@Paul: Wow! Better hope our clocks are stable. By the way, I now note that the relationship between the chip values for 8 and 9 is not unique: every single row in the table is the row above it shifted right by 2.
The Lecturer appears to have limited this lecture to a 6 year old version (year 2006) of the IEEE 802.15.4 standard. The year 2011 version (IEEE 802.15.4 - 2011) has many more modulation types and frequency bands defined in the standard. And since the year 2011 release, several more have been defined in the 802.15.4f and 802.15.4g standards.
@Paul: concerning the unique decoding of chips: I expected to see limited repeated sequences of 0s or 1s so that synchronization could be more easily maintained. In some modulation schemes bit stuffing is used to do this. However, I also expected to see unique overall sequencing of groups of 0s and 1s in the chip values for each of the data symbols. This is apparently not the case. For example, at 915MHz on slide 14, the chip values for data symbol 9 are identical to those for data symbol 8, but two bit times later (9's chip values lag those of 8 by 2 bit times). So 8 starts 01101 and 9 starts 0001101. I would think this would cause problems maintaining sync. Are there other symbols that resync the bit values that make up the chips?
Are chip values kind of like ASCII characters in the sense that it takes 1 byte for one ASCII character and for the chip values they may have to be 16 or 32 bits to represent one value?
What is the incentive in using 802.15.4 standard if interoperability is not required for an application... One could achieve higher bit rate without have to spread the signal.. .
I figured it was something like that David. Thx Kind of threw me a little by just showing 0 then reffering to 4 bit symbol on the slide. I wanted to make sure I was not missing something.
@Paul: slide 15 shows 15 chip values c0 to c14 for each input bit but the text above the table says that a "16 bit chip" is in use. Is there a missing or assumed bit to make the 16th bit in the chip value?
with me the audio problems is that in IE I have to constantly re-start audio and with Chrome/Firefox I have to wait for a long while before they start playing
For those of you just joining us, today's questions are: 1) If you are using ISM radios now, in which frequency band are you operating? 2)Has anyone listening studied the IEEE 802.15.4 standard?
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There are three recent amendments to 802.15.4. Two of which add new frequency bands and modulation methods 802.15.4f, 802.15.4g and the third adds new Medium Access Control layer frame formats.
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Slide deck, page 10 has an error - BPSK is spelled out as Binary Frequency Shift Keying, where it obviously is Binary Phase Shift Keying... just in case
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