Is Clear QAM common?

[Mormegil]

I live in Culver City / Los Angeles area. Is Clear QAM availability common?

Any way to find out if Clear QAM is available in my area?

I just called the Tech Support guys at my local Time Warner, and they've never heard of Clear QAM, much less if they have it or not.

Thanks

[Krispy Kritter]

I believe part of the issue you are having is the description. QAM is obviously a tuner but "Clear QAM" isn't an official term.

Anyway, I came across this post with a response from a TWC rep: http://forums.afterdawn.com/thread_view.cfm/248819

[SingSing]

I think he is asking about unencoded(aka un-encrypted) HDTV broadcasting.

From what I read, all local channels currently co-broadcast in HDTV are unencoded, becuase they have to provide free-access.

[Richard_G]

QAM is the modulation method (Quadrature amplitude modulation) and has nothing to do with whether the signal is encrypted or not. Any encryption is done BEFORE the signal is modulated and the decryption done AFTER the signal has been received. The method of modulation is irrelevant and is whatever the chosen broadcast standard is you the country you are in.

To answer the direct question, Is clear QAM common? Yes it is in the UK at least. All terrestrial DTV channels use either 16 or 64QAM as the modulation method, but only a very few are encrypted.

[redwudz]

My local cable company, Suddenlink, has no unencrypted digital channels available, local or otherwise, except temporarily when they are testing. Apparently they don't go by the 'rules'. But I can pick up the 5 digital local transmitters OTA with a antenna.

[SingSing]

QAM is the modulation method (Quadrature amplitude modulation) and has nothing to do with whether the signal is encrypted or not. Any encryption is done BEFORE the signal is modulated and the decryption done AFTER the signal has been received. The method of modulation is irrelevant and is whatever the chosen broadcast standard is you the country you are in.

No one implied the QAM is used as an encrypter. The poster used the term "Clear" "QAM".

Note : QAM can indeed be used as an encryption method. If the symbols feed into the QAM encoder, need a different matrix to decode, then that is a form of encryption. This can be further expended with a long sequantial matrix beyong a simple matrix pair.

[dphirschler]

QAM is not encoding, it is a method of modulation as Richard_G wrote. It's simply a way of carrying digital information over an analog transmission.


Darryl

[edDV]

In broad terms, it comes down to the state of upgrade in your cable system.

Almost all USA/Canada cable systems use MPeg2 for encoding and QAM for modulation. Many to most of the cable channels are encrypted during modulation so that a cable box is required to decrypt (unlock) various channels under various plans.

The FCC has ruled that "must carry" local channels (HD or SD) must be offered as digital QAM without encryption to basic service customers. Major network local channels usually operate under "retransmission consent" negotiations where channels usually are offered without encryption if this is negotiated by the TV station. In lieu of payment by the cable company to the TV station for retransmission rights, the local station often gets a second channel on the cable system like weather or alternative programming (e.g. The Tube). PBS has a special agreement where all subchannels presented to the cable company are made available as digital QAM without encryption (only the primary channel is offered in analog).

To get these "QAM" digital channels you need a cable box or a TV tuner with QAM tuner capability. Not all digital TV tuners offer QAM tuning. ATSC tuners will not work for a cable connection. Read the TV specs before you buy. Here are examples of digital SD TV sets with QAM tuner capability.

http://www.walmart.com/catalog/product.do?product_id=5633688#Specifications
http://www.walmart.com/catalog/product.do?product_id=5633691#Specifications

If you only have an analog TV, you need a cable box to get these channels.

[SingSing]

I am going to keep this light weight.

Modulation with digital signal is broken down to stages : Encode symbol/s into modulation vector, modulation actually take place when the vector is mixed ( aka multiply ) with the carrier, the mixed signal is filetered to extract the desirable sideband, and ampflier and match and then send to the antenna. If you use a non-standard scheme for exchanging symbols and vectors, then a SPECIAL system is created. Many of these schemes have been developed, but the developers keep their details out of sight.

A common example of using moduation as part of the encryption scheme is spread spectrum modulation.

[Richard_G]

I am going to keep this light weight.

Modulation with digital signal is broken down to stages : Encode symbol/s into modulation vector, modulation actually take place when the vector is mixed ( aka multiply ) with the carrier, the mixed signal is filetered to extract the desirable sideband, and ampflier and match and then send to the antenna. If you use a non-standard scheme for exchanging symbols and vectors, then a SPECIAL system is created. Many of these schemes have been developed, but the developers keep their details out of sight.

A common example of using moduation as part of the encryption scheme is spread spectrum modulation.

I've never read such a load of ill informed bollocks in all my life!

I work on this stuff every day. QAM, spread spectrum, UWB, straighforward good old Amplitude modulation, Frequency modulation, Quadrature Phase Shift Keying and many more are all modulation methods. They can handle any form of signal given to them, be it analogue or digital, encrypted or not. The modulation has nothing to do with the encryption.

Think about it, the very basic form of modulation is CW where the carrier is simply switched on and off. If it is sending morse code and you can read it, it is clear. If you can't, it is encrypted because you do not have the information to decrypt it.

[SingSing]

Encryption is simply hiding the information. As simple as fliping one and zero, when you not expected is a form of encryption.

Note 1 : Digital Radio technique breaks up the processing signal chain. Coding, scrambling, encryption, error correction, de/modulation, gain, shaping, filtering, recombine, channelisation, up-convert, down-convert, re-sampling etc.. are all treated as math in the device. All operations are fair games. It is up to the designer to implement a matched set of transmitter and receiver.

Note 2 : keep it lite.

[edDV]

The method the cable company uses to encrypt is unimportant unless you are trying to break the encryption (e.g. get HBO for free). Nobody is reporting success at this.

The issue is encrypted vs. "clear". A TV set with an internal digital QAM tuner will get only unencrypted channels unless it also has "Cablecard". Cablecard is a smart card provided by the cable company to allow decryption in the TV for the cable service plan you have contracted.
http://en.wikipedia.org/wiki/CableCARD