I’d like to find a used digital police scanner to keep and monitor in the studio. Haven’t found a reasonably priced one yet, but I am now wondering if it would cause any interference with my part 15 radio transmission.
I really don’t see how, since it’s just a receiver, but somewhere I read some reference which seemed to indicate that it could possibly cause some interference to nearby radios or tvs.
If that’s the case, then what interference might it cause to a nearby transmitter?
Not Likely…
I would doubt you’d encounter any interaction between the two. More likely you may hear your Part 15 broadcast interfere with the receiver audio stage.
I have one that I keep on NOAA WX which I stream on the internet. I have another that scans the 2 meter ham band and the VHF Public Safety band. I’ve had no problem either way.
These are both analog AM/FM operation. A digital scanner may be less affected unless your signal gets into the audio stages.
MRAM1500 and NOAA
You know that NOAA has several clips available via the internet that seem to match where they cover/broadcast the radio signal?
I just started cobbling a manual script (computer program) to round these up for our pseudo station.
All the low power folks here should be aware of what NOAA puts out for free. There are streams (online) as well as the audio files which are ideal for your stations:
http://www.nws.noaa.gov/nwr/streamaudio.htm#audio
NOAA MP3’s…
Yes, the Cleveland, Ohio NWS posts the audio clips for the NOAA stations in the area. These are broken down into forecast, current wx, marine wx, and others. This makes it nice to pick and choose what you want to use.
I use the MP3’s on my station. This is all automated using WGET and Windows scheduler to download the files once per hour. Then ZaraRadio automation puts it together along with current temp obtained from Weather Watcher for Zara automated temperature/humidity announcements.
The live NOAA is streamed nonstop and gets way more hits than my station stream, at least when bad weather threatens. Since I host the stream from home, I limit the max number of listeners to 32 due to my upload bandwidth limit. Generally during weather events, it gets maxed out.
My NOAA stream is listed on the NWS website for the Akron, Ohio area.
How are people finding your NOAA station?
@mram1500,
How are people finding your NOAA rebrocast online stream?
I found it via Shoutcast, but wasn’t searchable for NOAA or weather. Perhaps a stream name modification in order?
Better Fidelity
Those NOAA mp3’s are of far better audio quality than going out on their 3khz narrow bandwidth FM modulated VHF transmitters too.
RFB
Live NOAA Stream Always Current…
The NWS had a page of links to NOAA online broadcasts from individuals like myself. They contacted me for permission to link to my stream.
That was some time ago and perhaps they have removed that page in favor of streaming their own audio.
The main advantage to streaming the live NOAA audio is that it’s always current plus the severe weather adviseries will be heard as they occur.
I use the MP3 files for my Part 15 station weather ‘casts.
However, since I also use Weather Watcher Live to update ZaraRadio with current stats, it plays an audio alert when ever a severe weather alert is issued. It has the option of your selecting the audio alert to play. So, I produced my own announcement which prempts the regular program audio. That announcement advises listeners to turn on their NOAA WX radio for immediate details.
As my station runs full auto this wss the easiest way to make sure listeners are notified as the event happens.
3 khz huh?
Believe it or not. NOAA NWS stations transmit at 20/25khz bandwidth 🙂
But agreed, those MP3s DO sound better.
I was amazed myself when I found out they were that high, they certainly don’t sound like it.
Really?
“Believe it or not. NOAA NWS stations transmit at 20/25khz bandwidth :)”
I dunno about that. Using my Motorola R 2012 D communication analyzer, which is currently calibrated as of July 2012, and according to the deviation indication, that modulated deviation doesn’t push past 3.5Khz, 4Khz max in bandwidth.
Most of those sites are fed via a telco line, and your not going to get 25Khz bandwidth from that! The modulation levels may be incorrectly adjusted on the ones your observing. But if it was indeed 20-25 Khz audio bandwidth, those transmissions would sound exactly like the mp3’s they offer up.
Maybe those your observing are fed by a better audio feed than from a telco line? That might explain the wider bandwidth being heard/measured. But like AM, the end result coming out of the majority of NOAA receivers won’t even see that much bandwidth, much less push it through those tiny 2 inch speakers! 😀
I don’t doubt what your saying, Ive measured and observed a lot of those NOAA signals not exactly adjusted to specs..as they are setup, tuned up and left alone for months and months at a time..if not a couple years.
Sure would be nice to hear that wide audio bandwidth from NOAA over the signal here. But that won’t happen as the NOAA station in Casper is fed via telco line out of the NOAA weather center located in Riverton Wy. I’ve even checked the frequencies there in Riverton and they sound the same with narrow bandwidth audio.
