On Wed, Nov 30, 2005 at 05:05:04PM -0500, [EMAIL PROTECTED] wrote:
> I have generated an ASK (ON/OFF Keying) signal with the proper framing
> based on the simple_framer code and successfully demodulated the signal. I
> can see the rectangular pulses representing my data on the usrp scope (some
> ripple due to the passband filter). The scope shows the signal with the
> amplitude of the pulse going between about 100 to 7500 magnitude with the
> varying pulse width. Is this streaming data ready to be processed by the
> simple_correlator or does it need some signal conditioning (some type of
> conversions to bits/bytes). The data is 8 x oversample are required.
>
> Do I need to do further signal processing before it's sent to
> simple_correlator?
>
> I have been able to figure out what the simple_framer does but I am having
> a hard time understanding the simple_correlator code.
>
> How the Oversample is used? The only place I see it being used is in the
> code:
You might want to consider looking at the .h file too...
> Nor can I make out how this code counts bits?
>
> // return number of set bits in the low 32 bits of x
> int
> gr_count_bits32 (int x)
> {
> int count = 0;
>
> for (int i = 0; i < 32; i++)
> if (x & (1 << i))
> count++;
>
> return count;
> }
The first time through the loop the test is
if (x & (1 << 0)) // (1 << 0) == 0x00000001
The second time through the loop the test is
if (x & (1 << 1)) // (1 << 1) == 0x00000002
The third time through the loop the test is
if (x & (1 << 2)) // (1 << 2) == 0x00000004
...
The 32nd time through the loop the test is
if (x & (1 << 31)) // (1 << 31) == 0x80000000
It tests a single bit each time through the loop.
Eric
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