Only 6 steps for a non-repeater channel per the 1st link. If only used for listening that all that is needed. That's not too bad and some of thm we could key in before they leave. Then there is hoping that it won't lose the channels when the battery runs dry or is swapped, like bicycle "computers" often do.
-- Regards, Joerg http://www.analogconsultants.com/
The unit should be able to transmit at a legal level. Isn't it pretty common to have output power level control?
You haven't researched it. You are *assuming* all methods work the same. They go through entirely different bureaucracies. You have made up your mind. I won't bother you with this any further.
If you can make that first link to another person located in civilization, they can always contact rescue services. The trick is making that first link and getting your location info to them.
-- Rick C Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998
Sometimes. IIRC the early ones always transmitted at 5W.
[...]
That, and getting feedback that the message actually went through to a competent person and not just to a computer. Yesterday I have again experienced a prime example of the latter and how that can go wrong, with absolutely zero feedback that it did. Non-emergency but still aggravating.
-- Regards, Joerg http://www.analogconsultants.com/
Yeah, I think we won't bother and just use it. Mainly because scanners cost 3x or more and do not offer that much in other useful functionality for this case. Faster scanning speed, yes, but that isn't important as they'll never need to monitor more than one or two channels.
So now I'll have to re-digest the whole thread and find out which of the
4-5 models would be suited best. Maybe the one with the built-in flashlight. One thing I'll have to find out whether their Li-Ion is some sort of standard battery like their NiMH radios have.-- Regards, Joerg http://www.analogconsultants.com/
Den tirsdag den 19. december 2017 kl. 01.58.36 UTC+1 skrev John Larkin:
this doesn't answer yuor question?
" The RTL-SDR can be used as a wide band radio scanner. Applications include: Listening to unencrypted Police/Ambulance/Fire/EMS conversations. Listening to aircraft traffic control conversations. Tracking aircraft positions like a radar with ADSB decoding. Decoding aircraft ACARS short messages. Scanning trunking radio conversations. Decoding unencrypted digital voice transmissions. Tracking maritime boat positions like a radar with AIS decoding. Decoding POCSAG/FLEX pager traffic. Scanning for cordless phones and baby monitors. Tracking and receiving meteorological agency launched weather balloon data. Tracking your own self launched high altitude balloon for payload recovery. Receiving wireless temperature sensors and wireless power meter sensors. Listening to VHF amateur radio. Decoding ham radio APRS packets. Watching analogue broadcast TV. Sniffing GSM signals. Using rtl-sdr on your Android device as a portable radio scanner. Receiving GPS signals and decoding them. Using rtl-sdr as a spectrum analyzer. Receiving NOAA weather satellite images. Listening to satellites and the ISS. Radio astronomy. Monitoring meteor scatter. Listening to FM radio, and decoding RDS information. Listening to DAB broadcast radio. Use rtl-sdr as a panadapter for your traditional hardware radio. Decoding taxi mobile data terminal signals. Use rtl-sdr as a high quality entropy source for random number generation. Use rtl-sdr as a noise figure indicator. Reverse engineering unknown protocols. Triangulating the source of a signal. Searching for RF noise sources. Characterizing RF filters and measuring antenna SWR. "
Not a problem. Most radios since about 1980 use NVRAM (also known as a "code plug" in Motorola circles). A few use static RAM and a coin cell to storage, but those are usually larger boxes that have more room inside.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
It has a low power setting but at least here that does not make it legal on FRS. For that, it has to be fixed to FRS channels only and low power only. Models with different firmware are sold for that.
The range is not much dependent on the power. On half a watt you can talk to the space station. Obstructions are the main limit.
Yes, it does have a LOCK function: press and hold MENU and VM/CHAN. I did not even know that... just googled it.
It is a special pack, but spares are available from the same Chinese (Aliexpress) suppliers that sell the radio. They are LiIon so not as short-lived as NiCd or NiMH that was popular with older radios and cameras.
Yes. And we have repeaters with wide area coverage that are plagued with abusers. They are difficult to locate and impossible to terminate. (hand guns are illegal here)
The authorities really like to boast about the advanced radio direction finding equipment they have and how it is impossible to transmit anywere without being located, but reality is somewhat different.
In that case the B5 is better. I prefer a rotary encoder any day versus a key pad.
I am only subscribed to EBay but I guess they'll have those as well since you can get the radios on EBay. The Li-Ion pack in my bicycle MP3 player is already becoming tired after only about 100 cycles.
I found NiMH to not be so short-lived. I've got some that are at least
10 years old, have been cycled a lot and still work. However, per Watt-hour they weigh almost 2x of a Li-Ion battery.
Sometimes Bruno the Rottweiler will suffice to scare them off :-)
Especially in hilly terrain like ours. You think a signal comes from the south but in reality it comes from the west. It's just that the reflecting mountain side is south.
