900MHz vs. 2.4GHz vs. 5.8GHz vs. D.E.C.T.Apr 8, 2001 (Updated Apr 24, 2008) Write an essay on this topic.
Popular Products in PhonesThe Bottom Line Is GHz all there is to choosing a cordless phone? Be informed and don't end up paying for Hz you don't need.
Updated 2008 to include DECT frequencies
So, you are looking at the rows and rows of phones at your local Wal-mart/Target/Best Buy, and are puzzled between the real difference between 900MHz, 2.4GHz, 5.8GHz and the newest DECT 6 phones. It sure seems like more Hz = more dollars - so that MUST make them better phones?
In a wide open field, a higher frequency phone can outperform a lower frequency phone of equivalent design - but do you live in a field? Lower frequencies can penetrate some materials easier, and the higher frequency spectrums are very crowded. What can add a lot more quality to your signal is not so much the frequency as the method of transmission.
You will notice there are different flavours of 900MHz, 2.4GHz, and 5,8GHz - analog, digital, digital spread spectrum (DSS), frequency-hopping digital spread spectrum (FHSS), and Digital Enhanced Cordless Telecommunications (DECT). Despite the often used 'DECT 6.0' label, DECT phones actually run on the unrestricted 1.9Ghz frequency.
Moving up the ladder from analog to digital, and then to DSS can have a much greater effect on signal quality than moving from 900MHz to 2.4GHz to 5.8GHz using the same transmission method. FHSS adds the additional security feature of changing frequencies to prevent someone with a scanner from easily eavesdropping. Truthfully, equipment to intercept DSS is quite rare, and FHSS makes it quite unlikely anyone can listen in. DECT is a newer digital transmission method that is similar in concept to DSS - the signals are encoded in a similar way to cellular phone methods.
I had a Sony 900MHz DSS phone that outperformed many of my friends' 2.4GHz phones (until one fateful day it was left out on the deck in a rain storm). I was puzzled as to why the 2.4's wouldn't outrun my 900. I found that in the majority of cases, my friends' phones were not DSS - which added dramatic quality and range to both my 900, and to the odd 2.4 that had it. But, overall, we couldn't really find a better range with the 2.4GHz - even with DSS. I wondered why...
It turns out, that many of the 2.4GHz phones currently on the market use a hybrid transmission. They use 2.4GHz to send from the base to the handset, but 900MHz to return the signal from the handset to the base. You don't need to think too hard about that one - how can you 'double' the range of your phone when only 1/2 of it is using the higher frequency?
I replaced my Sony with a VTech 2.4GHz model that used this hybrid scheme (it was not DSS) and returned it a day later. It was so noisy and had less range than my Sony DSS did. I've since purchased a Uniden Tru2.4GHz Titanium T3, which is the first phone I've seen that has 2.4GHz send AND recieve, as well as DSS. This phone is sweet, in form, function, and performance.
For sure you need to check out the Tru2.4 series from Uniden, but my point is this: If you have found a phone that has the features and 'look' that you like, get into digital then DSS - THEN worry about moving into 2.4GHz if you still want more jam. Take a 900MHz DSS over a 2.4GHz non-DSS digital - especially if it's not a true 2.4GHz phone. In the 2.4GHz world, look for a send/receive of 2.4GHz both ways.
I'm sure that there will be more true 2.4GHz phones on the way. The 'Tru2.4' is a Uniden marketing label, and does not mean that no one else can come up with a similar phone. But for now, my 'Tru2.4' is the best performing phone I've seen. It's not overloaded with features, but does everything I want - once it is listed here I'll do a review of it as well.
What's with the new 5.8GHz?
Well my friends, the same issue I mentioned with the 2.4GHz phones is now an issue with the 5.8Ghz... that being that the 5.8's do not send and receive at the same frequency... that's right, the 5.8's use a combined 2.4/5.8 for send and receive. This, at the same time that most 2.4GHz phones now use the same frequency for sending and receiving.
Who cares? Well, it's more a matter of understanding the advertising and the small print... rushing out to get a 5.8GHz phone because you think your 2.4Ghz is obsolete is not the case... if you need a new phone, understand what you are paying for with the 5.8GHz.
For one thing, the 2.4Ghz frequency is a bit crowded. If you've got a wireless LAN nearby (801.11), they use this band, and your home microwave is close by as well. If you are getting interference with your wireless LAN, a newer 5.8 or 2.4 "Wireless friendly" phone might solve the problem.
Remember though, the same rules apply as above... invest in DSS or FHSS before buying more Hz. Higher frequencies do not go through obsticles as well - like walls and floors. Getting into a higher frequency phone might give you extra clarity of signal, but at the expense of loosing a bit of range. To compensate for that problem, the new 5.8Ghz phones send a more powerful signal from the phone - shortening the talk-time.
What's with the new DECT?
As I've alluded to above, the new DECT phones are often confused with being 6Ghz phones due to the "DECT 6.0' label on the boxes. The DECT phones operate in the unregulated 1.9Ghz frequency, where devices have to negotiate amongst themselves for air time. Right now, the main advantages of the 1.9Ghz range is it does not overlap with computer WiFi signals (2.4Ghz) and is far enough away from microwave signals that your 20 year old leaky microwave won't shut it down. DECT phones will have a better 'real world' range because of this, and won't jam up your home Wireless B/G/N router. The security measures on DECT are solid, but as I've said before, if you've got the equipment to crack any digital signal, you're probably NASA.
In short, DECT is the no-brainer choice for most people. The phones are feature-rich and the play well with others.
1. 1.9Ghz DECT 6.0
2. 5.8Ghz/2.4Ghz DSS (FHSS) send/receive
3. 2.4GHz DSS (FHSS)
4. 2.4GHz/900MHz DSS (FHSS) send/receive
5. 900MHz DSS (FHSS)
6. 2.4GHz digital
7. 900Mhz digital
8. 900MHz analog
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