Choosing a scanner - are they still worthwhile? - Page 1
Forum section: electronics / rf-microwave

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: October 31, 2017, 04:08:35 pm
content: I was thinking of buying a scanner. Some 4/5 years ago I had and AOR7000 which worked fine on HF and picked up some air band signals. I did pick up some signals in the higher VHF/UHF bands but just digital bleeps. I was advised that the AOR7000 will not decode these digital signals and I needed a more up-to-date scanner so I ended up selling it. Someone suggested the Yupiteru 7100, but the same would seem to apply here - very good receiver but capable only of receiving analog signals.I have an HF receiver with airband - a Tecsun PL660. This works nicely on the HF bands, but is rather difficult to use for listening to the airbands since by the time I find a signal and tune into it, I am fortunate to catch the tail end of the conversation. I'm thinking that a scanner would probably suit better here. My main interest currently is the VHF air band but I am also interested in astronomy and may find other signals of interest on other bands. It would also be interesting to pick up the comms from the local racing track as well as in the city police, ambulance and fire service. With regards to scanners I have been doing a bit of research to understand some of the terms being used in ads like Close Call (Uniden), trunking, CTCSS/DCS etc, and I have been looking at various reviews but I am still uncertain which scanner to buy.For example there is the Uniden UBC125XLT, which seems affordable but has band gaps and I think no trunking. There are older scanners like the ICOM IC-R20 or used options such as the Uniden USC230 or UBC3500. Not sure if any of them cover trunking? Current offerings from AOR cost well over 600GBP and so are unaffordable. I would think I could probably stretch to 200-250GBP. What would members recommend? What other buying decisions do I need to consider?Also I am not sure ho high to go in frequency? Some scanners go up to 3GHz, but is there anything that might be of interest using such high frequencies?

author: mark03
author_rank: Frequent Contributor
timestamp: October 31, 2017, 06:17:05 pm
content: It has been a long time since I used a scanner, but I would think surely nowadays you'd want to go the software-defined-radio (SDR) route? Unless you really need something in a handheld form factor. With SDR you could decode new signals as modems become available.

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: October 31, 2017, 08:29:19 pm
content: mark03, thanks. I have having a dip into the world of SDR with a cheap RTLSDR receiver. I did have some difficulty getting this working which was the subject of another thread. Now that I have it up and running, I will be expermenting with it over the next few weeks. I found your comment interesting as it sounds like scanners have been obsoleted and superceded by SDR - unless a handheld factor is required. Yet, I could not find a program that can perform a similar function to a scanner on a PC (on Linux or Windows) except maybe RTL-Airplay which I have just managed to set up. The results so far are rather uninspiring and it seems to be very slow at scanning. Having said that, the RTLSDR does give me a cheap way to explore various signals. If my intertest holds or I want get interested in a particular band or type of signal then I might eventually get a better SDR radio and a more appropriate antenna. I was planning to make a discone.I'm not sure at the moment whether I need a handheld factor or not. For air traffic, I have East Midlands airport which a is little less than 20 miles away to the north, and Birmingham airport which is around 30 miles away to the southwest. We also seem to be on a flight path as aircraft regularly fly overhead going northbound and southbound. I would like to be able to pick up signals between these and possibly the tower at East midlands if possible. Whether that would be possible from a base station using a discone or a Yagi remains to be seen. If not, then a mobile solution may well be preferred.