Recording is more for court, to prove beyond a reasonable doubt that it was his voice. Many law enforcement folks will confirm that it is easy to find and arrest a suspect. To get him convicted is not easy at all.
-- Regards, Joerg http://www.analogconsultants.com/
Are you sure about the fixed channels? So if you transmit otherwise legally using a unit that is also capable of transmitting on other frequencies that require a license, you are violating the law?
It's just that I've seen such units discussed in many places for people to use without a license. Not that it means they were right.
Exactly. But the space station has to be line of sight. You won't be having the conversation from behind a hill. I see this all the time with TV signals. Over here the signal is great, but just a bit down the road in a ridge shadow the signal doesn't come in.
I've wanted to get a marine VHF radio to listen to distress calls at my lake house. Then I learned about the limitations on line of sight. We would need a network of stations to cover the 20 miles because of all the twists and turns. Also, a ground station requires a special permit that you can't get very easily. But I figure they will only be used in an emergency, so who's going to arrest someone for saving a life?
-- Rick C Viewed the eclipse at Wintercrest Farms, on the centerline of totality since 1998
I think technically you are. Like with dirt bikes on roads, even if you add everything legally required it's not ok if the dirt bike is not certified as street-legal. Except there they'd catch you soon whereas with the radio the chances are slim. If someone gets busted during a drug deal and they find the radio, maybe they use that as added ammo. Just like they often convicted mobsters for tax code violations because that was the only thing that stuck in court.
"No signal" display != Doesn't come in
TVs are majorly dumbed down these days. We always have plenty of signal on all channels as evidenced by the spectrum analyzer. However, due to a not very smart decision by government folks a DTV system has been picked that greatly underwhelms in multipath conditions. The TVs always show "No signal" with blue screen when the decoder falls apart.
Not so. I did ham radio for decades. Mostly SSB and CW even on the 2m band but there also FM. For example, I had regular FM connection to guys at my old ham radio club 60+ miles and no line of sight at all, inclduing hills in between. 6W of power was all I had and most of them didn't use more than 10W. Got to have a decent antenna, I had a 10 element yagi but under the roof.
Out here all I have right now is a log-periodic TV antenna. With that and my trusty old FT-225RD transceiver I have listened to 2m FM transmissions from the Bay Area which is about 100mi south-west. There are two major hill regions in the path and there is no line of sight at all.
Exactly.
-- Regards, Joerg http://www.analogconsultants.com/
I program all the non-ham or frc channels for rx only. I use the pc software and cable. I guess you can do that with the keyboard as well but haven't tried.
Isn't there a defence of necessity if it is only used in a real emergency? You could transmit and he could listen then swap ends.
-- Regards, Martin Brown
Here, yes. Maybe not in the USA. But as mentioned before, they are not going to fine you for it, there essentially is no enforcement.
VHF (and more so, UHF) is mainly propagating along line-of-sight, unless there are tropospheric inversions or E-layer reflections (very seldom).
In a twisted canyon, those will not help you out. And as they are not always present, they are not suitable for emergency communications. For such purposes you would need a repeater on a mountain top that is mostly visible in the area.
True, but it requires special propagation conditions. Mainly tropospheric inversions. They may be more common in some regions than in others, over here that would work only a couple of days per year.
It is a combination of a tuner that downconverts a tunable band in the 25-1800 MHz range followed by an 8-bit A/D converter that samples it at a variable rate up to 2.4 Msps.
With appropriate software you can use it to "see" a band up to 2.4 MHz wide (like on a spectrum analyzer) and demodulate any signals that are in that band and that your software supports.
E.g. you can tune it to the FM band and receive a couple of radio stations or tune it to the 2M Ham Radio band and receive everything in there.
The 8-bit A/D resolution makes the dynamic range a bit limited, so you should watch out for very strong signals in or near the passband. For some purposes a filter may be required.
But it can do essentially anything when you have the proper software. From demodulating FM/NBFM/SSB to receiving GPS.
It depends on the actual model. For some reason everybody seems to prefer the original UV-5R model which is a pain to program, but other models like the UV-B5 are a lot easier. And that one also has a rotary dial that you can just tune across the range.
They don't lose programming when there is no power. Programming a repeater channel on the UV-5R is a pain, but the UV-B5 just has the familiar "shift" function where you set a repeater shift (per band) and direction and it is programmed into a memory channel along the other parameters. It can also "update" a memory so you can change some settings and re-write it. The UV-5R cannot do that, you need to "clear" the memory first and then program it from the VFO settings, which essentially means you have to start from scratch every time you want to change something (even the power output!)
This works every time I tried. VHF can propagate quite well via reflections off hillsides and other objects. Provided the signal is analog or has very multi-path tolerant digital encoding. UHF, different story. That is why I never understood why TV stations gave up their VHF channel without a fight.
-- Regards, Joerg http://www.analogconsultants.com/
Oh yes, in an emergency anything like that is appropriate IMO.
-- Regards, Joerg http://www.analogconsultants.com/
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