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Receiving Muzak on Subcarriers
Hi All,
I want to rebroadcast and play some Muzak "elevator music" on my old tube radios. I've been told that Muzak is aired via subcarriers that ride on FM broadcast signals, but I don't want to spend any money on an SCA receiver, so I wonder if I can decode subcarrier channels if I took the audio signal from the MPX FM output of my Heathkit AJ-11 or Dynakit FM-1 receiver and fed the signal into a crystal radio with a resonant circuit that tunes between 60 to 100 kHz? Thanks in advance. C.W. |
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#2
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Built one of those years ago from an article in a late 70's electronics
magazine.. perhaps Popular Electronics. If I remember it used a 567 phase locked loop. Worked ok, but was a little fussy to reject the reglar audio. Werner wrote: Hi All, I want to rebroadcast and play some Muzak "elevator music" on my old tube radios. I've been told that Muzak is aired via subcarriers that ride on FM broadcast signals, but I don't want to spend any money on an SCA receiver, so I wonder if I can decode subcarrier channels if I took the audio signal from the MPX FM output of my Heathkit AJ-11 or Dynakit FM-1 receiver and fed the signal into a crystal radio with a resonant circuit that tunes between 60 to 100 kHz? Thanks in advance. C.W. |
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#3
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in article ,
at wrote on 5/17/05 10:07 PM: Hi All, I want to rebroadcast and play some Muzak "elevator music" on my old tube radios. I've been told that Muzak is aired via subcarriers that ride on FM broadcast signals, but I don't want to spend any money on an SCA receiver, so I wonder if I can decode subcarrier channels if I took the audio signal from the MPX FM output of my Heathkit AJ-11 or Dynakit FM-1 receiver and fed the signal into a crystal radio with a resonant circuit that tunes between 60 to 100 kHz? Thanks in advance. C.W. Vectronics has a kit and a complete on-line manual: www.vectronics.com/man/pdf/VEC-422K.pdf If memory serves me correctly, the NE565 was the popular device for SCA detection. National Semi used to publish an application note with a circuit you could build. Jon |
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#4
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wrote in message oups.com... Hi All, I want to rebroadcast and play some Muzak "elevator music" on my old tube radios. I've been told that Muzak is aired via subcarriers that ride on FM broadcast signals, but I don't want to spend any money on an SCA receiver, so I wonder if I can decode subcarrier channels if I took the audio signal from the MPX FM output of my Heathkit AJ-11 or Dynakit FM-1 receiver and fed the signal into a crystal radio with a resonant circuit that tunes between 60 to 100 kHz? Thanks in advance. C.W. The subcarriers are FM and are riding on the FM carrier. You'll need a PLL to decode the SCA. SCA ready receivers for direct sale to consumers are illegal to sell under current FCC laws, but you can buy a subcarrier kit from Vectronics. BTW, the SCA bandwidth is restricted to about 5 kHz, so don't expect to recover high fidelity music from the SCA services. |
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#5
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Uncle Peter wrote:
wrote in message oups.com... Hi All, I want to rebroadcast and play some Muzak "elevator music" on my old tube radios. I've been told that Muzak is aired via subcarriers that ride on FM broadcast signals, but I don't want to spend any money on an SCA receiver, so I wonder if I can decode subcarrier channels if I took the audio signal from the MPX FM output of my Heathkit AJ-11 or Dynakit FM-1 receiver and fed the signal into a crystal radio with a resonant circuit that tunes between 60 to 100 kHz? Thanks in advance. C.W. The subcarriers are FM and are riding on the FM carrier. You'll need a PLL to decode the SCA. SCA ready receivers for direct sale to consumers are illegal to sell under current FCC laws, but you can buy a subcarrier kit from Vectronics. BTW, the SCA bandwidth is restricted to about 5 kHz, so don't expect to recover high fidelity music from the SCA services. Is 'Muzak' still available on SCA? I thought they went all satellite? -Bill |
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#6
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-exray- wrote:
The subcarriers are FM and are riding on the FM carrier. You'll need a PLL to decode the SCA. SCA ready receivers for direct sale to consumers are illegal to sell under current FCC laws, but you can buy a subcarrier kit from Vectronics. BTW, the SCA bandwidth is restricted to about 5 kHz, so don't expect to recover high fidelity music from the SCA services. Is 'Muzak' still available on SCA? I thought they went all satellite? Muzak dumped SCA as a method of transmission about 5 years ago. I saw one of their dishes on a building in Los Angeles a couple of years ago, but it was definitely NOT pointing toward the sky....It appears that they are using some kind of line-of-site microwave reception scheme from a centralized terrestrial location. Probably, the receiver uses some form of digital encryption scheme to prevent unauthorized reception. Other broadcasters are still using SCA, at least in Silicon Valley. I have a portable FM radio that has an SCA switch on it (it's not a mod either....it definitely came that way from the factory). The FM radio functions pretty much like any other FM radio, but on SCA it receives a fixed-frequency signal that is set by a user-inaccessable trimmer cap on the radio's main PC board. I can get at least two or three different SCA transmissions with it in most points in the bay area. It works fine, but it requires a very robust signal from the host transmitter for good reception and yes, the audio quality sucks. Plans for the construction of an SCA decoder appeared in the Popular Electronics/Radio-Electronics type magazines MANY times during the 1970s. Additionally, National Semiconductor's 1970s-era linear component databooks contained the schematic for one of these decoders to illustrate a "typical application" for one of their garden-variety PLL chips. For the most part, these plans call for off-the-shelf components that are still available today. However, I would be very careful about re-broadcasting this kind of programming. You must be absolutely sure that the re-broadcasted signal does not go beyond the boundaries of your home. There have been many, many lawsuits over the years regarding the unauthorized reception and use of these broadcasts. If the broadcasters were to find out what you were doing and went after you, they would definitely prevail in court. -Scott -- DO NOT REPLY TO THIS MESSAGE AT THE EMAIL ADDRESS ABOVE! Instead, go to the following web page to get my real email address: http://member.newsguy.com/~polezi/scottsaddy.htm (This has been done because I am sick of SPAMMERS making my email unusable) Need a schematic? check out the Schematic Bank at: http://techpreservation.dyndns.org/schematics/ Archive of alt.binaries.pictures.radio binary postings: http://techpreservation.dyndns.org/abpr/ |
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#7
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The subcarriers are FM and are riding on the FM carrier. If you should happen to be a ham and have a modern transceiver radio capable of reception down to 30KHz in narrowband FM, you could feed it the FM radio's detected audio (before the deemphasis circuit). Tune in 67KHz or 92KHz in FM mode on the transceiver, and then tune the FM radio around 88 to 108MHz to see if you find any SCA signals. You'll probably find a few data transmissions as well as a few audio programs. About 10& of all FM stations will have SCA subcarriers. Also try it with the FM sound detector inside a TV set, you should be able to find SAP channels at 78.67KHz. See my page http://www.geocities.com/CapeCanaver...radios/ham.htm about 3/4 the way down. |
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#8
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There's another way (and yet another, as I will explain) you can get
commercial-free music to play on your antique radios besides SCA. If you have digital cable/satellite TV, the service will almost certainly have digital music channels. Just run the audio output from the cable box or satellite receiver to the input of a low-power AM transmitter, set your old radios to the transmitter's frequency, and you're in business. The fidelity of these broadcasts is incredible if you are listening to them on a good stereo system, but don't expect hi-fi from a small 0.1-watt transmitter. You probably won't miss anything anyway, as many of the old radios (mostly the low-priced table models) weren't designed with high fidelity in mind. (The early radio programs were, after all, anything but high fidelity.) However, if you have a console such as the Zenith Stratosphere or any of the large consoles with 12" speakers, you will get very good sound, limited only by the frequency response of the program source. I have a 1963 Zenith K-731 AM/FM table model in a large walnut cabinet, with a two-way speaker system; the sound from this set is very good, with almost incredible bass response. These receivers would also do well with the low-power rebroadcasts of cable/satellite music channels, whether the transmitter is AM or FM. Another way you can pipe commercial-free music into your cherished old antique radios is to feed the output of a cassette or reel-to-reel tape deck, or even a CD player, into the same 0.1-watt AM transmitter I mentioned above. Jeff Strieble, WB8NHV Fairport Harbor, Ohio |
