I’ve updated a few of things. There is a direct download or play link just below the Flash Player for devices not compatible with Flash. Be aware it is a large amount of data and there can be buffering, but you can download the file. There is a new picture of the Funcube Pro Plus dongle and I replied to the last comment from Emily Taylor, which explains what my main interest is now. I can assure you they are not fishing and hunting!
Direct mp4 download or play: BRM 8-09-2015
Here is my recording of a baby room monitor using a software defined radio. It was recorded from inside my living room using my discone antenna, Airspy, and SDR# (SDRSharp). Video and audio were captured with Daum Potplayer at a true 16×9 resolution of 848 by 480 pixels.
I thought by now everyone using baby room monitors would have moved away from 49 megahertz analog technology. Reception is noisy because of a somewhat weak signal and humming sound, possibly a fan blowing on the microphone. Maybe that fan was upsetting the baby. Also note, I neglected to show the waterfall display on the video itself, and the tuning was off by .016. My fault.
screen capture setup, showing middle waterfall display, not showing on video – click image for clearer view
Airspy software defined radio
Funcube Pro Plus software defined radio
SDRSharp – still image captured at 1024 x 768 – not cropped – video itself is cropped to 848 x 480
Notice the waveform for the selected signal (49.830 megahertz) is more pointy compared to the video.This happened after I stopped recording.
Comet DS – 150 discone antenna
12 users commented on " BRM 8-09-2015 (updated) "
Follow-up comment rss or Leave a Trackbackthe world is a really ugly sour place. seems nobody cares about anyone but themselves anymore,..harumph,.
Hey Mr. Weatherman,
What do you think of the Airspy sdr? Also,the same question for the previously mentioned FUNcube?
Both SDRs work quite well on Windows 7, 64 bit, with my Asus Xonar Essence STX soundcard. They both operate on SDRSharp and HDSDR software. In fact, I can run both radios simultaneously. The only problem is a lot of USB noise (I think) gets into the receivers, even with multiple ferrite beads and shielded USB cable. I’m more inclined to believe the computer motherboard or the operator (me) is the problem. But It’s not bad. Also, my location, in Seattle, has very strong local digital TV and analog fm broadcasts, especially KUOW at 94.9 megahertz. I installed a Par Electronics VHF FM trap inline with the Airspy, but 94.9 MHz can still, at times, overload the tuner. In addition, there is quite a lot of general electrical noise in my neighborhood. I measured nearly 10 volts AC between a metal window frame in the front of my house and ground. That window is less than 50 feet from the overhead primary electrical lines. With all of that to deal with and the fact I have much more to learn about this technology, I think these receivers are very good. I am able to pick up CIOC in Victoria, BC at 98.5 MHz, FM and CBC Radio 2 at 92.1 MHz, FM (unknown transmitter location) and KFBK 1530, AM in Sacramento, California on the FUNcube. I received a wireless microphone system from the recent 2015 Seattle Seafair at 637.700 MHz, wide FM, on the Airspy, as well. So, I guess I’m doing something right.
The software is a lot like VST(Virtual Studio Technology, sound recording) and I was actually able to run SDRSharp in soundcard mode and use it like an effects plugin. Now, any audio can be made to sound like being tuned on a radio, just like in my favorite movie, THX 1138!
Wow same noise floor as the RTL on that airspy. I’m surprised to have found those too haha I have a much better antenna for the lowband and have picked these up with the scanner, about 5 some from pretty far away. I thought the band was gonna be empty cuz I had some 6 watt commercial fm radios I had programmed onto parts of 49mhz a while back i used to use. Wonder how many times it must’ve blasted through some peoples receivers haha try looking around 30mhz sometimes I hear mcdonalds and sonics drivethru system.
pretty good signal strength there, SDR is just a deaf piece of crap lol look at that noise floor, just as bad as the rtl lmao
Emily, you’re pretty much right, but I am at an extreme disadvantage as far as receiving too much RF from a variety of sources. I can see the TV towers for some of the local Seattle broadcast stations from my living room window. These include KOMO on UHF channel 38, KIRO on UHF channel 39, and KING on UHF channel 48. These are digital signals, 6 megahertz wide, sometimes called “haystacks” referring to how the signal looks on a spectrum display. Another very annoying signal is the new Motorola digital voice radio known as MOTOTRBO. There are lots of these, and they seem to pop up everywhere, sometimes covering analog voice transmissions. There are other types of “digital modes” as well. This will ultimately force me to learn how to decode those signals. Did I mention cell phone signals in the 700 and 800 megahertz range? Shortwave reception is pretty much “deaf,” but AM broadcast is very good. KFBK (1530 kilohertz) in Sacramento, California comes in quite well at night, here in Seattle. Believe it or not, FM broadcast DX is quite good considering I’m able to hear CBC radio 2 (Canadian Broadcasting Corporation) at 92.1 megahertz, most of the time. At times I can hear CIOC “Ocean 98.5” from Victoria, British Columbia. I’m considering the purchase of possibly multiple professional high-end RF traps. These could help the reception, but are quite expensive. I could go on, but I think you probably get the idea. I’m quite pleased how well this technology works, regardless of the noisy RF environment. By the way, I have an RTL dongle, and the noise floor is much worse.