But those mp3’s sure do sound sweet! When the weather starts to get funny here, especially like it did on Saturday night into Sunday morning, around 3am, the temperature dropped suddenly from 14* to -5* within a 20 minute time frame! No joking either, it hit a new record for Casper and was highly noted on The Weather Channel. Last year same thing happened and Casper hit -23 in the same month and was the coldest city in the entire country, and noted on The Weather Channel and also broke a record set back in 1932.
What do you expect at altitudes of 6,000+ feet ASL! 😀
BURRRRR!
RFB
20/25 Explained
My backup of their bandwidth comes from how we program Motorola Radios.
When we put in WX channels, they have to be be set in wideband (20/25). If they are set in narrowband (12.5) mode, it sounds awful and distorted.
I don’t doubt your measurements at all. All NOAA stations I’ve heard sound tinny. I’m not sure why I’ve never thought of looking at a NOAA station with our service monitors.
All the low power folks here
All the low power folks here should be aware of what NOAA puts out for free. There are streams (online) as well as the audio files which are ideal for your stations:
http://www.nws.noaa.gov/nwr/streamaudio.htm#audio
Mram, When I click the link for Savannah Georgia it just gives me a page saying “The requested URL /nwr/ga/ was not found on this server”
I thought it was just a temporary error at first but it’s doing the same thing today.. I also get the same error from nearby cities in Georgia as well.
I guess I’ll try to find a contact link and inform them, I’d sure like to utilize that audio
The receiver shouldn’t
The receiver shouldn’t interfere.
Your Part 15 AM station can interfere with other receivers, depending on the frequency and the image rejection on the front end of those receivers. I’ve had issues with a Part 15 AM signal getting into the amateur radio and shortwave frequencies (the 2 antennas were pretty close). I’ve never encountered any interference with FM broadcast band frequencies or higher (such as 2 meters).
From Experience
For several years I’ve operated numerous models of communications receivers, capable of receiving from long wave up into the gigaHertz range, right smack in the intense near-field from the antenna for AM 1550.
The transmitter is deaf and blind to the receivers, although I get some spurious odd signals from the transmitter at many places on the receiver dial, but it has not blocked any essential receptions.
Back to topic 🙂
There are tons of cheap police scanners, handhelds as well as older models.
See:
http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1313&_nkw=police+scanner
and
http://www.scannermaster.com
There are also computer controlled models. Haven’t used any with exception of the Winradio’s. Others should comment on these and what they might use/recommend.
In lieu of that and on the cheap, should check out on your local streaming audio options via radioreference.com. There are piles of broadcasts on there and works fairly good:
http://www.radioreference.com
Yeah, I almost bought a cheap
Yeah, I almost bought a cheap police scanner a couple weeks ago, but then postponed after a little research and am now attempting to find a used digital unit (because they start at around $300).
Police scanners are different than they used to be, the last scanner I owned about 15 years or so ago just entailed putting in the correct crystals to enable monitoring of the police channels.
But nowadays, with a regular police scanners you can’t hear what’s going on, you only know that something is occurring.. because you can not hear the police at all, all you can hear is the dispatcher!
To hear the police a digital police scanner is required – and there’s a huge price jump for those. So I’m trying to find a used on in the $100 range.. so far without luck.
If one doesn’t turn up, I’ll just get a run-of-the-mill one. It’s not that I consider them useless, quite the contrary, they are very useful; EMS, fire dept., weather, road crews, etc..
But you know, I’d really like to hear the police too.
Not all police departments in all areas of the states have switched to digital and trunking, but a great many have. They certainly have here in my area
TRUNKED!
What you hear there is a trunked system.
Bigger cities typically have that. I’m kinda surprised Tybee Island is on a trunked system.
Id imagine it must be an LTR system, or a county shared system.
That being said, if its NOT LTR and its in the 800mhz area, it may very well be a motorola type II system.
If its the motorola system a used scanner has a VERY high chance of not working, due to rebanding.
Now if its truly digital, it would be P25. which you wouldn’t hear at ALL. not even the dispatcher.
If its P25, you will not find a scanner for under $500, if you do, PLEASE share your find with me! 🙂
Back in the Analog Days..
“.. I read some reference which seemed to indicate that it could possibly cause some interference to nearby radios or tvs.”
