Reply by Eric Jacobsen●February 17, 20062006-02-17
On Thu, 16 Feb 2006 06:29:20 -0600, "Karl" <rikhe521@student.liu.se>
wrote:
>
>Hi
>
>A squarewave subcarrier is common in satellite communication
>and road tolls....I guess because its very easy to modulate
>a squarewave with BPSK. One just have to count edges and then
>change the reflect coefficient.
>
>Karl
It is? Usually satellite transponders are very expensive resources
so control of adjacent channel energy (splatter) is critical. I've
not heard of using such a system for satellite communications before.
For a road-toll system it's probably not as bad since the range is
short and the client equipment needs to be very low-cost. I dunno
what sort of equipment is used for those, though.
Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org
Reply by Jerry Avins●February 16, 20062006-02-16
Karl wrote:
> Hi
>
> A squarewave subcarrier is common in satellite communication
> and road tolls....I guess because its very easy to modulate
> a squarewave with BPSK. One just have to count edges and then
> change the reflect coefficient.
I guess that at such low powers, they're not concerned with splatter.
There's always more than meets the eye. Thanks.
...
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Karl●February 16, 20062006-02-16
Hi
A squarewave subcarrier is common in satellite communication
and road tolls....I guess because its very easy to modulate
a squarewave with BPSK. One just have to count edges and then
change the reflect coefficient.
Karl
>john wrote:
>> Jerry Avins wrote:
>>
>>>Karl wrote:
>>>
>>>>Hi
>>>>
>>>>First there is a squarewave subcarrier, then this squarewave is
>>>>modulated with BPSK with NRZI-data. I'll usa a Costas + DTTL!
>>>
>>>I'm curious about the square-wave carrier. A 2 MHz square wave has
>>>significant energy at 18 MHz. Some 20% of the power is in the
harmonics.
>>>What good does it do?
>>>
>>
>>
>> Could be that it was easier to implement that way, maybe it is old
>> technology.
>
>One wouldn't provide transmission or storage capacity for a 2 MHz square
>wave when a 2 MHz sine wave would do, and if no transmission or storage
>is involved, why encode? I'd like to know, rather than guess. Maybe Karl
>will tell us.
>
>Jerry
>--
>Engineering is the art of making what you want from things you can get.
>�����������������������������������������������������������������������
>
Reply by Jerry Avins●February 7, 20062006-02-07
john wrote:
> Jerry Avins wrote:
>
>>Karl wrote:
>>
>>>Hi
>>>
>>>First there is a squarewave subcarrier, then this squarewave is
>>>modulated with BPSK with NRZI-data. I'll usa a Costas + DTTL!
>>
>>I'm curious about the square-wave carrier. A 2 MHz square wave has
>>significant energy at 18 MHz. Some 20% of the power is in the harmonics.
>>What good does it do?
>>
>
>
> Could be that it was easier to implement that way, maybe it is old
> technology.
One wouldn't provide transmission or storage capacity for a 2 MHz square
wave when a 2 MHz sine wave would do, and if no transmission or storage
is involved, why encode? I'd like to know, rather than guess. Maybe Karl
will tell us.
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by john●February 7, 20062006-02-07
Jerry Avins wrote:
> Karl wrote:
> > Hi
> >
> > First there is a squarewave subcarrier, then this squarewave is
> > modulated with BPSK with NRZI-data. I'll usa a Costas + DTTL!
>
> I'm curious about the square-wave carrier. A 2 MHz square wave has
> significant energy at 18 MHz. Some 20% of the power is in the harmonics.
> What good does it do?
>
Could be that it was easier to implement that way, maybe it is old
technology.
John
Reply by Jerry Avins●February 7, 20062006-02-07
Karl wrote:
> Hi
>
> First there is a squarewave subcarrier, then this squarewave is
> modulated with BPSK with NRZI-data. I'll usa a Costas + DTTL!
I'm curious about the square-wave carrier. A 2 MHz square wave has
significant energy at 18 MHz. Some 20% of the power is in the harmonics.
What good does it do?
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Karl●February 7, 20062006-02-07
Hi
First there is a squarewave subcarrier, then this squarewave is
modulated with BPSK with NRZI-data. I'll usa a Costas + DTTL!
Reply by Jerry Avins●February 6, 20062006-02-06
Vladimir Vassilevsky wrote:
>
>
> Karl wrote:
...
>> As you see, I have major problems. Please help
>
>
> No you don't. There is the only one major problem: where to go for lunch.
Now here's a man who has his priorities straight! :-)
...
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by Tim Wescott●February 6, 20062006-02-06
Karl wrote:
> Hello,
>
> I forgot to mention that the NRZI data signal is BPSK-modulated.
>
> /Karl
1. Please include pertinent context when replying to posts -- see just
about any other reply in this newsgroup for an example.
2. Do you mean that the NRZI data signal itself is BPSK modulated, or
do you mean that it modulates the carrier?
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Reply by Karl●February 6, 20062006-02-06
Hello,
I forgot to mention that the NRZI data signal is BPSK-modulated.
/Karl