author: cdev
author_rank: Super Contributor
timestamp: October 31, 2017, 10:15:15 pm
content: For broadband omni you might have better luck with a biconical antenna than a discone. There is a UK company that sells a biconical for scanner use. I dont know how good they are. But thats an outdoor option that wont cost you an arm and a leg. If you ever plan on getting a ham ticket you should do research with hams as to the suitability of all these antennas for transmitting, especially their SWR.One thing that isnt discussed much but which is quite important, make sure whatever antenna you buy uses an N connector rather than a SO-239. Much less loss.For indoor receive use you could try the so called planar disc antenna.They are very easy to make for next to nothing in parts and perform surprisingly well. The main advantage of them over a discone is low angle of radiation at the horizon. A discone favors signals arriving at an angle which is not optimal for land mobile reception at a distance.You can scan with an RTLSDR. they can change frequencies fairly quickly. Also, they can receive an entire 2.6 MHz or more wide band all at once. A program like CubicSDR can pipe multiple channels to multiple demodulators and audio outputs all at the same time.The reason why scanning is less popular now than it used to be is that more and more services are digital and use trunking. Some also are often encrypted - (Encryption is not the same as trunking without encryption) In the first case, receiving them is not realistically possible - and may not even be legal in some countries, unless you have been given a key. I.e. have a reason to need to use it. In the second its just more difficult, sometimes there its just a daunting challenge technically.)That said there is software to demodulate many digital modes out there, one center of scanning activity is radioreference.com. You'll typically need to pipe the signals from your RTLSDR into another program to turn the signals into anything useful.Quote from: WaveyDipole on October 31, 2017, 08:29:19 pm

author: denverpilot
author_rank: Regular Contributor
timestamp: November 01, 2017, 04:49:03 am
content: Wavey, are you in the UK? If so, try to tell OFCOM to stop being idiots... hahaha. No seriously.Technically... even you aren’t supposed to listen to aircraft according to them.From:https://www.liveatc.net/faq/“Why don't you have any feeds from the UK?It is illegal to provide air traffic control feeds from within the UK due to an outdated law that originated back in 1942. The antiquated law states that although it is not illegal to sell, buy or own a scanning receiver in the UK, it must only be used to listen to transmissions meant to be broadcast to the general public.OfCom (the U.K. regulatory authority for communications) has stated on numerous occasions: "It is an offence to listen to any other radio services unless you are authorised by a designated person to do so."This means that it is illegal to listen to anything other than general reception transmissions unless you are either a licensed user of the frequencies in question or have been specifically authorized to do so by an authorized person. This is clearly a law that needs to be updated in light of the many educational uses for listening to aircraft communications. Furthermore, the original reasons for this law have long since become irrelevant.Let's hope this law gets modified - there has been at least one online petition aimed at attempting to get some attention but it does not seem to have had much of an effect on Ofcom. If you are a UK citizen, please contact your MP and see if they can help make an exception to this law. “I enjoy listening to stuff all over the world via Dave’s (different Dave!) little project idea... but OFCOM thinks they’re saving the world from something with their weird rule.Honest question: Do they ever prosecute anyone there for listening to stuff they’re not authorized to listen to, other than “stealing” OTA TV signals (that’s weird, too)?Everyplace has its oddities, I know.

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: November 01, 2017, 06:24:37 pm
content: Quote from: denverpilot on November 01, 2017, 04:49:03 amWell, yes I am in the Uk and that is something that I wasn't even aware of. However doing a bit more research I also came across this which is a transcript from a radio show, although it doesn't quote any sources:https://www.frequencycast.co.uk/scannerlaw.htmlThis one does quote the official source, namely something called "RA169":http://www.monitoringtimes.com/html/mtlaws_may04.htmlIt took me a while, but I did eventually find a copy of it here:http://webarchive.nationalarchives.gov.uk/20150703225654/http://www.ofcom.org.uk/static/archive/ra/publication/ra_info/ra169r7.pdfI have to say I find it a bit vague. Some references I found suggest that in the context of airband listening while illegal it is generally tollerated:https://forum.keypublishing.com/showthread.php?17514-Airband-REceivers-are-they-legal#13But on the other hand the law carries sufficient weight to prevent some entities from making use of airband:https://forums.flyer.co.uk/viewtopic.php?p=1460120#p1460120I have in the past seen plenty of enthusiasts at UK airports with scanners/radios in hand. I found an e-mail address on the official government site so I might, just for the fun of it, fire off a query to them.Quote from: cdev on October 31, 2017, 10:15:15 pmThanks. I will have a look into both types of antenna.I trust they haven't made receiving VLF signals illegal yet?

