What is DSS?
http://live.pirillo.com/ - Pilot_51 want’s to know what DSS is and why should he care about it?
In the world of wireless phones, DSS stands for Digital Spread Spectrum, which offers users a good level of security to protect their wireless conversations. The basic idea is that your phone will hop across various frequencies so that it is difficult for a third party to listen in to your conversation.
HowStuffWorks has a nice description of what DSS does for you:
A cordless DSS telephone provides… highest security. Due to digital transmissions and constantly changing frequency channels in use, only the matching receiver has a copy of the pre-assigned spreading code. Millions of scrambling codes are available and are selected automatically when the headset is lifted from the cradle. Common radio scanners cannot hear a DSS cordless telephone conversation.
So that’s DSS in a nutshell. Do you have any recommendations for a DSS-enabled phone?
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3 Comments
wylis
May 24th, 2007
at 11:26am
Chris your screensaver looks awesome on those dual monitors! Show us a demo some time with a media player visualization over both screens.
michael spanos
May 24th, 2007
at 1:13pm
Close, but no cigar. These newbs! ;-) Your explanation of FHSS (frequency hopping spread spectrum) is OK, but to me, DSS is Direct Sequence Spreading. There are crutial differences: FHSS can be used on either a digital or an analog signal and works as Heddy Lamar envisioned. More modern is the DSS where every bit of a digital signal is convolved (XOR’d if you are geeky enough) with a PN (pseudo-random number) sequence. A normal digitized signal is broad (frequency-wise) and this convolving spreads it even further to where it just looks like noise if you don’t know the PN sequence. If you do know the sequence, when you apply it you get gain (amplification) equal to the sequence length applied. I believe Qualcom developed CDMA which first applies DSS and then applies FHSS to the “noise”, using two different PN sequences! This way they can stack many users into any frequency segment; i.e. other users look like hopping noise to any particular user and little is lost because all users would use different random PN sequences.
WiFi Packet Sniffing « Pirillovision
July 11th, 2007
at 8:43am
[...] Check out our other security videos: What is DSS? and Wireless Security Camera [...]