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Old 10-01-2010, 6:30 PM
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Default "Unblocked" receiver

Hi. I was looking at AOR receivers on eBay. There is a listing for an "unblocked" receiver. What is normally "blocked"?

Thanks!
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Old 10-01-2010, 6:35 PM
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Cellphone frequencies
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Old 10-01-2010, 7:07 PM
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That's what I thought. However, I've read on the internet that you can pick up analog frequencies, but not digital ones. Most of the stuff that I've read says that newer phones use some sort of digital transmission or encrypting or something that makes the calls very difficult to intercept. Is this not true?
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Old 10-01-2010, 7:25 PM
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Quote:
Originally Posted by JohnDistai View Post
That's what I thought. However, I've read on the internet that you can pick up analog frequencies, but not digital ones. Most of the stuff that I've read says that newer phones use some sort of digital transmission or encrypting or something that makes the calls very difficult to intercept. Is this not true?
I have a pro 2006 with the Cell freqs . I have not heard anything as far as cell phone calls in years
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Old 10-01-2010, 7:27 PM
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That's because they are all digital now. I think the last analog cell service ended a few years ago in the U.S.
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Old 10-01-2010, 7:54 PM
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yeah it means the cell freqs. you can pick up digital, but it will sound like you are listening to a modem.

Analog Cellular requirements sunset several years ago, which simply meant that carriers were no longer REQUIRED to keep analog online, but not that they had to kill it. you may run across an analog site way out in the boondocks somewhere, but in most areas spectrum is so valuable that they are all digital just to be able to carry more calls per channel.
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Old 10-10-2010, 7:18 PM
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I've got an unblocked analog scanner and don't get anything on the cell freq's. Believe me I've spent hours searching. There's just nothing there on analog. I've been told it's useless on digital too.
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Old 10-10-2010, 7:25 PM
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I can't believe they still require the 800MHz Cell Phones to be blocked anyway. Everyone has gone digital now and you can't decrypt them unless you have some really special equipment. Our company was the last to turn off the old analog stuff and we just did it in 2008!

I have always bought unblocked scanners just because. If you have one with a spec-an built in, you can see the 800 spectrum in use and where you used to have a single blip as one conversation, you now see one giant blip for the whole band.
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Old 10-10-2010, 7:28 PM
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Quote:
Originally Posted by JohnDistai View Post
That's what I thought. However, I've read on the internet that you can pick up analog frequencies, but not digital ones. Most of the stuff that I've read says that newer phones use some sort of digital transmission or encrypting or something that makes the calls very difficult to intercept. Is this not true?
A cell phone is pretty much a fancy encrypted radio, and a huge felony to monitor where I'm from
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Old 10-12-2010, 9:49 AM
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It is extremely unlikely that you're going to decode a digital cell call under any circumstances unless you're receiving that call on your cell phone.

The cellular frequencies blocking law is outdated and obsolete, since (a) cellular frequencies now occupy more than just that one 800 MHz band, and (b) no equipment is available (aside from some super-expensive cellular test equipment that isn't available outside of the cell test industry) that will decode a digital cell call anyway.

If the law were repealed, it would not compromise the security of cell phones in the slightest. It would, however, make scanners just a little bit less expensive without a need to put a frequency range blocking system into them.

Elroy
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Old 10-26-2010, 7:39 PM
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Quote:
Originally Posted by JohnDistai View Post
That's what I thought. However, I've read on the internet that you can pick up analog frequencies, but not digital ones. Most of the stuff that I've read says that newer phones use some sort of digital transmission or encrypting or something that makes the calls very difficult to intercept. Is this not true?
To answer your question, yes, the cellular band is blocked, though there is no real reason for this due to encryption and modulation type. Cellular radios (after all, a cell phone is just a hand-held radio) utilize a digital signal, Gaussian Phase Shift Keying (GMSK) to be exact, and are heavily encrypted. GSM utilizes A5/1 encryption, which is not decipherable by any off-the-shelf radios, it requires computers to break it out, though it is not impossible, as A5/1 has some pretty exploitable flaws.

If you haven't already done so, check out Radio-Electronics.com: resources and analysis for electronics engineers, as the site has some great beginners' tutorials on modulation technologies, including those used by cellular standards.

In the United States, any monitoring of cell phones is under the jurisdiction of the National Security Agency, and the FCC regulates the civilian side of this, which is why the government tends to restrict the ability for commercial scanners and receivers to monitor the cellular bands.

I definitely agree with Elroy that the laws blocking the cellular bands are obsolete, not that the government has any right to regulate the EM spectrum anyway. Always get an unblocked scanner, if for no other reason than to stick it to the man.

- Ethernaut
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Old 10-26-2010, 7:44 PM
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Quote:
Originally Posted by JohnDistai View Post
That's what I thought. However, I've read on the internet that you can pick up analog frequencies, but not digital ones. Most of the stuff that I've read says that newer phones use some sort of digital transmission or encrypting or something that makes the calls very difficult to intercept. Is this not true?
I apologize, in correction of my last post, the term is "Gaussian Minimum Shift Keying".

- Ethernaut
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