author: cdev
author_rank: Super Contributor
timestamp: November 01, 2017, 06:32:12 pm
content: My guess is that the London Blitz, i.e. the wartime period of intense bombing and the atmosphere of fear surrounding being under attack by a foe who clearly meant to do the nation grievous harm had something to do with it.https://en.wikipedia.org/wiki/The_BlitzOne of my family members - was also killed around the same time, by a different dictator, so I can relate.There is no better explanation that I can think of.At that time it made sense, a very good argument could be made now though to Parliament that it really no longer does now.

author: denverpilot
author_rank: Regular Contributor
timestamp: November 01, 2017, 06:48:46 pm
content: Quote from: cdev on November 01, 2017, 06:32:12 pmThat’s my assumption too, but it truly shows the laziness of politicians who don’t just have a staffer write up something to dump old/useless laws... for over half a century.It’s not like any of them aren’t surrounded by unpaid or low-paid sycophants more than willing to put their name on some legislation paperwork to further their careers in politics, and stay up late to do it. LOL. Oh well!Politicians. The only people who think paperwork stops the laws of physics and radio receivers for AM modulation are something new. Haha.

author: cdev
author_rank: Super Contributor
timestamp: November 04, 2017, 08:54:21 pm
content: It strikes me as crazy in this day and age to have "in the clear" reception of anything be illegal because robust encryption is fairly easy. Neither should attempting to decrypt anything be illegal because security would be best encouraged by the robustness of the encryption being strong enough to be so difficult that neither people nor governments of modest capabilities could trivially decrypt it which is what I would expect to happen if such was the case. In fact, it wouldnt be a bad idea to offer prizes to people who could poke holes in encryption and submit them as part of a process so loopholes would be promptly fixed.Having robust encryption likely does not stop (government-level) entities from decrypting communications but it does discourage casual decryption of communications. Which should be difficult or privacy around the world will be a casualty with potentially devastating results.I think the cost to society of that loss of privacy is potentially much higher than most realize. As all taxpayers pay for government its primary duty should be to serve the people and companies to help all improve security, not weaken it.The government(s) should promote mathematical and computer and security literacy. Algorithms should be open and security accomplished by means which can be verified mathematically.

author: janoc
author_rank: Super Contributor
timestamp: November 04, 2017, 11:53:33 pm
content: Didn't look into UK regulations specifically but I believe they are not that much different than of any other ITU member.FYI, it usually isn't illegal tolistento transmissions not intended for you as such (that would be very hard to enforce - some countries/regime did and do try, though!), it is very much illegal todisclosetheir content to 3rd parties (= publish it online). That's part of the telecom laws pretty much everywhere - it relates to the telecommunication secrecy, following from the requirements set out by the ITU rules which require member countries to protect the secrecy of communication.EDIT: Apparently in the UKit is illegalto listen to anything else than stuff meant for general reception. The above linked document is quite explicit about it.(this one:http://webarchive.nationalarchives.gov.uk/20150703225654/http://www.ofcom.org.uk/static/archive/ra/publication/ra_info/ra169r7.pdf)Encryption (or lack of it) doesn't play a role - keep in mind that these rules have been established long before encryption for radio communications was practical. That something isn't encrypted/scrambled doesn't mean it is free-for-all.If the transmission content is not meant for public consumption in some way - e.g. tv/radio broadcasting, various meteorological stations or beacons and similar, you typically have no right to disclose/publish the content of the transmission that you have intercepted unless it was meant for you. I.e. I can publish a recording of a chat I had on air with a HAM friend of mine (with their consent!) but I am not allowed to publish an intercepted communication of someone else.So while I cannot comment on the specific UK law, UK is not really "behind" or "being boneheaded" here - at least not more than any other country. Services like liveatc.net (or rather people feeding them the data) are pretty much skirting the law in many places on this.When talking about the airband listening, the transponder ADS-B data is usually tolerated because it is often considered as "public information" meant for collision avoidance and navigation by all users of the airspace. However stuff like ATC conversations, ACARS data and similar are a very iffy thing to publish. It then depends only on the local regulator whether they decide to throw the book at you or not.To WaveyDipole:Legal issues aside, if you want to listen to police, fire or ambulance traffic you will most likely be out of luck with a simple scanner. Unlike in the US, in Europe most of these services today use digital systems where you will at best hear some chirps and noise. Many are also going to be encrypted, for obvious reasons.

