On Sun, 07 Aug 2005 05:19:02 GMT, NS <NS@NoSpam.com> wrote:
>But in fact there are more issues to consider here, such as error
>sensitivity (robustness), average power & SNR, etc.
The question, copied from the OP, was just:
>>>2. What two PSK modulation orders differ exactly by a factor of two
>>>in spectral efficiency?
Spectral efficiency in this sense is independent of the things you're
mentioning.
>
>
>Eric Jacobsen wrote:
>> On 3 Aug 2005 03:54:17 -0700, "johny" <miranda.wu@gmail.com> wrote:
>>
>>
>>>Hello. I got these question while viewing old articles. Could anyone
>>>please answer next two ?
>>>
>>>1. Under what conditions is the available bandwidth of a digital system
>>>Fs Hz instead of Fs/2 Hz?
>>
>>
>> Been addressed previously, so...
>>
>>
>>>2. What two PSK modulation orders differ exactly by a factor of two
>>>in spectral efficiency?
>>
>>
>> There are only three PSK modes in common use, BPSK, QPSK, and 8-PSK
>> (16-QAM, as well as higher orders, is more efficient than 16-PSK, so
>> it kinda stops there).
>>
>> Of those, QPSK gets double the number of bits in the same bandwidth as
>> BPSK. 8-PSK is three times BPSK, and 1.5 times QPSK.
>>
>> Or, to continue to beat the horse,
>>
>> BPSK, one bit per symbol
>> QPSK, two bits per symbol
>> 8-PSK, three bits per symbol
>>
>> The question as posed assumes the symbol rates are equivalent.
>>
>>
>>
>>
>> Eric Jacobsen
>> Minister of Algorithms, Intel Corp.
>> My opinions may not be Intel's opinions.
>> http://www.ericjacobsen.org
Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org
Reply by NS●August 7, 20052005-08-07
But in fact there are more issues to consider here, such as error
sensitivity (robustness), average power & SNR, etc.
Eric Jacobsen wrote:
> On 3 Aug 2005 03:54:17 -0700, "johny" <miranda.wu@gmail.com> wrote:
>
>
>>Hello. I got these question while viewing old articles. Could anyone
>>please answer next two ?
>>
>>1. Under what conditions is the available bandwidth of a digital system
>>Fs Hz instead of Fs/2 Hz?
>
>
> Been addressed previously, so...
>
>
>>2. What two PSK modulation orders differ exactly by a factor of two
>>in spectral efficiency?
>
>
> There are only three PSK modes in common use, BPSK, QPSK, and 8-PSK
> (16-QAM, as well as higher orders, is more efficient than 16-PSK, so
> it kinda stops there).
>
> Of those, QPSK gets double the number of bits in the same bandwidth as
> BPSK. 8-PSK is three times BPSK, and 1.5 times QPSK.
>
> Or, to continue to beat the horse,
>
> BPSK, one bit per symbol
> QPSK, two bits per symbol
> 8-PSK, three bits per symbol
>
> The question as posed assumes the symbol rates are equivalent.
>
>
>
>
> Eric Jacobsen
> Minister of Algorithms, Intel Corp.
> My opinions may not be Intel's opinions.
> http://www.ericjacobsen.org
Reply by Eric Jacobsen●August 4, 20052005-08-04
On 3 Aug 2005 03:54:17 -0700, "johny" <miranda.wu@gmail.com> wrote:
>Hello. I got these question while viewing old articles. Could anyone
>please answer next two ?
>
>1. Under what conditions is the available bandwidth of a digital system
>Fs Hz instead of Fs/2 Hz?
Been addressed previously, so...
>2. What two PSK modulation orders differ exactly by a factor of two
>in spectral efficiency?
There are only three PSK modes in common use, BPSK, QPSK, and 8-PSK
(16-QAM, as well as higher orders, is more efficient than 16-PSK, so
it kinda stops there).
Of those, QPSK gets double the number of bits in the same bandwidth as
BPSK. 8-PSK is three times BPSK, and 1.5 times QPSK.
Or, to continue to beat the horse,
BPSK, one bit per symbol
QPSK, two bits per symbol
8-PSK, three bits per symbol
The question as posed assumes the symbol rates are equivalent.
Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org
Reply by Jerry Avins●August 3, 20052005-08-03
Erik de Castro Lopo wrote:
> johny wrote:
>
>>Hello. I got these question while viewing old articles. Could anyone
>>please answer next two ?
>>
>>1. Under what conditions is the available bandwidth of a digital system
>>Fs Hz instead of Fs/2 Hz?
>
>
> If you are sampling a complex analytic signal.
In other words, when each sample counts for two.
...
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Erik de Castro Lopo●August 3, 20052005-08-03
johny wrote:
>
> Hello. I got these question while viewing old articles. Could anyone
> please answer next two ?
>
> 1. Under what conditions is the available bandwidth of a digital system
> Fs Hz instead of Fs/2 Hz?
If you are sampling a complex analytic signal.
> 2. What two PSK modulation orders differ exactly by a factor of two
> in spectral efficiency?
I'll leave that for someone else.
Erik
--
+-----------------------------------------------------------+
Erik de Castro Lopo nospam@mega-nerd.com (Yes it's valid)
+-----------------------------------------------------------+
"C++ is history repeated as tragedy. Java is history repeated as farce."
-- Scott McKay
Reply by johny●August 3, 20052005-08-03
Hello. I got these question while viewing old articles. Could anyone
please answer next two ?
1. Under what conditions is the available bandwidth of a digital system
Fs Hz instead of Fs/2 Hz?
2. What two PSK modulation orders differ exactly by a factor of two
in spectral efficiency?
Many thanks !