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RE:I-Q and HF SSB/AM/FM questions, bulk buy for 200Mhz SAW oscs
- Subject: RE:I-Q and HF SSB/AM/FM questions, bulk buy for 200Mhz SAW oscs
- From: Leif Asbrink <leif.asbrink@xxxxxxxxxxxxxxxxxxxx
- Date: Fri, 4 Jul 2003 18:54:56 +0200
Hi Jim and All,
> I am in the process of building an HF receiver based on the SDR-1000, see
> http://www.flex-radio.com which is a based on a Tayloe detector
> and produces I-Q signals at baseband, one going to the left input
> on my SB16 (yes, I know it's not great) and one to the right.
Oooh! The SB16 IS GREAT!! There are several versions of them but
if you are happy with a single RF channel and 40kHz bandwidth
I think you will find it is good enough:)
(But do not use microphone input.)
> I noticed that Linrad has an SSB and FM mode with I-Q input, but
> I can't find
> any guide to using it this way. Does anyone have any pointers for
> getting the
> software tuned for SSB/AM and FM, and which controls are relevant for its
> reception once you're in the main window?
This is cheating;)
Linrad will have modes for FM and SSB but I have not written the code yet.
When you enter SSB mode you will get the same software as in weak cw.
The idea is that you should select different parameters to make Linrad
run nicely for SSB. You should select the same fft size for fft2 as for
fft1, a smaller first mixer resampling ratio to allow more output
bandwidth, deselect AGC and finally you might set a higher output sampling
speed for more output bandwidth.
For AM you can use coherent processing but FM does not work right now.
There is no AGC in weak cw mode so you will not have the AGC that should
be in place in "normal" modes. There is an RF clipper at the output
however so SSB works pretty well without AGC.
You just click on the SSB signal to get it in the loudspeaker.
I have planned for an automatic BFO setting in SSB mode and some
other fancy stuff but everything takes time....
> On another note, my design, as does the SDR-1000, requires a
> low-jitter source
> of 200MHz to clock the AD9854 DDS in order not to degrade its good phase
> noise performance. I have found a source for these (Epson QD, EG2121CA,
> jitter sub 5ps) but the price is a little high at 38UKP each.
> Does anyone on
> the list know, or have, anything as good as these at a better price? If
> others are interested in these I may be able to get a discount on
> more than 5.
What does 5ps mean in terms of phase noise? How many dBc/Hz at 20kHz?
Leif / SM5BSZ