Hi Albin,
Hmm.. Good to know. I had tried a frequency translating filter to
create
a 10khz IF, but it didn't seem to make any difference. I need to take
another look at that.
Thanks!
---
Barry Duggan KV4FV
On 2019-10-28 11:32, Albin Stigö wrote:
> A direct conversation SDR receiver like the funcube dongle pro plus has
> a
> large DC spike, it's not the carrier, it will mask your carrier
> though.. IQ
> correction will remove it, but that will also remove an AM carrier at
> 0Hz
> so it's common practice to offset a bit with a frequency translating
> filter.
>
> On Mon, Oct 28, 2019, 15:24 Barry Duggan <address@hidden> wrote:
>
>> Hi Albin and Volker,
>>
>> I added a PLL Carrier Tracking block to take care of the tuning
>> problem.
>> See the revised
>> https://wiki.gnuradio.org/index.php/File:FunCube_AM.png
>>
>> Albin, that 'spike' is the carrier! This is AM ;)
>>
>> Thank you both for your suggestions.
>> ---
>> Barry Duggan KV4FV
>>
>>
>> On 2019-10-27 07:13, Albin Stigö wrote:
>> > Hi Barry,
>> >
>> > Some thoughts:
>> >
>> > You have a large DC spike at the center, try using the frequency
>> > xlating
>> > fir filter to tune an offset frequency.
>> >
>> > Why don't you decimate at the channel filter?
>> >
>> > Try observing the signal at various points using the frequency sink.
>> >
>> > Good luck,
>> > Albin SM6WJM
>> >
>> > On Sat, Oct 26, 2019, 21:02 Barry Duggan <address@hidden> wrote:
>> >
>> >> Hi,
>> >>
>> >> I've been working on a gnuradio AM broadcast receiver, and have found
>> >> that the tuning is very critical to obtaining clear audio. My
>> >> flowgraph
>> >> can be seen at
>> >> https://wiki.gnuradio.org/index.php/File:FunCube_AM.png.
>> >> Are there any alternate demodulation methods which are not so
>> >> sensitive
>> >> to exact tuning?
>> >>
>> >> Thanks,
>> >> --
>> >> Barry Duggan KV4FV
>> >>
>> >>
>>
Complex_to_Mag.png