Weatherman, I can’t remember, but did you ever post that BRM recording you made where the baby sounded like the baby from Eraserhead?
I can’t recall where or how I heard it, but it remains one of my favorite ever, even as unsettling as that sounds.
Lately I’ve been hearing soft rock music on .830 within a good distance. I can travel around the neighborhood and can pick it up a good mile or so away on a PRO-97 with a telescoping antenna. From the sound quality I betcha they’re just feeding a modified K-Mart Fischer Price transmitter with a line-in jack replacing the microphone (a well-known baby monitor mod) and maybe a good high gain antenna. Even in a stock configuration some of those baby monitor headends have pretty ridiculous power for what they are.
Stupid Seth, I’m confused. What do you mean by .830? Usually, that means .830 megahertz or 830 kilohertz, which is in the AM broadcast band. There are no baby monitors in that range. I’m assuming you forgot the 49 and you meant 49.830. If so, just without thinking, you’re probably picking up a BRM with a radio, stereo, or TV left on in the room. That may be done deliberately. Do a YouTube search for “soothing baby sounds for sleep.” I hear that sort of thing all the time. Sometimes the audio is quite clear, but then a baby starts to cry or people come into the room and start talking. The real live voices are much clearer than the sound of a radio or TV speaker. By the way, I modified a RadioShack BRM transmitter by installing an external microphone jack. It has a switch to either select the built-in microphone or external. An added bonus, since the built-in microphone is an electret condenser type, there is plugin phantom power (several volts DC, center conductor positive) available. This will power virtually any external electret condenser microphone capsule.
49.830. I’ve often seen radio guys state only the kilohertz offset as a kind of “shorthand” when the megahertz position is already known (e.g. “.450” in Los Angeles = 146.450 repeater). Also I really doubt it’s an acoustic-coupled setup because the audio is much too clear and there’s no room echo, like a direct-wired connection. It’s also not always on, usually only in the daytime when the weather’s decent, so it could be somebody using it to move audio around their property, like feeding a scanner in the shed from a satellite receiver or a computer in the house. In fact I think it *might* be the ham radio guy a couple blocks over since he’s known for his oddball radio experiments like this (like parking a shortwave receiver set to 3840 SSB on a 440 MHz transmitter.) I think a foxhunt might be in store for one of these Saturdays when the weather’s better.
Hmmm. I had a garage sortout last week and came across my old modded Fischer Price transmitter, might just have to power it up one of these days when .830 is clear *wink*
Speaking of haystacks, do you get any spurs on any of your receivers? I live within eyeshot/antennashot of Portland and KGW’s NTSC signal always overloaded my big old Radioshack SW-100 (you know, the one with the big T-shaped growth on its head that’s supposed to be the AM antenna).
KGW audio used to come in loud and clear not only on channel 8 but also smack in the middle of the marine VHF band! Now I can try tuning that range and it’s basically obliterated by loud ATSC hash instead of video buzz. I’d put an RF trap on it but that radio’s such a piece of junk it’s not even worth it.
Oh well, at least it’s still useful as a mono phono amplifier 😉
Stupid Seth, maybe the 49.83 MHz signal is a cordless headphone transmitter. I have one that transmits high fidelity wideband FM at about 49.910 MHz. I’ve connected a high-quality tube mic. preamp with a cheap plug-in power condenser mic. capsule, with an Alesis Nanocompressor in line to the cordless headphone transmitter. The microphone is placed just outside a window on the back of my house. I often will play this to my Airspy receiver in the living room computer. This computer uses an outboard soundcard (Mackie Blackjack) which feeds My stereo setup with big vintage Klipsch speakers. Sometimes I leave the transmitter on at night and listen in bed with an older Regency communications receiver that just happens to have wideband FM. The sound quality is good enough that sometimes I think a burglar is creeping around my house! Hopefully, it’s just raccoons or cats.
As far as Rf interference goes it’s quite challenging, as I can see the local Seattle TV stations tower lights from my living room. When tuning Airspy there are many blocks of 6 MHz ATSC signals from 180 MHz (channel 8)up to nearly 700 MHz (channel 51). In addition, I can cause the pointer on an analog voltmeter to move up with no electrical power when holding then plugged in test leads in certain positions. I don’t what signals are causing this, but I think it might be KUOW at 94.9 MHz. This may be the source of this extremely strong RF signal. I think, sometimes it gets into my audio system. Occasionally, I can faintly hear some scholarly sounding radio voice coming from the speakers when there should be silence. Of course, that can only be NPR! I’m thinking of buying a large bandpass filter with multiple sections, like the ones I used to see installed at the headend of the cable TV system I worked for in the 1980s. Back then it was Televents of Contra Costa County, which became TCI, and now Comcast. Also, 94.9 shows the highest signal reading on any radio I own. I guess I’m slowly being fried! Check out my post: http://www.negativland.com/dumb/blog/archives/6026 for another type of electrical interference I have to deal with.