will do all of that (especially CB and air band, which is AM iirc), it would also be illegal. Each radio needs to be type approved for the service it is intended for. Could you buy a unlocked Wouxon/Baofeng and do 2m/70, FRS, and your VHF public service? Yes you can, in fact, I believe the new Wouxuns are part 90 certified for public safety. You could possibly mod a mobile HF ham radio to do CB but that would be illegal if you got caught using, not like they enforce any rules anymore anyway, though. But afaik, air band will need it's own dedicated radio if you intend to be able to transmit and recieve.
DaveInDenver
Middle Income Semi-Redneck
What Henry's talking about:
http://www.fireengineering.com/arti...igibility-of-digital-radio-transmissions.html
There's no fundamental reason that digital can never be used by a fire department. That said, vocoders can be confused by background noise and so I can understand how voice synthesis problems would be legitimate and need to be addressed. Analog radios will distort with the distortion becoming increasingly difficult to understand as the audio level increases. Analog is much more tolerant of this in comparison to digital systems, just the nature of sampling. Add to that RFI from pumps and engines causing packet drops, I could see digital radios being problematic. I don't see technically why they should not be solvable, though.
http://www.iafc.org/files/digProb_PortableRadioBestPractices.pdf
http://www.motorola.com/web/Busines...ments/Static Files/FRI_Paper_RO-99-2169_3.pdf
Narrow banding won't affect digital voice levels, the end user wouldn't know if a channel is 25KHz wide, 12.5KHz or even 6.25KHz. For example, Phase 1 P25 consumes 6.25KHz of bandwidth, for equivalent efficiency and potential future compliance. When (well if, they have not hinted they will require it yet) the FCC decides to impose 6.25KHz spacing it's almost certainly going to force digital. It's technically possible to fit an analog voice channel in 6.25KHz spacing, but it won't allow much room for error nor fidelity. My personal opinion is that digital voice is probably not worth the problems, making things more complex than they need. But the departments all want encryption, so digital has an allure to it.
That you mention the switch has yielded a 6% decrease in audio level makes it pretty clear that the 25KHz channel bandwidth was quite inefficient. It really is a throw back to when channel adjacency had to be large because of the limitation of the radios themselves. Radios now are orders better staying on frequency and within bandwidth. So I think 12.5KHz is probably the best compromise if analog is still in demand. A 6.25KHz analog channel will be pretty compressed and unnatural.
http://www.fireengineering.com/arti...igibility-of-digital-radio-transmissions.html
There's no fundamental reason that digital can never be used by a fire department. That said, vocoders can be confused by background noise and so I can understand how voice synthesis problems would be legitimate and need to be addressed. Analog radios will distort with the distortion becoming increasingly difficult to understand as the audio level increases. Analog is much more tolerant of this in comparison to digital systems, just the nature of sampling. Add to that RFI from pumps and engines causing packet drops, I could see digital radios being problematic. I don't see technically why they should not be solvable, though.
http://www.iafc.org/files/digProb_PortableRadioBestPractices.pdf
http://www.motorola.com/web/Busines...ments/Static Files/FRI_Paper_RO-99-2169_3.pdf
Narrow banding won't affect digital voice levels, the end user wouldn't know if a channel is 25KHz wide, 12.5KHz or even 6.25KHz. For example, Phase 1 P25 consumes 6.25KHz of bandwidth, for equivalent efficiency and potential future compliance. When (well if, they have not hinted they will require it yet) the FCC decides to impose 6.25KHz spacing it's almost certainly going to force digital. It's technically possible to fit an analog voice channel in 6.25KHz spacing, but it won't allow much room for error nor fidelity. My personal opinion is that digital voice is probably not worth the problems, making things more complex than they need. But the departments all want encryption, so digital has an allure to it.
That you mention the switch has yielded a 6% decrease in audio level makes it pretty clear that the 25KHz channel bandwidth was quite inefficient. It really is a throw back to when channel adjacency had to be large because of the limitation of the radios themselves. Radios now are orders better staying on frequency and within bandwidth. So I think 12.5KHz is probably the best compromise if analog is still in demand. A 6.25KHz analog channel will be pretty compressed and unnatural.
Good morning,
I thought I read, somewhere, that using the phone to receive scanner info is against the law in some states ... even though the phone is not a scanner ....
I will try to locate the info ...
Best regards,
Mike