author: denverpilot
author_rank: Regular Contributor
timestamp: November 05, 2017, 06:40:44 am
content: Quote from: janoc on November 04, 2017, 11:53:33 pmBelieve or know? Examples?ITU membership has absolutely nothing to do with it. Nor ICAO for that matter who handles air band concerns at all of the WRCs for the most part.

author: janoc
author_rank: Super Contributor
timestamp: November 05, 2017, 10:18:39 am
content: Quote from: denverpilot on November 05, 2017, 06:40:44 amICAO doesn't regulate telecommunications, they regulate only specific air-traffic related parts, such as phraseology and similar. ICAO regulations still follow ITU ones.And re ITU:http://search.itu.int/history/HistoryDigitalCollectionDocLibrary/1.43.48.en.101.pdfp. 245, chapter V, article 17:QuoteIs that sufficient? UK is an ITU member so here you have the reason for the UK law prohibiting listening to non-public signals. There may well be other reasons for it too but this alone is enough to justify the UK regulation - they are bound to it by the international treaties they are a part of.

author: cdev
author_rank: Super Contributor
timestamp: November 05, 2017, 12:55:34 pm
content: Well, at least the UK doesn't make use of a tunable radio or TV a capital offense like one East Asian country does!Thank goodness.

author: Hawke
author_rank: Contributor
timestamp: November 05, 2017, 03:02:24 pm
content: SDRplay is an SDR manufactured in England and lightyears above the cheap USB dongle's you can buy. Check them out its run by a bunch of hams. As for software try GNUradio on linux there's not much better and SDRsharp is okay for Windows. Even with your current dongle you can listen to P25 trunked services you will need to download another bit of software called VBEcable and there are instructions on YouTube on how to set that up. Encrypted channels aren't hard to decode either depending on what they are running but the law over there may not allow it. Its usually boring stuff like Taxis with pickup points etc. The real " you shouldn't listen to it " transmissions cant be listened to regardless of software as they run real time encryption on dedicated chips. Just remembered you need the P25 module as well and its only for windows unless its been ported. Think the English SDRplay can hit 2.4 gigs on receive> I cant remember the specs exactly. Another option is HackeRF One which is up to about 6 gig now but also has the ability to transmit on the bandwidth it can receive but at low power. Great for opening you're neighbours garage every time he closes it for a chuckle. Probably illegal in the UK but still funny no matter where you live. If you need a radio with just FM in it you can get a Kyodo KG108 which has receive transmit from 30 megs up-to 550 with no band breaks and 1000 memory channels plus its easy to program. Scanning isn't quite dead especially with lots of satellites to listen to. Just a few options there without going into the handheld market. Cheers 73s

author: denverpilot
author_rank: Regular Contributor
timestamp: November 05, 2017, 03:56:39 pm
content: Quote from: cdev on November 05, 2017, 12:55:34 pmI guess if all you can get is half-stupid law, it is better than full-stupid law?

