[ejere2]

There was no thread for this exam so I though I'd make one So how is revision going?

[Drajl]

How did you find the exam?

[crazyhazy]

(Original post by Drajl)
How did you find the exam?

It was okay... the question on how a mobile phone connects was a little WTF moment, how did you find it? What about ELEC 4?

[R-I-See-Kay]

Did anyone notice that the questions were a little more wordy and harder to understand than previous papers? I thought the paper was harder just because I didn't know what they wanted me to do.

Also ELEC4 i didn't get the photodiode voltage derivation and the assembler code to configure the ports completely had me. But maybe it was because I just didn't revise them well enough.

[ejere2]

Yes this exam was abit too wordy compared to the previous past papers.

[Drajl]

(Original post by R-I-See-Kay)
Did anyone notice that the questions were a little more wordy and harder to understand than previous papers? I thought the paper was harder just because I didn't know what they wanted me to do.

Also ELEC4 i didn't get the photodiode voltage derivation and the assembler code to configure the ports completely had me. But maybe it was because I just didn't revise them well enough.

You'll kick yourself if i tell you the voltage derivation was just V=IR

As for ELEC5, I liked the style of the paper as it was less diagramatic than ELEC4, does anyone have the questions for ELEC5?

[Drajl]

(Original post by crazyhazy)
It was okay... the question on how a mobile phone connects was a little WTF moment, how did you find it? What about ELEC 4?

For the mobile phone I put that the analogue speech signal it converted to digital using an ADC which is then split up using time division multiplexing then sent to the base station via a 25Mhz uplink channel. Then said the opposite for receiving speech.

[R-I-See-Kay]

(Original post by Drajl)
You'll kick yourself if i tell you the voltage derivation was just V=IR

As for ELEC5, I liked the style of the paper as it was less diagramatic than ELEC4, does anyone have the questions for ELEC5?

Thankfully I just guessed and wrote that...I think. But still I feel kinda stupid at how simple the derivation is.

[michaelfiford]

Yeah, quite a different paper. Not bad though, considering I was dreading the exam.

Was taken a bit aback by the superheterodyne question. Turned staight over after seeing it xD. Of course, came back to it (had about 20 minutes at the end, even after doing this question). AGC = Automatic Gain Control, right? They had come up the day before in a past paper. I intended to go home and revise it, but I had M2 and D2 exams the morning of ELEC5, and chose to do those instead :/.

No doubt I got the questions about the "second channel/image" wrong from the superhet, but I looked at the subsystem diagram for it, and I guess mod/demod the right way around .

I rambled on for 2 more lines than the 10 given about mobile phone connectivity. Hopefully picked up the marks there.

Analogue speech signal it converted to digital using an ADC which is then split up using time division multiplexing then sent to the base station via a 25Mhz uplink channel.

This isn't true is it? I have no idea about the Freq, but I thought the phone sent it to the base station non multiplexed, as the phone can't know when the base station is expecting it, and it only has one set of data to send; and it only received it multiplexed. Which I forgot to mention.


Photodiode questions were unusual. I guessed to use V=IR, due to only having 3 values to use. It worked out okay, although I normally hate these things.

Also ELEC4 i didn't get the photodiode voltage derivation and the assembler code to configure the ports completely had me. But maybe it was because I just didn't revise them well enough.

Wasn't this just a case of setting the direction registers? Something like this: (I can't remember the exact values)
MOVW 0X0F
MOVWR TRISA
MOVWR TRISB
MOVW 0XF0
MOVWR TRISB

Nothing really do do with photodiodes. Although the flow chart in ELEC 4 really stumped me. Also wasn't expecting that final logic question. Put one too many NAND gates in to substitute my OR (as a NOT on the end :/), as well as I think mine didn't take into account when Control was 0, that the display wasn't supposed to illuminate. Although this is ELEC 5 thread, so I'll stop straying off topic.

[crazyhazy]

(Original post by michaelfiford)
Wasn't this just a case of setting the direction registers? Something like this: (I can't remember the exact values)
MOVW 0X0F
MOVWR TRISA
MOVWR TRISB
MOVW 0XF0
MOVWR TRISB

Wouldn't it be 0xFF and 0x00 respectively cos logic 1 is output/input can't remember which way round at the moment (luckily they told us in the exam :P), and FF = 11111111 and 00 = 00000000

Did anyone else not notice that it was microseconds for the first question like I did?

Does anyone have the paper and/or the solutions??

[michaelfiford]

I don't remember the question, so I was just guessing with the numbers. Yeah, that does sound familiar, but at the time I was thinking that half of a port was input, and half was output, or something.

And yeah, I can never remember which is 0 and which is 1 for input and output.

I'll see if I can get my hands on a copy of the paper.