I just came here to ask the same thing, I can't find anything useful online and the textbooks at college aren't much help either so I have no idea how to revise
Hey guys I was revising encryption and on the spec it says
So I now what Caeser cipher is, but im not sure why it is easily cracked?
Could anyone help?
Thanks
I am not sure but i would say because there are only 26 different caesar ciphers (26 letters of the alphabet). It is fairly easy to crack using brute force by trying each of the 26 keys and seeing which one works.
Hi guys, I was reading through the AQA A Level Computer Science (new) specifcation and in section 3.9.1.2 "Communication Basics" it says
Spoiler
But I was wondering, the additional information next to baud rate says "Bit rate can be higher than baud rate if more than one bit is encoded in each signal change"
Should it not be the other way around? Since (according to my book) baud rate usually has 1 signal change per second, but it is possible to encode multiple signal changes in one second and then baud rate can potentially surpass bit rate.
Isn't it then suppose to say "Baud rate can be higher than bit rate if more than one bit is encoded in each signal change."
Hi guys, I was reading through the AQA A Level Computer Science (new) specifcation and in section 3.9.1.2 "Communication Basics" it says
Spoiler
But I was wondering, the additional information next to baud rate says "Bit rate can be higher than baud rate if more than one bit is encoded in each signal change"
Should it not be the other way around? Since (according to my book) baud rate usually has 1 signal change per second, but it is possible to encode multiple signal changes in one second and then baud rate can potentially surpass bit rate.
Isn't it then suppose to say "Baud rate can be higher than bit rate if more than one bit is encoded in each signal change."
Im confused?
Bit rate is the number of bits that can be sent per second Baud rate is the number of signal changes per second
If one bit (a 1 or a 0) is sent per signal then the bit rate and the baud rate are equal. If more than one bit is sent per signal then more bits are being sent each second than the number of signal changes, hence the bit rate would be higher than the baud rate.
Increasing the baud rate would increase the bit rate, having more signals means sending more bits. Baud rate cannot be higher than the bit rate.
Bit rate is the number of bits that can be sent per second Baud rate is the number of signal changes per second
If one bit (a 1 or a 0) is sent per signal then the bit rate and the baud rate are equal. If more than one bit is sent per signal then more bits are being sent each second than the number of signal changes, hence the bit rate would be higher than the baud rate.
Increasing the baud rate would increase the bit rate, having more signals means sending more bits. Baud rate cannot be higher than the bit rate.
Oh wow thanks so much for clearing that up, it makes at lot more sense now!
Has anyone got the full pre-liminary material? All I've received is the skeleton code and was jus wondering if anyone has receive extra for Sections A and B for PAPER 1
Has anyone got the full pre-liminary material? All I've received is the skeleton code and was jus wondering if anyone has receive extra for Sections A and B for PAPER 1
Extra what? The only preliminary material produced is the stuff about the skeleton program. If the exam is like the specimen paper then section A will have some theory questions and an algorithm to convert into code. Section B will have questions about the skeleton program that will not require any coding. To get an idea of the type of questions asked for section B and the algorithms, you should have a look at the Comp1 papers on the AQA web site.