Back some years ago, I was called to a local FD for an interference issue on their main Fire frequency RX. (low band, csq. rx.) They were getting bursts of something in the rcvr. of the base, mobiles, and portables near the station. (pink noise, just breaking the squelch, ~2 time a second) It was constant but it would stop once in a while for short periods and then start up again. They had speakers in the bays so it was driving them nuts! Couldn’t tighten the squelch up enough to keep it out!
Got the spectrum analyzer out and found a very wide interference in bursts, too wide to even find a good center frequency! Broke out the service monitor and dialed in the rx. frequency of the FD and sure enough, there it was. Checked the building out by taking the monitor from room to room and found the interference was stronger on the east end of the building, Decided that it wasn’t in the building anywhere so I went on a witch hunt..
Fired the monitor up in the van outside the FD and connected a mag mount antenna on the roof. Fixed on an amplitude level on the scope because the bursts were so short that I couldn’t get a good fs level. I started driving around to the east of the building, watching the scope..
3 blocks away I had to adjust the attenuation to keep it in the screen! Drove north and south through the streets and narrowed it down to a block of houses. Started looking in the air and found a house with a hula-hoop of an old starduster groundplane cb antenna mounted upside down on a pole. Had one of the fd portables with me. I removed the antenna and could still hear the crap!
There was a couple kids playing in one of the yards and I asked them if they knew who lived in that house. One of the kids said that he lived there. I asked him if I could talk to one of his parents. He ran inside and his father stepped out. Introduced myself and explained the situation. He said he had a scanner connected to the hula-hoop. Asked him if I could take a look at his scanner. He said NP..
8 channel Bearcat, crystal-controlled with the led’s. Standing there with the portable, I shut the scanner off. The interference went away! Observed a little and when the scanner stopped on a channel, the noise would stop. Watched the led’s and the interference was just on one frequency that he had in the scanner. Everytime it would scan that particular frequency, it would cause the burst. Disabled that frequency and the problem went away. (low band hwy. patrol frequency)
The guy had no idea what was going on and he was embarrassed to cause any problems. Asked him not to scan that frequency and he was OK with it. Problem solved..
Wonder what else he was ripping up.. LOL
Tremendous Catch
12vman that is a spectacular signal tracing adventure. Very neat work on your part.
Any idea why the particular low band frequency caused a burst to be generated?
No Clue, Carl..
The Hwy. Patrol at that time was in the 40mHz. area, somewhere between 42-45 mHz. The FD was in the 30 mHz. area. (39.720 mHz, IIRC) Must have been some mix of the I.F. in the scanner and the patrol frequency crystal. I imagine the antenna being out of band may have had something to do with it. Them RF’s are strange critters sometimes..
Found an abandoned BDA for the Nextel system in a school ~20 mi. away from an 800 mHz. county system tower taking out all 5 of the control channels, putting the tower into failsoft and shutting down the whole county! It was self-oscillating and going all over the place! Found it, unplugged it and all was fine..
Hunt For Squaking Jam Box
Yeah back in the great days of old scanner designs, they were not very well built and shielded around their TTL and divider circuits, producing all kinds of junk. It’s not surprising 12vman that the unit you found causing the interference was an older crystal controlled scanner..obviously having some issues with it’s frequency switching and dividing IC’s, considering most IC’s used in consumer stuff in those days were not exactly military level specifications!
Great hunting job though!
RFB
Am I On the Right Link
I think that NOAA Weather audio has been one of the scanner subjects discussed earlier, and I was surprised on the list of towns that offer mp3 clips, my town is not one of them, even though we have a NOAA radio station that has the usual tinny phone line audio.
In the 1960s I worked at the FM station that provided a tower for NOAA, and indeed their audio came in on a budget phone circuit, what I think is called a “dry line”, because it is not equalized for wide-band but cannot hang itself up, as with a dial-up.
Anyway, I don’t broadcast to the local area, so what I’m thinking of doing is tapping into NOAA audio files when something happens in the U.S., like Sandy or Katrina… I could grab weather from the affected areas and I myself would tune in with great interest.
Creative thinking slows down in cold weather, but it doesn’t stop completely.
I would recommend looking at
I would recommend looking at radioreference.com and find the signal type needed in your area. Analog scanners cost around $100 while digital scanners can cost around $500. So you can save by buying an analog scanner. If you’re going to get a digital scanner I’d recommend the Uniden BCD436HP handheld digital scanner – it has great reviews and is really easy to use compared to the old scanners. It will be worth the $ as it just came out.
Here is a place that sells the 436:
http://www.zipscanners.com/uniden-bearcat-bcd436hp-handheld-digital-police-scanner.html
Hope this helps!