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: November 05, 2017, 10:54:44 pm
content: Quote from: janoc on November 04, 2017, 11:53:33 pmThanks for answering that particular point. I used to hear a lot of chirps and noise on my old AR7000 and wondered what would be required to decode them, bit if this is not possible then no point thinking about it especially if it is likely to be illegal anyway.Regarding SDR's I just "won" a FunCube SDR (the Pro plus version). It doesn't have the coverage of a HackRF, but still slightly better than an RTL SDR. I was hoping that it would be more stable at say 1500MHz than the RTLSDR which I understand is prone to locking up due to overheating. I am hoping the performance is better to, especially from a noise point of view.

author: cdev
author_rank: Super Contributor
timestamp: November 06, 2017, 01:05:05 am
content: Make sure not to break the law in your country!FunCube Pro is a significantly better SDR than RTL-SDRs in part because it has a much better ADC.But like all SDRs it likely can benefit greatly from a preselector/antenna tuner or even bandpass filters.Most of the RTLSDRs are based on these TV sticks.http://www.newskysz.com/228/101.html

author: janoc
author_rank: Super Contributor
timestamp: November 07, 2017, 11:04:42 am
content: Quote from: WaveyDipole on November 05, 2017, 10:54:44 pmThe UK police and other services apparently use something called "Airwave" which is a trunked system. It is something between a normal walkie-talkie and cellphone service. It is possible to listen to such a system but not trivial - you would need to listen to multiple frequencies simultaneously, possibly also to the service channels in order to know which frequencies to use. The calls are digitally encoded, so a decoder would be needed as well.Moreover, it seems that in their infinite wisdom the politicians are trying to push for budget savings by replacing this with a priority access to a normal 4G phone network where you would be totally out of luck with a scanner. A pretty insane idea (the 4G, not the lack of scanner monitoring), IMO. The same thing has been done in Slovakia for some ambulance services - and now they are putting the radios back in the cars in a hurry because people have actually died when the cellular network was overloaded/down making the services unable to dispatch. And cellular tends to go down usually exactly when there is some sort of a disaster unfolding - typically when you need the police/ambulance/fire services the most. It was a major scandal.Quote from: WaveyDipole on November 05, 2017, 10:54:44 pmI have an RTL SDR dongle and it isn't locking up - it probably depends a lot on which model you have, there are tons of variants around.

author: denverpilot
author_rank: Regular Contributor
timestamp: November 07, 2017, 05:39:47 pm
content: It’s TETRA. And yes, it is trivial, unless encrypted. Google TETRA and SDR.

author: janoc
author_rank: Super Contributor
timestamp: November 07, 2017, 09:28:13 pm
content: Quote from: denverpilot on November 07, 2017, 05:39:47 pmYes, correct.Here is an explanation of it:https://en.wikipedia.org/wiki/Terrestrial_Trunked_RadioExplanation of how to receive it using RTL SDR, in case someone is interested in it. No idea whether this works in UK, but given that the recording on that page is in English, it may well be from UK or Ireland:https://www.rtl-sdr.com/rtl-sdr-tutorial-listening-tetra-radio-channels/However, I wouldn't call this trivial - it needs a fair bit of software to setup + computer and an SDR device. A lot more complex than a simple scanner. And before anyone tries it, make sure to consult your local laws.

author: cdev
author_rank: Super Contributor
timestamp: November 07, 2017, 09:38:08 pm
content: People have run multiple rtlsdrs off the same clock to give multiple synchronous receivers and used them for passive radar applications.'imaging' high flying aircraft in conjunction with a very distant, over the horizon broadcast station.

author: AG6QR
author_rank: Frequent Contributor
timestamp: November 07, 2017, 11:14:58 pm
content: VHF air band is unencrypted AM, and is likely to remain so for a long time. It works well enough, and the aviation community is slow to change a working system. There is a safety advantage to having all aircraft in an area able to hear each other as well as the controller.The Icom IC R2 is a very capable and very compact scanner that performs well on AM airband, both civil VHF and military UHF. I've enjoyed mine for around 20 years. It's a discontinued model, replaced by the current R6. I have no experience with the R6, but would expect it to be good.Either of these also work well for analog FM, if there is any of that to be heard in your area.