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#9
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Scott W. Harvey wrote:
-exray- wrote: Is 'Muzak' still available on SCA? I thought they went all satellite? Muzak dumped SCA as a method of transmission about 5 years ago. I saw one of their dishes on a building in Los Angeles a couple of years ago, but it was definitely NOT pointing toward the sky....It appears that they are using some kind of line-of-site microwave reception scheme from a centralized terrestrial location. Probably, the receiver uses some form of digital encryption scheme to prevent unauthorized reception. I did a bit of Googling and it appears that Muzak nowadays has about 70 digital channels of programming coming from various satellites with some spot-beaming thrown in for good measure. One group of channels, for instance, is on EchoStar7 right there with DishNetwork...and on the same transponder as some of the Sirius channels. http://www.lyngsat.com/packages/dish119.html According to that site they are digital and in the clear. It wouldn't surprise me if they had terrestrial headends in major areas like LA where they collected the signals from the various sats and sent them around via microwave. -Bill |
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#10
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In article aQxie.15475$iU.5759@lakeread05, " Uncle Peter"
wrote: The subcarriers are FM and are riding on the FM carrier. You'll need a PLL to decode the SCA. SCA ready receivers for direct sale to consumers are illegal to sell under current FCC laws, but you can buy a subcarrier kit from Vectronics. BTW, the SCA bandwidth is restricted to about 5 kHz, so don't expect to recover high fidelity music from the SCA services. Hello, and you can also use a conventional ratio detector circuit to decode the SCA broadcast. I built one in the early `70s from the cover article in an issue of Popular Electronics Magazine. The device also used one active component (a JFET) as a tuned, 67 kHz RF amplifier ahead of the detector. Later on I built two SCA decoders from kits that used PLLs. The units worked OK but the biggest problem was that the main channel program always bled through albeit at low volume. Also, you had to have a fairly strong signal to obtain decent SCA reception. I still have all the units that I built but in recent years a lot of services have moved to satellite or simply went defunct. About the only SCA programs on the air here in the Washington, DC metro area are a service for the vision-impaired and Asian-language programs. Subsidiary Communications Authorization (SCA) broadcasts are still a cheap way (i.e. by piggy-backing on the main program FM signal) to deliver program content but their limited bandwidth (not so good for music but OK for voice) and the availability of satellite services limits their utility these days. I'm not sure if MUZAK is still providing service via SCA. Sincerely, John Wood (Code 5550) e-mail: Naval Research Laboratory 4555 Overlook Avenue, SW Washington, DC 20375-5337 |
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#11
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#12
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Can I get Muzak from the TV cable (cable FM)? Has anyone tried cable
FM with an SCA receiver for Muzak???? Scott W. Harvey wrote: Muzak dumped SCA as a method of transmission about 5 years ago. |
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#13
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#14
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Hello, and now for an ideal acoustic tortu A pair of tight
cover-the-ear stereo headphones with MUZAK on the left channel and rap music on the right ;-) John Wood (Code 5550) e-mail: Naval Research Laboratory 4555 Overlook Avenue, SW Washington, DC 20375-5337 |
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#15
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J. B. Wood wrote:
Hello, and now for an ideal acoustic tortu A pair of tight cover-the-ear stereo headphones with MUZAK on the left channel and rap music on the right ;-) You're evil! However, I'll take the Muzak over the rap.... |
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