Sorry, I probably should have been more specific about my aims
I'm looking to receive and demodulate an Australian HDTV signal. We use a
COFDM (Coded Orthogonal Frequency Division Multiplexing) modulation
scheme instead of the ATSC scheme used in the US but the bandwidth
requirements are approximately the same, around 6-7MHz. This, I believe,
rules out the possibilities of trying to use undersampling techniques to
sample the signals, as I don't think I can fit the entire signal into a
Nyquist region.
I'm looking at trying to downconvert the 10.7MHz IF to a center somewhere
in the range of 5-6MHz, which I think should be possible though I'm
currently unsure if there is an IC on the market which will do the job
while still maintaining a decent IF bandwidth. I'm still looking into the
possibilities, but again, if anyone has an opinion it's most welcome
Alan
At 07:58 AM 14/05/03 -0700, you wrote:
Alan,
I thought that many of the applications for SDR had baseband bandwidths
on the order of 10MHz... how low of an IF are you looking for? Check
out the datasheet for the max2450 (http://www.maxim-ic.com/max2450) --
its an I/Q mod/demod, but its set up for a 70MHz IF, so it won't work
here.
I'm looking into a zero-IF solution, but it seems like a 10.7MHz IF
solution makes your 20Msps ADC _almost_ good enough -- how much margin
over Nyquist are you looking for? It just seems too easy to stick with
10.7 since LOs, filters, etc are sooooo cheap. I take it you really like
your ADC?
Brian.
On Wednesday, May 14, 2003, at 06:52 AM, Alan Gray wrote:
Hi all,
I've recently found that I have access to several standard radio
receivers,
including an AOR AR5000 and AR8600. Naturally, these both have a 10.7MHz
output IF and thus aren't much use in combination with my 20MSPS A/D
card
but I was wondering if anyone has looked into the possibility of adding
an
extra downconversion stage after this to obtain a usable IF.
I haven't much experience in dealing with the radio side of things, but
a
quick look at some books on the subject seem to indicate that it might
not
be too hard a circuit to put together. If anyone has looked into doing
this
or has ideas on if it will/will not work, any information would be most
welcome
Alan
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